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-rw-r--r--drivers/platform/surface/surface_dtx.c1284
1 files changed, 1284 insertions, 0 deletions
diff --git a/drivers/platform/surface/surface_dtx.c b/drivers/platform/surface/surface_dtx.c
new file mode 100644
index 000000000..ed3694446
--- /dev/null
+++ b/drivers/platform/surface/surface_dtx.c
@@ -0,0 +1,1284 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Surface Book (gen. 2 and later) detachment system (DTX) driver.
+ *
+ * Provides a user-space interface to properly handle clipboard/tablet
+ * (containing screen and processor) detachment from the base of the device
+ * (containing the keyboard and optionally a discrete GPU). Allows to
+ * acknowledge (to speed things up), abort (e.g. in case the dGPU is still in
+ * use), or request detachment via user-space.
+ *
+ * Copyright (C) 2019-2022 Maximilian Luz <luzmaximilian@gmail.com>
+ */
+
+#include <linux/fs.h>
+#include <linux/input.h>
+#include <linux/ioctl.h>
+#include <linux/kernel.h>
+#include <linux/kfifo.h>
+#include <linux/kref.h>
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/platform_device.h>
+#include <linux/poll.h>
+#include <linux/rwsem.h>
+#include <linux/slab.h>
+#include <linux/workqueue.h>
+
+#include <linux/surface_aggregator/controller.h>
+#include <linux/surface_aggregator/device.h>
+#include <linux/surface_aggregator/dtx.h>
+
+
+/* -- SSAM interface. ------------------------------------------------------- */
+
+enum sam_event_cid_bas {
+ SAM_EVENT_CID_DTX_CONNECTION = 0x0c,
+ SAM_EVENT_CID_DTX_REQUEST = 0x0e,
+ SAM_EVENT_CID_DTX_CANCEL = 0x0f,
+ SAM_EVENT_CID_DTX_LATCH_STATUS = 0x11,
+};
+
+enum ssam_bas_base_state {
+ SSAM_BAS_BASE_STATE_DETACH_SUCCESS = 0x00,
+ SSAM_BAS_BASE_STATE_ATTACHED = 0x01,
+ SSAM_BAS_BASE_STATE_NOT_FEASIBLE = 0x02,
+};
+
+enum ssam_bas_latch_status {
+ SSAM_BAS_LATCH_STATUS_CLOSED = 0x00,
+ SSAM_BAS_LATCH_STATUS_OPENED = 0x01,
+ SSAM_BAS_LATCH_STATUS_FAILED_TO_OPEN = 0x02,
+ SSAM_BAS_LATCH_STATUS_FAILED_TO_REMAIN_OPEN = 0x03,
+ SSAM_BAS_LATCH_STATUS_FAILED_TO_CLOSE = 0x04,
+};
+
+enum ssam_bas_cancel_reason {
+ SSAM_BAS_CANCEL_REASON_NOT_FEASIBLE = 0x00, /* Low battery. */
+ SSAM_BAS_CANCEL_REASON_TIMEOUT = 0x02,
+ SSAM_BAS_CANCEL_REASON_FAILED_TO_OPEN = 0x03,
+ SSAM_BAS_CANCEL_REASON_FAILED_TO_REMAIN_OPEN = 0x04,
+ SSAM_BAS_CANCEL_REASON_FAILED_TO_CLOSE = 0x05,
+};
+
+struct ssam_bas_base_info {
+ u8 state;
+ u8 base_id;
+} __packed;
+
+static_assert(sizeof(struct ssam_bas_base_info) == 2);
+
+SSAM_DEFINE_SYNC_REQUEST_N(ssam_bas_latch_lock, {
+ .target_category = SSAM_SSH_TC_BAS,
+ .target_id = 0x01,
+ .command_id = 0x06,
+ .instance_id = 0x00,
+});
+
+SSAM_DEFINE_SYNC_REQUEST_N(ssam_bas_latch_unlock, {
+ .target_category = SSAM_SSH_TC_BAS,
+ .target_id = 0x01,
+ .command_id = 0x07,
+ .instance_id = 0x00,
+});
+
+SSAM_DEFINE_SYNC_REQUEST_N(ssam_bas_latch_request, {
+ .target_category = SSAM_SSH_TC_BAS,
+ .target_id = 0x01,
+ .command_id = 0x08,
+ .instance_id = 0x00,
+});
+
+SSAM_DEFINE_SYNC_REQUEST_N(ssam_bas_latch_confirm, {
+ .target_category = SSAM_SSH_TC_BAS,
+ .target_id = 0x01,
+ .command_id = 0x09,
+ .instance_id = 0x00,
+});
+
+SSAM_DEFINE_SYNC_REQUEST_N(ssam_bas_latch_heartbeat, {
+ .target_category = SSAM_SSH_TC_BAS,
+ .target_id = 0x01,
+ .command_id = 0x0a,
+ .instance_id = 0x00,
+});
+
+SSAM_DEFINE_SYNC_REQUEST_N(ssam_bas_latch_cancel, {
+ .target_category = SSAM_SSH_TC_BAS,
+ .target_id = 0x01,
+ .command_id = 0x0b,
+ .instance_id = 0x00,
+});
+
+SSAM_DEFINE_SYNC_REQUEST_R(ssam_bas_get_base, struct ssam_bas_base_info, {
+ .target_category = SSAM_SSH_TC_BAS,
+ .target_id = 0x01,
+ .command_id = 0x0c,
+ .instance_id = 0x00,
+});
+
+SSAM_DEFINE_SYNC_REQUEST_R(ssam_bas_get_device_mode, u8, {
+ .target_category = SSAM_SSH_TC_BAS,
