Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

7 files changed, 4725 insertions, 0 deletions

diff --git a/drivers/most/Kconfig b/drivers/most/Kconfig
new file mode 100644
index 0000000000..69c9e728b7
--- /dev/null
+++ b/drivers/most/Kconfig
@@ -0,0 +1,45 @@
+# SPDX-License-Identifier: GPL-2.0
+menuconfig MOST
+	tristate "MOST (Media Oriented Systems Transport) support"
+	depends on HAS_DMA && CONFIGFS_FS
+	default n
+	help
+	  Say Y here if you want to enable MOST support.
+	  This driver needs at least one additional component to enable the
+	  desired access from userspace (e.g. character devices) and one that
+	  matches the network controller's hardware interface (e.g. USB).
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called most_core.
+
+	  If in doubt, say N here.
+
+if MOST
+config MOST_USB_HDM
+	tristate "USB"
+	depends on USB
+	help
+	  Say Y here if you want to connect via USB to network transceiver.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called most_usb.
+
+config MOST_CDEV
+	tristate "Cdev"
+
+	help
+	  Say Y here if you want to commumicate via character devices.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called most_cdev.
+
+config MOST_SND
+	tristate "Sound"
+	depends on SND
+	select SND_PCM
+	help
+	  Say Y here if you want to commumicate via ALSA/sound devices.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called most_sound.
+endif
diff --git a/drivers/most/Makefile b/drivers/most/Makefile
new file mode 100644
index 0000000000..60db6cd378
--- /dev/null
+++ b/drivers/most/Makefile
@@ -0,0 +1,8 @@
+# SPDX-License-Identifier: GPL-2.0
+obj-$(CONFIG_MOST) += most_core.o
+most_core-y :=	core.o \
+		configfs.o
+
+obj-$(CONFIG_MOST_USB_HDM) += most_usb.o
+obj-$(CONFIG_MOST_CDEV) += most_cdev.o
+obj-$(CONFIG_MOST_SND) += most_snd.o
diff --git a/drivers/most/configfs.c b/drivers/most/configfs.c
new file mode 100644
index 0000000000..36d8c917f6
--- /dev/null
+++ b/drivers/most/configfs.c
@@ -0,0 +1,724 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * configfs.c - Implementation of configfs interface to the driver stack
+ *
+ * Copyright (C) 2013-2015 Microchip Technology Germany II GmbH & Co. KG
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/configfs.h>
+#include <linux/most.h>
+
+#define MAX_STRING_SIZE 80
+
+struct mdev_link {
+	struct config_item item;
+	struct list_head list;
+	bool create_link;
+	bool destroy_link;
+	u16 num_buffers;
+	u16 buffer_size;
+	u16 subbuffer_size;
+	u16 packets_per_xact;
+	u16 dbr_size;
+	char datatype[MAX_STRING_SIZE];
+	char direction[MAX_STRING_SIZE];
+	char name[MAX_STRING_SIZE];
+	char device[MAX_STRING_SIZE];
+	char channel[MAX_STRING_SIZE];
+	char comp[MAX_STRING_SIZE];
+	char comp_params[MAX_STRING_SIZE];
+};
+
+static struct list_head mdev_link_list;
+
+static int set_cfg_buffer_size(struct mdev_link *link)
+{
+	return most_set_cfg_buffer_size(link->device, link->channel,
+					link->buffer_size);
+}
+
+static int set_cfg_subbuffer_size(struct mdev_link *link)
+{
+	return most_set_cfg_subbuffer_size(link->device, link->channel,
+					   link->subbuffer_size);
+}
+
+static int set_cfg_dbr_size(struct mdev_link *link)
+{
+	return most_set_cfg_dbr_size(link->device, link->channel,
+				     link->dbr_size);
+}
+
+static int set_cfg_num_buffers(struct mdev_link *link)
+{
+	return most_set_cfg_num_buffers(link->device, link->channel,
+					link->num_buffers);
+}
+
+static int set_cfg_packets_xact(struct mdev_link *link)
+{
+	return most_set_cfg_packets_xact(link->device, link->channel,
+					 link->packets_per_xact);
+}
+
+static int set_cfg_direction(struct mdev_link *link)
+{
+	return most_set_cfg_direction(link->device, link->channel,
+				      link->direction);
+}
+
+static int set_cfg_datatype(struct mdev_link *link)
+{
+	return most_set_cfg_datatype(link->device, link->channel,
+				     link->datatype);
+}
+
+static int (*set_config_val[])(struct mdev_link *link) = {
+	set_cfg_buffer_size,
+	set_cfg_subbuffer_size,
+	set_cfg_dbr_size,
+	set_cfg_num_buffers,
+	set_cfg_packets_xact,
+	set_cfg_direction,
+	set_cfg_datatype,
+};
+
+static struct mdev_link *to_mdev_link(struct config_item *item)
+{
+	return container_of(item, struct mdev_link, item);
+}
+
+static int set_config_and_add_link(struct mdev_link *mdev_link)
+{
+	int i;
+	int ret;
+
+	for (i = 0; i < ARRAY_SIZE(set_config_val); i++) {
+		ret = set_config_val[i](mdev_link);
+		if (ret < 0 && ret != -ENODEV) {
+			pr_err("Config failed\n");
+			return ret;
+		}
+	}
+
+	return most_add_link(mdev_link->device, mdev_link->channel,
+			     mdev_link->comp, mdev_link->name,
+			     mdev_link->comp_params);
+}
+
+static ssize_t mdev_link_create_link_store(struct config_item *item,
+					   const char *page, size_t count)
+{
+	struct mdev_link *mdev_link = to_mdev_link(item);
+	bool tmp;
+	int ret;
+
+	ret = kstrtobool(page, &tmp);
+	if (ret)
+		return ret;
+	if (!tmp)
+		return count;
+	ret = set_config_and_add_link(mdev_link);
+	if (ret && ret != -ENODEV)
+		return ret;
+	list_add_tail(&mdev_link->list, &mdev_link_list);
+	mdev_link->create_link = tmp;
+	mdev_link->destroy_link = false;
+
+	return count;
+}
+
+static ssize_t mdev_link_destroy_link_store(struct config_item *item,
+					    const char *page, size_t count)
+{
+	struct mdev_link *mdev_link = to_mdev_link(item);
+	bool tmp;
+	int ret;
+
+	ret = kstrtobool(page, &tmp);
+	if (ret)
+		return ret;
+	if (!tmp)
+		return count;
+
+	ret = most_remove_link(mdev_link->device, mdev_link->channel,
+			       mdev_link->comp);
+	if (ret)
+		return ret;
+	if (!list_empty(&mdev_link_list))
+		list_del(&mdev_link->list);
+
+	mdev_link->destroy_link = tmp;
+
+	return count;
+}
+
+static ssize_t mdev_link_direction_show(struct config_item *item, char *page)
+{
+	return snprintf(page, PAGE_SIZE, "%s\n", to_mdev_link(item)->direction);
+}
+
+static ssize_t mdev_link_direction_store(struct config_item *item,
+					 const char *page, size_t count)
+{
+	struct mdev_link *mdev_link = to_mdev_link(item);
+
+	if (!sysfs_streq(page, "dir_rx") && !sysfs_streq(page, "rx") &&
+	    !sysfs_streq(page, "dir_tx") && !sysfs_streq(page, "tx"))
+		return -EINVAL;
+	strcpy(mdev_link->direction, page);
+	strim(mdev_link->direction);
+	return count;
+}
+
+static ssize_t mdev_link_datatype_show(struct config_item *item, char *page)
+{
+	return snprintf(page, PAGE_SIZE, "%s\n", to_mdev_link(item)->datatype);
+}
+
+static ssize_t mdev_link_datatype_store(struct config_item *item,
+					const char *page, size_t count)
+{
+	struct mdev_link *mdev_link = to_mdev_link(item);
+
+	if (!sysfs_streq(page, "control") && !sysfs_streq(page, "async") &&
+	    !sysfs_streq(page, "sync") && !sysfs_streq(page, "isoc") &&
+	    !sysfs_streq(page, "isoc_avp"))
+		return -EINVAL;
+	strcpy(mdev_link->datatype, page);
+	strim(mdev_link->datatype);
+	return count;
+}
+
+static ssize_t mdev_link_device_show(struct config_item *item, char *page)
+{
+	return snprintf(page, PAGE_SIZE, "%s\n", to_mdev_link(item)->device);
+}
+
+static ssize_t mdev_link_device_store(struct config_item *item,
+				      const char *page, size_t count)
+{
+	struct mdev_link *mdev_link = to_mdev_link(item);
+
+	strscpy(mdev_link->device, page, sizeof(mdev_link->device));
+	strim(mdev_link->device);
+	return count;
+}
+
+static ssize_t mdev_link_channel_show(struct config_item *item, char *page)
+{
+	return snprintf(page, PAGE_SIZE, "%s\n", to_mdev_link(item)->channel);
+}
+
+static ssize_t mdev_link_channel_store(struct config_item *item,
+				       const char *page, size_t count)
+{
+	struct mdev_link *mdev_link = to_mdev_link(item);
+
+	strscpy(mdev_link->channel, page, sizeof(mdev_link->channel));
+	strim(mdev_link->channel);
+	return count;
+}
+
+static ssize_t mdev_link_comp_show(struct config_item *item, char *page)
+{
+	return snprintf(page, PAGE_SIZE, "%s\n", to_mdev_link(item)->comp);
+}
+
+static ssize_t mdev_link_comp_store(struct config_item *item,
+				    const char *page, size_t count)
+{
+	struct mdev_link *mdev_link = to_mdev_link(item);
+
+	strscpy(mdev_link->comp, page, sizeof(mdev_link->comp));
+	strim(mdev_link->comp);
+	return count;
+}
+
+static ssize_t mdev_link_comp_params_show(struct config_item *item, char *page)
+{
+	return snprintf(page, PAGE_SIZE, "%s\n",
+			to_mdev_link(item)->comp_params);
+}
+
+static ssize_t mdev_link_comp_params_store(struct config_item *item,
+					   const char *page, size_t count)
+{
+	struct mdev_link *mdev_link = to_mdev_link(item);
+
+	strscpy(mdev_link->comp_params, page, sizeof(mdev_link->comp_params));
+	strim(mdev_link->comp_params);
+	return count;
+}
+
+static ssize_t mdev_link_num_buffers_show(struct config_item *item, char *page)
+{
+	return snprintf(page, PAGE_SIZE, "%d\n",
+			to_mdev_link(item)->num_buffers);
+}
+
+static ssize_t mdev_link_num_buffers_store(struct config_item *item,
+					   const char *page, size_t count)
+{
+	struct mdev_link *mdev_link = to_mdev_link(item);
+	int ret;
+
+	ret = kstrtou16(page, 0, &mdev_link->num_buffers);
+	if (ret)
+		return ret;
+	return count;
+}
+
+static ssize_t mdev_link_buffer_size_show(struct config_item *item, char *page)
+{
+	return snprintf(page, PAGE_SIZE, "%d\n",
+			to_mdev_link(item)->buffer_size);
+}
+
+static ssize_t mdev_link_buffer_size_store(struct config_item *item,
+					   const char *page, size_t count)
+{
+	struct mdev_link *mdev_link = to_mdev_link(item);
+	int ret;
+
+	ret = kstrtou16(page, 0, &mdev_link->buffer_size);
+	if (ret)
+		return ret;
+	return count;
+}
+
+static ssize_t mdev_link_subbuffer_size_show(struct config_item *item,
+					     char *page)
+{
+	return snprintf(page, PAGE_SIZE, "%d\n",
+			to_mdev_link(item)->subbuffer_size);
+}
+
+static ssize_t mdev_link_subbuffer_size_store(struct config_item *item,
+					      const char *page, size_t count)
+{
+	struct mdev_link *mdev_link = to_mdev_link(item);
+	int ret;
+
+	ret = kstrtou16(page, 0, &mdev_link->subbuffer_size);
+	if (ret)
+		return ret;
+	return count;
+}
+
+static ssize_t mdev_link_packets_per_xact_show(struct config_item *item,
+					       char *page)
+{
+	return snprintf(page, PAGE_SIZE, "%d\n",
+			to_mdev_link(item)->packets_per_xact);
+}
+
+static ssize_t mdev_link_packets_per_xact_store(struct config_item *item,
+						const char *page, size_t count)
+{
+	struct mdev_link *mdev_link = to_mdev_link(item);
+	int ret;
+
+	ret = kstrtou16(page, 0, &mdev_link->packets_per_xact);
+	if (ret)
+		return ret;
+	return count;
+}
+
+static ssize_t mdev_link_dbr_size_show(struct config_item *item, char *page)
+{
+	return snprintf(page, PAGE_SIZE, "%d\n", to_mdev_link(item)->dbr_size);
+}
+
+static ssize_t mdev_link_dbr_size_store(struct config_item *item,
+					const char *page, size_t count)
+{
+	struct mdev_link *mdev_link = to_mdev_link(item);
+	int ret;
+
+	ret = kstrtou16(page, 0, &mdev_link->dbr_size);
+	if (ret)
+		return ret;
+	return count;
+}
+
+CONFIGFS_ATTR_WO(mdev_link_, create_link);
+CONFIGFS_ATTR_WO(mdev_link_, destroy_link);
+CONFIGFS_ATTR(mdev_link_, device);
+CONFIGFS_ATTR(mdev_link_, channel);
+CONFIGFS_ATTR(mdev_link_, comp);
+CONFIGFS_ATTR(mdev_link_, comp_params);
+CONFIGFS_ATTR(mdev_link_, num_buffers);
+CONFIGFS_ATTR(mdev_link_, buffer_size);
+CONFIGFS_ATTR(mdev_link_, subbuffer_size);
+CONFIGFS_ATTR(mdev_link_, packets_per_xact);
+CONFIGFS_ATTR(mdev_link_, datatype);
+CONFIGFS_ATTR(mdev_link_, direction);
+CONFIGFS_ATTR(mdev_link_, dbr_size);
+
+static struct configfs_attribute *mdev_link_attrs[] = {
+	&mdev_link_attr_create_link,
+	&mdev_link_attr_destroy_link,
+	&mdev_link_attr_device,
+	&mdev_link_attr_channel,
+	&mdev_link_attr_comp,
+	&mdev_link_attr_comp_params,
+	&mdev_link_attr_num_buffers,
+	&mdev_link_attr_buffer_size,
+	&mdev_link_attr_subbuffer_size,
+	&mdev_link_attr_packets_per_xact,
+	&mdev_link_attr_datatype,
+	&mdev_link_attr_direction,
+	&mdev_link_attr_dbr_size,
+	NULL,
+};
+
+static void mdev_link_release(struct config_item *item)
+{
+	struct mdev_link *mdev_link = to_mdev_link(item);
+	int ret;
+
+	if (mdev_link->destroy_link)
+		goto free_item;
+
+	ret = most_remove_link(mdev_link->device, mdev_link->channel,
+			       mdev_link->comp);
+	if (ret) {
+		pr_err("Removing link failed.\n");
+		goto free_item;
+	}
+
+	if (!list_empty(&mdev_link_list))
+		list_del(&mdev_link->list);
+
+free_item:
+	kfree(to_mdev_link(item));
+}
+
+static struct configfs_item_operations mdev_link_item_ops = {
+	.release		= mdev_link_release,
+};
+
+static const struct config_item_type mdev_link_type = {
+	.ct_item_ops	= &mdev_link_item_ops,
+	.ct_attrs	= mdev_link_attrs,
+	.ct_owner	= THIS_MODULE,
+};
+
+struct most_common {
+	struct config_group group;
+	struct module *mod;
+	struct configfs_subsystem subsys;
+};
+
+static struct most_common *to_most_common(struct configfs_subsystem *subsys)
+{
+	return container_of(subsys, struct most_common, subsys);
+}
+
+static struct config_item *most_common_make_item(struct config_group *group,
+						 const char *name)
+{
+	struct mdev_link *mdev_link;
+	struct most_common *mc = to_most_common(group->cg_subsys);
+
+	mdev_link = kzalloc(sizeof(*mdev_link), GFP_KERNEL);
+	if (!mdev_link)
+		return ERR_PTR(-ENOMEM);
+
+	if (!try_module_get(mc->mod)) {
+		kfree(mdev_link);
+		return ERR_PTR(-ENOLCK);
+	}
+	config_item_init_type_name(&mdev_link->item, name,
+				   &mdev_link_type);
+
+	if (!strcmp(group->cg_item.ci_namebuf, "most_cdev"))
+		strcpy(mdev_link->comp, "cdev");
+	else if (!strcmp(group->cg_item.ci_namebuf, "most_net"))
+		strcpy(mdev_link->comp, "net");
+	else if (!strcmp(group->cg_item.ci_namebuf, "most_video"))
+		strcpy(mdev_link->comp, "video");
+	strcpy(mdev_link->name, name);
+	return &mdev_link->item;
+}
+
+static void most_common_release(struct config_item *item)
+{
+	struct config_group *group = to_config_group(item);
+
+	kfree(to_most_common(group->cg_subsys));
+}
+
+static struct configfs_item_operations most_common_item_ops = {
+	.release	= most_common_release,
+};
+
+static void most_common_disconnect(struct config_group *group,
+				   struct config_item *item)
+{
+	struct most_common *mc = to_most_common(group->cg_subsys);
+
+	module_put(mc->mod);
+}
+
+static struct configfs_group_operations most_common_group_ops = {
+	.make_item	= most_common_make_item,
+	.disconnect_notify = most_common_disconnect,
+};
+
+static const struct config_item_type most_common_type = {
+	.ct_item_ops	= &most_common_item_ops,
+	.ct_group_ops	= &most_common_group_ops,
+	.ct_owner	= THIS_MODULE,
+};
+
+static struct most_common most_cdev = {
+	.subsys = {
+		.su_group = {
+			.cg_item = {
+				.ci_namebuf = "most_cdev",
+				.ci_type = &most_common_type,
+			},
+		},
+	},
+};
+
+static struct most_common most_net = {
+	.subsys = {
+		.su_group = {
+			.cg_item = {
+				.ci_namebuf = "most_net",
+				.ci_type = &most_common_type,
+			},
+		},
+	},
+};
+
+static struct most_common most_video = {
+	.subsys = {
+		.su_group = {
+			.cg_item = {
+				.ci_namebuf = "most_video",
+				.ci_type = &most_common_type,
+			},
+		},
+	},
+};
+
+struct most_snd_grp {
+	struct config_group group;
+	bool create_card;
+	struct list_head list;
+};
+
+static struct most_snd_grp *to_most_snd_grp(struct config_item *item)
+{
+	return container_of(to_config_group(item), struct most_snd_grp, group);
+}
+
+static struct config_item *most_snd_grp_make_item(struct config_group *group,
+						  const char *name)
+{
+	struct mdev_link *mdev_link;
+
+	mdev_link = kzalloc(sizeof(*mdev_link), GFP_KERNEL);
+	if (!mdev_link)
+		return ERR_PTR(-ENOMEM);
+
+	config_item_init_type_name(&mdev_link->item, name, &mdev_link_type);
+	mdev_link->create_link = false;
+	strcpy(mdev_link->name, name);
