1 files changed, 607 insertions, 0 deletions
diff --git a/drivers/base/component.c b/drivers/base/component.c
new file mode 100644
index 000000000..ee4d3b388
--- /dev/null
+++ b/drivers/base/component.c
@@ -0,0 +1,607 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Componentized device handling.
+ *
+ * This is work in progress.  We gather up the component devices into a list,
+ * and bind them when instructed.  At the moment, we're specific to the DRM
+ * subsystem, and only handles one master device, but this doesn't have to be
+ * the case.
+ */
+#include <linux/component.h>
+#include <linux/device.h>
+#include <linux/kref.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+#include <linux/debugfs.h>
+
+struct component;
+
+struct component_match_array {
+	void *data;
+	int (*compare)(struct device *, void *);
+	void (*release)(struct device *, void *);
+	struct component *component;
+	bool duplicate;
+};
+
+struct component_match {
+	size_t alloc;
+	size_t num;
+	struct component_match_array *compare;
+};
+
+struct master {
+	struct list_head node;
+	bool bound;
+
+	const struct component_master_ops *ops;
+	struct device *dev;
+	struct component_match *match;
+	struct dentry *dentry;
+};
+
+struct component {
+	struct list_head node;
+	struct master *master;
+	bool bound;
+
+	const struct component_ops *ops;
+	struct device *dev;
+};
+
+static DEFINE_MUTEX(component_mutex);
+static LIST_HEAD(component_list);
+static LIST_HEAD(masters);
+
+#ifdef CONFIG_DEBUG_FS
+
+static struct dentry *component_debugfs_dir;
+
+static int component_devices_show(struct seq_file *s, void *data)
+{
+	struct master *m = s->private;
+	struct component_match *match = m->match;
+	size_t i;
+
+	mutex_lock(&component_mutex);
+	seq_printf(s, "%-40s %20s\n", "master name", "status");
+	seq_puts(s, "-------------------------------------------------------------\n");
+	seq_printf(s, "%-40s %20s\n\n",
+		   dev_name(m->dev), m->bound ? "bound" : "not bound");
+
+	seq_printf(s, "%-40s %20s\n", "device name", "status");
+	seq_puts(s, "-------------------------------------------------------------\n");
+	for (i = 0; i < match->num; i++) {
+		struct component *component = match->compare[i].component;
+
+		seq_printf(s, "%-40s %20s\n",
+			   component ? dev_name(component->dev) : "(unknown)",
+			   component ? (component->bound ? "bound" : "not bound") : "not registered");
+	}
+	mutex_unlock(&component_mutex);
+
+	return 0;
+}
+
+static int component_devices_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, component_devices_show, inode->i_private);
+}
+
+static const struct file_operations component_devices_fops = {
+	.open = component_devices_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = single_release,
+};
+
+static int __init component_debug_init(void)
+{
+	component_debugfs_dir = debugfs_create_dir("device_component", NULL);
+
+	return 0;
+}
+
+core_initcall(component_debug_init);
+
+static void component_master_debugfs_add(struct master *m)
+{
+	m->dentry = debugfs_create_file(dev_name(m->dev), 0444,
+					component_debugfs_dir,
+					m, &component_devices_fops);
+}
+
+static void component_master_debugfs_del(struct master *m)
+{
+	debugfs_remove(m->dentry);
+	m->dentry = NULL;
+}
+
+#else
+
+static void component_master_debugfs_add(struct master *m)
+{ }
+
+static void component_master_debugfs_del(struct master *m)
+{ }
+
+#endif
+
+static struct master *__master_find(struct device *dev,
+	const struct component_master_ops *ops)
+{
+	struct master *m;
+
+	list_for_each_entry(m, &masters, node)
+		if (m->dev == dev && (!ops || m->ops == ops))
+			return m;
+
+	return NULL;
+}
+
+static struct component *find_component(struct master *master,
+	int (*compare)(struct device *, void *), void *compare_data)
+{
+	struct component *c;
+
+	list_for_each_entry(c, &component_list, node) {
+		if (c->master && c->master != master)
+			continue;
+
+		if (compare(c->dev, compare_data))
+			return c;
+	}
+
+	return NULL;
+}
+
+static int find_components(struct master *master)
+{
+	struct component_match *match = master->match;
+	size_t i;
+	int ret = 0;
+
+	/*
+	 * Scan the array of match functions and attach
+	 * any components which are found to this master.