+ .target_id = 0x01,
+ .command_id = 0x0d,
+ .instance_id = 0x00,
+});
+
+SSAM_DEFINE_SYNC_REQUEST_R(ssam_bas_get_latch_status, u8, {
+ .target_category = SSAM_SSH_TC_BAS,
+ .target_id = 0x01,
+ .command_id = 0x11,
+ .instance_id = 0x00,
+});
+
+
+/* -- Main structures. ------------------------------------------------------ */
+
+enum sdtx_device_state {
+ SDTX_DEVICE_SHUTDOWN_BIT = BIT(0),
+ SDTX_DEVICE_DIRTY_BASE_BIT = BIT(1),
+ SDTX_DEVICE_DIRTY_MODE_BIT = BIT(2),
+ SDTX_DEVICE_DIRTY_LATCH_BIT = BIT(3),
+};
+
+struct sdtx_device {
+ struct kref kref;
+ struct rw_semaphore lock; /* Guards device and controller reference. */
+
+ struct device *dev;
+ struct ssam_controller *ctrl;
+ unsigned long flags;
+
+ struct miscdevice mdev;
+ wait_queue_head_t waitq;
+ struct mutex write_lock; /* Guards order of events/notifications. */
+ struct rw_semaphore client_lock; /* Guards client list. */
+ struct list_head client_list;
+
+ struct delayed_work state_work;
+ struct {
+ struct ssam_bas_base_info base;
+ u8 device_mode;
+ u8 latch_status;
+ } state;
+
+ struct delayed_work mode_work;
+ struct input_dev *mode_switch;
+
+ struct ssam_event_notifier notif;
+};
+
+enum sdtx_client_state {
+ SDTX_CLIENT_EVENTS_ENABLED_BIT = BIT(0),
+};
+
+struct sdtx_client {
+ struct sdtx_device *ddev;
+ struct list_head node;
+ unsigned long flags;
+
+ struct fasync_struct *fasync;
+
+ struct mutex read_lock; /* Guards FIFO buffer read access. */
+ DECLARE_KFIFO(buffer, u8, 512);
+};
+
+static void __sdtx_device_release(struct kref *kref)
+{
+ struct sdtx_device *ddev = container_of(kref, struct sdtx_device, kref);
+
+ mutex_destroy(&ddev->write_lock);
+ kfree(ddev);
+}
+
+static struct sdtx_device *sdtx_device_get(struct sdtx_device *ddev)
+{
+ if (ddev)
+ kref_get(&ddev->kref);
+
+ return ddev;
+}
+
+static void sdtx_device_put(struct sdtx_device *ddev)
+{
+ if (ddev)
+ kref_put(&ddev->kref, __sdtx_device_release);
+}
+
+
+/* -- Firmware value translations. ------------------------------------------ */
+
+static u16 sdtx_translate_base_state(struct sdtx_device *ddev, u8 state)
+{
+ switch (state) {
+ case SSAM_BAS_BASE_STATE_ATTACHED:
+ return SDTX_BASE_ATTACHED;
+
+ case SSAM_BAS_BASE_STATE_DETACH_SUCCESS:
+ return SDTX_BASE_DETACHED;
+
+ case SSAM_BAS_BASE_STATE_NOT_FEASIBLE:
+ return SDTX_DETACH_NOT_FEASIBLE;
+
+ default:
+ dev_err(ddev->dev, "unknown base state: %#04x\n", state);
+ return SDTX_UNKNOWN(state);
+ }
+}
+
+static u16 sdtx_translate_latch_status(struct sdtx_device *ddev, u8 status)
+{
+ switch (status) {
+ case SSAM_BAS_LATCH_STATUS_CLOSED:
+ return SDTX_LATCH_CLOSED;
+
+ case SSAM_BAS_LATCH_STATUS_OPENED:
+ return SDTX_LATCH_OPENED;
+
+ case SSAM_BAS_LATCH_STATUS_FAILED_TO_OPEN:
+ return SDTX_ERR_FAILED_TO_OPEN;
+
+ case SSAM_BAS_LATCH_STATUS_FAILED_TO_REMAIN_OPEN:
+ return SDTX_ERR_FAILED_TO_REMAIN_OPEN;
+
+ case SSAM_BAS_LATCH_STATUS_FAILED_TO_CLOSE:
+ return SDTX_ERR_FAILED_TO_CLOSE;
+
+ default:
+ dev_err(ddev->dev, "unknown latch status: %#04x\n", status);
+ return SDTX_UNKNOWN(status);
+ }
+}
+
+static u16 sdtx_translate_cancel_reason(struct sdtx_device *ddev, u8 reason)
+{
+ switch (reason) {
+ case SSAM_BAS_CANCEL_REASON_NOT_FEASIBLE:
+ return SDTX_DETACH_NOT_FEASIBLE;
+
+ case SSAM_BAS_CANCEL_REASON_TIMEOUT:
+ return SDTX_DETACH_TIMEDOUT;
+
+ case SSAM_BAS_CANCEL_REASON_FAILED_TO_OPEN:
+ return SDTX_ERR_FAILED_TO_OPEN;
+
+ case SSAM_BAS_CANCEL_REASON_FAILED_TO_REMAIN_OPEN:
+ return SDTX_ERR_FAILED_TO_REMAIN_OPEN;
+
+ case SSAM_BAS_CANCEL_REASON_FAILED_TO_CLOSE:
+ return SDTX_ERR_FAILED_TO_CLOSE;
+
+ default:
+ dev_err(ddev->dev, "unknown cancel reason: %#04x\n", reason);
+ return SDTX_UNKNOWN(reason);
+ }
+}
+
+
+/* -- IOCTLs. --------------------------------------------------------------- */