+	strcpy(mdev_link->comp, "sound");
+	return &mdev_link->item;
+}
+
+static ssize_t most_snd_grp_create_card_store(struct config_item *item,
+					      const char *page, size_t count)
+{
+	struct most_snd_grp *snd_grp = to_most_snd_grp(item);
+	int ret;
+	bool tmp;
+
+	ret = kstrtobool(page, &tmp);
+	if (ret)
+		return ret;
+	if (tmp) {
+		ret = most_cfg_complete("sound");
+		if (ret)
+			return ret;
+	}
+	snd_grp->create_card = tmp;
+	return count;
+}
+
+CONFIGFS_ATTR_WO(most_snd_grp_, create_card);
+
+static struct configfs_attribute *most_snd_grp_attrs[] = {
+	&most_snd_grp_attr_create_card,
+	NULL,
+};
+
+static void most_snd_grp_release(struct config_item *item)
+{
+	struct most_snd_grp *group = to_most_snd_grp(item);
+
+	list_del(&group->list);
+	kfree(group);
+}
+
+static struct configfs_item_operations most_snd_grp_item_ops = {
+	.release	= most_snd_grp_release,
+};
+
+static struct configfs_group_operations most_snd_grp_group_ops = {
+	.make_item	= most_snd_grp_make_item,
+};
+
+static const struct config_item_type most_snd_grp_type = {
+	.ct_item_ops	= &most_snd_grp_item_ops,
+	.ct_group_ops	= &most_snd_grp_group_ops,
+	.ct_attrs	= most_snd_grp_attrs,
+	.ct_owner	= THIS_MODULE,
+};
+
+struct most_sound {
+	struct configfs_subsystem subsys;
+	struct list_head soundcard_list;
+	struct module *mod;
+};
+
+static struct config_group *most_sound_make_group(struct config_group *group,
+						  const char *name)
+{
+	struct most_snd_grp *most;
+	struct most_sound *ms = container_of(group->cg_subsys,
+					     struct most_sound, subsys);
+
+	list_for_each_entry(most, &ms->soundcard_list, list) {
+		if (!most->create_card) {
+			pr_info("adapter configuration still in progress.\n");
+			return ERR_PTR(-EPROTO);
+		}
+	}
+	if (!try_module_get(ms->mod))
+		return ERR_PTR(-ENOLCK);
+	most = kzalloc(sizeof(*most), GFP_KERNEL);
+	if (!most) {
+		module_put(ms->mod);
+		return ERR_PTR(-ENOMEM);
+	}
+	config_group_init_type_name(&most->group, name, &most_snd_grp_type);
+	list_add_tail(&most->list, &ms->soundcard_list);
+	return &most->group;
+}
+
+static void most_sound_disconnect(struct config_group *group,
+				  struct config_item *item)
+{
+	struct most_sound *ms = container_of(group->cg_subsys,
+					     struct most_sound, subsys);
+	module_put(ms->mod);
+}
+
+static struct configfs_group_operations most_sound_group_ops = {
+	.make_group	= most_sound_make_group,
+	.disconnect_notify = most_sound_disconnect,
+};
+
+static const struct config_item_type most_sound_type = {
+	.ct_group_ops	= &most_sound_group_ops,
+	.ct_owner	= THIS_MODULE,
+};
+
+static struct most_sound most_sound_subsys = {
+	.subsys = {
+		.su_group = {
+			.cg_item = {
+				.ci_namebuf = "most_sound",
+				.ci_type = &most_sound_type,
+			},
+		},
+	},
+};
+
+int most_register_configfs_subsys(struct most_component *c)
+{
+	int ret;
+
+	if (!strcmp(c->name, "cdev")) {
+		most_cdev.mod = c->mod;
+		ret = configfs_register_subsystem(&most_cdev.subsys);
+	} else if (!strcmp(c->name, "net")) {
+		most_net.mod = c->mod;
+		ret = configfs_register_subsystem(&most_net.subsys);
+	} else if (!strcmp(c->name, "video")) {
+		most_video.mod = c->mod;
+		ret = configfs_register_subsystem(&most_video.subsys);
+	} else if (!strcmp(c->name, "sound")) {
+		most_sound_subsys.mod = c->mod;
+		ret = configfs_register_subsystem(&most_sound_subsys.subsys);
+	} else {
+		return -ENODEV;
+	}
+
+	if (ret) {
+		pr_err("Error %d while registering subsystem %s\n",
+		       ret, c->name);
+	}
+	return ret;
+}
+EXPORT_SYMBOL_GPL(most_register_configfs_subsys);
+
+void most_interface_register_notify(const char *mdev)
+{
+	bool register_snd_card = false;
+	struct mdev_link *mdev_link;
+
+	list_for_each_entry(mdev_link, &mdev_link_list, list) {
+		if (!strcmp(mdev_link->device, mdev)) {
+			set_config_and_add_link(mdev_link);
+			if (!strcmp(mdev_link->comp, "sound"))
+				register_snd_card = true;
+		}
+	}
+	if (register_snd_card)
+		most_cfg_complete("sound");
+}
+
+void most_deregister_configfs_subsys(struct most_component *c)
+{
+	if (!strcmp(c->name, "cdev"))
+		configfs_unregister_subsystem(&most_cdev.subsys);
+	else if (!strcmp(c->name, "net"))
+		configfs_unregister_subsystem(&most_net.subsys);
+	else if (!strcmp(c->name, "video"))
+		configfs_unregister_subsystem(&most_video.subsys);
+	else if (!strcmp(c->name, "sound"))
+		configfs_unregister_subsystem(&most_sound_subsys.subsys);
+}
+EXPORT_SYMBOL_GPL(most_deregister_configfs_subsys);
+
+int __init configfs_init(void)
+{
+	config_group_init(&most_cdev.subsys.su_group);
+	mutex_init(&most_cdev.subsys.su_mutex);
+
+	config_group_init(&most_net.subsys.su_group);
+	mutex_init(&most_net.subsys.su_mutex);
+
+	config_group_init(&most_video.subsys.su_group);
+	mutex_init(&most_video.subsys.su_mutex);
+
+	config_group_init(&most_sound_subsys.subsys.su_group);
+	mutex_init(&most_sound_subsys.subsys.su_mutex);
+
+	INIT_LIST_HEAD(&most_sound_subsys.soundcard_list);
+	INIT_LIST_HEAD(&mdev_link_list);
+
+	return 0;
+}
diff --git a/drivers/most/core.c b/drivers/most/core.c
new file mode 100644
index 0000000000..e4412c7d25
--- /dev/null
+++ b/drivers/most/core.c
@@ -0,0 +1,1488 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * core.c - Implementation of core module of MOST Linux driver stack
+ *
+ * Copyright (C) 2013-2020 Microchip Technology Germany II GmbH & Co. KG
+ */
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/device.h>
+#include <linux/list.h>
+#include <linux/poll.h>
+#include <linux/wait.h>
+#include <linux/kobject.h>
+#include <linux/mutex.h>
+#include <linux/completion.h>
+#include <linux/sysfs.h>
+#include <linux/kthread.h>
+#include <linux/dma-mapping.h>
+#include <linux/idr.h>
+#include <linux/most.h>
+
+#define MAX_CHANNELS	64
+#define STRING_SIZE	80
+
+static struct ida mdev_id;
+static int dummy_num_buffers;
+static struct list_head comp_list;
+
+struct pipe {
+	struct most_component *comp;
+	int refs;
+	int num_buffers;
+};
+
+struct most_channel {
+	struct device dev;
+	struct completion cleanup;
+	atomic_t mbo_ref;
+	atomic_t mbo_nq_level;
+	u16 channel_id;
+	char name[STRING_SIZE];
+	bool is_poisoned;
+	struct mutex start_mutex; /* channel activation synchronization */
+	struct mutex nq_mutex; /* nq thread synchronization */
+	int is_starving;
+	struct most_interface *iface;
+	struct most_channel_config cfg;
+	bool keep_mbo;
+	bool enqueue_halt;
+	struct list_head fifo;
+	spinlock_t fifo_lock; /* fifo access synchronization */
+	struct list_head halt_fifo;
+	struct list_head list;
+	struct pipe pipe0;
+	struct pipe pipe1;
+	struct list_head trash_fifo;
+	struct task_struct *hdm_enqueue_task;
+	wait_queue_head_t hdm_fifo_wq;
+
+};
+
+#define to_channel(d) container_of(d, struct most_channel, dev)
+
+struct interface_private {
+	int dev_id;
+	char name[STRING_SIZE];
+	struct most_channel *channel[MAX_CHANNELS];
+	struct list_head channel_list;
+};
+
+static const struct {
+	int most_ch_data_type;
+	const char *name;
+} ch_data_type[] = {
+	{ MOST_CH_CONTROL, "control" },
+	{ MOST_CH_ASYNC, "async" },
+	{ MOST_CH_SYNC, "sync" },
+	{ MOST_CH_ISOC, "isoc"},
+	{ MOST_CH_ISOC, "isoc_avp"},
+};
+
+/**
+ * list_pop_mbo - retrieves the first MBO of the list and removes it
+ * @ptr: the list head to grab the MBO from.
+ */
+#define list_pop_mbo(ptr)						\
+({									\
+	struct mbo *_mbo = list_first_entry(ptr, struct mbo, list);	\
+	list_del(&_mbo->list);						\
+	_mbo;								\
+})
+
+/**
+ * most_free_mbo_coherent - free an MBO and its coherent buffer
+ * @mbo: most buffer
+ */
+static void most_free_mbo_coherent(struct mbo *mbo)
+{
+	struct most_channel *c = mbo->context;
+	u16 const coherent_buf_size = c->cfg.buffer_size + c->cfg.extra_len;
+
+	if (c->iface->dma_free)
+		c->iface->dma_free(mbo, coherent_buf_size);
+	else
+		kfree(mbo->virt_address);
+	kfree(mbo);
+	if (atomic_sub_and_test(1, &c->mbo_ref))
+		complete(&c->cleanup);
+}
+
+/**
+ * flush_channel_fifos - clear the channel fifos
+ * @c: pointer to channel object
+ */
+static void flush_channel_fifos(struct most_channel *c)
+{
+	unsigned long flags, hf_flags;
+	struct mbo *mbo, *tmp;
+
+	if (list_empty(&c->fifo) && list_empty(&c->halt_fifo))
+		return;
+
+	spin_lock_irqsave(&c->fifo_lock, flags);
+	list_for_each_entry_safe(mbo, tmp, &c->fifo, list) {
+		list_del(&mbo->list);
+		spin_unlock_irqrestore(&c->fifo_lock, flags);
+		most_free_mbo_coherent(mbo);
+		spin_lock_irqsave(&c->fifo_lock, flags);
+	}
+	spin_unlock_irqrestore(&c->fifo_lock, flags);
+
+	spin_lock_irqsave(&c->fifo_lock, hf_flags);
+	list_for_each_entry_safe(mbo, tmp, &c->halt_fifo, list) {
+		list_del(&mbo->list);
+		spin_unlock_irqrestore(&c->fifo_lock, hf_flags);
+		most_free_mbo_coherent(mbo);
+		spin_lock_irqsave(&c->fifo_lock, hf_flags);
+	}
+	spin_unlock_irqrestore(&c->fifo_lock, hf_flags);
+
+	if (unlikely((!list_empty(&c->fifo) || !list_empty(&c->halt_fifo))))
+		dev_warn(&c->dev, "Channel or trash fifo not empty\n");
+}
+
+/**
+ * flush_trash_fifo - clear the trash fifo
+ * @c: pointer to channel object
+ */
+static int flush_trash_fifo(struct most_channel *c)
+{
+	struct mbo *mbo, *tmp;
+	unsigned long flags;
+
+	spin_lock_irqsave(&c->fifo_lock, flags);
+	list_for_each_entry_safe(mbo, tmp, &c->trash_fifo, list) {
+		list_del(&mbo->list);
+		spin_unlock_irqrestore(&c->fifo_lock, flags);
+		most_free_mbo_coherent(mbo);
+		spin_lock_irqsave(&c->fifo_lock, flags);
+	}
+	spin_unlock_irqrestore(&c->fifo_lock, flags);
+	return 0;
+}
+
+static ssize_t available_directions_show(struct device *dev,
+					 struct device_attribute *attr,
+					 char *buf)
+{
+	struct most_channel *c = to_channel(dev);
+	unsigned int i = c->channel_id;
+
+	strcpy(buf, "");
+	if (c->iface->channel_vector[i].direction & MOST_CH_RX)
+		strcat(buf, "rx ");
+	if (c->iface->channel_vector[i].direction & MOST_CH_TX)
+		strcat(buf, "tx ");
+	strcat(buf, "\n");
+	return strlen(buf);
+}
+
+static ssize_t available_datatypes_show(struct device *dev,
+					struct device_attribute *attr,
+					char *buf)
+{
+	struct most_channel *c = to_channel(dev);
+	unsigned int i = c->channel_id;
+
+	strcpy(buf, "");
+	if (c->iface->channel_vector[i].data_type & MOST_CH_CONTROL)
+		strcat(buf, "control ");
+	if (c->iface->channel_vector[i].data_type & MOST_CH_ASYNC)
+		strcat(buf, "async ");
+	if (c->iface->channel_vector[i].data_type & MOST_CH_SYNC)
+		strcat(buf, "sync ");
+	if (c->iface->channel_vector[i].data_type & MOST_CH_ISOC)
+		strcat(buf, "isoc ");
+	strcat(buf, "\n");
+	return strlen(buf);
+}
+
+static ssize_t number_of_packet_buffers_show(struct device *dev,
+					     struct device_attribute *attr,
+					     char *buf)
+{
+	struct most_channel *c = to_channel(dev);
+	unsigned int i = c->channel_id;
+
+	return snprintf(buf, PAGE_SIZE, "%d\n",
+			c->iface->channel_vector[i].num_buffers_packet);
+}
+
+static ssize_t number_of_stream_buffers_show(struct device *dev,
+					     struct device_attribute *attr,
+					     char *buf)
+{
+	struct most_channel *c = to_channel(dev);
+	unsigned int i = c->channel_id;
+
+	return snprintf(buf, PAGE_SIZE, "%d\n",
+			c->iface->channel_vector[i].num_buffers_streaming);
+}
+
+static ssize_t size_of_packet_buffer_show(struct device *dev,
+					  struct device_attribute *attr,
+					  char *buf)
+{
+	struct most_channel *c = to_channel(dev);
+	unsigned int i = c->channel_id;
+
+	return snprintf(buf, PAGE_SIZE, "%d\n",
+			c->iface->channel_vector[i].buffer_size_packet);
+}
+
+static ssize_t size_of_stream_buffer_show(struct device *dev,
+					  struct device_attribute *attr,
+					  char *buf)
+{
+	struct most_channel *c = to_channel(dev);
+	unsigned int i = c->channel_id;
+
+	return snprintf(buf, PAGE_SIZE, "%d\n",
+			c->iface->channel_vector[i].buffer_size_streaming);
+}
+
+static ssize_t channel_starving_show(struct device *dev,
+				     struct device_attribute *attr,
+				     char *buf)
+{
+	struct most_channel *c = to_channel(dev);
+
+	return snprintf(buf, PAGE_SIZE, "%d\n", c->is_starving);
+}
+
+static ssize_t set_number_of_buffers_show(struct device *dev,
+					  struct device_attribute *attr,
+					  char *buf)
+{
+	struct most_channel *c = to_channel(dev);
+
+	return snprintf(buf, PAGE_SIZE, "%d\n", c->cfg.num_buffers);
+}
+
+static ssize_t set_buffer_size_show(struct device *dev,
+				    struct device_attribute *attr,
+				    char *buf)
+{
+	struct most_channel *c = to_channel(dev);
+
+	return snprintf(buf, PAGE_SIZE, "%d\n", c->cfg.buffer_size);
+}
+
+static ssize_t set_direction_show(struct device *dev,
+				  struct device_attribute *attr,
+				  char *buf)
+{
+	struct most_channel *c = to_channel(dev);
+
+	if (c->cfg.direction & MOST_CH_TX)
+		return snprintf(buf, PAGE_SIZE, "tx\n");
+	else if (c->cfg.direction & MOST_CH_RX)
+		return snprintf(buf, PAGE_SIZE, "rx\n");
+	return snprintf(buf, PAGE_SIZE, "unconfigured\n");
+}
+
+static ssize_t set_datatype_show(struct device *dev,
+				 struct device_attribute *attr,
+				 char *buf)
+{
+	int i;
+	struct most_channel *c = to_channel(dev);
+
+	for (i = 0; i < ARRAY_SIZE(ch_data_type); i++) {
+		if (c->cfg.data_type & ch_data_type[i].most_ch_data_type)
+			return snprintf(buf, PAGE_SIZE, "%s",
+					ch_data_type[i].name);
+	}
+	return snprintf(buf, PAGE_SIZE, "unconfigured\n");
+}
+
+static ssize_t set_subbuffer_size_show(struct device *dev,
+				       struct device_attribute *attr,
+				       char *buf)
+{
+	struct most_channel *c = to_channel(dev);
+
+	return snprintf(buf, PAGE_SIZE, "%d\n", c->cfg.subbuffer_size);
+}
+
+static ssize_t set_packets_per_xact_show(struct device *dev,
+					 struct device_attribute *attr,
+					 char *buf)
+{
+	struct most_channel *c = to_channel(dev);
+
+	return snprintf(buf, PAGE_SIZE, "%d\n", c->cfg.packets_per_xact);
+}
+
+static ssize_t set_dbr_size_show(struct device *dev,
+				 struct device_attribute *attr, char *buf)
+{
+	struct most_channel *c = to_channel(dev);
+
+	return snprintf(buf, PAGE_SIZE, "%d\n", c->cfg.dbr_size);
+}
+
+#define to_dev_attr(a) container_of(a, struct device_attribute, attr)
+static umode_t channel_attr_is_visible(struct kobject *kobj,
+				       struct attribute *attr, int index)
+{
+	struct device_attribute *dev_attr = to_dev_attr(attr);
+	struct device *dev = kobj_to_dev(kobj);
+	struct most_channel *c = to_channel(dev);
+
+	if (!strcmp(dev_attr->attr.name, "set_dbr_size") &&
+	    (c->iface->interface != ITYPE_MEDIALB_DIM2))
+		return 0;
+	if (!strcmp(dev_attr->attr.name, "set_packets_per_xact") &&
+	    (c->iface->interface != ITYPE_USB))
+		return 0;
+
+	return attr->mode;
+}
+
+#define DEV_ATTR(_name)  (&dev_attr_##_name.attr)
+
+static DEVICE_ATTR_RO(available_directions);
+static DEVICE_ATTR_RO(available_datatypes);
+static DEVICE_ATTR_RO(number_of_packet_buffers);
+static DEVICE_ATTR_RO(number_of_stream_buffers);
+static DEVICE_ATTR_RO(size_of_stream_buffer);
+static DEVICE_ATTR_RO(size_of_packet_buffer);
+static DEVICE_ATTR_RO(channel_starving);
+static DEVICE_ATTR_RO(set_buffer_size);
+static DEVICE_ATTR_RO(set_number_of_buffers);
+static DEVICE_ATTR_RO(set_direction);
+static DEVICE_ATTR_RO(set_datatype);
+static DEVICE_ATTR_RO(set_subbuffer_size);
+static DEVICE_ATTR_RO(set_packets_per_xact);
+static DEVICE_ATTR_RO(set_dbr_size);
+
+static struct attribute *channel_attrs[] = {
+	DEV_ATTR(available_directions),
+	DEV_ATTR(available_datatypes),
+	DEV_ATTR(number_of_packet_buffers),
+	DEV_ATTR(number_of_stream_buffers),
+	DEV_ATTR(size_of_stream_buffer),
+	DEV_ATTR(size_of_packet_buffer),
+	DEV_ATTR(channel_starving),
+	DEV_ATTR(set_buffer_size),
+	DEV_ATTR(set_number_of_buffers),
+	DEV_ATTR(set_direction),
+	DEV_ATTR(set_datatype),
+	DEV_ATTR(set_subbuffer_size),
+	DEV_ATTR(set_packets_per_xact),