+	 */
+	for (i = 0; i < match->num; i++) {
+		struct component_match_array *mc = &match->compare[i];
+		struct component *c;
+
+		dev_dbg(master->dev, "Looking for component %zu\n", i);
+
+		if (match->compare[i].component)
+			continue;
+
+		c = find_component(master, mc->compare, mc->data);
+		if (!c) {
+			ret = -ENXIO;
+			break;
+		}
+
+		dev_dbg(master->dev, "found component %s, duplicate %u\n", dev_name(c->dev), !!c->master);
+
+		/* Attach this component to the master */
+		match->compare[i].duplicate = !!c->master;
+		match->compare[i].component = c;
+		c->master = master;
+	}
+	return ret;
+}
+
+/* Detach component from associated master */
+static void remove_component(struct master *master, struct component *c)
+{
+	size_t i;
+
+	/* Detach the component from this master. */
+	for (i = 0; i < master->match->num; i++)
+		if (master->match->compare[i].component == c)
+			master->match->compare[i].component = NULL;
+}
+
+/*
+ * Try to bring up a master.  If component is NULL, we're interested in
+ * this master, otherwise it's a component which must be present to try
+ * and bring up the master.
+ *
+ * Returns 1 for successful bringup, 0 if not ready, or -ve errno.
+ */
+static int try_to_bring_up_master(struct master *master,
+	struct component *component)
+{
+	int ret;
+
+	dev_dbg(master->dev, "trying to bring up master\n");
+
+	if (find_components(master)) {
+		dev_dbg(master->dev, "master has incomplete components\n");
+		return 0;
+	}
+
+	if (component && component->master != master) {
+		dev_dbg(master->dev, "master is not for this component (%s)\n",
+			dev_name(component->dev));
+		return 0;
+	}
+
+	if (!devres_open_group(master->dev, NULL, GFP_KERNEL))
+		return -ENOMEM;
+
+	/* Found all components */
+	ret = master->ops->bind(master->dev);
+	if (ret < 0) {
+		devres_release_group(master->dev, NULL);
+		if (ret != -EPROBE_DEFER)
+			dev_info(master->dev, "master bind failed: %d\n", ret);
+		return ret;
+	}
+
+	master->bound = true;
+	return 1;
+}
+
+static int try_to_bring_up_masters(struct component *component)
+{
+	struct master *m;
+	int ret = 0;
+
+	list_for_each_entry(m, &masters, node) {
+		if (!m->bound) {
+			ret = try_to_bring_up_master(m, component);
+			if (ret != 0)
+				break;
+		}
+	}
+
+	return ret;
+}
+
+static void take_down_master(struct master *master)
+{
+	if (master->bound) {
+		master->ops->unbind(master->dev);
+		devres_release_group(master->dev, NULL);
+		master->bound = false;
+	}
+}
+
+static void component_match_release(struct device *master,
+	struct component_match *match)
+{
+	unsigned int i;
+
+	for (i = 0; i < match->num; i++) {
+		struct component_match_array *mc = &match->compare[i];
+
+		if (mc->release)
+			mc->release(master, mc->data);
+	}
+
+	kfree(match->compare);
+}
+
+static void devm_component_match_release(struct device *dev, void *res)
+{
+	component_match_release(dev, res);
+}
+
+static int component_match_realloc(struct device *dev,
+	struct component_match *match, size_t num)
+{
+	struct component_match_array *new;
+
+	if (match->alloc == num)
+		return 0;
+
+	new = kmalloc_array(num, sizeof(*new), GFP_KERNEL);
+	if (!new)
+		return -ENOMEM;
+
+	if (match->compare) {
+		memcpy(new, match->compare, sizeof(*new) *
+					    min(match->num, num));
+		kfree(match->compare);
+	}
+	match->compare = new;
+	match->alloc = num;
+
+	return 0;
+}
+
+/*
+ * Add a component to be matched, with a release function.