+
+static int sdtx_ioctl_get_base_info(struct sdtx_device *ddev,
+ struct sdtx_base_info __user *buf)
+{
+ struct ssam_bas_base_info raw;
+ struct sdtx_base_info info;
+ int status;
+
+ lockdep_assert_held_read(&ddev->lock);
+
+ status = ssam_retry(ssam_bas_get_base, ddev->ctrl, &raw);
+ if (status < 0)
+ return status;
+
+ info.state = sdtx_translate_base_state(ddev, raw.state);
+ info.base_id = SDTX_BASE_TYPE_SSH(raw.base_id);
+
+ if (copy_to_user(buf, &info, sizeof(info)))
+ return -EFAULT;
+
+ return 0;
+}
+
+static int sdtx_ioctl_get_device_mode(struct sdtx_device *ddev, u16 __user *buf)
+{
+ u8 mode;
+ int status;
+
+ lockdep_assert_held_read(&ddev->lock);
+
+ status = ssam_retry(ssam_bas_get_device_mode, ddev->ctrl, &mode);
+ if (status < 0)
+ return status;
+
+ return put_user(mode, buf);
+}
+
+static int sdtx_ioctl_get_latch_status(struct sdtx_device *ddev, u16 __user *buf)
+{
+ u8 latch;
+ int status;
+
+ lockdep_assert_held_read(&ddev->lock);
+
+ status = ssam_retry(ssam_bas_get_latch_status, ddev->ctrl, &latch);
+ if (status < 0)
+ return status;
+
+ return put_user(sdtx_translate_latch_status(ddev, latch), buf);
+}
+
+static long __surface_dtx_ioctl(struct sdtx_client *client, unsigned int cmd, unsigned long arg)
+{
+ struct sdtx_device *ddev = client->ddev;
+
+ lockdep_assert_held_read(&ddev->lock);
+
+ switch (cmd) {
+ case SDTX_IOCTL_EVENTS_ENABLE:
+ set_bit(SDTX_CLIENT_EVENTS_ENABLED_BIT, &client->flags);
+ return 0;
+
+ case SDTX_IOCTL_EVENTS_DISABLE:
+ clear_bit(SDTX_CLIENT_EVENTS_ENABLED_BIT, &client->flags);
+ return 0;
+
+ case SDTX_IOCTL_LATCH_LOCK:
+ return ssam_retry(ssam_bas_latch_lock, ddev->ctrl);
+
+ case SDTX_IOCTL_LATCH_UNLOCK:
+ return ssam_retry(ssam_bas_latch_unlock, ddev->ctrl);
+
+ case SDTX_IOCTL_LATCH_REQUEST:
+ return ssam_retry(ssam_bas_latch_request, ddev->ctrl);
+
+ case SDTX_IOCTL_LATCH_CONFIRM:
+ return ssam_retry(ssam_bas_latch_confirm, ddev->ctrl);
+
+ case SDTX_IOCTL_LATCH_HEARTBEAT:
+ return ssam_retry(ssam_bas_latch_heartbeat, ddev->ctrl);
+
+ case SDTX_IOCTL_LATCH_CANCEL:
+ return ssam_retry(ssam_bas_latch_cancel, ddev->ctrl);
+
+ case SDTX_IOCTL_GET_BASE_INFO:
+ return sdtx_ioctl_get_base_info(ddev, (struct sdtx_base_info __user *)arg);
+
+ case SDTX_IOCTL_GET_DEVICE_MODE:
+ return sdtx_ioctl_get_device_mode(ddev, (u16 __user *)arg);
+
+ case SDTX_IOCTL_GET_LATCH_STATUS:
+ return sdtx_ioctl_get_latch_status(ddev, (u16 __user *)arg);
+
+ default:
+ return -EINVAL;
+ }
+}
+
+static long surface_dtx_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+ struct sdtx_client *client = file->private_data;
+ long status;
+
+ if (down_read_killable(&client->ddev->lock))
+ return -ERESTARTSYS;
+
+ if (test_bit(SDTX_DEVICE_SHUTDOWN_BIT, &client->ddev->flags)) {
+ up_read(&client->ddev->lock);
+ return -ENODEV;
+ }
+
+ status = __surface_dtx_ioctl(client, cmd, arg);
+
+ up_read(&client->ddev->lock);
+ return status;
+}
+
+
+/* -- File operations. ------------------------------------------------------ */
+
+static int surface_dtx_open(struct inode *inode, struct file *file)
+{
+ struct sdtx_device *ddev = container_of(file->private_data, struct sdtx_device, mdev);
+ struct sdtx_client *client;
+
+ /* Initialize client. */
+ client = kzalloc(sizeof(*client), GFP_KERNEL);
+ if (!client)
+ return -ENOMEM;
+
+ client->ddev = sdtx_device_get(ddev);
+
+ INIT_LIST_HEAD(&client->node);
+
+ mutex_init(&client->read_lock);
+ INIT_KFIFO(client->buffer);
+
+ file->private_data = client;
+
+ /* Attach client. */
+ down_write(&ddev->client_lock);
+
+ /*
+ * Do not add a new client if the device has been shut down. Note that
+ * it's enough to hold the client_lock here as, during shutdown, we
+ * only acquire that lock and remove clients after marking the device
+ * as shut down.