+	DEV_ATTR(set_dbr_size),
+	NULL,
+};
+
+static const struct attribute_group channel_attr_group = {
+	.attrs = channel_attrs,
+	.is_visible = channel_attr_is_visible,
+};
+
+static const struct attribute_group *channel_attr_groups[] = {
+	&channel_attr_group,
+	NULL,
+};
+
+static ssize_t description_show(struct device *dev,
+				struct device_attribute *attr,
+				char *buf)
+{
+	struct most_interface *iface = dev_get_drvdata(dev);
+
+	return snprintf(buf, PAGE_SIZE, "%s\n", iface->description);
+}
+
+static ssize_t interface_show(struct device *dev,
+			      struct device_attribute *attr,
+			      char *buf)
+{
+	struct most_interface *iface = dev_get_drvdata(dev);
+
+	switch (iface->interface) {
+	case ITYPE_LOOPBACK:
+		return snprintf(buf, PAGE_SIZE, "loopback\n");
+	case ITYPE_I2C:
+		return snprintf(buf, PAGE_SIZE, "i2c\n");
+	case ITYPE_I2S:
+		return snprintf(buf, PAGE_SIZE, "i2s\n");
+	case ITYPE_TSI:
+		return snprintf(buf, PAGE_SIZE, "tsi\n");
+	case ITYPE_HBI:
+		return snprintf(buf, PAGE_SIZE, "hbi\n");
+	case ITYPE_MEDIALB_DIM:
+		return snprintf(buf, PAGE_SIZE, "mlb_dim\n");
+	case ITYPE_MEDIALB_DIM2:
+		return snprintf(buf, PAGE_SIZE, "mlb_dim2\n");
+	case ITYPE_USB:
+		return snprintf(buf, PAGE_SIZE, "usb\n");
+	case ITYPE_PCIE:
+		return snprintf(buf, PAGE_SIZE, "pcie\n");
+	}
+	return snprintf(buf, PAGE_SIZE, "unknown\n");
+}
+
+static DEVICE_ATTR_RO(description);
+static DEVICE_ATTR_RO(interface);
+
+static struct attribute *interface_attrs[] = {
+	DEV_ATTR(description),
+	DEV_ATTR(interface),
+	NULL,
+};
+
+static const struct attribute_group interface_attr_group = {
+	.attrs = interface_attrs,
+};
+
+static const struct attribute_group *interface_attr_groups[] = {
+	&interface_attr_group,
+	NULL,
+};
+
+static struct most_component *match_component(char *name)
+{
+	struct most_component *comp;
+
+	list_for_each_entry(comp, &comp_list, list) {
+		if (!strcmp(comp->name, name))
+			return comp;
+	}
+	return NULL;
+}
+
+struct show_links_data {
+	int offs;
+	char *buf;
+};
+
+static int print_links(struct device *dev, void *data)
+{
+	struct show_links_data *d = data;
+	int offs = d->offs;
+	char *buf = d->buf;
+	struct most_channel *c;
+	struct most_interface *iface = dev_get_drvdata(dev);
+
+	list_for_each_entry(c, &iface->p->channel_list, list) {
+		if (c->pipe0.comp) {
+			offs += scnprintf(buf + offs,
+					 PAGE_SIZE - offs,
+					 "%s:%s:%s\n",
+					 c->pipe0.comp->name,
+					 dev_name(iface->dev),
+					 dev_name(&c->dev));
+		}
+		if (c->pipe1.comp) {
+			offs += scnprintf(buf + offs,
+					 PAGE_SIZE - offs,
+					 "%s:%s:%s\n",
+					 c->pipe1.comp->name,
+					 dev_name(iface->dev),
+					 dev_name(&c->dev));
+		}
+	}
+	d->offs = offs;
+	return 0;
+}
+
+static int most_match(struct device *dev, struct device_driver *drv)
+{
+	if (!strcmp(dev_name(dev), "most"))
+		return 0;
+	else
+		return 1;
+}
+
+static struct bus_type mostbus = {
+	.name = "most",
+	.match = most_match,
+};
+
+static ssize_t links_show(struct device_driver *drv, char *buf)
+{
+	struct show_links_data d = { .buf = buf };
+
+	bus_for_each_dev(&mostbus, NULL, &d, print_links);
+	return d.offs;
+}
+
+static ssize_t components_show(struct device_driver *drv, char *buf)
+{
+	struct most_component *comp;
+	int offs = 0;
+
+	list_for_each_entry(comp, &comp_list, list) {
+		offs += scnprintf(buf + offs, PAGE_SIZE - offs, "%s\n",
+				 comp->name);
+	}
+	return offs;
+}
+
+/**
+ * get_channel - get pointer to channel
+ * @mdev: name of the device interface
+ * @mdev_ch: name of channel
+ */
+static struct most_channel *get_channel(char *mdev, char *mdev_ch)
+{
+	struct device *dev = NULL;
+	struct most_interface *iface;
+	struct most_channel *c, *tmp;
+
+	dev = bus_find_device_by_name(&mostbus, NULL, mdev);
+	if (!dev)
+		return NULL;
+	put_device(dev);
+	iface = dev_get_drvdata(dev);
+	list_for_each_entry_safe(c, tmp, &iface->p->channel_list, list) {
+		if (!strcmp(dev_name(&c->dev), mdev_ch))
+			return c;
+	}
+	return NULL;
+}
+
+static
+inline int link_channel_to_component(struct most_channel *c,
+				     struct most_component *comp,
+				     char *name,
+				     char *comp_param)
+{
+	int ret;
+	struct most_component **comp_ptr;
+
+	if (!c->pipe0.comp)
+		comp_ptr = &c->pipe0.comp;
+	else if (!c->pipe1.comp)
+		comp_ptr = &c->pipe1.comp;
+	else
+		return -ENOSPC;
+
+	*comp_ptr = comp;
+	ret = comp->probe_channel(c->iface, c->channel_id, &c->cfg, name,
+				  comp_param);
+	if (ret) {
+		*comp_ptr = NULL;
+		return ret;
+	}
+	return 0;
+}
+
+int most_set_cfg_buffer_size(char *mdev, char *mdev_ch, u16 val)
+{
+	struct most_channel *c = get_channel(mdev, mdev_ch);
+
+	if (!c)
+		return -ENODEV;
+	c->cfg.buffer_size = val;
+	return 0;
+}
+
+int most_set_cfg_subbuffer_size(char *mdev, char *mdev_ch, u16 val)
+{
+	struct most_channel *c = get_channel(mdev, mdev_ch);
+
+	if (!c)
+		return -ENODEV;
+	c->cfg.subbuffer_size = val;
+	return 0;
+}
+
+int most_set_cfg_dbr_size(char *mdev, char *mdev_ch, u16 val)
+{
+	struct most_channel *c = get_channel(mdev, mdev_ch);
+
+	if (!c)
+		return -ENODEV;
+	c->cfg.dbr_size = val;
+	return 0;
+}
+
+int most_set_cfg_num_buffers(char *mdev, char *mdev_ch, u16 val)
+{
+	struct most_channel *c = get_channel(mdev, mdev_ch);
+
+	if (!c)
+		return -ENODEV;
+	c->cfg.num_buffers = val;
+	return 0;
+}
+
+int most_set_cfg_datatype(char *mdev, char *mdev_ch, char *buf)
+{
+	int i;
+	struct most_channel *c = get_channel(mdev, mdev_ch);
+
+	if (!c)
+		return -ENODEV;
+	for (i = 0; i < ARRAY_SIZE(ch_data_type); i++) {
+		if (!strcmp(buf, ch_data_type[i].name)) {
+			c->cfg.data_type = ch_data_type[i].most_ch_data_type;
+			break;
+		}
+	}
+
+	if (i == ARRAY_SIZE(ch_data_type))
+		dev_warn(&c->dev, "Invalid attribute settings\n");
+	return 0;
+}
+
+int most_set_cfg_direction(char *mdev, char *mdev_ch, char *buf)
+{
+	struct most_channel *c = get_channel(mdev, mdev_ch);
+
+	if (!c)
+		return -ENODEV;
+	if (!strcmp(buf, "dir_rx")) {
+		c->cfg.direction = MOST_CH_RX;
+	} else if (!strcmp(buf, "rx")) {
+		c->cfg.direction = MOST_CH_RX;
+	} else if (!strcmp(buf, "dir_tx")) {
+		c->cfg.direction = MOST_CH_TX;
+	} else if (!strcmp(buf, "tx")) {
+		c->cfg.direction = MOST_CH_TX;
+	} else {
+		dev_err(&c->dev, "Invalid direction\n");
+		return -ENODATA;
+	}
+	return 0;
+}
+
+int most_set_cfg_packets_xact(char *mdev, char *mdev_ch, u16 val)
+{
+	struct most_channel *c = get_channel(mdev, mdev_ch);
+
+	if (!c)
+		return -ENODEV;
+	c->cfg.packets_per_xact = val;
+	return 0;
+}
+
+int most_cfg_complete(char *comp_name)
+{
+	struct most_component *comp;
+
+	comp = match_component(comp_name);
+	if (!comp)
+		return -ENODEV;
+
+	return comp->cfg_complete();
+}
+
+int most_add_link(char *mdev, char *mdev_ch, char *comp_name, char *link_name,
+		  char *comp_param)
+{
+	struct most_channel *c = get_channel(mdev, mdev_ch);
+	struct most_component *comp = match_component(comp_name);
+
+	if (!c || !comp)
+		return -ENODEV;
+
+	return link_channel_to_component(c, comp, link_name, comp_param);
+}
+
+int most_remove_link(char *mdev, char *mdev_ch, char *comp_name)
+{
+	struct most_channel *c;
+	struct most_component *comp;
+
+	comp = match_component(comp_name);
+	if (!comp)
+		return -ENODEV;
+	c = get_channel(mdev, mdev_ch);
+	if (!c)
+		return -ENODEV;
+
+	if (comp->disconnect_channel(c->iface, c->channel_id))
+		return -EIO;
+	if (c->pipe0.comp == comp)
+		c->pipe0.comp = NULL;
+	if (c->pipe1.comp == comp)
+		c->pipe1.comp = NULL;
+	return 0;
+}
+
+#define DRV_ATTR(_name)  (&driver_attr_##_name.attr)
+
+static DRIVER_ATTR_RO(links);
+static DRIVER_ATTR_RO(components);
+
+static struct attribute *mc_attrs[] = {
+	DRV_ATTR(links),
+	DRV_ATTR(components),
+	NULL,
+};
+
+static const struct attribute_group mc_attr_group = {
+	.attrs = mc_attrs,
+};
+
+static const struct attribute_group *mc_attr_groups[] = {
+	&mc_attr_group,
+	NULL,
+};
+
+static struct device_driver mostbus_driver = {
+	.name = "most_core",
+	.bus = &mostbus,
+	.groups = mc_attr_groups,
+};
+
+static inline void trash_mbo(struct mbo *mbo)
+{
+	unsigned long flags;
+	struct most_channel *c = mbo->context;
+
+	spin_lock_irqsave(&c->fifo_lock, flags);
+	list_add(&mbo->list, &c->trash_fifo);
+	spin_unlock_irqrestore(&c->fifo_lock, flags);
+}
+
+static bool hdm_mbo_ready(struct most_channel *c)
+{
+	bool empty;
+
+	if (c->enqueue_halt)
+		return false;
+
+	spin_lock_irq(&c->fifo_lock);
+	empty = list_empty(&c->halt_fifo);
+	spin_unlock_irq(&c->fifo_lock);
+
+	return !empty;
+}
+
+static void nq_hdm_mbo(struct mbo *mbo)
+{
+	unsigned long flags;
+	struct most_channel *c = mbo->context;
+
+	spin_lock_irqsave(&c->fifo_lock, flags);
+	list_add_tail(&mbo->list, &c->halt_fifo);
+	spin_unlock_irqrestore(&c->fifo_lock, flags);
+	wake_up_interruptible(&c->hdm_fifo_wq);
+}
+
+static int hdm_enqueue_thread(void *data)
+{
+	struct most_channel *c = data;
+	struct mbo *mbo;
+	int ret;
+	typeof(c->iface->enqueue) enqueue = c->iface->enqueue;
+
+	while (likely(!kthread_should_stop())) {
+		wait_event_interruptible(c->hdm_fifo_wq,
+					 hdm_mbo_ready(c) ||
+					 kthread_should_stop());
+
+		mutex_lock(&c->nq_mutex);
+		spin_lock_irq(&c->fifo_lock);
+		if (unlikely(c->enqueue_halt || list_empty(&c->halt_fifo))) {
+			spin_unlock_irq(&c->fifo_lock);
+			mutex_unlock(&c->nq_mutex);
+			continue;
+		}
+
+		mbo = list_pop_mbo(&c->halt_fifo);
+		spin_unlock_irq(&c->fifo_lock);
+
+		if (c->cfg.direction == MOST_CH_RX)
+			mbo->buffer_length = c->cfg.buffer_size;
+
+		ret = enqueue(mbo->ifp, mbo->hdm_channel_id, mbo);
+		mutex_unlock(&c->nq_mutex);
+
+		if (unlikely(ret)) {
+			dev_err(&c->dev, "Buffer enqueue failed\n");
+			nq_hdm_mbo(mbo);
+			c->hdm_enqueue_task = NULL;
+			return 0;
+		}
+	}
+
+	return 0;
+}
+
+static int run_enqueue_thread(struct most_channel *c, int channel_id)
+{
+	struct task_struct *task =
+		kthread_run(hdm_enqueue_thread, c, "hdm_fifo_%d",
+			    channel_id);
+
+	if (IS_ERR(task))
+		return PTR_ERR(task);
+
+	c->hdm_enqueue_task = task;
+	return 0;
+}
+
+/**
+ * arm_mbo - recycle MBO for further usage
+ * @mbo: most buffer
+ *
+ * This puts an MBO back to the list to have it ready for up coming
+ * tx transactions.
+ *
+ * In case the MBO belongs to a channel that recently has been
+ * poisoned, the MBO is scheduled to be trashed.
+ * Calls the completion handler of an attached component.
+ */
+static void arm_mbo(struct mbo *mbo)
+{
+	unsigned long flags;
+	struct most_channel *c;
+
+	c = mbo->context;
+
+	if (c->is_poisoned) {
+		trash_mbo(mbo);
+		return;
+	}
+
+	spin_lock_irqsave(&c->fifo_lock, flags);
+	++*mbo->num_buffers_ptr;
+	list_add_tail(&mbo->list, &c->fifo);
+	spin_unlock_irqrestore(&c->fifo_lock, flags);
+
+	if (c->pipe0.refs && c->pipe0.comp->tx_completion)
+		c->pipe0.comp->tx_completion(c->iface, c->channel_id);
+
+	if (c->pipe1.refs && c->pipe1.comp->tx_completion)
+		c->pipe1.comp->tx_completion(c->iface, c->channel_id);
+}
+
+/**
+ * arm_mbo_chain - helper function that arms an MBO chain for the HDM
+ * @c: pointer to interface channel
+ * @dir: direction of the channel
+ * @compl: pointer to completion function
+ *
+ * This allocates buffer objects including the containing DMA coherent
+ * buffer and puts them in the fifo.
+ * Buffers of Rx channels are put in the kthread fifo, hence immediately
+ * submitted to the HDM.
+ *
+ * Returns the number of allocated and enqueued MBOs.
+ */
+static int arm_mbo_chain(struct most_channel *c, int dir,
+			 void (*compl)(struct mbo *))
+{
+	unsigned int i;
+	struct mbo *mbo;
+	unsigned long flags;
+	u32 coherent_buf_size = c->cfg.buffer_size + c->cfg.extra_len;
+
+	atomic_set(&c->mbo_nq_level, 0);
+
+	for (i = 0; i < c->cfg.num_buffers; i++) {
+		mbo = kzalloc(sizeof(*mbo), GFP_KERNEL);
+		if (!mbo)
+			goto flush_fifos;
+
+		mbo->context = c;
+		mbo->ifp = c->iface;
+		mbo->hdm_channel_id = c->channel_id;
+		if (c->iface->dma_alloc) {
+			mbo->virt_address =
+				c->iface->dma_alloc(mbo, coherent_buf_size);
+		} else {
+			mbo->virt_address =
+				kzalloc(coherent_buf_size, GFP_KERNEL);
+		}
+		if (!mbo->virt_address)
+			goto release_mbo;
+
+		mbo->complete = compl;
+		mbo->num_buffers_ptr = &dummy_num_buffers;
+		if (dir == MOST_CH_RX) {
+			nq_hdm_mbo(mbo);
+			atomic_inc(&c->mbo_nq_level);
+		} else {
+			spin_lock_irqsave(&c->fifo_lock, flags);
+			list_add_tail(&mbo->list, &c->fifo);
+			spin_unlock_irqrestore(&c->fifo_lock, flags);
+		}
+	}
+	return c->cfg.num_buffers;
+
+release_mbo:
+	kfree(mbo);
+
+flush_fifos:
+	flush_channel_fifos(c);
+	return 0;
+}
+
+/**
+ * most_submit_mbo - submits an MBO to fifo
+ * @mbo: most buffer
+ */
+void most_submit_mbo(struct mbo *mbo)
+{
+	if (WARN_ONCE(!mbo || !mbo->context,
+		      "Bad buffer or missing channel reference\n"))
+		return;
+
+	nq_hdm_mbo(mbo);
+}
+EXPORT_SYMBOL_GPL(most_submit_mbo);
+
+/**
+ * most_write_completion - write completion handler
+ * @mbo: most buffer
+ *
+ * This recycles the MBO for further usage. In case the channel has been
+ * poisoned, the MBO is scheduled to be trashed.
+ */
+static void most_write_completion(struct mbo *mbo)
+{
+	struct most_channel *c;
+
+	c = mbo->context;
+	if (unlikely(c->is_poisoned || (mbo->status == MBO_E_CLOSE)))
+		trash_mbo(mbo);
+	else
+		arm_mbo(mbo);
+}
+
+int channel_has_mbo(struct most_interface *iface, int id,
+		    struct most_component *comp)
+{
+	struct most_channel *c = iface->p->channel[id];
+	unsigned long flags;
+	int empty;
+
+	if (unlikely(!c))
+		return -EINVAL;
+
+	if (c->pipe0.refs && c->pipe1.refs &&
+	    ((comp == c->pipe0.comp && c->pipe0.num_buffers <= 0) ||
+	     (comp == c->pipe1.comp && c->pipe1.num_buffers <= 0)))
+		return 0;
+
+	spin_lock_irqsave(&c->fifo_lock, flags);
+	empty = list_empty(&c->fifo);
+	spin_unlock_irqrestore(&c->fifo_lock, flags);
+	return !empty;
+}
+EXPORT_SYMBOL_GPL(channel_has_mbo);
+
+/**
+ * most_get_mbo - get pointer to an MBO of pool
+ * @iface: pointer to interface instance
+ * @id: channel ID
+ * @comp: driver component
+ *
+ * This attempts to get a free buffer out of the channel fifo.
+ * Returns a pointer to MBO on success or NULL otherwise.
+ */
+struct mbo *most_get_mbo(struct most_interface *iface, int id,
+			 struct most_component *comp)
+{
+	struct mbo *mbo;
+	struct most_channel *c;
+	unsigned long flags;
+	int *num_buffers_ptr;
+
+	c = iface->p->channel[id];
+	if (unlikely(!c))
+		return NULL;
+
+	if (c->pipe0.refs && c->pipe1.refs &&
+	    ((comp == c->pipe0.comp && c->pipe0.num_buffers <= 0) ||
+	     (comp == c->pipe1.comp && c->pipe1.num_buffers <= 0)))
+		return NULL;
+
+	if (comp == c->pipe0.comp)
+		num_buffers_ptr = &c->pipe0.num_buffers;
+	else if (comp == c->pipe1.comp)
+		num_buffers_ptr = &c->pipe1.num_buffers;
+	else
+		num_buffers_ptr = &dummy_num_buffers;
+
+	spin_lock_irqsave(&c->fifo_lock, flags);
+	if (list_empty(&c->fifo)) {
+		spin_unlock_irqrestore(&c->fifo_lock, flags);
+		return NULL;
+	}
+	mbo = list_pop_mbo(&c->fifo);
+	--*num_buffers_ptr;
+	spin_unlock_irqrestore(&c->fifo_lock, flags);
+
+	mbo->num_buffers_ptr = num_buffers_ptr;
+	mbo->buffer_length = c->cfg.buffer_size;
+	return mbo;
+}
+EXPORT_SYMBOL_GPL(most_get_mbo);
+
+/**
+ * most_put_mbo - return buffer to pool
+ * @mbo: most buffer
+ */
+void most_put_mbo(struct mbo *mbo)
+{
+	struct most_channel *c = mbo->context;
+
+	if (c->cfg.direction == MOST_CH_TX) {
+		arm_mbo(mbo);
+		return;
+	}
+	nq_hdm_mbo(mbo);
+	atomic_inc(&c->mbo_nq_level);
+}
+EXPORT_SYMBOL_GPL(most_put_mbo);
+
+/**
+ * most_read_completion - read completion handler
+ * @mbo: most buffer
+ *
+ * This function is called by the HDM when data has been received from the
+ * hardware and copied to the buffer of the MBO.