+ *
+ * The match array is first created or extended if necessary.
+ */
+void component_match_add_release(struct device *master,
+	struct component_match **matchptr,
+	void (*release)(struct device *, void *),
+	int (*compare)(struct device *, void *), void *compare_data)
+{
+	struct component_match *match = *matchptr;
+
+	if (IS_ERR(match))
+		return;
+
+	if (!match) {
+		match = devres_alloc(devm_component_match_release,
+				     sizeof(*match), GFP_KERNEL);
+		if (!match) {
+			*matchptr = ERR_PTR(-ENOMEM);
+			return;
+		}
+
+		devres_add(master, match);
+
+		*matchptr = match;
+	}
+
+	if (match->num == match->alloc) {
+		size_t new_size = match->alloc + 16;
+		int ret;
+
+		ret = component_match_realloc(master, match, new_size);
+		if (ret) {
+			*matchptr = ERR_PTR(ret);
+			return;
+		}
+	}
+
+	match->compare[match->num].compare = compare;
+	match->compare[match->num].release = release;
+	match->compare[match->num].data = compare_data;
+	match->compare[match->num].component = NULL;
+	match->num++;
+}
+EXPORT_SYMBOL(component_match_add_release);
+
+static void free_master(struct master *master)
+{
+	struct component_match *match = master->match;
+	int i;
+
+	component_master_debugfs_del(master);
+	list_del(&master->node);
+
+	if (match) {
+		for (i = 0; i < match->num; i++) {
+			struct component *c = match->compare[i].component;
+			if (c)
+				c->master = NULL;
+		}
+	}
+
+	kfree(master);
+}
+
+int component_master_add_with_match(struct device *dev,
+	const struct component_master_ops *ops,
+	struct component_match *match)
+{
+	struct master *master;
+	int ret;
+
+	/* Reallocate the match array for its true size */
+	ret = component_match_realloc(dev, match, match->num);
+	if (ret)
+		return ret;
+
+	master = kzalloc(sizeof(*master), GFP_KERNEL);
+	if (!master)
+		return -ENOMEM;
+
+	master->dev = dev;
+	master->ops = ops;
+	master->match = match;
+
+	component_master_debugfs_add(master);
+	/* Add to the list of available masters. */
+	mutex_lock(&component_mutex);
+	list_add(&master->node, &masters);
+
+	ret = try_to_bring_up_master(master, NULL);
+
+	if (ret < 0)
+		free_master(master);
+
+	mutex_unlock(&component_mutex);
+
+	return ret < 0 ? ret : 0;
+}
+EXPORT_SYMBOL_GPL(component_master_add_with_match);
+
+void component_master_del(struct device *dev,
+	const struct component_master_ops *ops)
+{
+	struct master *master;
+
+	mutex_lock(&component_mutex);
+	master = __master_find(dev, ops);
+	if (master) {
+		take_down_master(master);
+		free_master(master);
+	}
+	mutex_unlock(&component_mutex);
+}
+EXPORT_SYMBOL_GPL(component_master_del);
+
+static void component_unbind(struct component *component,
+	struct master *master, void *data)
+{
+	WARN_ON(!component->bound);
+
+	component->ops->unbind(component->dev, master->dev, data);
+	component->bound = false;
+
+	/* Release all resources claimed in the binding of this component */
+	devres_release_group(component->dev, component);
+}
+
+void component_unbind_all(struct device *master_dev, void *data)
+{
+	struct master *master;
+	struct component *c;
+	size_t i;
+
+	WARN_ON(!mutex_is_locked(&component_mutex));
+
+	master = __master_find(master_dev, NULL);
+	if (!master)
+		return;
+
+	/* Unbind components in reverse order */
+	for (i = master->match->num; i--; )
+		if (!master->match->compare[i].duplicate) {
+			c = master->match->compare[i].component;
+			component_unbind(c, master, data);
+		}
+}
+EXPORT_SYMBOL_GPL(component_unbind_all);
+
+static int component_bind(struct component *component, struct master *master,
+	void *data)
+{
+	int ret;
+
+	/*
+	 * Each component initialises inside its own devres group.