+ */
+ if (test_bit(SDTX_DEVICE_SHUTDOWN_BIT, &ddev->flags)) {
+ up_write(&ddev->client_lock);
+ mutex_destroy(&client->read_lock);
+ sdtx_device_put(client->ddev);
+ kfree(client);
+ return -ENODEV;
+ }
+
+ list_add_tail(&client->node, &ddev->client_list);
+ up_write(&ddev->client_lock);
+
+ stream_open(inode, file);
+ return 0;
+}
+
+static int surface_dtx_release(struct inode *inode, struct file *file)
+{
+ struct sdtx_client *client = file->private_data;
+
+ /* Detach client. */
+ down_write(&client->ddev->client_lock);
+ list_del(&client->node);
+ up_write(&client->ddev->client_lock);
+
+ /* Free client. */
+ sdtx_device_put(client->ddev);
+ mutex_destroy(&client->read_lock);
+ kfree(client);
+
+ return 0;
+}
+
+static ssize_t surface_dtx_read(struct file *file, char __user *buf, size_t count, loff_t *offs)
+{
+ struct sdtx_client *client = file->private_data;
+ struct sdtx_device *ddev = client->ddev;
+ unsigned int copied;
+ int status = 0;
+
+ if (down_read_killable(&ddev->lock))
+ return -ERESTARTSYS;
+
+ /* Make sure we're not shut down. */
+ if (test_bit(SDTX_DEVICE_SHUTDOWN_BIT, &ddev->flags)) {
+ up_read(&ddev->lock);
+ return -ENODEV;
+ }
+
+ do {
+ /* Check availability, wait if necessary. */
+ if (kfifo_is_empty(&client->buffer)) {
+ up_read(&ddev->lock);
+
+ if (file->f_flags & O_NONBLOCK)
+ return -EAGAIN;
+
+ status = wait_event_interruptible(ddev->waitq,
+ !kfifo_is_empty(&client->buffer) ||
+ test_bit(SDTX_DEVICE_SHUTDOWN_BIT,
+ &ddev->flags));
+ if (status < 0)
+ return status;
+
+ if (down_read_killable(&ddev->lock))
+ return -ERESTARTSYS;
+
+ /* Need to check that we're not shut down again. */
+ if (test_bit(SDTX_DEVICE_SHUTDOWN_BIT, &ddev->flags)) {
+ up_read(&ddev->lock);
+ return -ENODEV;
+ }
+ }
+
+ /* Try to read from FIFO. */
+ if (mutex_lock_interruptible(&client->read_lock)) {
+ up_read(&ddev->lock);
+ return -ERESTARTSYS;
+ }
+
+ status = kfifo_to_user(&client->buffer, buf, count, &copied);
+ mutex_unlock(&client->read_lock);
+
+ if (status < 0) {
+ up_read(&ddev->lock);
+ return status;
+ }
+
+ /* We might not have gotten anything, check this here. */
+ if (copied == 0 && (file->f_flags & O_NONBLOCK)) {
+ up_read(&ddev->lock);
+ return -EAGAIN;
+ }
+ } while (copied == 0);
+
+ up_read(&ddev->lock);
+ return copied;
+}
+
+static __poll_t surface_dtx_poll(struct file *file, struct poll_table_struct *pt)
+{
+ struct sdtx_client *client = file->private_data;
+ __poll_t events = 0;
+
+ if (test_bit(SDTX_DEVICE_SHUTDOWN_BIT, &client->ddev->flags))
+ return EPOLLHUP | EPOLLERR;
+
+ poll_wait(file, &client->ddev->waitq, pt);
+
+ if (!kfifo_is_empty(&client->buffer))
+ events |= EPOLLIN | EPOLLRDNORM;
+
+ return events;
+}
+
+static int surface_dtx_fasync(int fd, struct file *file, int on)
+{
+ struct sdtx_client *client = file->private_data;
+
+ return fasync_helper(fd, file, on, &client->fasync);
+}
+
+static const struct file_operations surface_dtx_fops = {
+ .owner = THIS_MODULE,
+ .open = surface_dtx_open,
+ .release = surface_dtx_release,
+ .read = surface_dtx_read,
+ .poll = surface_dtx_poll,
+ .fasync = surface_dtx_fasync,
+ .unlocked_ioctl = surface_dtx_ioctl,
+ .compat_ioctl = surface_dtx_ioctl,
+ .llseek = no_llseek,
+};
+
+
+/* -- Event handling/forwarding. -------------------------------------------- */
+
+/*
+ * The device operation mode is not immediately updated on the EC when the
+ * base has been connected, i.e. querying the device mode inside the
+ * connection event callback yields an outdated value. Thus, we can only
+ * determine the new tablet-mode switch and device mode values after some
+ * time.
+ *
+ * These delays have been chosen by experimenting. We first delay on connect
+ * events, then check and validate the device mode against the base state and
+ * if invalid delay again by the "recheck" delay.
+ */
+#define SDTX_DEVICE_MODE_DELAY_CONNECT msecs_to_jiffies(100)
+#define SDTX_DEVICE_MODE_DELAY_RECHECK msecs_to_jiffies(100)
+
+struct sdtx_status_event {
+ struct sdtx_event e;
+ __u16 v;
+} __packed;
+
+struct sdtx_base_info_event {
+ struct sdtx_event e;
+ struct sdtx_base_info v;
+} __packed;
+
+union sdtx_generic_event {
+ struct sdtx_event common;
+ struct sdtx_status_event status;
+ struct sdtx_base_info_event base;
+};
+
+static void sdtx_update_device_mode(struct sdtx_device *ddev, unsigned long delay);
+
+/* Must be executed with ddev->write_lock held. */
+static void sdtx_push_event(struct sdtx_device *ddev, struct sdtx_event *evt)
+{
+ const size_t len = sizeof(struct sdtx_event) + evt->length;
+ struct sdtx_client *client;
+
+ lockdep_assert_held(&ddev->write_lock);
+
+ down_read(&ddev->client_lock);
+ list_for_each_entry(client, &ddev->client_list, node) {
+ if (!test_bit(SDTX_CLIENT_EVENTS_ENABLED_BIT, &client->flags))
+ continue;
+
+ if (likely(kfifo_avail(&client->buffer) >= len))
+ kfifo_in(&client->buffer, (const u8 *)evt, len);
+ else
+ dev_warn(ddev->dev, "event buffer overrun\n");
+
+ kill_fasync(&client->fasync, SIGIO, POLL_IN);
+ }
+ up_read(&ddev->client_lock);
+
+ wake_up_interruptible(&ddev->waitq);
+}
+
+static u32 sdtx_notifier(struct ssam_event_notifier *nf, const struct ssam_event *in)
+{
+ struct sdtx_device *ddev = container_of(nf, struct sdtx_device, notif);
+ union sdtx_generic_event event;
+ size_t len;
+
+ /* Validate event payload length. */
+ switch (in->command_id) {
+ case SAM_EVENT_CID_DTX_CONNECTION:
+ len = 2 * sizeof(u8);
+ break;
+
+ case SAM_EVENT_CID_DTX_REQUEST:
+ len = 0;
+ break;
+
+ case SAM_EVENT_CID_DTX_CANCEL:
+ len = sizeof(u8);
+ break;
+
+ case SAM_EVENT_CID_DTX_LATCH_STATUS:
+ len = sizeof(u8);
+ break;
+
+ default:
+ return 0;
+ }
+
+ if (in->length != len) {
+ dev_err(ddev->dev,
+ "unexpected payload size for event %#04x: got %u, expected %zu\n",
+ in->command_id, in->length, len);
+ return 0;
+ }
+
+ mutex_lock(&ddev->write_lock);
+
+ /* Translate event. */
+ switch (in->command_id) {
+ case SAM_EVENT_CID_DTX_CONNECTION:
+ clear_bit(SDTX_DEVICE_DIRTY_BASE_BIT, &ddev->flags);
+
+ /* If state has not changed: do not send new event. */
+ if (ddev->state.base.state == in->data[0] &&
+ ddev->state.base.base_id == in->data[1])
+ goto out;
+
+ ddev->state.base.state = in->data[0];
+ ddev->state.base.base_id = in->data[1];
+
+ event.base.e.length = sizeof(struct sdtx_base_info);
+ event.base.e.code = SDTX_EVENT_BASE_CONNECTION;
+ event.base.v.state = sdtx_translate_base_state(ddev, in->data[0]);
+ event.base.v.base_id = SDTX_BASE_TYPE_SSH(in->data[1]);
+ break;
+
+ case SAM_EVENT_CID_DTX_REQUEST:
+ event.common.code = SDTX_EVENT_REQUEST;
+ event.common.length = 0;
+ break;
+
+ case SAM_EVENT_CID_DTX_CANCEL:
+ event.status.e.length = sizeof(u16);
+ event.status.e.code = SDTX_EVENT_CANCEL;
+ event.status.v = sdtx_translate_cancel_reason(ddev, in->data[0]);
+ break;
+
+ case SAM_EVENT_CID_DTX_LATCH_STATUS:
+ clear_bit(SDTX_DEVICE_DIRTY_LATCH_BIT, &ddev->flags);
+
+ /* If state has not changed: do not send new event. */
+ if (ddev->state.latch_status == in->data[0])
+ goto out;
+
+ ddev->state.latch_status = in->data[0];
+
+ event.status.e.length = sizeof(u16);
+ event.status.e.code = SDTX_EVENT_LATCH_STATUS;
+ event.status.v = sdtx_translate_latch_status(ddev, in->data[0]);
+ break;
+ }
+
+ sdtx_push_event(ddev, &event.common);
+
+ /* Update device mode on base connection change. */
+ if (in->command_id == SAM_EVENT_CID_DTX_CONNECTION) {
+ unsigned long delay;
+
+ delay = in->data[0] ? SDTX_DEVICE_MODE_DELAY_CONNECT : 0;
+ sdtx_update_device_mode(ddev, delay);
+ }
+
+out:
+ mutex_unlock(&ddev->write_lock);
+ return SSAM_NOTIF_HANDLED;
+}
+
+
+/* -- State update functions. ----------------------------------------------- */
+
+static bool sdtx_device_mode_invalid(u8 mode, u8 base_state)
+{
+ return ((base_state == SSAM_BAS_BASE_STATE_ATTACHED) &&
+ (mode == SDTX_DEVICE_MODE_TABLET)) ||
+ ((base_state == SSAM_BAS_BASE_STATE_DETACH_SUCCESS) &&
+ (mode != SDTX_DEVICE_MODE_TABLET));
+}
+
+static void sdtx_device_mode_workfn(struct work_struct *work)
+{
+ struct sdtx_device *ddev = container_of(work, struct sdtx_device, mode_work.work);
+ struct sdtx_status_event event;
+ struct ssam_bas_base_info base;
+ int status, tablet;
+ u8 mode;
+
+ /* Get operation mode. */
+ status = ssam_retry(ssam_bas_get_device_mode, ddev->ctrl, &mode);
+ if (status) {
+ dev_err(ddev->dev, "failed to get device mode: %d\n", status);
+ return;
+ }
+
+ /* Get base info. */
+ status = ssam_retry(ssam_bas_get_base, ddev->ctrl, &base);
+ if (status) {
+ dev_err(ddev->dev, "failed to get base info: %d\n", status);
+ return;
+ }
+
+ /*
+ * In some cases (specifically when attaching the base), the device
+ * mode isn't updated right away. Thus we check if the device mode
+ * makes sense for the given base state and try again later if it
+ * doesn't.
+ */
+ if (sdtx_device_mode_invalid(mode, base.state)) {
+ dev_dbg(ddev->dev, "device mode is invalid, trying again\n");
+ sdtx_update_device_mode(ddev, SDTX_DEVICE_MODE_DELAY_RECHECK);
+ return;
+ }
+
+ mutex_lock(&ddev->write_lock);
+ clear_bit(SDTX_DEVICE_DIRTY_MODE_BIT, &ddev->flags);
+
+ /* Avoid sending duplicate device-mode events. */
+ if (ddev->state.device_mode == mode) {
+ mutex_unlock(&ddev->write_lock);
+ return;
+ }
+
+ ddev->state.device_mode = mode;
+
+ event.e.length = sizeof(u16);
+ event.e.code = SDTX_EVENT_DEVICE_MODE;
+ event.v = mode;
+
+ sdtx_push_event(ddev, &event.e);
+
+ /* Send SW_TABLET_MODE event. */
+ tablet = mode != SDTX_DEVICE_MODE_LAPTOP;
+ input_report_switch(ddev->mode_switch, SW_TABLET_MODE, tablet);
+ input_sync(ddev->mode_switch);
+
+ mutex_unlock(&ddev->write_lock);
+}
+
+static void sdtx_update_device_mode(struct sdtx_device *ddev, unsigned long delay)
+{
+ schedule_delayed_work(&ddev->mode_work, delay);
+}
+
+/* Must be executed with ddev->write_lock held. */
+static void __sdtx_device_state_update_base(struct sdtx_device *ddev,
+ struct ssam_bas_base_info info)
+{
+ struct sdtx_base_info_event event;
+
+ lockdep_assert_held(&ddev->write_lock);
+
+ /* Prevent duplicate events. */
+ if (ddev->state.base.state == info.state &&
+ ddev->state.base.base_id == info.base_id)
+ return;
+
+ ddev->state.base = info;
+
+ event.e.length = sizeof(struct sdtx_base_info);
+ event.e.code = SDTX_EVENT_BASE_CONNECTION;
+ event.v.state = sdtx_translate_base_state(ddev, info.state);
+ event.v.base_id = SDTX_BASE_TYPE_SSH(info.base_id);
+
+ sdtx_push_event(ddev, &event.e);
+}
+
+/* Must be executed with ddev->write_lock held. */
+static void __sdtx_device_state_update_mode(struct sdtx_device *ddev, u8 mode)
+{
+ struct sdtx_status_event event;
+ int tablet;
+
+ /*
+ * Note: This function must be called after updating the base state
+ * via __sdtx_device_state_update_base(), as we rely on the updated
+ * base state value in the validity check below.