+ *
+ * In case the channel has been poisoned it puts the buffer in the trash queue.
+ * Otherwise, it passes the buffer to an component for further processing.
+ */
+static void most_read_completion(struct mbo *mbo)
+{
+	struct most_channel *c = mbo->context;
+
+	if (unlikely(c->is_poisoned || (mbo->status == MBO_E_CLOSE))) {
+		trash_mbo(mbo);
+		return;
+	}
+
+	if (mbo->status == MBO_E_INVAL) {
+		nq_hdm_mbo(mbo);
+		atomic_inc(&c->mbo_nq_level);
+		return;
+	}
+
+	if (atomic_sub_and_test(1, &c->mbo_nq_level))
+		c->is_starving = 1;
+
+	if (c->pipe0.refs && c->pipe0.comp->rx_completion &&
+	    c->pipe0.comp->rx_completion(mbo) == 0)
+		return;
+
+	if (c->pipe1.refs && c->pipe1.comp->rx_completion &&
+	    c->pipe1.comp->rx_completion(mbo) == 0)
+		return;
+
+	most_put_mbo(mbo);
+}
+
+/**
+ * most_start_channel - prepares a channel for communication
+ * @iface: pointer to interface instance
+ * @id: channel ID
+ * @comp: driver component
+ *
+ * This prepares the channel for usage. Cross-checks whether the
+ * channel's been properly configured.
+ *
+ * Returns 0 on success or error code otherwise.
+ */
+int most_start_channel(struct most_interface *iface, int id,
+		       struct most_component *comp)
+{
+	int num_buffer;
+	int ret;
+	struct most_channel *c = iface->p->channel[id];
+
+	if (unlikely(!c))
+		return -EINVAL;
+
+	mutex_lock(&c->start_mutex);
+	if (c->pipe0.refs + c->pipe1.refs > 0)
+		goto out; /* already started by another component */
+
+	if (!try_module_get(iface->mod)) {
+		dev_err(&c->dev, "Failed to acquire HDM lock\n");
+		mutex_unlock(&c->start_mutex);
+		return -ENOLCK;
+	}
+
+	c->cfg.extra_len = 0;
+	if (c->iface->configure(c->iface, c->channel_id, &c->cfg)) {
+		dev_err(&c->dev, "Channel configuration failed. Go check settings...\n");
+		ret = -EINVAL;
+		goto err_put_module;
+	}
+
+	init_waitqueue_head(&c->hdm_fifo_wq);
+
+	if (c->cfg.direction == MOST_CH_RX)
+		num_buffer = arm_mbo_chain(c, c->cfg.direction,
+					   most_read_completion);
+	else
+		num_buffer = arm_mbo_chain(c, c->cfg.direction,
+					   most_write_completion);
+	if (unlikely(!num_buffer)) {
+		ret = -ENOMEM;
+		goto err_put_module;
+	}
+
+	ret = run_enqueue_thread(c, id);
+	if (ret)
+		goto err_put_module;
+
+	c->is_starving = 0;
+	c->pipe0.num_buffers = c->cfg.num_buffers / 2;
+	c->pipe1.num_buffers = c->cfg.num_buffers - c->pipe0.num_buffers;
+	atomic_set(&c->mbo_ref, num_buffer);
+
+out:
+	if (comp == c->pipe0.comp)
+		c->pipe0.refs++;
+	if (comp == c->pipe1.comp)
+		c->pipe1.refs++;
+	mutex_unlock(&c->start_mutex);
+	return 0;
+
+err_put_module:
+	module_put(iface->mod);
+	mutex_unlock(&c->start_mutex);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(most_start_channel);
+
+/**
+ * most_stop_channel - stops a running channel
+ * @iface: pointer to interface instance
+ * @id: channel ID
+ * @comp: driver component
+ */
+int most_stop_channel(struct most_interface *iface, int id,
+		      struct most_component *comp)
+{
+	struct most_channel *c;
+
+	if (unlikely((!iface) || (id >= iface->num_channels) || (id < 0))) {
+		pr_err("Bad interface or index out of range\n");
+		return -EINVAL;
+	}
+	c = iface->p->channel[id];
+	if (unlikely(!c))
+		return -EINVAL;
+
+	mutex_lock(&c->start_mutex);
+	if (c->pipe0.refs + c->pipe1.refs >= 2)
+		goto out;
+
+	if (c->hdm_enqueue_task)
+		kthread_stop(c->hdm_enqueue_task);
+	c->hdm_enqueue_task = NULL;
+
+	if (iface->mod)
+		module_put(iface->mod);
+
+	c->is_poisoned = true;
+	if (c->iface->poison_channel(c->iface, c->channel_id)) {
+		dev_err(&c->dev, "Failed to stop channel %d of interface %s\n", c->channel_id,
+			c->iface->description);
+		mutex_unlock(&c->start_mutex);
+		return -EAGAIN;
+	}
+	flush_trash_fifo(c);
+	flush_channel_fifos(c);
+
+#ifdef CMPL_INTERRUPTIBLE
+	if (wait_for_completion_interruptible(&c->cleanup)) {
+		dev_err(&c->dev, "Interrupted while cleaning up channel %d\n", c->channel_id);
+		mutex_unlock(&c->start_mutex);
+		return -EINTR;
+	}
+#else
+	wait_for_completion(&c->cleanup);
+#endif
+	c->is_poisoned = false;
+
+out:
+	if (comp == c->pipe0.comp)
+		c->pipe0.refs--;
+	if (comp == c->pipe1.comp)
+		c->pipe1.refs--;
+	mutex_unlock(&c->start_mutex);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(most_stop_channel);
+
+/**
+ * most_register_component - registers a driver component with the core
+ * @comp: driver component
+ */
+int most_register_component(struct most_component *comp)
+{
+	if (!comp) {
+		pr_err("Bad component\n");
+		return -EINVAL;
+	}
+	list_add_tail(&comp->list, &comp_list);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(most_register_component);
+
+static int disconnect_channels(struct device *dev, void *data)
+{
+	struct most_interface *iface;
+	struct most_channel *c, *tmp;
+	struct most_component *comp = data;
+
+	iface = dev_get_drvdata(dev);
+	list_for_each_entry_safe(c, tmp, &iface->p->channel_list, list) {
+		if (c->pipe0.comp == comp || c->pipe1.comp == comp)
+			comp->disconnect_channel(c->iface, c->channel_id);
+		if (c->pipe0.comp == comp)
+			c->pipe0.comp = NULL;
+		if (c->pipe1.comp == comp)
+			c->pipe1.comp = NULL;
+	}
+	return 0;
+}
+
+/**
+ * most_deregister_component - deregisters a driver component with the core
+ * @comp: driver component
+ */
+int most_deregister_component(struct most_component *comp)
+{
+	if (!comp) {
+		pr_err("Bad component\n");
+		return -EINVAL;
+	}
+
+	bus_for_each_dev(&mostbus, NULL, comp, disconnect_channels);
+	list_del(&comp->list);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(most_deregister_component);
+
+static void release_channel(struct device *dev)
+{
+	struct most_channel *c = to_channel(dev);
+
+	kfree(c);
+}
+
+/**
+ * most_register_interface - registers an interface with core
+ * @iface: device interface
+ *
+ * Allocates and initializes a new interface instance and all of its channels.
+ * Returns a pointer to kobject or an error pointer.
+ */
+int most_register_interface(struct most_interface *iface)
+{
+	unsigned int i;
+	int id;
+	struct most_channel *c;
+
+	if (!iface || !iface->enqueue || !iface->configure ||
+	    !iface->poison_channel || (iface->num_channels > MAX_CHANNELS))
+		return -EINVAL;
+
+	id = ida_simple_get(&mdev_id, 0, 0, GFP_KERNEL);
+	if (id < 0) {
+		dev_err(iface->dev, "Failed to allocate device ID\n");
+		return id;
+	}
+
+	iface->p = kzalloc(sizeof(*iface->p), GFP_KERNEL);
+	if (!iface->p) {
+		ida_simple_remove(&mdev_id, id);
+		return -ENOMEM;
+	}
+
+	INIT_LIST_HEAD(&iface->p->channel_list);
+	iface->p->dev_id = id;
+	strscpy(iface->p->name, iface->description, sizeof(iface->p->name));
+	iface->dev->bus = &mostbus;
+	iface->dev->groups = interface_attr_groups;
+	dev_set_drvdata(iface->dev, iface);
+	if (device_register(iface->dev)) {
+		dev_err(iface->dev, "Failed to register interface device\n");
+		kfree(iface->p);
+		put_device(iface->dev);
+		ida_simple_remove(&mdev_id, id);
+		return -ENOMEM;
+	}
+
+	for (i = 0; i < iface->num_channels; i++) {
+		const char *name_suffix = iface->channel_vector[i].name_suffix;
+
+		c = kzalloc(sizeof(*c), GFP_KERNEL);
+		if (!c)
+			goto err_free_resources;
+		if (!name_suffix)
+			snprintf(c->name, STRING_SIZE, "ch%d", i);
+		else
+			snprintf(c->name, STRING_SIZE, "%s", name_suffix);
+		c->dev.init_name = c->name;
+		c->dev.parent = iface->dev;
+		c->dev.groups = channel_attr_groups;
+		c->dev.release = release_channel;
+		iface->p->channel[i] = c;
+		c->is_starving = 0;
+		c->iface = iface;
+		c->channel_id = i;
+		c->keep_mbo = false;
+		c->enqueue_halt = false;
+		c->is_poisoned = false;
+		c->cfg.direction = 0;
+		c->cfg.data_type = 0;
+		c->cfg.num_buffers = 0;
+		c->cfg.buffer_size = 0;
+		c->cfg.subbuffer_size = 0;
+		c->cfg.packets_per_xact = 0;
+		spin_lock_init(&c->fifo_lock);
+		INIT_LIST_HEAD(&c->fifo);
+		INIT_LIST_HEAD(&c->trash_fifo);
+		INIT_LIST_HEAD(&c->halt_fifo);
+		init_completion(&c->cleanup);
+		atomic_set(&c->mbo_ref, 0);
+		mutex_init(&c->start_mutex);
+		mutex_init(&c->nq_mutex);
+		list_add_tail(&c->list, &iface->p->channel_list);
+		if (device_register(&c->dev)) {
+			dev_err(&c->dev, "Failed to register channel device\n");
+			goto err_free_most_channel;
+		}
+	}
+	most_interface_register_notify(iface->description);
+	return 0;
+
+err_free_most_channel:
+	put_device(&c->dev);
+
+err_free_resources:
+	while (i > 0) {
+		c = iface->p->channel[--i];
+		device_unregister(&c->dev);
+	}
+	kfree(iface->p);
+	device_unregister(iface->dev);
+	ida_simple_remove(&mdev_id, id);
+	return -ENOMEM;
+}
+EXPORT_SYMBOL_GPL(most_register_interface);
+
+/**
+ * most_deregister_interface - deregisters an interface with core
+ * @iface: device interface
+ *
+ * Before removing an interface instance from the list, all running
+ * channels are stopped and poisoned.
+ */
+void most_deregister_interface(struct most_interface *iface)
+{
+	int i;
+	struct most_channel *c;
+
+	for (i = 0; i < iface->num_channels; i++) {
+		c = iface->p->channel[i];
+		if (c->pipe0.comp)
+			c->pipe0.comp->disconnect_channel(c->iface,
+							c->channel_id);
+		if (c->pipe1.comp)
+			c->pipe1.comp->disconnect_channel(c->iface,
+							c->channel_id);
+		c->pipe0.comp = NULL;
+		c->pipe1.comp = NULL;
+		list_del(&c->list);
+		device_unregister(&c->dev);
+	}
+
+	ida_simple_remove(&mdev_id, iface->p->dev_id);
+	kfree(iface->p);
+	device_unregister(iface->dev);
+}
+EXPORT_SYMBOL_GPL(most_deregister_interface);
+
+/**
+ * most_stop_enqueue - prevents core from enqueueing MBOs
+ * @iface: pointer to interface
+ * @id: channel id
+ *
+ * This is called by an HDM that _cannot_ attend to its duties and
+ * is imminent to get run over by the core. The core is not going to
+ * enqueue any further packets unless the flagging HDM calls
+ * most_resume enqueue().
+ */
+void most_stop_enqueue(struct most_interface *iface, int id)
+{
+	struct most_channel *c = iface->p->channel[id];
+
+	if (!c)
+		return;
+
+	mutex_lock(&c->nq_mutex);
+	c->enqueue_halt = true;
+	mutex_unlock(&c->nq_mutex);
+}
+EXPORT_SYMBOL_GPL(most_stop_enqueue);
+
+/**
+ * most_resume_enqueue - allow core to enqueue MBOs again
+ * @iface: pointer to interface
+ * @id: channel id
+ *
+ * This clears the enqueue halt flag and enqueues all MBOs currently
+ * sitting in the wait fifo.
+ */
+void most_resume_enqueue(struct most_interface *iface, int id)
+{
+	struct most_channel *c = iface->p->channel[id];
+
+	if (!c)
+		return;
+
+	mutex_lock(&c->nq_mutex);
+	c->enqueue_halt = false;
+	mutex_unlock(&c->nq_mutex);
+
+	wake_up_interruptible(&c->hdm_fifo_wq);
+}
+EXPORT_SYMBOL_GPL(most_resume_enqueue);
+
+static int __init most_init(void)
+{
+	int err;
+
+	INIT_LIST_HEAD(&comp_list);
+	ida_init(&mdev_id);
+
+	err = bus_register(&mostbus);
+	if (err) {
+		pr_err("Failed to register most bus\n");
+		return err;
+	}
+	err = driver_register(&mostbus_driver);
+	if (err) {
+		pr_err("Failed to register core driver\n");
+		goto err_unregister_bus;
+	}
+	configfs_init();
+	return 0;
+
+err_unregister_bus:
+	bus_unregister(&mostbus);
+	return err;
+}
+
+static void __exit most_exit(void)
+{
+	driver_unregister(&mostbus_driver);
+	bus_unregister(&mostbus);
+	ida_destroy(&mdev_id);
+}
+
+subsys_initcall(most_init);
+module_exit(most_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Christian Gromm <christian.gromm@microchip.com>");
+MODULE_DESCRIPTION("Core module of stacked MOST Linux driver");
diff --git a/drivers/most/most_cdev.c b/drivers/most/most_cdev.c
new file mode 100644
index 0000000000..3ed8f461e0
--- /dev/null
+++ b/drivers/most/most_cdev.c
@@ -0,0 +1,542 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * cdev.c - Character device component for Mostcore
+ *
+ * Copyright (C) 2013-2015 Microchip Technology Germany II GmbH & Co. KG
+ */
+
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/device.h>
+#include <linux/cdev.h>
+#include <linux/poll.h>
+#include <linux/kfifo.h>
+#include <linux/uaccess.h>
+#include <linux/idr.h>
+#include <linux/most.h>
+
+#define CHRDEV_REGION_SIZE 50
+
+static struct cdev_component {
+	dev_t devno;
+	struct ida minor_id;
+	unsigned int major;
+	struct class *class;
+	struct most_component cc;
+} comp;
+
+struct comp_channel {
+	wait_queue_head_t wq;
+	spinlock_t unlink;	/* synchronization lock to unlink channels */
+	struct cdev cdev;
+	struct device *dev;
+	struct mutex io_mutex;
+	struct most_interface *iface;
+	struct most_channel_config *cfg;
+	unsigned int channel_id;
+	dev_t devno;
+	size_t mbo_offs;
+	DECLARE_KFIFO_PTR(fifo, typeof(struct mbo *));
+	int access_ref;
+	struct list_head list;
+};
+
+#define to_channel(d) container_of(d, struct comp_channel, cdev)
+static LIST_HEAD(channel_list);
+static DEFINE_SPINLOCK(ch_list_lock);
+
+static inline bool ch_has_mbo(struct comp_channel *c)
+{
+	return channel_has_mbo(c->iface, c->channel_id, &comp.cc) > 0;
+}
+
+static inline struct mbo *ch_get_mbo(struct comp_channel *c, struct mbo **mbo)
+{
+	if (!kfifo_peek(&c->fifo, mbo)) {
+		*mbo = most_get_mbo(c->iface, c->channel_id, &comp.cc);
+		if (*mbo)
+			kfifo_in(&c->fifo, mbo, 1);
+	}
+	return *mbo;
+}
+
+static struct comp_channel *get_channel(struct most_interface *iface, int id)
+{
+	struct comp_channel *c, *tmp;
+	unsigned long flags;
+
+	spin_lock_irqsave(&ch_list_lock, flags);
+	list_for_each_entry_safe(c, tmp, &channel_list, list) {
+		if ((c->iface == iface) && (c->channel_id == id)) {
+			spin_unlock_irqrestore(&ch_list_lock, flags);
+			return c;
+		}
+	}
+	spin_unlock_irqrestore(&ch_list_lock, flags);
+	return NULL;
+}
+
+static void stop_channel(struct comp_channel *c)
+{
+	struct mbo *mbo;
+
+	while (kfifo_out((struct kfifo *)&c->fifo, &mbo, 1))
+		most_put_mbo(mbo);
+	most_stop_channel(c->iface, c->channel_id, &comp.cc);
+}
+
+static void destroy_cdev(struct comp_channel *c)
+{
+	unsigned long flags;
+
+	device_destroy(comp.class, c->devno);
+	cdev_del(&c->cdev);
+	spin_lock_irqsave(&ch_list_lock, flags);
+	list_del(&c->list);
+	spin_unlock_irqrestore(&ch_list_lock, flags);
+}
+
+static void destroy_channel(struct comp_channel *c)
+{
+	ida_simple_remove(&comp.minor_id, MINOR(c->devno));
+	kfifo_free(&c->fifo);
+	kfree(c);
+}
+
+/**
+ * comp_open - implements the syscall to open the device
+ * @inode: inode pointer
+ * @filp: file pointer
+ *
+ * This stores the channel pointer in the private data field of
+ * the file structure and activates the channel within the core.
+ */
+static int comp_open(struct inode *inode, struct file *filp)
+{
+	struct comp_channel *c;
+	int ret;
+
+	c = to_channel(inode->i_cdev);
+	filp->private_data = c;
+
+	if (((c->cfg->direction == MOST_CH_RX) &&
+	     ((filp->f_flags & O_ACCMODE) != O_RDONLY)) ||
+	     ((c->cfg->direction == MOST_CH_TX) &&
+		((filp->f_flags & O_ACCMODE) != O_WRONLY))) {
+		return -EACCES;
+	}
+
+	mutex_lock(&c->io_mutex);
+	if (!c->dev) {
+		mutex_unlock(&c->io_mutex);
+		return -ENODEV;
+	}
+
+	if (c->access_ref) {
+		mutex_unlock(&c->io_mutex);
+		return -EBUSY;
+	}
+
+	c->mbo_offs = 0;
+	ret = most_start_channel(c->iface, c->channel_id, &comp.cc);
+	if (!ret)
+		c->access_ref = 1;
+	mutex_unlock(&c->io_mutex);
+	return ret;
+}
+
+/**
+ * comp_close - implements the syscall to close the device
+ * @inode: inode pointer
+ * @filp: file pointer
+ *
+ * This stops the channel within the core.
