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linux-zen-server/drivers/platform/surface/surface_dtx.c

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// 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 = SSAM_SSH_TID_SAM,
.command_id = 0x06,
.instance_id = 0x00,
});
SSAM_DEFINE_SYNC_REQUEST_N(ssam_bas_latch_unlock, {
.target_category = SSAM_SSH_TC_BAS,
.target_id = SSAM_SSH_TID_SAM,
.command_id = 0x07,
.instance_id = 0x00,
});
SSAM_DEFINE_SYNC_REQUEST_N(ssam_bas_latch_request, {
.target_category = SSAM_SSH_TC_BAS,
.target_id = SSAM_SSH_TID_SAM,
.command_id = 0x08,
.instance_id = 0x00,
});
SSAM_DEFINE_SYNC_REQUEST_N(ssam_bas_latch_confirm, {
.target_category = SSAM_SSH_TC_BAS,
.target_id = SSAM_SSH_TID_SAM,
.command_id = 0x09,
.instance_id = 0x00,
});
SSAM_DEFINE_SYNC_REQUEST_N(ssam_bas_latch_heartbeat, {
.target_category = SSAM_SSH_TC_BAS,
.target_id = SSAM_SSH_TID_SAM,
.command_id = 0x0a,
.instance_id = 0x00,
});
SSAM_DEFINE_SYNC_REQUEST_N(ssam_bas_latch_cancel, {
.target_category = SSAM_SSH_TC_BAS,
.target_id = SSAM_SSH_TID_SAM,
.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 = SSAM_SSH_TID_SAM,
.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 = SSAM_SSH_TID_SAM,
.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 = SSAM_SSH_TID_SAM,
.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, SAM, 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");
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