+ */
+
+ lockdep_assert_held(&ddev->write_lock);
+
+ if (sdtx_device_mode_invalid(mode, ddev->state.base.state)) {
+ dev_dbg(ddev->dev, "device mode is invalid, trying again\n");
+ sdtx_update_device_mode(ddev, SDTX_DEVICE_MODE_DELAY_RECHECK);
+ return;
+ }
+
+ /* Prevent duplicate events. */
+ if (ddev->state.device_mode == mode)
+ return;
+
+ ddev->state.device_mode = mode;
+
+ /* Send event. */
+ event.e.length = sizeof(u16);
+ event.e.code = SDTX_EVENT_DEVICE_MODE;
+ event.v = mode;
+
+ sdtx_push_event(ddev, &event.e);
+
+ /* Send SW_TABLET_MODE event. */
+ tablet = mode != SDTX_DEVICE_MODE_LAPTOP;
+ input_report_switch(ddev->mode_switch, SW_TABLET_MODE, tablet);
+ input_sync(ddev->mode_switch);
+}
+
+/* Must be executed with ddev->write_lock held. */
+static void __sdtx_device_state_update_latch(struct sdtx_device *ddev, u8 status)
+{
+ struct sdtx_status_event event;
+
+ lockdep_assert_held(&ddev->write_lock);
+
+ /* Prevent duplicate events. */
+ if (ddev->state.latch_status == status)
+ return;
+
+ ddev->state.latch_status = status;
+
+ event.e.length = sizeof(struct sdtx_base_info);
+ event.e.code = SDTX_EVENT_BASE_CONNECTION;
+ event.v = sdtx_translate_latch_status(ddev, status);
+
+ sdtx_push_event(ddev, &event.e);
+}
+
+static void sdtx_device_state_workfn(struct work_struct *work)
+{
+ struct sdtx_device *ddev = container_of(work, struct sdtx_device, state_work.work);
+ struct ssam_bas_base_info base;
+ u8 mode, latch;
+ int status;
+
+ /* Mark everything as dirty. */
+ set_bit(SDTX_DEVICE_DIRTY_BASE_BIT, &ddev->flags);
+ set_bit(SDTX_DEVICE_DIRTY_MODE_BIT, &ddev->flags);
+ set_bit(SDTX_DEVICE_DIRTY_LATCH_BIT, &ddev->flags);
+
+ /*
+ * Ensure that the state gets marked as dirty before continuing to
+ * query it. Necessary to ensure that clear_bit() calls in
+ * sdtx_notifier() and sdtx_device_mode_workfn() actually clear these
+ * bits if an event is received while updating the state here.
+ */
+ smp_mb__after_atomic();
+
+ status = ssam_retry(ssam_bas_get_base, ddev->ctrl, &base);
+ if (status) {
+ dev_err(ddev->dev, "failed to get base state: %d\n", status);
+ return;
+ }
+
+ status = ssam_retry(ssam_bas_get_device_mode, ddev->ctrl, &mode);
+ if (status) {
+ dev_err(ddev->dev, "failed to get device mode: %d\n", status);
+ return;
+ }
+
+ status = ssam_retry(ssam_bas_get_latch_status, ddev->ctrl, &latch);
+ if (status) {
+ dev_err(ddev->dev, "failed to get latch status: %d\n", status);
+ return;
+ }
+
+ mutex_lock(&ddev->write_lock);
+
+ /*
+ * If the respective dirty-bit has been cleared, an event has been
+ * received, updating this state. The queried state may thus be out of
+ * date. At this point, we can safely assume that the state provided
+ * by the event is either up to date, or we're about to receive
+ * another event updating it.