+ */
+static int comp_close(struct inode *inode, struct file *filp)
+{
+	struct comp_channel *c = to_channel(inode->i_cdev);
+
+	mutex_lock(&c->io_mutex);
+	spin_lock(&c->unlink);
+	c->access_ref = 0;
+	spin_unlock(&c->unlink);
+	if (c->dev) {
+		stop_channel(c);
+		mutex_unlock(&c->io_mutex);
+	} else {
+		mutex_unlock(&c->io_mutex);
+		destroy_channel(c);
+	}
+	return 0;
+}
+
+/**
+ * comp_write - implements the syscall to write to the device
+ * @filp: file pointer
+ * @buf: pointer to user buffer
+ * @count: number of bytes to write
+ * @offset: offset from where to start writing
+ */
+static ssize_t comp_write(struct file *filp, const char __user *buf,
+			  size_t count, loff_t *offset)
+{
+	int ret;
+	size_t to_copy, left;
+	struct mbo *mbo = NULL;
+	struct comp_channel *c = filp->private_data;
+
+	mutex_lock(&c->io_mutex);
+	while (c->dev && !ch_get_mbo(c, &mbo)) {
+		mutex_unlock(&c->io_mutex);
+
+		if ((filp->f_flags & O_NONBLOCK))
+			return -EAGAIN;
+		if (wait_event_interruptible(c->wq, ch_has_mbo(c) || !c->dev))
+			return -ERESTARTSYS;
+		mutex_lock(&c->io_mutex);
+	}
+
+	if (unlikely(!c->dev)) {
+		ret = -ENODEV;
+		goto unlock;
+	}
+
+	to_copy = min(count, c->cfg->buffer_size - c->mbo_offs);
+	left = copy_from_user(mbo->virt_address + c->mbo_offs, buf, to_copy);
+	if (left == to_copy) {
+		ret = -EFAULT;
+		goto unlock;
+	}
+
+	c->mbo_offs += to_copy - left;
+	if (c->mbo_offs >= c->cfg->buffer_size ||
+	    c->cfg->data_type == MOST_CH_CONTROL ||
+	    c->cfg->data_type == MOST_CH_ASYNC) {
+		kfifo_skip(&c->fifo);
+		mbo->buffer_length = c->mbo_offs;
+		c->mbo_offs = 0;
+		most_submit_mbo(mbo);
+	}
+
+	ret = to_copy - left;
+unlock:
+	mutex_unlock(&c->io_mutex);
+	return ret;
+}
+
+/**
+ * comp_read - implements the syscall to read from the device
+ * @filp: file pointer
+ * @buf: pointer to user buffer
+ * @count: number of bytes to read
+ * @offset: offset from where to start reading
+ */
+static ssize_t
+comp_read(struct file *filp, char __user *buf, size_t count, loff_t *offset)
+{
+	size_t to_copy, not_copied, copied;
+	struct mbo *mbo = NULL;
+	struct comp_channel *c = filp->private_data;
+
+	mutex_lock(&c->io_mutex);
+	while (c->dev && !kfifo_peek(&c->fifo, &mbo)) {
+		mutex_unlock(&c->io_mutex);
+		if (filp->f_flags & O_NONBLOCK)
+			return -EAGAIN;
+		if (wait_event_interruptible(c->wq,
+					     (!kfifo_is_empty(&c->fifo) ||
+					      (!c->dev))))
+			return -ERESTARTSYS;
+		mutex_lock(&c->io_mutex);
+	}
+
+	/* make sure we don't submit to gone devices */
+	if (unlikely(!c->dev)) {
+		mutex_unlock(&c->io_mutex);
+		return -ENODEV;
+	}
+
+	to_copy = min_t(size_t,
+			count,
+			mbo->processed_length - c->mbo_offs);
+
+	not_copied = copy_to_user(buf,
+				  mbo->virt_address + c->mbo_offs,
+				  to_copy);
+
+	copied = to_copy - not_copied;
+
+	c->mbo_offs += copied;
+	if (c->mbo_offs >= mbo->processed_length) {
+		kfifo_skip(&c->fifo);
+		most_put_mbo(mbo);
+		c->mbo_offs = 0;
+	}
+	mutex_unlock(&c->io_mutex);
+	return copied;
+}
+
+static __poll_t comp_poll(struct file *filp, poll_table *wait)
+{
+	struct comp_channel *c = filp->private_data;
+	__poll_t mask = 0;
+
+	poll_wait(filp, &c->wq, wait);
+
+	mutex_lock(&c->io_mutex);
+	if (c->cfg->direction == MOST_CH_RX) {
+		if (!c->dev || !kfifo_is_empty(&c->fifo))
+			mask |= EPOLLIN | EPOLLRDNORM;
+	} else {
+		if (!c->dev || !kfifo_is_empty(&c->fifo) || ch_has_mbo(c))
+			mask |= EPOLLOUT | EPOLLWRNORM;
+	}
+	mutex_unlock(&c->io_mutex);
+	return mask;
+}
+
+/*
+ * Initialization of struct file_operations
+ */
+static const struct file_operations channel_fops = {
+	.owner = THIS_MODULE,
+	.read = comp_read,
+	.write = comp_write,
+	.open = comp_open,
+	.release = comp_close,
+	.poll = comp_poll,
+};
+
+/**
+ * comp_disconnect_channel - disconnect a channel
+ * @iface: pointer to interface instance
+ * @channel_id: channel index
+ *
+ * This frees allocated memory and removes the cdev that represents this
+ * channel in user space.
+ */
+static int comp_disconnect_channel(struct most_interface *iface, int channel_id)
+{
+	struct comp_channel *c;
+
+	c = get_channel(iface, channel_id);
+	if (!c)
+		return -EINVAL;
+
+	mutex_lock(&c->io_mutex);
+	spin_lock(&c->unlink);
+	c->dev = NULL;
+	spin_unlock(&c->unlink);
+	destroy_cdev(c);
+	if (c->access_ref) {
+		stop_channel(c);
+		wake_up_interruptible(&c->wq);
+		mutex_unlock(&c->io_mutex);
+	} else {
+		mutex_unlock(&c->io_mutex);
+		destroy_channel(c);
+	}
+	return 0;
+}
+
+/**
+ * comp_rx_completion - completion handler for rx channels
+ * @mbo: pointer to buffer object that has completed
+ *
+ * This searches for the channel linked to this MBO and stores it in the local
+ * fifo buffer.
+ */
+static int comp_rx_completion(struct mbo *mbo)
+{
+	struct comp_channel *c;
+
+	if (!mbo)
+		return -EINVAL;
+
+	c = get_channel(mbo->ifp, mbo->hdm_channel_id);
+	if (!c)
+		return -EINVAL;
+
+	spin_lock(&c->unlink);
+	if (!c->access_ref || !c->dev) {
+		spin_unlock(&c->unlink);
+		return -ENODEV;
+	}
+	kfifo_in(&c->fifo, &mbo, 1);
+	spin_unlock(&c->unlink);
+#ifdef DEBUG_MESG
+	if (kfifo_is_full(&c->fifo))
+		dev_warn(c->dev, "Fifo is full\n");
+#endif
+	wake_up_interruptible(&c->wq);
+	return 0;
+}
+
+/**
+ * comp_tx_completion - completion handler for tx channels
+ * @iface: pointer to interface instance
+ * @channel_id: channel index/ID
+ *
+ * This wakes sleeping processes in the wait-queue.
+ */
+static int comp_tx_completion(struct most_interface *iface, int channel_id)
+{
+	struct comp_channel *c;
+
+	c = get_channel(iface, channel_id);
+	if (!c)
+		return -EINVAL;
+
+	if ((channel_id < 0) || (channel_id >= iface->num_channels)) {
+		dev_warn(c->dev, "Channel ID out of range\n");
+		return -EINVAL;
+	}
+
+	wake_up_interruptible(&c->wq);
+	return 0;
+}
+
+/**
+ * comp_probe - probe function of the driver module
+ * @iface: pointer to interface instance
+ * @channel_id: channel index/ID
+ * @cfg: pointer to actual channel configuration
+ * @name: name of the device to be created
+ * @args: pointer to array of component parameters (from configfs)
+ *
+ * This allocates a channel object and creates the device node in /dev
+ *
+ * Returns 0 on success or error code otherwise.
+ */
+static int comp_probe(struct most_interface *iface, int channel_id,
+		      struct most_channel_config *cfg, char *name, char *args)
+{
+	struct comp_channel *c;
+	unsigned long cl_flags;
+	int retval;
+	int current_minor;
+
+	if (!cfg || !name)
+		return -EINVAL;
+
+	c = get_channel(iface, channel_id);
+	if (c)
+		return -EEXIST;
+
+	current_minor = ida_simple_get(&comp.minor_id, 0, 0, GFP_KERNEL);
+	if (current_minor < 0)
+		return current_minor;
+
+	c = kzalloc(sizeof(*c), GFP_KERNEL);
+	if (!c) {
+		retval = -ENOMEM;
+		goto err_remove_ida;
+	}
+
+	c->devno = MKDEV(comp.major, current_minor);
+	cdev_init(&c->cdev, &channel_fops);
+	c->cdev.owner = THIS_MODULE;
+	retval = cdev_add(&c->cdev, c->devno, 1);
+	if (retval < 0)
+		goto err_free_c;
+	c->iface = iface;
+	c->cfg = cfg;
+	c->channel_id = channel_id;
+	c->access_ref = 0;
+	spin_lock_init(&c->unlink);
+	INIT_KFIFO(c->fifo);
+	retval = kfifo_alloc(&c->fifo, cfg->num_buffers, GFP_KERNEL);
+	if (retval)
+		goto err_del_cdev_and_free_channel;
+	init_waitqueue_head(&c->wq);
+	mutex_init(&c->io_mutex);
+	spin_lock_irqsave(&ch_list_lock, cl_flags);
+	list_add_tail(&c->list, &channel_list);
+	spin_unlock_irqrestore(&ch_list_lock, cl_flags);
+	c->dev = device_create(comp.class, NULL, c->devno, NULL, "%s", name);
+
+	if (IS_ERR(c->dev)) {
+		retval = PTR_ERR(c->dev);
+		goto err_free_kfifo_and_del_list;
+	}
+	kobject_uevent(&c->dev->kobj, KOBJ_ADD);
+	return 0;
+
+err_free_kfifo_and_del_list:
+	kfifo_free(&c->fifo);
+	list_del(&c->list);
+err_del_cdev_and_free_channel:
+	cdev_del(&c->cdev);
+err_free_c:
+	kfree(c);
+err_remove_ida:
+	ida_simple_remove(&comp.minor_id, current_minor);
+	return retval;
+}
+
+static struct cdev_component comp = {
+	.cc = {
+		.mod = THIS_MODULE,
+		.name = "cdev",
+		.probe_channel = comp_probe,
+		.disconnect_channel = comp_disconnect_channel,
+		.rx_completion = comp_rx_completion,
+		.tx_completion = comp_tx_completion,
+	},
+};
+
+static int __init most_cdev_init(void)
+{
+	int err;
+
+	comp.class = class_create("most_cdev");
+	if (IS_ERR(comp.class))
+		return PTR_ERR(comp.class);
+
+	ida_init(&comp.minor_id);
+
+	err = alloc_chrdev_region(&comp.devno, 0, CHRDEV_REGION_SIZE, "cdev");
+	if (err < 0)
+		goto dest_ida;
+	comp.major = MAJOR(comp.devno);
+	err = most_register_component(&comp.cc);
+	if (err)
+		goto free_cdev;
+	err = most_register_configfs_subsys(&comp.cc);
+	if (err)
+		goto deregister_comp;
+	return 0;
+
+deregister_comp:
+	most_deregister_component(&comp.cc);
+free_cdev:
+	unregister_chrdev_region(comp.devno, CHRDEV_REGION_SIZE);
+dest_ida:
+	ida_destroy(&comp.minor_id);
+	class_destroy(comp.class);
+	return err;
+}
+
+static void __exit most_cdev_exit(void)
+{
+	struct comp_channel *c, *tmp;
+
+	most_deregister_configfs_subsys(&comp.cc);
+	most_deregister_component(&comp.cc);
+
+	list_for_each_entry_safe(c, tmp, &channel_list, list) {
+		destroy_cdev(c);
+		destroy_channel(c);
+	}
+	unregister_chrdev_region(comp.devno, CHRDEV_REGION_SIZE);
+	ida_destroy(&comp.minor_id);
+	class_destroy(comp.class);
+}
+
+module_init(most_cdev_init);
+module_exit(most_cdev_exit);
+MODULE_AUTHOR("Christian Gromm <christian.gromm@microchip.com>");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("character device component for mostcore");
diff --git a/drivers/most/most_snd.c b/drivers/most/most_snd.c
new file mode 100644
index 0000000000..45d762804c
--- /dev/null
+++ b/drivers/most/most_snd.c
@@ -0,0 +1,747 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * sound.c - Sound component for Mostcore
+ *
+ * Copyright (C) 2015 Microchip Technology Germany II GmbH & Co. KG
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/printk.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <sound/core.h>
+#include <sound/pcm.h>
+#include <sound/pcm_params.h>
+#include <linux/sched.h>
+#include <linux/kthread.h>
+#include <linux/most.h>
+
+#define DRIVER_NAME "sound"
+#define STRING_SIZE	80
+
+static struct most_component comp;
+
+/**
+ * struct channel - private structure to keep channel specific data
+ * @substream: stores the substream structure
+ * @pcm_hardware: low-level hardware description
+ * @iface: interface for which the channel belongs to
+ * @cfg: channel configuration
+ * @card: registered sound card
+ * @list: list for private use
+ * @id: channel index
+ * @period_pos: current period position (ring buffer)
+ * @buffer_pos: current buffer position (ring buffer)
+ * @is_stream_running: identifies whether a stream is running or not
+ * @opened: set when the stream is opened
+ * @playback_task: playback thread
+ * @playback_waitq: waitq used by playback thread
+ * @copy_fn: copy function for PCM-specific format and width
+ */
+struct channel {
+	struct snd_pcm_substream *substream;
+	struct snd_pcm_hardware pcm_hardware;
+	struct most_interface *iface;
+	struct most_channel_config *cfg;
+	struct snd_card *card;
+	struct list_head list;
+	int id;
+	unsigned int period_pos;
+	unsigned int buffer_pos;
+	bool is_stream_running;
+	struct task_struct *playback_task;
+	wait_queue_head_t playback_waitq;
+	void (*copy_fn)(void *alsa, void *most, unsigned int bytes);
+};
+
+struct sound_adapter {
+	struct list_head dev_list;
+	struct most_interface *iface;
+	struct snd_card *card;
+	struct list_head list;
+	bool registered;
+	int pcm_dev_idx;
+};
+
+static struct list_head adpt_list;
+
+#define MOST_PCM_INFO (SNDRV_PCM_INFO_MMAP | \
+		       SNDRV_PCM_INFO_MMAP_VALID | \
+		       SNDRV_PCM_INFO_BATCH | \
+		       SNDRV_PCM_INFO_INTERLEAVED | \
+		       SNDRV_PCM_INFO_BLOCK_TRANSFER)
+
+static void swap_copy16(u16 *dest, const u16 *source, unsigned int bytes)
+{
+	unsigned int i = 0;
+
+	while (i < (bytes / 2)) {
+		dest[i] = swab16(source[i]);
+		i++;
+	}
+}
+
+static void swap_copy24(u8 *dest, const u8 *source, unsigned int bytes)
+{
+	unsigned int i = 0;
+
+	if (bytes < 2)
+		return;
+	while (i < bytes - 2) {
+		dest[i] = source[i + 2];
+		dest[i + 1] = source[i + 1];
+		dest[i + 2] = source[i];
+		i += 3;
+	}
+}
+
+static void swap_copy32(u32 *dest, const u32 *source, unsigned int bytes)
+{
+	unsigned int i = 0;
+
+	while (i < bytes / 4) {
+		dest[i] = swab32(source[i]);
+		i++;
+	}
+}
+
+static void alsa_to_most_memcpy(void *alsa, void *most, unsigned int bytes)
+{
+	memcpy(most, alsa, bytes);
+}
+
+static void alsa_to_most_copy16(void *alsa, void *most, unsigned int bytes)
+{
+	swap_copy16(most, alsa, bytes);
+}
+
+static void alsa_to_most_copy24(void *alsa, void *most, unsigned int bytes)
+{
+	swap_copy24(most, alsa, bytes);
+}
+
+static void alsa_to_most_copy32(void *alsa, void *most, unsigned int bytes)
+{
+	swap_copy32(most, alsa, bytes);
+}
+
+static void most_to_alsa_memcpy(void *alsa, void *most, unsigned int bytes)
+{
+	memcpy(alsa, most, bytes);
+}
+
+static void most_to_alsa_copy16(void *alsa, void *most, unsigned int bytes)
+{
+	swap_copy16(alsa, most, bytes);
+}
+
+static void most_to_alsa_copy24(void *alsa, void *most, unsigned int bytes)
+{
+	swap_copy24(alsa, most, bytes);
+}
+
+static void most_to_alsa_copy32(void *alsa, void *most, unsigned int bytes)
+{
+	swap_copy32(alsa, most, bytes);
+}
+
+/**
+ * get_channel - get pointer to channel
+ * @iface: interface structure
+ * @channel_id: channel ID
+ *
+ * This traverses the channel list and returns the channel matching the
+ * ID and interface.
+ *
+ * Returns pointer to channel on success or NULL otherwise.
+ */
+static struct channel *get_channel(struct most_interface *iface,
+				   int channel_id)
+{
+	struct sound_adapter *adpt = iface->priv;
+	struct channel *channel;
+
+	list_for_each_entry(channel, &adpt->dev_list, list) {
+		if ((channel->iface == iface) && (channel->id == channel_id))
+			return channel;
+	}
+	return NULL;
+}
+
+/**
+ * copy_data - implements data copying function
+ * @channel: channel
+ * @mbo: MBO from core
+ *
+ * Copy data from/to ring buffer to/from MBO and update the buffer position
+ */
+static bool copy_data(struct channel *channel, struct mbo *mbo)
+{
+	struct snd_pcm_runtime *const runtime = channel->substream->runtime;
+	unsigned int const frame_bytes = channel->cfg->subbuffer_size;
+	unsigned int const buffer_size = runtime->buffer_size;
+	unsigned int frames;
+	unsigned int fr0;
+
+	if (channel->cfg->direction & MOST_CH_RX)
+		frames = mbo->processed_length / frame_bytes;
+	else
+		frames = mbo->buffer_length / frame_bytes;
+	fr0 = min(buffer_size - channel->buffer_pos, frames);
+
+	channel->copy_fn(runtime->dma_area + channel->buffer_pos * frame_bytes,
+			 mbo->virt_address,
+			 fr0 * frame_bytes);
+
+	if (frames > fr0) {
+		/* wrap around at end of ring buffer */
+		channel->copy_fn(runtime->dma_area,
+				 mbo->virt_address + fr0 * frame_bytes,
+				 (frames - fr0) * frame_bytes);
+	}
+
+	channel->buffer_pos += frames;
+	if (channel->buffer_pos >= buffer_size)
+		channel->buffer_pos -= buffer_size;
+	channel->period_pos += frames;
+	if (channel->period_pos >= runtime->period_size) {
+		channel->period_pos -= runtime->period_size;
+		return true;
+	}
+	return false;
+}
+
+/**
+ * playback_thread - function implements the playback thread
+ * @data: private data
+ *
+ * Thread which does the playback functionality in a loop. It waits for a free
+ * MBO from mostcore for a particular channel and copy the data from ring buffer
+ * to MBO. Submit the MBO back to mostcore, after copying the data.
+ *
+ * Returns 0 on success or error code otherwise.
+ */
+static int playback_thread(void *data)
+{
+	struct channel *const channel = data;
+
+	while (!kthread_should_stop()) {
+		struct mbo *mbo = NULL;
+		bool period_elapsed = false;
+
+		wait_event_interruptible(
+			channel->playback_waitq,
+			kthread_should_stop() ||
+			(channel->is_stream_running &&
+			 (mbo = most_get_mbo(channel->iface, channel->id,
+					     &comp))));
+		if (!mbo)
+			continue;
+
+		if (channel->is_stream_running)
+			period_elapsed = copy_data(channel, mbo);
+		else
+			memset(mbo->virt_address, 0, mbo->buffer_length);
+
+		most_submit_mbo(mbo);
+		if (period_elapsed)
+			snd_pcm_period_elapsed(channel->substream);
+	}
+	return 0;
+}
+
+/**
+ * pcm_open - implements open callback function for PCM middle layer
+ * @substream: pointer to ALSA PCM substream
+ *
+ * This is called when a PCM substream is opened. At least, the function should
+ * initialize the runtime->hw record.
+ *
+ * Returns 0 on success or error code otherwise.