+	 * This allows us to roll-back a failed component without
+	 * affecting anything else.
+	 */
+	if (!devres_open_group(master->dev, NULL, GFP_KERNEL))
+		return -ENOMEM;
+
+	/*
+	 * Also open a group for the device itself: this allows us
+	 * to release the resources claimed against the sub-device
+	 * at the appropriate moment.
+	 */
+	if (!devres_open_group(component->dev, component, GFP_KERNEL)) {
+		devres_release_group(master->dev, NULL);
+		return -ENOMEM;
+	}
+
+	dev_dbg(master->dev, "binding %s (ops %ps)\n",
+		dev_name(component->dev), component->ops);
+
+	ret = component->ops->bind(component->dev, master->dev, data);
+	if (!ret) {
+		component->bound = true;
+
+		/*
+		 * Close the component device's group so that resources
+		 * allocated in the binding are encapsulated for removal
+		 * at unbind.  Remove the group on the DRM device as we
+		 * can clean those resources up independently.
+		 */
+		devres_close_group(component->dev, NULL);
+		devres_remove_group(master->dev, NULL);
+
+		dev_info(master->dev, "bound %s (ops %ps)\n",
+			 dev_name(component->dev), component->ops);
+	} else {
+		devres_release_group(component->dev, NULL);
+		devres_release_group(master->dev, NULL);
+
+		if (ret != -EPROBE_DEFER)
+			dev_err(master->dev, "failed to bind %s (ops %ps): %d\n",
+				dev_name(component->dev), component->ops, ret);
+	}
+
+	return ret;
+}
+
+int component_bind_all(struct device *master_dev, void *data)
+{
+	struct master *master;
+	struct component *c;
+	size_t i;
+	int ret = 0;
+
+	WARN_ON(!mutex_is_locked(&component_mutex));
+
+	master = __master_find(master_dev, NULL);
+	if (!master)
+		return -EINVAL;
+
+	/* Bind components in match order */
+	for (i = 0; i < master->match->num; i++)
+		if (!master->match->compare[i].duplicate) {
+			c = master->match->compare[i].component;
+			ret = component_bind(c, master, data);
+			if (ret)
+				break;
+		}
+
+	if (ret != 0) {
+		for (; i > 0; i--)
+			if (!master->match->compare[i - 1].duplicate) {
+				c = master->match->compare[i - 1].component;
+				component_unbind(c, master, data);
+			}
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(component_bind_all);
+
+int component_add(struct device *dev, const struct component_ops *ops)
+{
+	struct component *component;
+	int ret;
+
+	component = kzalloc(sizeof(*component), GFP_KERNEL);
+	if (!component)
+		return -ENOMEM;
+
+	component->ops = ops;
+	component->dev = dev;
+
+	dev_dbg(dev, "adding component (ops %ps)\n", ops);
+
+	mutex_lock(&component_mutex);
+	list_add_tail(&component->node, &component_list);
+
+	ret = try_to_bring_up_masters(component);
+	if (ret < 0) {
+		if (component->master)
+			remove_component(component->master, component);
+		list_del(&component->node);
+
+		kfree(component);
+	}
+	mutex_unlock(&component_mutex);
+
+	return ret < 0 ? ret : 0;
+}
+EXPORT_SYMBOL_GPL(component_add);
+
+void component_del(struct device *dev, const struct component_ops *ops)
+{
+	struct component *c, *component = NULL;
+
+	mutex_lock(&component_mutex);
+	list_for_each_entry(c, &component_list, node)
+		if (c->dev == dev && c->ops == ops) {
+			list_del(&c->node);
+			component = c;
+			break;
+		}
+
+	if (component && component->master) {
+		take_down_master(component->master);
+		remove_component(component->master, component);
+	}
+
+	mutex_unlock(&component_mutex);
+
+	WARN_ON(!component);
+	kfree(component);
+}
+EXPORT_SYMBOL_GPL(component_del);
+
+MODULE_LICENSE("GPL v2");