+ */
+
+ if (test_and_clear_bit(SDTX_DEVICE_DIRTY_BASE_BIT, &ddev->flags))
+ __sdtx_device_state_update_base(ddev, base);
+
+ if (test_and_clear_bit(SDTX_DEVICE_DIRTY_MODE_BIT, &ddev->flags))
+ __sdtx_device_state_update_mode(ddev, mode);
+
+ if (test_and_clear_bit(SDTX_DEVICE_DIRTY_LATCH_BIT, &ddev->flags))
+ __sdtx_device_state_update_latch(ddev, latch);
+
+ mutex_unlock(&ddev->write_lock);
+}
+
+static void sdtx_update_device_state(struct sdtx_device *ddev, unsigned long delay)
+{
+ schedule_delayed_work(&ddev->state_work, delay);
+}
+
+
+/* -- Common device initialization. ----------------------------------------- */
+
+static int sdtx_device_init(struct sdtx_device *ddev, struct device *dev,
+ struct ssam_controller *ctrl)
+{
+ int status, tablet_mode;
+
+ /* Basic initialization. */
+ kref_init(&ddev->kref);
+ init_rwsem(&ddev->lock);
+ ddev->dev = dev;
+ ddev->ctrl = ctrl;
+
+ ddev->mdev.minor = MISC_DYNAMIC_MINOR;
+ ddev->mdev.name = "surface_dtx";
+ ddev->mdev.nodename = "surface/dtx";
+ ddev->mdev.fops = &surface_dtx_fops;
+
+ ddev->notif.base.priority = 1;
+ ddev->notif.base.fn = sdtx_notifier;
+ ddev->notif.event.reg = SSAM_EVENT_REGISTRY_SAM;
+ ddev->notif.event.id.target_category = SSAM_SSH_TC_BAS;
+ ddev->notif.event.id.instance = 0;
+ ddev->notif.event.mask = SSAM_EVENT_MASK_NONE;
+ ddev->notif.event.flags = SSAM_EVENT_SEQUENCED;
+
+ init_waitqueue_head(&ddev->waitq);
+ mutex_init(&ddev->write_lock);
+ init_rwsem(&ddev->client_lock);
+ INIT_LIST_HEAD(&ddev->client_list);
+
+ INIT_DELAYED_WORK(&ddev->mode_work, sdtx_device_mode_workfn);
+ INIT_DELAYED_WORK(&ddev->state_work, sdtx_device_state_workfn);
+
+ /*
+ * Get current device state. We want to guarantee that events are only
+ * sent when state actually changes. Thus we cannot use special
+ * "uninitialized" values, as that would cause problems when manually
+ * querying the state in surface_dtx_pm_complete(). I.e. we would not
+ * be able to detect state changes there if no change event has been
+ * received between driver initialization and first device suspension.
+ *
+ * Note that we also need to do this before registering the event
+ * notifier, as that may access the state values.
+ */
+ status = ssam_retry(ssam_bas_get_base, ddev->ctrl, &ddev->state.base);
+ if (status)
+ return status;
+
+ status = ssam_retry(ssam_bas_get_device_mode, ddev->ctrl, &ddev->state.device_mode);
+ if (status)
+ return status;
+
+ status = ssam_retry(ssam_bas_get_latch_status, ddev->ctrl, &ddev->state.latch_status);
+ if (status)
+ return status;
+
+ /* Set up tablet mode switch. */
+ ddev->mode_switch = input_allocate_device();
+ if (!ddev->mode_switch)
+ return -ENOMEM;
+
+ ddev->mode_switch->name = "Microsoft Surface DTX Device Mode Switch";
+ ddev->mode_switch->phys = "ssam/01:11:01:00:00/input0";
+ ddev->mode_switch->id.bustype = BUS_HOST;
+ ddev->mode_switch->dev.parent = ddev->dev;
+
+ tablet_mode = (ddev->state.device_mode != SDTX_DEVICE_MODE_LAPTOP);
+ input_set_capability(ddev->mode_switch, EV_SW, SW_TABLET_MODE);
+ input_report_switch(ddev->mode_switch, SW_TABLET_MODE, tablet_mode);
+
+ status = input_register_device(ddev->mode_switch);
+ if (status) {
+ input_free_device(ddev->mode_switch);
+ return status;
+ }
+
+ /* Set up event notifier. */
+ status = ssam_notifier_register(ddev->ctrl, &ddev->notif);
+ if (status)
+ goto err_notif;
+
+ /* Register miscdevice. */
+ status = misc_register(&ddev->mdev);
+ if (status)
+ goto err_mdev;
+
+ /*
+ * Update device state in case it has changed between getting the
+ * initial mode and registering the event notifier.
+ */
+ sdtx_update_device_state(ddev, 0);
+ return 0;
+
+err_notif:
+ ssam_notifier_unregister(ddev->ctrl, &ddev->notif);
+ cancel_delayed_work_sync(&ddev->mode_work);
+err_mdev:
+ input_unregister_device(ddev->mode_switch);
+ return status;
+}
+
+static struct sdtx_device *sdtx_device_create(struct device *dev, struct ssam_controller *ctrl)
+{
+ struct sdtx_device *ddev;
+ int status;
+
+ ddev = kzalloc(sizeof(*ddev), GFP_KERNEL);
+ if (!ddev)
+ return ERR_PTR(-ENOMEM);
+
+ status = sdtx_device_init(ddev, dev, ctrl);
+ if (status) {
+ sdtx_device_put(ddev);
+ return ERR_PTR(status);
+ }
+
+ return ddev;
+}
+
+static void sdtx_device_destroy(struct sdtx_device *ddev)
+{
+ struct sdtx_client *client;
+
+ /*
+ * Mark device as shut-down. Prevent new clients from being added and
+ * new operations from being executed.
+ */
+ set_bit(SDTX_DEVICE_SHUTDOWN_BIT, &ddev->flags);
+
+ /* Disable notifiers, prevent new events from arriving. */
+ ssam_notifier_unregister(ddev->ctrl, &ddev->notif);
+
+ /* Stop mode_work, prevent access to mode_switch. */
+ cancel_delayed_work_sync(&ddev->mode_work);
+
+ /* Stop state_work. */
+ cancel_delayed_work_sync(&ddev->state_work);
+
+ /* With mode_work canceled, we can unregister the mode_switch. */
+ input_unregister_device(ddev->mode_switch);
+
+ /* Wake up async clients. */
+ down_write(&ddev->client_lock);
+ list_for_each_entry(client, &ddev->client_list, node) {
+ kill_fasync(&client->fasync, SIGIO, POLL_HUP);
+ }
+ up_write(&ddev->client_lock);
+
+ /* Wake up blocking clients. */
+ wake_up_interruptible(&ddev->waitq);
+
+ /*
+ * Wait for clients to finish their current operation. After this, the
+ * controller and device references are guaranteed to be no longer in
+ * use.
+ */
+ down_write(&ddev->lock);
+ ddev->dev = NULL;
+ ddev->ctrl = NULL;
+ up_write(&ddev->lock);
+
+ /* Finally remove the misc-device. */
+ misc_deregister(&ddev->mdev);
+
+ /*
+ * We're now guaranteed that sdtx_device_open() won't be called any
+ * more, so we can now drop out reference.