+ */
+static int pcm_open(struct snd_pcm_substream *substream)
+{
+	struct channel *channel = substream->private_data;
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	struct most_channel_config *cfg = channel->cfg;
+	int ret;
+
+	channel->substream = substream;
+
+	if (cfg->direction == MOST_CH_TX) {
+		channel->playback_task = kthread_run(playback_thread, channel,
+						     "most_audio_playback");
+		if (IS_ERR(channel->playback_task)) {
+			pr_err("Couldn't start thread\n");
+			return PTR_ERR(channel->playback_task);
+		}
+	}
+
+	ret = most_start_channel(channel->iface, channel->id, &comp);
+	if (ret) {
+		pr_err("most_start_channel() failed!\n");
+		if (cfg->direction == MOST_CH_TX)
+			kthread_stop(channel->playback_task);
+		return ret;
+	}
+
+	runtime->hw = channel->pcm_hardware;
+	return 0;
+}
+
+/**
+ * pcm_close - implements close callback function for PCM middle layer
+ * @substream: sub-stream pointer
+ *
+ * Obviously, this is called when a PCM substream is closed. Any private
+ * instance for a PCM substream allocated in the open callback will be
+ * released here.
+ *
+ * Returns 0 on success or error code otherwise.
+ */
+static int pcm_close(struct snd_pcm_substream *substream)
+{
+	struct channel *channel = substream->private_data;
+
+	if (channel->cfg->direction == MOST_CH_TX)
+		kthread_stop(channel->playback_task);
+	most_stop_channel(channel->iface, channel->id, &comp);
+	return 0;
+}
+
+/**
+ * pcm_prepare - implements prepare callback function for PCM middle layer
+ * @substream: substream pointer
+ *
+ * This callback is called when the PCM is "prepared". Format rate, sample rate,
+ * etc., can be set here. This callback can be called many times at each setup.
+ *
+ * Returns 0 on success or error code otherwise.
+ */
+static int pcm_prepare(struct snd_pcm_substream *substream)
+{
+	struct channel *channel = substream->private_data;
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	struct most_channel_config *cfg = channel->cfg;
+	int width = snd_pcm_format_physical_width(runtime->format);
+
+	channel->copy_fn = NULL;
+
+	if (cfg->direction == MOST_CH_TX) {
+		if (snd_pcm_format_big_endian(runtime->format) || width == 8)
+			channel->copy_fn = alsa_to_most_memcpy;
+		else if (width == 16)
+			channel->copy_fn = alsa_to_most_copy16;
+		else if (width == 24)
+			channel->copy_fn = alsa_to_most_copy24;
+		else if (width == 32)
+			channel->copy_fn = alsa_to_most_copy32;
+	} else {
+		if (snd_pcm_format_big_endian(runtime->format) || width == 8)
+			channel->copy_fn = most_to_alsa_memcpy;
+		else if (width == 16)
+			channel->copy_fn = most_to_alsa_copy16;
+		else if (width == 24)
+			channel->copy_fn = most_to_alsa_copy24;
+		else if (width == 32)
+			channel->copy_fn = most_to_alsa_copy32;
+	}
+
+	if (!channel->copy_fn)
+		return -EINVAL;
+	channel->period_pos = 0;
+	channel->buffer_pos = 0;
+	return 0;
+}
+
+/**
+ * pcm_trigger - implements trigger callback function for PCM middle layer
+ * @substream: substream pointer
+ * @cmd: action to perform
+ *
+ * This is called when the PCM is started, stopped or paused. The action will be
+ * specified in the second argument, SNDRV_PCM_TRIGGER_XXX
+ *
+ * Returns 0 on success or error code otherwise.
+ */
+static int pcm_trigger(struct snd_pcm_substream *substream, int cmd)
+{
+	struct channel *channel = substream->private_data;
+
+	switch (cmd) {
+	case SNDRV_PCM_TRIGGER_START:
+		channel->is_stream_running = true;
+		wake_up_interruptible(&channel->playback_waitq);
+		return 0;
+
+	case SNDRV_PCM_TRIGGER_STOP:
+		channel->is_stream_running = false;
+		return 0;
+
+	default:
+		return -EINVAL;
+	}
+	return 0;
+}
+
+/**
+ * pcm_pointer - implements pointer callback function for PCM middle layer
+ * @substream: substream pointer
+ *
+ * This callback is called when the PCM middle layer inquires the current
+ * hardware position on the buffer. The position must be returned in frames,
+ * ranging from 0 to buffer_size-1.
+ */
+static snd_pcm_uframes_t pcm_pointer(struct snd_pcm_substream *substream)
+{
+	struct channel *channel = substream->private_data;
+
+	return channel->buffer_pos;
+}
+
+/*
+ * Initialization of struct snd_pcm_ops
+ */
+static const struct snd_pcm_ops pcm_ops = {
+	.open       = pcm_open,
+	.close      = pcm_close,
+	.prepare    = pcm_prepare,
+	.trigger    = pcm_trigger,
+	.pointer    = pcm_pointer,
+};
+
+static int split_arg_list(char *buf, u16 *ch_num, char **sample_res)
+{
+	char *num;
+	int ret;
+
+	num = strsep(&buf, "x");
+	if (!num)
+		goto err;
+	ret = kstrtou16(num, 0, ch_num);
+	if (ret)
+		goto err;
+	*sample_res = strsep(&buf, ".\n");
+	if (!*sample_res)
+		goto err;
+	return 0;
+
+err:
+	pr_err("Bad PCM format\n");
+	return -EINVAL;
+}
+
+static const struct sample_resolution_info {
+	const char *sample_res;
+	int bytes;
+	u64 formats;
+} sinfo[] = {
+	{ "8", 1, SNDRV_PCM_FMTBIT_S8 },
+	{ "16", 2, SNDRV_PCM_FMTBIT_S16_LE | SNDRV_PCM_FMTBIT_S16_BE },
+	{ "24", 3, SNDRV_PCM_FMTBIT_S24_3LE | SNDRV_PCM_FMTBIT_S24_3BE },
+	{ "32", 4, SNDRV_PCM_FMTBIT_S32_LE | SNDRV_PCM_FMTBIT_S32_BE },
+};
+
+static int audio_set_hw_params(struct snd_pcm_hardware *pcm_hw,
+			       u16 ch_num, char *sample_res,
+			       struct most_channel_config *cfg)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(sinfo); i++) {
+		if (!strcmp(sample_res, sinfo[i].sample_res))
+			goto found;
+	}
+	pr_err("Unsupported PCM format\n");
+	return -EINVAL;
+
+found:
+	if (!ch_num) {
+		pr_err("Bad number of channels\n");
+		return -EINVAL;
+	}
+
+	if (cfg->subbuffer_size != ch_num * sinfo[i].bytes) {
+		pr_err("Audio resolution doesn't fit subbuffer size\n");
+		return -EINVAL;
+	}
+
+	pcm_hw->info = MOST_PCM_INFO;
+	pcm_hw->rates = SNDRV_PCM_RATE_48000;
+	pcm_hw->rate_min = 48000;
+	pcm_hw->rate_max = 48000;
+	pcm_hw->buffer_bytes_max = cfg->num_buffers * cfg->buffer_size;
+	pcm_hw->period_bytes_min = cfg->buffer_size;
+	pcm_hw->period_bytes_max = cfg->buffer_size;
+	pcm_hw->periods_min = 1;
+	pcm_hw->periods_max = cfg->num_buffers;
+	pcm_hw->channels_min = ch_num;
+	pcm_hw->channels_max = ch_num;
+	pcm_hw->formats = sinfo[i].formats;
+	return 0;
+}
+
+static void release_adapter(struct sound_adapter *adpt)
+{
+	struct channel *channel, *tmp;
+
+	list_for_each_entry_safe(channel, tmp, &adpt->dev_list, list) {
+		list_del(&channel->list);
+		kfree(channel);
+	}
+	if (adpt->card)
+		snd_card_free(adpt->card);
+	list_del(&adpt->list);
+	kfree(adpt);
+}
+
+/**
+ * audio_probe_channel - probe function of the driver module
+ * @iface: pointer to interface instance
+ * @channel_id: channel index/ID
+ * @cfg: pointer to actual channel configuration
+ * @device_name: name of the device to be created in /dev
+ * @arg_list: string that provides the desired audio resolution
+ *
+ * Creates sound card, pcm device, sets pcm ops and registers sound card.
+ *
+ * Returns 0 on success or error code otherwise.
+ */
+static int audio_probe_channel(struct most_interface *iface, int channel_id,
+			       struct most_channel_config *cfg,
+			       char *device_name, char *arg_list)
+{
+	struct channel *channel;
+	struct sound_adapter *adpt;
+	struct snd_pcm *pcm;
+	int playback_count = 0;
+	int capture_count = 0;
+	int ret;
+	int direction;
+	u16 ch_num;
+	char *sample_res;
+	char arg_list_cpy[STRING_SIZE];
+
+	if (cfg->data_type != MOST_CH_SYNC) {
+		pr_err("Incompatible channel type\n");
+		return -EINVAL;
+	}
+	strscpy(arg_list_cpy, arg_list, STRING_SIZE);
+	ret = split_arg_list(arg_list_cpy, &ch_num, &sample_res);
+	if (ret < 0)
+		return ret;
+
+	list_for_each_entry(adpt, &adpt_list, list) {
+		if (adpt->iface != iface)
+			continue;
+		if (adpt->registered)
+			return -ENOSPC;
+		adpt->pcm_dev_idx++;
+		goto skip_adpt_alloc;
+	}
+	adpt = kzalloc(sizeof(*adpt), GFP_KERNEL);
+	if (!adpt)
+		return -ENOMEM;
+
+	adpt->iface = iface;
+	INIT_LIST_HEAD(&adpt->dev_list);
+	iface->priv = adpt;
+	list_add_tail(&adpt->list, &adpt_list);
+	ret = snd_card_new(iface->driver_dev, -1, "INIC", THIS_MODULE,
+			   sizeof(*channel), &adpt->card);
+	if (ret < 0)
+		goto err_free_adpt;
+	snprintf(adpt->card->driver, sizeof(adpt->card->driver),
+		 "%s", DRIVER_NAME);
+	snprintf(adpt->card->shortname, sizeof(adpt->card->shortname),
+		 "Microchip INIC");
+	snprintf(adpt->card->longname, sizeof(adpt->card->longname),
+		 "%s at %s", adpt->card->shortname, iface->description);
+skip_adpt_alloc:
+	if (get_channel(iface, channel_id)) {
+		pr_err("channel (%s:%d) is already linked\n",
+		       iface->description, channel_id);
+		return -EEXIST;
+	}
+
+	if (cfg->direction == MOST_CH_TX) {
+		playback_count = 1;
+		direction = SNDRV_PCM_STREAM_PLAYBACK;
+	} else {
+		capture_count = 1;
+		direction = SNDRV_PCM_STREAM_CAPTURE;
+	}
+	channel = kzalloc(sizeof(*channel), GFP_KERNEL);
+	if (!channel) {
+		ret = -ENOMEM;
+		goto err_free_adpt;
+	}
+	channel->card = adpt->card;
+	channel->cfg = cfg;
+	channel->iface = iface;
+	channel->id = channel_id;
+	init_waitqueue_head(&channel->playback_waitq);
+	list_add_tail(&channel->list, &adpt->dev_list);
+
+	ret = audio_set_hw_params(&channel->pcm_hardware, ch_num, sample_res,
+				  cfg);
+	if (ret)
+		goto err_free_adpt;
+
+	ret = snd_pcm_new(adpt->card, device_name, adpt->pcm_dev_idx,
+			  playback_count, capture_count, &pcm);
+
+	if (ret < 0)
+		goto err_free_adpt;
+
+	pcm->private_data = channel;
+	strscpy(pcm->name, device_name, sizeof(pcm->name));
+	snd_pcm_set_ops(pcm, direction, &pcm_ops);
+	snd_pcm_set_managed_buffer_all(pcm, SNDRV_DMA_TYPE_VMALLOC, NULL, 0, 0);
+	return 0;
+
+err_free_adpt:
+	release_adapter(adpt);
+	return ret;
+}
+
+static int audio_create_sound_card(void)
+{
+	int ret;
+	struct sound_adapter *adpt;
+
+	list_for_each_entry(adpt, &adpt_list, list) {
+		if (!adpt->registered)
+			goto adpt_alloc;
+	}
+	return -ENODEV;
+adpt_alloc:
+	ret = snd_card_register(adpt->card);
+	if (ret < 0) {
+		release_adapter(adpt);
+		return ret;
+	}
+	adpt->registered = true;
+	return 0;
+}
+
+/**
+ * audio_disconnect_channel - function to disconnect a channel
+ * @iface: pointer to interface instance
+ * @channel_id: channel index
+ *
+ * This frees allocated memory and removes the sound card from ALSA
+ *
+ * Returns 0 on success or error code otherwise.
+ */
+static int audio_disconnect_channel(struct most_interface *iface,
+				    int channel_id)
+{
+	struct channel *channel;
+	struct sound_adapter *adpt = iface->priv;
+
+	channel = get_channel(iface, channel_id);
+	if (!channel)
+		return -EINVAL;
+
+	list_del(&channel->list);
+
+	kfree(channel);
+	if (list_empty(&adpt->dev_list))
+		release_adapter(adpt);
+	return 0;
+}
+
+/**
+ * audio_rx_completion - completion handler for rx channels
+ * @mbo: pointer to buffer object that has completed
+ *
+ * This searches for the channel this MBO belongs to and copy the data from MBO
+ * to ring buffer
+ *
+ * Returns 0 on success or error code otherwise.
+ */
+static int audio_rx_completion(struct mbo *mbo)
+{
+	struct channel *channel = get_channel(mbo->ifp, mbo->hdm_channel_id);
+	bool period_elapsed = false;
+
+	if (!channel)
+		return -EINVAL;
+	if (channel->is_stream_running)
+		period_elapsed = copy_data(channel, mbo);
+	most_put_mbo(mbo);
+	if (period_elapsed)
+		snd_pcm_period_elapsed(channel->substream);
+	return 0;
+}
+
+/**
+ * audio_tx_completion - completion handler for tx channels
+ * @iface: pointer to interface instance
+ * @channel_id: channel index/ID
+ *
+ * This searches the channel that belongs to this combination of interface
+ * pointer and channel ID and wakes a process sitting in the wait queue of
+ * this channel.
+ *
+ * Returns 0 on success or error code otherwise.
+ */
+static int audio_tx_completion(struct most_interface *iface, int channel_id)
+{
+	struct channel *channel = get_channel(iface, channel_id);
+
+	if (!channel)
+		return -EINVAL;
+
+	wake_up_interruptible(&channel->playback_waitq);
+	return 0;
+}
+
+/*
+ * Initialization of the struct most_component
+ */
+static struct most_component comp = {
+	.mod = THIS_MODULE,
+	.name = DRIVER_NAME,
+	.probe_channel = audio_probe_channel,
+	.disconnect_channel = audio_disconnect_channel,
+	.rx_completion = audio_rx_completion,
+	.tx_completion = audio_tx_completion,
+	.cfg_complete = audio_create_sound_card,
+};
+
+static int __init audio_init(void)
+{
+	int ret;
+
+	INIT_LIST_HEAD(&adpt_list);
+
+	ret = most_register_component(&comp);
+	if (ret) {
+		pr_err("Failed to register %s\n", comp.name);
+		return ret;
+	}
+	ret = most_register_configfs_subsys(&comp);
+	if (ret) {
+		pr_err("Failed to register %s configfs subsys\n", comp.name);
+		most_deregister_component(&comp);
+	}
+	return ret;
+}
+
+static void __exit audio_exit(void)
+{
+	most_deregister_configfs_subsys(&comp);
+	most_deregister_component(&comp);
+}
+
+module_init(audio_init);
+module_exit(audio_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Christian Gromm <christian.gromm@microchip.com>");
+MODULE_DESCRIPTION("Sound Component Module for Mostcore");
diff --git a/drivers/most/most_usb.c b/drivers/most/most_usb.c
new file mode 100644
index 0000000000..485d5ca399
--- /dev/null
+++ b/drivers/most/most_usb.c
@@ -0,0 +1,1171 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * usb.c - Hardware dependent module for USB
+ *
+ * Copyright (C) 2013-2015 Microchip Technology Germany II GmbH & Co. KG
+ */
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/usb.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/cdev.h>
+#include <linux/device.h>
+#include <linux/list.h>
+#include <linux/completion.h>
+#include <linux/mutex.h>
+#include <linux/spinlock.h>
+#include <linux/interrupt.h>
+#include <linux/workqueue.h>
+#include <linux/sysfs.h>
+#include <linux/dma-mapping.h>
+#include <linux/etherdevice.h>
+#include <linux/uaccess.h>
+#include <linux/most.h>
+
+#define USB_MTU			512
+#define NO_ISOCHRONOUS_URB	0
+#define AV_PACKETS_PER_XACT	2
+#define BUF_CHAIN_SIZE		0xFFFF
+#define MAX_NUM_ENDPOINTS	30
+#define MAX_SUFFIX_LEN		10
+#define MAX_STRING_LEN		80
+#define MAX_BUF_SIZE		0xFFFF
+
+#define USB_VENDOR_ID_SMSC	0x0424  /* VID: SMSC */
+#define USB_DEV_ID_BRDG		0xC001  /* PID: USB Bridge */
+#define USB_DEV_ID_OS81118	0xCF18  /* PID: USB OS81118 */
+#define USB_DEV_ID_OS81119	0xCF19  /* PID: USB OS81119 */
+#define USB_DEV_ID_OS81210	0xCF30  /* PID: USB OS81210 */
+/* DRCI Addresses */
+#define DRCI_REG_NI_STATE	0x0100
+#define DRCI_REG_PACKET_BW	0x0101
+#define DRCI_REG_NODE_ADDR	0x0102
+#define DRCI_REG_NODE_POS	0x0103
+#define DRCI_REG_MEP_FILTER	0x0140
+#define DRCI_REG_HASH_TBL0	0x0141
+#define DRCI_REG_HASH_TBL1	0x0142
+#define DRCI_REG_HASH_TBL2	0x0143
+#define DRCI_REG_HASH_TBL3	0x0144
+#define DRCI_REG_HW_ADDR_HI	0x0145
+#define DRCI_REG_HW_ADDR_MI	0x0146
+#define DRCI_REG_HW_ADDR_LO	0x0147
+#define DRCI_REG_BASE		0x1100
+#define DRCI_COMMAND		0x02
+#define DRCI_READ_REQ		0xA0
+#define DRCI_WRITE_REQ		0xA1
+
+/**
+ * struct most_dci_obj - Direct Communication Interface
+ * @kobj:position in sysfs
+ * @usb_device: pointer to the usb device
+ * @reg_addr: register address for arbitrary DCI access
+ */
+struct most_dci_obj {
+	struct device dev;
+	struct usb_device *usb_device;
+	u16 reg_addr;
+};
+
+#define to_dci_obj(p) container_of(p, struct most_dci_obj, dev)
+
+struct most_dev;
+
+struct clear_hold_work {
+	struct work_struct ws;
+	struct most_dev *mdev;
+	unsigned int channel;
+	int pipe;
+};
+
+#define to_clear_hold_work(w) container_of(w, struct clear_hold_work, ws)
+
+/**
+ * struct most_dev - holds all usb interface specific stuff
+ * @usb_device: pointer to usb device
+ * @iface: hardware interface
+ * @cap: channel capabilities
+ * @conf: channel configuration
+ * @dci: direct communication interface of hardware
+ * @ep_address: endpoint address table
+ * @description: device description
+ * @suffix: suffix for channel name
+ * @channel_lock: synchronize channel access
+ * @padding_active: indicates channel uses padding
+ * @is_channel_healthy: health status table of each channel
+ * @busy_urbs: list of anchored items
+ * @io_mutex: synchronize I/O with disconnect
+ * @link_stat_timer: timer for link status reports
+ * @poll_work_obj: work for polling link status
+ */
+struct most_dev {
+	struct device dev;
+	struct usb_device *usb_device;
+	struct most_interface iface;
+	struct most_channel_capability *cap;
+	struct most_channel_config *conf;
+	struct most_dci_obj *dci;
+	u8 *ep_address;
+	char description[MAX_STRING_LEN];
+	char suffix[MAX_NUM_ENDPOINTS][MAX_SUFFIX_LEN];
+	spinlock_t channel_lock[MAX_NUM_ENDPOINTS]; /* sync channel access */
+	bool padding_active[MAX_NUM_ENDPOINTS];
+	bool is_channel_healthy[MAX_NUM_ENDPOINTS];
+	struct clear_hold_work clear_work[MAX_NUM_ENDPOINTS];
+	struct usb_anchor *busy_urbs;
+	struct mutex io_mutex;
+	struct timer_list link_stat_timer;
+	struct work_struct poll_work_obj;
+	void (*on_netinfo)(struct most_interface *most_iface,
+			   unsigned char link_state, unsigned char *addrs);
+};
+
+#define to_mdev(d) container_of(d, struct most_dev, iface)
+#define to_mdev_from_dev(d) container_of(d, struct most_dev, dev)
+#define to_mdev_from_work(w) container_of(w, struct most_dev, poll_work_obj)
+
+static void wq_clear_halt(struct work_struct *wq_obj);
+static void wq_netinfo(struct work_struct *wq_obj);
+
+/**
+ * drci_rd_reg - read a DCI register
+ * @dev: usb device
+ * @reg: register address
+ * @buf: buffer to store data
+ *
+ * This is reads data from INIC's direct register communication interface
+ */
+static inline int drci_rd_reg(struct usb_device *dev, u16 reg, u16 *buf)
+{
+	int retval;
+	__le16 *dma_buf;
+	u8 req_type = USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE;
+
+	dma_buf = kzalloc(sizeof(*dma_buf), GFP_KERNEL);
+	if (!dma_buf)
+		return -ENOMEM;
+
+	retval = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
+				 DRCI_READ_REQ, req_type,
+				 0x0000,
+				 reg, dma_buf, sizeof(*dma_buf),
+				 USB_CTRL_GET_TIMEOUT);
+	*buf = le16_to_cpu(*dma_buf);
+	kfree(dma_buf);
+
+	if (retval < 0)
+		return retval;
+	return 0;
+}
+
+/**
+ * drci_wr_reg - write a DCI register
+ * @dev: usb device
+ * @reg: register address
+ * @data: data to write
+ *
+ * This is writes data to INIC's direct register communication interface
+ */
+static inline int drci_wr_reg(struct usb_device *dev, u16 reg, u16 data)
+{
+	return usb_control_msg(dev,
+			       usb_sndctrlpipe(dev, 0),
+			       DRCI_WRITE_REQ,
+			       USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
+			       data,
+			       reg,
+			       NULL,
+			       0,
+			       USB_CTRL_SET_TIMEOUT);
+}
+
+static inline int start_sync_ep(struct usb_device *usb_dev, u16 ep)
+{
+	return drci_wr_reg(usb_dev, DRCI_REG_BASE + DRCI_COMMAND + ep * 16, 1);
+}
+
+/**
+ * get_stream_frame_size - calculate frame size of current configuration
+ * @dev: device structure
+ * @cfg: channel configuration
+ */
+static unsigned int get_stream_frame_size(struct device *dev,
+					  struct most_channel_config *cfg)
+{
+	unsigned int frame_size;
+	unsigned int sub_size = cfg->subbuffer_size;
+
+	if (!sub_size) {
+		dev_warn(dev, "Misconfig: Subbuffer size zero.\n");
+		return 0;
+	}
+	switch (cfg->data_type) {
+	case MOST_CH_ISOC:
+		frame_size = AV_PACKETS_PER_XACT * sub_size;
+		break;
+	case MOST_CH_SYNC:
+		if (cfg->packets_per_xact == 0) {
+			dev_warn(dev, "Misconfig: Packets per XACT zero\n");
+			frame_size = 0;
+		} else if (cfg->packets_per_xact == 0xFF) {
+			frame_size = (USB_MTU / sub_size) * sub_size;
+		} else {
+			frame_size = cfg->packets_per_xact * sub_size;
+		}
+		break;
+	default:
+		dev_warn(dev, "Query frame size of non-streaming channel\n");
+		frame_size = 0;
+		break;
+	}
+	return frame_size;
+}
+
+/**
+ * hdm_poison_channel - mark buffers of this channel as invalid
+ * @iface: pointer to the interface
+ * @channel: channel ID
+ *
+ * This unlinks all URBs submitted to the HCD,
+ * calls the associated completion function of the core and removes
+ * them from the list.
+ *
+ * Returns 0 on success or error code otherwise.
+ */
+static int hdm_poison_channel(struct most_interface *iface, int channel)
+{
+	struct most_dev *mdev = to_mdev(iface);
+	unsigned long flags;
+	spinlock_t *lock; /* temp. lock */
+
+	if (channel < 0 || channel >= iface->num_channels) {
+		dev_warn(&mdev->usb_device->dev, "Channel ID out of range.\n");
+		return -ECHRNG;
+	}
+
+	lock = mdev->channel_lock + channel;
+	spin_lock_irqsave(lock, flags);
+	mdev->is_channel_healthy[channel] = false;
+	spin_unlock_irqrestore(lock, flags);
+
+	cancel_work_sync(&mdev->clear_work[channel].ws);
+
+	mutex_lock(&mdev->io_mutex);
+	usb_kill_anchored_urbs(&mdev->busy_urbs[channel]);
+	if (mdev->padding_active[channel])
+		mdev->padding_active[channel] = false;
+
+	if (mdev->conf[channel].data_type == MOST_CH_ASYNC) {
+		del_timer_sync(&mdev->link_stat_timer);
+		cancel_work_sync(&mdev->poll_work_obj);
+	}
+	mutex_unlock(&mdev->io_mutex);
+	return 0;
+}
+
+/**
+ * hdm_add_padding - add padding bytes
+ * @mdev: most device
+ * @channel: channel ID
+ * @mbo: buffer object
+ *
+ * This inserts the INIC hardware specific padding bytes into a streaming
+ * channel's buffer
+ */
+static int hdm_add_padding(struct most_dev *mdev, int channel, struct mbo *mbo)
+{
+	struct most_channel_config *conf = &mdev->conf[channel];
+	unsigned int frame_size = get_stream_frame_size(&mdev->dev, conf);
+	unsigned int j, num_frames;
+
+	if (!frame_size)
+		return -EINVAL;
+	num_frames = mbo->buffer_length / frame_size;
+
+	if (num_frames < 1) {
+		dev_err(&mdev->usb_device->dev,
+			"Missed minimal transfer unit.\n");
+		return -EINVAL;
+	}
+
+	for (j = num_frames - 1; j > 0; j--)
+		memmove(mbo->virt_address + j * USB_MTU,
+			mbo->virt_address + j * frame_size,
+			frame_size);
+	mbo->buffer_length = num_frames * USB_MTU;
+	return 0;
+}
+
+/**
+ * hdm_remove_padding - remove padding bytes
+ * @mdev: most device
+ * @channel: channel ID
+ * @mbo: buffer object
+ *
+ * This takes the INIC hardware specific padding bytes off a streaming
+ * channel's buffer.
+ */
+static int hdm_remove_padding(struct most_dev *mdev, int channel,
+			      struct mbo *mbo)
+{
+	struct most_channel_config *const conf = &mdev->conf[channel];
+	unsigned int frame_size = get_stream_frame_size(&mdev->dev, conf);
+	unsigned int j, num_frames;
+
+	if (!frame_size)
+		return -EINVAL;
+	num_frames = mbo->processed_length / USB_MTU;
+
+	for (j = 1; j < num_frames; j++)
+		memmove(mbo->virt_address + frame_size * j,
+			mbo->virt_address + USB_MTU * j,
+			frame_size);
+
+	mbo->processed_length = frame_size * num_frames;
+	return 0;
+}
+
+/**
+ * hdm_write_completion - completion function for submitted Tx URBs
+ * @urb: the URB that has been completed
+ *
+ * This checks the status of the completed URB. In case the URB has been
+ * unlinked before, it is immediately freed. On any other error the MBO
+ * transfer flag is set. On success it frees allocated resources and calls
+ * the completion function.
+ *
+ * Context: interrupt!
+ */
+static void hdm_write_completion(struct urb *urb)
+{
+	struct mbo *mbo = urb->context;
+	struct most_dev *mdev = to_mdev(mbo->ifp);
+	unsigned int channel = mbo->hdm_channel_id;
+	spinlock_t *lock = mdev->channel_lock + channel;
+	unsigned long flags;
+
+	spin_lock_irqsave(lock, flags);
+
+	mbo->processed_length = 0;
+	mbo->status = MBO_E_INVAL;
+	if (likely(mdev->is_channel_healthy[channel])) {
+		switch (urb->status) {
+		case 0:
+		case -ESHUTDOWN:
+			mbo->processed_length = urb->actual_length;
+			mbo->status = MBO_SUCCESS;
+			break;
+		case -EPIPE:
+			dev_warn(&mdev->usb_device->dev,
+				 "Broken pipe on ep%02x\n",
+				 mdev->ep_address[channel]);
+			mdev->is_channel_healthy[channel] = false;
+			mdev->clear_work[channel].pipe = urb->pipe;
+			schedule_work(&mdev->clear_work[channel].ws);
+			break;
+		case -ENODEV:
+		case -EPROTO:
+			mbo->status = MBO_E_CLOSE;
+			break;
+		}
+	}
+
+	spin_unlock_irqrestore(lock, flags);
+
+	if (likely(mbo->complete))
+		mbo->complete(mbo);
+	usb_free_urb(urb);
+}
+
+/**
+ * hdm_read_completion - completion function for submitted Rx URBs
+ * @urb: the URB that has been completed
+ *
+ * This checks the status of the completed URB. In case the URB has been
+ * unlinked before it is immediately freed. On any other error the MBO transfer
+ * flag is set. On success it frees allocated resources, removes
+ * padding bytes -if necessary- and calls the completion function.
+ *
+ * Context: interrupt!
+ */
+static void hdm_read_completion(struct urb *urb)
+{
+	struct mbo *mbo = urb->context;
+	struct most_dev *mdev = to_mdev(mbo->ifp);
+	unsigned int channel = mbo->hdm_channel_id;
+	struct device *dev = &mdev->usb_device->dev;
+	spinlock_t *lock = mdev->channel_lock + channel;
+	unsigned long flags;
+
+	spin_lock_irqsave(lock, flags);
+
+	mbo->processed_length = 0;
+	mbo->status = MBO_E_INVAL;
+	if (likely(mdev->is_channel_healthy[channel])) {
+		switch (urb->status) {
+		case 0:
+		case -ESHUTDOWN:
+			mbo->processed_length = urb->actual_length;
+			mbo->status = MBO_SUCCESS;
+			if (mdev->padding_active[channel] &&
+			    hdm_remove_padding(mdev, channel, mbo)) {
+				mbo->processed_length = 0;
+				mbo->status = MBO_E_INVAL;
+			}
+			break;
+		case -EPIPE:
+			dev_warn(dev, "Broken pipe on ep%02x\n",
+				 mdev->ep_address[channel]);
+			mdev->is_channel_healthy[channel] = false;
+			mdev->clear_work[channel].pipe = urb->pipe;
+			schedule_work(&mdev->clear_work[channel].ws);
+			break;
+		case -ENODEV:
+		case -EPROTO:
+			mbo->status = MBO_E_CLOSE;
+			break;
+		case -EOVERFLOW:
+			dev_warn(dev, "Babble on ep%02x\n",
+				 mdev->ep_address[channel]);
+			break;
+		}
+	}
+
+	spin_unlock_irqrestore(lock, flags);
+
+	if (likely(mbo->complete))
+		mbo->complete(mbo);
+	usb_free_urb(urb);
+}
+
+/**
+ * hdm_enqueue - receive a buffer to be used for data transfer
+ * @iface: interface to enqueue to
+ * @channel: ID of the channel
+ * @mbo: pointer to the buffer object
+ *
+ * This allocates a new URB and fills it according to the channel
+ * that is being used for transmission of data. Before the URB is
+ * submitted it is stored in the private anchor list.
+ *
+ * Returns 0 on success. On any error the URB is freed and a error code
+ * is returned.
+ *
+ * Context: Could in _some_ cases be interrupt!
+ */
+static int hdm_enqueue(struct most_interface *iface, int channel,
+		       struct mbo *mbo)
+{
+	struct most_dev *mdev = to_mdev(iface);
+	struct most_channel_config *conf;
+	int retval = 0;
+	struct urb *urb;
+	unsigned long length;
+	void *virt_address;
+
+	if (!mbo)
+		return -EINVAL;
+	if (iface->num_channels <= channel || channel < 0)
+		return -ECHRNG;
+
+	urb = usb_alloc_urb(NO_ISOCHRONOUS_URB, GFP_KERNEL);
+	if (!urb)
+		return -ENOMEM;
+
+	conf = &mdev->conf[channel];
+
+	mutex_lock(&mdev->io_mutex);
+	if (!mdev->usb_device) {
+		retval = -ENODEV;
+		goto err_free_urb;
+	}
+
+	if ((conf->direction & MOST_CH_TX) && mdev->padding_active[channel] &&
+	    hdm_add_padding(mdev, channel, mbo)) {
+		retval = -EINVAL;
+		goto err_free_urb;
+	}
+
+	urb->transfer_dma = mbo->bus_address;
+	virt_address = mbo->virt_address;
+	length = mbo->buffer_length;
+
+	if (conf->direction & MOST_CH_TX) {
+		usb_fill_bulk_urb(urb, mdev->usb_device,
+				  usb_sndbulkpipe(mdev->usb_device,
+						  mdev->ep_address[channel]),
+				  virt_address,
+				  length,
+				  hdm_write_completion,
+				  mbo);
+		if (conf->data_type != MOST_CH_ISOC &&
+		    conf->data_type != MOST_CH_SYNC)
+			urb->transfer_flags |= URB_ZERO_PACKET;
+	} else {
+		usb_fill_bulk_urb(urb, mdev->usb_device,
+				  usb_rcvbulkpipe(mdev->usb_device,
+						  mdev->ep_address[channel]),
+				  virt_address,
+				  length + conf->extra_len,
+				  hdm_read_completion,
+				  mbo);
+	}
+	urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
+
+	usb_anchor_urb(urb, &mdev->busy_urbs[channel]);
+
+	retval = usb_submit_urb(urb, GFP_KERNEL);
+	if (retval) {
+		dev_err(&mdev->usb_device->dev,
+			"URB submit failed with error %d.\n", retval);
+		goto err_unanchor_urb;
+	}
+	mutex_unlock(&mdev->io_mutex);
+	return 0;
+
+err_unanchor_urb:
+	usb_unanchor_urb(urb);
+err_free_urb:
+	usb_free_urb(urb);
+	mutex_unlock(&mdev->io_mutex);
+	return retval;
+}
+
+static void *hdm_dma_alloc(struct mbo *mbo, u32 size)
+{
+	struct most_dev *mdev = to_mdev(mbo->ifp);
+
+	return usb_alloc_coherent(mdev->usb_device, size, GFP_KERNEL,
+				  &mbo->bus_address);
+}
+
+static void hdm_dma_free(struct mbo *mbo, u32 size)
+{
+	struct most_dev *mdev = to_mdev(mbo->ifp);
+
+	usb_free_coherent(mdev->usb_device, size, mbo->virt_address,
+			  mbo->bus_address);
+}
+
+/**
+ * hdm_configure_channel - receive channel configuration from core
+ * @iface: interface
+ * @channel: channel ID
+ * @conf: structure that holds the configuration information
+ *
+ * The attached network interface controller (NIC) supports a padding mode
+ * to avoid short packets on USB, hence increasing the performance due to a
+ * lower interrupt load. This mode is default for synchronous data and can
+ * be switched on for isochronous data. In case padding is active the
+ * driver needs to know the frame size of the payload in order to calculate
+ * the number of bytes it needs to pad when transmitting or to cut off when
+ * receiving data.
+ *
+ */
+static int hdm_configure_channel(struct most_interface *iface, int channel,
+				 struct most_channel_config *conf)
+{
+	unsigned int num_frames;
+	unsigned int frame_size;
+	struct most_dev *mdev = to_mdev(iface);
+	struct device *dev = &mdev->usb_device->dev;
+
+	if (!conf) {
+		dev_err(dev, "Bad config pointer.\n");
+		return -EINVAL;
+	}
+	if (channel < 0 || channel >= iface->num_channels) {
+		dev_err(dev, "Channel ID out of range.\n");
+		return -EINVAL;
+	}
+
+	mdev->is_channel_healthy[channel] = true;
+	mdev->clear_work[channel].channel = channel;
+	mdev->clear_work[channel].mdev = mdev;
+	INIT_WORK(&mdev->clear_work[channel].ws, wq_clear_halt);
+
+	if (!conf->num_buffers || !conf->buffer_size) {
+		dev_err(dev, "Misconfig: buffer size or #buffers zero.\n");
+		return -EINVAL;
+	}
+
+	if (conf->data_type != MOST_CH_SYNC &&
+	    !(conf->data_type == MOST_CH_ISOC &&
+	      conf->packets_per_xact != 0xFF)) {
+		mdev->padding_active[channel] = false;
+		/*
+		 * Since the NIC's padding mode is not going to be
+		 * used, we can skip the frame size calculations and
+		 * move directly on to exit.
+		 */
+		goto exit;
+	}
+
+	mdev->padding_active[channel] = true;
+
+	frame_size = get_stream_frame_size(&mdev->dev, conf);
+	if (frame_size == 0 || frame_size > USB_MTU) {
+		dev_warn(dev, "Misconfig: frame size wrong\n");
+		return -EINVAL;
+	}
+
+	num_frames = conf->buffer_size / frame_size;
+
+	if (conf->buffer_size % frame_size) {
+		u16 old_size = conf->buffer_size;
+
+		conf->buffer_size = num_frames * frame_size;
+		dev_warn(dev, "%s: fixed buffer size (%d -> %d)\n",
+			 mdev->suffix[channel], old_size, conf->buffer_size);
+	}
+
+	/* calculate extra length to comply w/ HW padding */
+	conf->extra_len = num_frames * (USB_MTU - frame_size);
+
+exit:
+	mdev->conf[channel] = *conf;
+	if (conf->data_type == MOST_CH_ASYNC) {
+		u16 ep = mdev->ep_address[channel];
+
+		if (start_sync_ep(mdev->usb_device, ep) < 0)
+			dev_warn(dev, "sync for ep%02x failed", ep);
+	}
+	return 0;
+}
+
+/**
+ * hdm_request_netinfo - request network information
+ * @iface: pointer to interface
+ * @channel: channel ID
+ *
+ * This is used as trigger to set up the link status timer that
+ * polls for the NI state of the INIC every 2 seconds.
+ *
+ */
+static void hdm_request_netinfo(struct most_interface *iface, int channel,
+				void (*on_netinfo)(struct most_interface *,
+						   unsigned char,
+						   unsigned char *))
+{
+	struct most_dev *mdev = to_mdev(iface);
+
+	mdev->on_netinfo = on_netinfo;
+	if (!on_netinfo)
+		return;
+
+	mdev->link_stat_timer.expires = jiffies + HZ;
+	mod_timer(&mdev->link_stat_timer, mdev->link_stat_timer.expires);
+}
+
+/**
+ * link_stat_timer_handler - schedule work obtaining mac address and link status
+ * @t: pointer to timer_list which holds a pointer to the USB device instance
+ *
+ * The handler runs in interrupt context. That's why we need to defer the
+ * tasks to a work queue.