+ */
+ sdtx_device_put(ddev);
+}
+
+
+/* -- PM ops. --------------------------------------------------------------- */
+
+#ifdef CONFIG_PM_SLEEP
+
+static void surface_dtx_pm_complete(struct device *dev)
+{
+ struct sdtx_device *ddev = dev_get_drvdata(dev);
+
+ /*
+ * Normally, the EC will store events while suspended (i.e. in
+ * display-off state) and release them when resumed (i.e. transitioned
+ * to display-on state). During hibernation, however, the EC will be
+ * shut down and does not store events. Furthermore, events might be
+ * dropped during prolonged suspension (it is currently unknown how
+ * big this event buffer is and how it behaves on overruns).
+ *
+ * To prevent any problems, we update the device state here. We do
+ * this delayed to ensure that any events sent by the EC directly
+ * after resuming will be handled first. The delay below has been
+ * chosen (experimentally), so that there should be ample time for
+ * these events to be handled, before we check and, if necessary,
+ * update the state.
+ */
+ sdtx_update_device_state(ddev, msecs_to_jiffies(1000));
+}
+
+static const struct dev_pm_ops surface_dtx_pm_ops = {
+ .complete = surface_dtx_pm_complete,
+};
+
+#else /* CONFIG_PM_SLEEP */
+
+static const struct dev_pm_ops surface_dtx_pm_ops = {};
+
+#endif /* CONFIG_PM_SLEEP */
+
+
+/* -- Platform driver. ------------------------------------------------------ */
+
+static int surface_dtx_platform_probe(struct platform_device *pdev)
+{
+ struct ssam_controller *ctrl;
+ struct sdtx_device *ddev;
+
+ /* Link to EC. */
+ ctrl = ssam_client_bind(&pdev->dev);
+ if (IS_ERR(ctrl))
+ return PTR_ERR(ctrl) == -ENODEV ? -EPROBE_DEFER : PTR_ERR(ctrl);
+
+ ddev = sdtx_device_create(&pdev->dev, ctrl);
+ if (IS_ERR(ddev))
+ return PTR_ERR(ddev);
+
+ platform_set_drvdata(pdev, ddev);
+ return 0;
+}
+
+static int surface_dtx_platform_remove(struct platform_device *pdev)
+{
+ sdtx_device_destroy(platform_get_drvdata(pdev));
+ return 0;
+}
+
+static const struct acpi_device_id surface_dtx_acpi_match[] = {
+ { "MSHW0133", 0 },
+ { },
+};
+MODULE_DEVICE_TABLE(acpi, surface_dtx_acpi_match);
+
+static struct platform_driver surface_dtx_platform_driver = {
+ .probe = surface_dtx_platform_probe,
+ .remove = surface_dtx_platform_remove,
+ .driver = {
+ .name = "surface_dtx_pltf",
+ .acpi_match_table = surface_dtx_acpi_match,
+ .pm = &surface_dtx_pm_ops,
+ .probe_type = PROBE_PREFER_ASYNCHRONOUS,
+ },
+};
+
+
+/* -- SSAM device driver. --------------------------------------------------- */
+
+#ifdef CONFIG_SURFACE_AGGREGATOR_BUS
+
+static int surface_dtx_ssam_probe(struct ssam_device *sdev)
+{
+ struct sdtx_device *ddev;
+
+ ddev = sdtx_device_create(&sdev->dev, sdev->ctrl);
+ if (IS_ERR(ddev))
+ return PTR_ERR(ddev);
+
+ ssam_device_set_drvdata(sdev, ddev);
+ return 0;
+}
+
+static void surface_dtx_ssam_remove(struct ssam_device *sdev)
+{
+ sdtx_device_destroy(ssam_device_get_drvdata(sdev));
+}
+
+static const struct ssam_device_id surface_dtx_ssam_match[] = {
+ { SSAM_SDEV(BAS, 0x01, 0x00, 0x00) },
+ { },
+};
+MODULE_DEVICE_TABLE(ssam, surface_dtx_ssam_match);
+
+static struct ssam_device_driver surface_dtx_ssam_driver = {
+ .probe = surface_dtx_ssam_probe,
+ .remove = surface_dtx_ssam_remove,
+ .match_table = surface_dtx_ssam_match,
+ .driver = {
+ .name = "surface_dtx",
+ .pm = &surface_dtx_pm_ops,
+ .probe_type = PROBE_PREFER_ASYNCHRONOUS,
+ },
+};
+
+static int ssam_dtx_driver_register(void)
+{
+ return ssam_device_driver_register(&surface_dtx_ssam_driver);
+}
+
+static void ssam_dtx_driver_unregister(void)
+{
+ ssam_device_driver_unregister(&surface_dtx_ssam_driver);
+}
+
+#else /* CONFIG_SURFACE_AGGREGATOR_BUS */
+
+static int ssam_dtx_driver_register(void)
+{
+ return 0;
+}
+
+static void ssam_dtx_driver_unregister(void)
+{
+}
+
+#endif /* CONFIG_SURFACE_AGGREGATOR_BUS */
+
+
+/* -- Module setup. --------------------------------------------------------- */
+
+static int __init surface_dtx_init(void)
+{
+ int status;
+
+ status = ssam_dtx_driver_register();
+ if (status)
+ return status;
+
+ status = platform_driver_register(&surface_dtx_platform_driver);
+ if (status)
+ ssam_dtx_driver_unregister();
+
+ return status;
+}
+module_init(surface_dtx_init);
+
+static void __exit surface_dtx_exit(void)
+{
+ platform_driver_unregister(&surface_dtx_platform_driver);
+ ssam_dtx_driver_unregister();
+}
+module_exit(surface_dtx_exit);
+
+MODULE_AUTHOR("Maximilian Luz <luzmaximilian@gmail.com>");
+MODULE_DESCRIPTION("Detachment-system driver for Surface System Aggregator Module");
+MODULE_LICENSE("GPL");
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-01 22:07:32 +0000