+ */
+static void link_stat_timer_handler(struct timer_list *t)
+{
+	struct most_dev *mdev = from_timer(mdev, t, link_stat_timer);
+
+	schedule_work(&mdev->poll_work_obj);
+	mdev->link_stat_timer.expires = jiffies + (2 * HZ);
+	add_timer(&mdev->link_stat_timer);
+}
+
+/**
+ * wq_netinfo - work queue function to deliver latest networking information
+ * @wq_obj: object that holds data for our deferred work to do
+ *
+ * This retrieves the network interface status of the USB INIC
+ */
+static void wq_netinfo(struct work_struct *wq_obj)
+{
+	struct most_dev *mdev = to_mdev_from_work(wq_obj);
+	struct usb_device *usb_device = mdev->usb_device;
+	struct device *dev = &usb_device->dev;
+	u16 hi, mi, lo, link;
+	u8 hw_addr[6];
+
+	if (drci_rd_reg(usb_device, DRCI_REG_HW_ADDR_HI, &hi)) {
+		dev_err(dev, "Vendor request 'hw_addr_hi' failed\n");
+		return;
+	}
+
+	if (drci_rd_reg(usb_device, DRCI_REG_HW_ADDR_MI, &mi)) {
+		dev_err(dev, "Vendor request 'hw_addr_mid' failed\n");
+		return;
+	}
+
+	if (drci_rd_reg(usb_device, DRCI_REG_HW_ADDR_LO, &lo)) {
+		dev_err(dev, "Vendor request 'hw_addr_low' failed\n");
+		return;
+	}
+
+	if (drci_rd_reg(usb_device, DRCI_REG_NI_STATE, &link)) {
+		dev_err(dev, "Vendor request 'link status' failed\n");
+		return;
+	}
+
+	hw_addr[0] = hi >> 8;
+	hw_addr[1] = hi;
+	hw_addr[2] = mi >> 8;
+	hw_addr[3] = mi;
+	hw_addr[4] = lo >> 8;
+	hw_addr[5] = lo;
+
+	if (mdev->on_netinfo)
+		mdev->on_netinfo(&mdev->iface, link, hw_addr);
+}
+
+/**
+ * wq_clear_halt - work queue function
+ * @wq_obj: work_struct object to execute
+ *
+ * This sends a clear_halt to the given USB pipe.
+ */
+static void wq_clear_halt(struct work_struct *wq_obj)
+{
+	struct clear_hold_work *clear_work = to_clear_hold_work(wq_obj);
+	struct most_dev *mdev = clear_work->mdev;
+	unsigned int channel = clear_work->channel;
+	int pipe = clear_work->pipe;
+	int snd_pipe;
+	int peer;
+
+	mutex_lock(&mdev->io_mutex);
+	most_stop_enqueue(&mdev->iface, channel);
+	usb_kill_anchored_urbs(&mdev->busy_urbs[channel]);
+	if (usb_clear_halt(mdev->usb_device, pipe))
+		dev_warn(&mdev->usb_device->dev, "Failed to reset endpoint.\n");
+
+	/* If the functional Stall condition has been set on an
+	 * asynchronous rx channel, we need to clear the tx channel
+	 * too, since the hardware runs its clean-up sequence on both
+	 * channels, as they are physically one on the network.
+	 *
+	 * The USB interface that exposes the asynchronous channels
+	 * contains always two endpoints, and two only.
+	 */
+	if (mdev->conf[channel].data_type == MOST_CH_ASYNC &&
+	    mdev->conf[channel].direction == MOST_CH_RX) {
+		if (channel == 0)
+			peer = 1;
+		else
+			peer = 0;
+		snd_pipe = usb_sndbulkpipe(mdev->usb_device,
+					   mdev->ep_address[peer]);
+		usb_clear_halt(mdev->usb_device, snd_pipe);
+	}
+	mdev->is_channel_healthy[channel] = true;
+	most_resume_enqueue(&mdev->iface, channel);
+	mutex_unlock(&mdev->io_mutex);
+}
+
+/*
+ * hdm_usb_fops - file operation table for USB driver
+ */
+static const struct file_operations hdm_usb_fops = {
+	.owner = THIS_MODULE,
+};
+
+/*
+ * usb_device_id - ID table for HCD device probing
+ */
+static const struct usb_device_id usbid[] = {
+	{ USB_DEVICE(USB_VENDOR_ID_SMSC, USB_DEV_ID_BRDG), },
+	{ USB_DEVICE(USB_VENDOR_ID_SMSC, USB_DEV_ID_OS81118), },
+	{ USB_DEVICE(USB_VENDOR_ID_SMSC, USB_DEV_ID_OS81119), },
+	{ USB_DEVICE(USB_VENDOR_ID_SMSC, USB_DEV_ID_OS81210), },
+	{ } /* Terminating entry */
+};
+
+struct regs {
+	const char *name;
+	u16 reg;
+};
+
+static const struct regs ro_regs[] = {
+	{ "ni_state", DRCI_REG_NI_STATE },
+	{ "packet_bandwidth", DRCI_REG_PACKET_BW },
+	{ "node_address", DRCI_REG_NODE_ADDR },
+	{ "node_position", DRCI_REG_NODE_POS },
+};
+
+static const struct regs rw_regs[] = {
+	{ "mep_filter", DRCI_REG_MEP_FILTER },
+	{ "mep_hash0", DRCI_REG_HASH_TBL0 },
+	{ "mep_hash1", DRCI_REG_HASH_TBL1 },
+	{ "mep_hash2", DRCI_REG_HASH_TBL2 },
+	{ "mep_hash3", DRCI_REG_HASH_TBL3 },
+	{ "mep_eui48_hi", DRCI_REG_HW_ADDR_HI },
+	{ "mep_eui48_mi", DRCI_REG_HW_ADDR_MI },
+	{ "mep_eui48_lo", DRCI_REG_HW_ADDR_LO },
+};
+
+static int get_stat_reg_addr(const struct regs *regs, int size,
+			     const char *name, u16 *reg_addr)
+{
+	int i;
+
+	for (i = 0; i < size; i++) {
+		if (sysfs_streq(name, regs[i].name)) {
+			*reg_addr = regs[i].reg;
+			return 0;
+		}
+	}
+	return -EINVAL;
+}
+
+#define get_static_reg_addr(regs, name, reg_addr) \
+	get_stat_reg_addr(regs, ARRAY_SIZE(regs), name, reg_addr)
+
+static ssize_t value_show(struct device *dev, struct device_attribute *attr,
+			  char *buf)
+{
+	const char *name = attr->attr.name;
+	struct most_dci_obj *dci_obj = to_dci_obj(dev);
+	u16 val;
+	u16 reg_addr;
+	int err;
+
+	if (sysfs_streq(name, "arb_address"))
+		return sysfs_emit(buf, "%04x\n", dci_obj->reg_addr);
+
+	if (sysfs_streq(name, "arb_value"))
+		reg_addr = dci_obj->reg_addr;
+	else if (get_static_reg_addr(ro_regs, name, &reg_addr) &&
+		 get_static_reg_addr(rw_regs, name, &reg_addr))
+		return -EINVAL;
+
+	err = drci_rd_reg(dci_obj->usb_device, reg_addr, &val);
+	if (err < 0)
+		return err;
+
+	return sysfs_emit(buf, "%04x\n", val);
+}
+
+static ssize_t value_store(struct device *dev, struct device_attribute *attr,
+			   const char *buf, size_t count)
+{
+	u16 val;
+	u16 reg_addr;
+	const char *name = attr->attr.name;
+	struct most_dci_obj *dci_obj = to_dci_obj(dev);
+	struct usb_device *usb_dev = dci_obj->usb_device;
+	int err;
+
+	err = kstrtou16(buf, 16, &val);
+	if (err)
+		return err;
+
+	if (sysfs_streq(name, "arb_address")) {
+		dci_obj->reg_addr = val;
+		return count;
+	}
+
+	if (sysfs_streq(name, "arb_value"))
+		err = drci_wr_reg(usb_dev, dci_obj->reg_addr, val);
+	else if (sysfs_streq(name, "sync_ep"))
+		err = start_sync_ep(usb_dev, val);
+	else if (!get_static_reg_addr(rw_regs, name, &reg_addr))
+		err = drci_wr_reg(usb_dev, reg_addr, val);
+	else
+		return -EINVAL;
+
+	if (err < 0)
+		return err;
+
+	return count;
+}
+
+static DEVICE_ATTR(ni_state, 0444, value_show, NULL);
+static DEVICE_ATTR(packet_bandwidth, 0444, value_show, NULL);
+static DEVICE_ATTR(node_address, 0444, value_show, NULL);
+static DEVICE_ATTR(node_position, 0444, value_show, NULL);
+static DEVICE_ATTR(sync_ep, 0200, NULL, value_store);
+static DEVICE_ATTR(mep_filter, 0644, value_show, value_store);
+static DEVICE_ATTR(mep_hash0, 0644, value_show, value_store);
+static DEVICE_ATTR(mep_hash1, 0644, value_show, value_store);
+static DEVICE_ATTR(mep_hash2, 0644, value_show, value_store);
+static DEVICE_ATTR(mep_hash3, 0644, value_show, value_store);
+static DEVICE_ATTR(mep_eui48_hi, 0644, value_show, value_store);
+static DEVICE_ATTR(mep_eui48_mi, 0644, value_show, value_store);
+static DEVICE_ATTR(mep_eui48_lo, 0644, value_show, value_store);
+static DEVICE_ATTR(arb_address, 0644, value_show, value_store);
+static DEVICE_ATTR(arb_value, 0644, value_show, value_store);
+
+static struct attribute *dci_attrs[] = {
+	&dev_attr_ni_state.attr,
+	&dev_attr_packet_bandwidth.attr,
+	&dev_attr_node_address.attr,
+	&dev_attr_node_position.attr,
+	&dev_attr_sync_ep.attr,
+	&dev_attr_mep_filter.attr,
+	&dev_attr_mep_hash0.attr,
+	&dev_attr_mep_hash1.attr,
+	&dev_attr_mep_hash2.attr,
+	&dev_attr_mep_hash3.attr,
+	&dev_attr_mep_eui48_hi.attr,
+	&dev_attr_mep_eui48_mi.attr,
+	&dev_attr_mep_eui48_lo.attr,
+	&dev_attr_arb_address.attr,
+	&dev_attr_arb_value.attr,
+	NULL,
+};
+
+ATTRIBUTE_GROUPS(dci);
+
+static void release_dci(struct device *dev)
+{
+	struct most_dci_obj *dci = to_dci_obj(dev);
+
+	put_device(dev->parent);
+	kfree(dci);
+}
+
+static void release_mdev(struct device *dev)
+{
+	struct most_dev *mdev = to_mdev_from_dev(dev);
+
+	kfree(mdev);
+}
+/**
+ * hdm_probe - probe function of USB device driver
+ * @interface: Interface of the attached USB device
+ * @id: Pointer to the USB ID table.
+ *
+ * This allocates and initializes the device instance, adds the new
+ * entry to the internal list, scans the USB descriptors and registers
+ * the interface with the core.
+ * Additionally, the DCI objects are created and the hardware is sync'd.
+ *
+ * Return 0 on success. In case of an error a negative number is returned.
+ */
+static int
+hdm_probe(struct usb_interface *interface, const struct usb_device_id *id)
+{
+	struct usb_host_interface *usb_iface_desc = interface->cur_altsetting;
+	struct usb_device *usb_dev = interface_to_usbdev(interface);
+	struct device *dev = &usb_dev->dev;
+	struct most_dev *mdev;
+	unsigned int i;
+	unsigned int num_endpoints;
+	struct most_channel_capability *tmp_cap;
+	struct usb_endpoint_descriptor *ep_desc;
+	int ret = -ENOMEM;
+
+	mdev = kzalloc(sizeof(*mdev), GFP_KERNEL);
+	if (!mdev)
+		return -ENOMEM;
+
+	usb_set_intfdata(interface, mdev);
+	num_endpoints = usb_iface_desc->desc.bNumEndpoints;
+	if (num_endpoints > MAX_NUM_ENDPOINTS) {
+		kfree(mdev);
+		return -EINVAL;
+	}
+	mutex_init(&mdev->io_mutex);
+	INIT_WORK(&mdev->poll_work_obj, wq_netinfo);
+	timer_setup(&mdev->link_stat_timer, link_stat_timer_handler, 0);
+
+	mdev->usb_device = usb_dev;
+	mdev->link_stat_timer.expires = jiffies + (2 * HZ);
+
+	mdev->iface.mod = hdm_usb_fops.owner;
+	mdev->iface.dev = &mdev->dev;
+	mdev->iface.driver_dev = &interface->dev;
+	mdev->iface.interface = ITYPE_USB;
+	mdev->iface.configure = hdm_configure_channel;
+	mdev->iface.request_netinfo = hdm_request_netinfo;
+	mdev->iface.enqueue = hdm_enqueue;
+	mdev->iface.poison_channel = hdm_poison_channel;
+	mdev->iface.dma_alloc = hdm_dma_alloc;
+	mdev->iface.dma_free = hdm_dma_free;
+	mdev->iface.description = mdev->description;
+	mdev->iface.num_channels = num_endpoints;
+
+	snprintf(mdev->description, sizeof(mdev->description),
+		 "%d-%s:%d.%d",
+		 usb_dev->bus->busnum,
+		 usb_dev->devpath,
+		 usb_dev->config->desc.bConfigurationValue,
+		 usb_iface_desc->desc.bInterfaceNumber);
+
+	mdev->dev.init_name = mdev->description;
+	mdev->dev.parent = &interface->dev;
+	mdev->dev.release = release_mdev;
+	mdev->conf = kcalloc(num_endpoints, sizeof(*mdev->conf), GFP_KERNEL);
+	if (!mdev->conf)
+		goto err_free_mdev;
+
+	mdev->cap = kcalloc(num_endpoints, sizeof(*mdev->cap), GFP_KERNEL);
+	if (!mdev->cap)
+		goto err_free_conf;
+
+	mdev->iface.channel_vector = mdev->cap;
+	mdev->ep_address =
+		kcalloc(num_endpoints, sizeof(*mdev->ep_address), GFP_KERNEL);
+	if (!mdev->ep_address)
+		goto err_free_cap;
+
+	mdev->busy_urbs =
+		kcalloc(num_endpoints, sizeof(*mdev->busy_urbs), GFP_KERNEL);
+	if (!mdev->busy_urbs)
+		goto err_free_ep_address;
+
+	tmp_cap = mdev->cap;
+	for (i = 0; i < num_endpoints; i++) {
+		ep_desc = &usb_iface_desc->endpoint[i].desc;
+		mdev->ep_address[i] = ep_desc->bEndpointAddress;
+		mdev->padding_active[i] = false;
+		mdev->is_channel_healthy[i] = true;
+
+		snprintf(&mdev->suffix[i][0], MAX_SUFFIX_LEN, "ep%02x",
+			 mdev->ep_address[i]);
+
+		tmp_cap->name_suffix = &mdev->suffix[i][0];
+		tmp_cap->buffer_size_packet = MAX_BUF_SIZE;
+		tmp_cap->buffer_size_streaming = MAX_BUF_SIZE;
+		tmp_cap->num_buffers_packet = BUF_CHAIN_SIZE;
+		tmp_cap->num_buffers_streaming = BUF_CHAIN_SIZE;
+		tmp_cap->data_type = MOST_CH_CONTROL | MOST_CH_ASYNC |
+				     MOST_CH_ISOC | MOST_CH_SYNC;
+		if (usb_endpoint_dir_in(ep_desc))
+			tmp_cap->direction = MOST_CH_RX;
+		else
+			tmp_cap->direction = MOST_CH_TX;
+		tmp_cap++;
+		init_usb_anchor(&mdev->busy_urbs[i]);
+		spin_lock_init(&mdev->channel_lock[i]);
+	}
+	dev_dbg(dev, "claimed gadget: Vendor=%4.4x ProdID=%4.4x Bus=%02x Device=%02x\n",
+		le16_to_cpu(usb_dev->descriptor.idVendor),
+		le16_to_cpu(usb_dev->descriptor.idProduct),
+		usb_dev->bus->busnum,
+		usb_dev->devnum);
+
+	dev_dbg(dev, "device path: /sys/bus/usb/devices/%d-%s:%d.%d\n",
+		usb_dev->bus->busnum,
+		usb_dev->devpath,
+		usb_dev->config->desc.bConfigurationValue,
+		usb_iface_desc->desc.bInterfaceNumber);
+
+	ret = most_register_interface(&mdev->iface);
+	if (ret)
+		goto err_free_busy_urbs;
+
+	mutex_lock(&mdev->io_mutex);
+	if (le16_to_cpu(usb_dev->descriptor.idProduct) == USB_DEV_ID_OS81118 ||
+	    le16_to_cpu(usb_dev->descriptor.idProduct) == USB_DEV_ID_OS81119 ||
+	    le16_to_cpu(usb_dev->descriptor.idProduct) == USB_DEV_ID_OS81210) {
+		mdev->dci = kzalloc(sizeof(*mdev->dci), GFP_KERNEL);
+		if (!mdev->dci) {
+			mutex_unlock(&mdev->io_mutex);
+			most_deregister_interface(&mdev->iface);
+			ret = -ENOMEM;
+			goto err_free_busy_urbs;
+		}
+
+		mdev->dci->dev.init_name = "dci";
+		mdev->dci->dev.parent = get_device(mdev->iface.dev);
+		mdev->dci->dev.groups = dci_groups;
+		mdev->dci->dev.release = release_dci;
+		if (device_register(&mdev->dci->dev)) {
+			mutex_unlock(&mdev->io_mutex);
+			most_deregister_interface(&mdev->iface);
+			ret = -ENOMEM;
+			goto err_free_dci;
+		}
+		mdev->dci->usb_device = mdev->usb_device;
+	}
+	mutex_unlock(&mdev->io_mutex);
+	return 0;
+err_free_dci:
+	put_device(&mdev->dci->dev);
+err_free_busy_urbs:
+	kfree(mdev->busy_urbs);
+err_free_ep_address:
+	kfree(mdev->ep_address);
+err_free_cap:
+	kfree(mdev->cap);
+err_free_conf:
+	kfree(mdev->conf);
+err_free_mdev:
+	put_device(&mdev->dev);
+	return ret;
+}
+
+/**
+ * hdm_disconnect - disconnect function of USB device driver
+ * @interface: Interface of the attached USB device
+ *
+ * This deregisters the interface with the core, removes the kernel timer
+ * and frees resources.
+ *
+ * Context: hub kernel thread
+ */
+static void hdm_disconnect(struct usb_interface *interface)
+{
+	struct most_dev *mdev = usb_get_intfdata(interface);
+
+	mutex_lock(&mdev->io_mutex);
+	usb_set_intfdata(interface, NULL);
+	mdev->usb_device = NULL;
+	mutex_unlock(&mdev->io_mutex);
+
+	del_timer_sync(&mdev->link_stat_timer);
+	cancel_work_sync(&mdev->poll_work_obj);
+
+	if (mdev->dci)
+		device_unregister(&mdev->dci->dev);
+	most_deregister_interface(&mdev->iface);
+
+	kfree(mdev->busy_urbs);
+	kfree(mdev->cap);
+	kfree(mdev->conf);
+	kfree(mdev->ep_address);
+	put_device(&mdev->dci->dev);
+	put_device(&mdev->dev);
+}
+
+static int hdm_suspend(struct usb_interface *interface, pm_message_t message)
+{
+	struct most_dev *mdev = usb_get_intfdata(interface);
+	int i;
+
+	mutex_lock(&mdev->io_mutex);
+	for (i = 0; i < mdev->iface.num_channels; i++) {
+		most_stop_enqueue(&mdev->iface, i);
+		usb_kill_anchored_urbs(&mdev->busy_urbs[i]);
+	}
+	mutex_unlock(&mdev->io_mutex);
+	return 0;
+}
+
+static int hdm_resume(struct usb_interface *interface)
+{
+	struct most_dev *mdev = usb_get_intfdata(interface);
+	int i;
+
+	mutex_lock(&mdev->io_mutex);
+	for (i = 0; i < mdev->iface.num_channels; i++)
+		most_resume_enqueue(&mdev->iface, i);
+	mutex_unlock(&mdev->io_mutex);
+	return 0;
+}
+
+static struct usb_driver hdm_usb = {
+	.name = "hdm_usb",
+	.id_table = usbid,
+	.probe = hdm_probe,
+	.disconnect = hdm_disconnect,
+	.resume = hdm_resume,
+	.suspend = hdm_suspend,
+};
+
+module_usb_driver(hdm_usb);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Christian Gromm <christian.gromm@microchip.com>");
+MODULE_DESCRIPTION("HDM_4_USB");