diff options
Diffstat (limited to 'drivers/platform/surface/surface_dtx.c')
| -rw-r--r-- | drivers/platform/surface/surface_dtx.c | 1289 |
1 files changed, 1289 insertions, 0 deletions
diff --git a/drivers/platform/surface/surface_dtx.c b/drivers/platform/surface/surface_dtx.c new file mode 100644 index 000000000000..63ce587e79e3 --- /dev/null +++ b/drivers/platform/surface/surface_dtx.c @@ -0,0 +1,1289 @@ +// 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) 2019-2021 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); + 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 (down_read_killable(&client->ddev->lock)) + return -ERESTARTSYS; + + if (test_bit(SDTX_DEVICE_SHUTDOWN_BIT, &client->ddev->flags)) { + up_read(&client->ddev->lock); + return EPOLLHUP | EPOLLERR; + } + + poll_wait(file, &client->ddev->waitq, pt); + + if (!kfifo_is_empty(&client->buffer)) + events |= EPOLLIN | EPOLLRDNORM; + + up_read(&client->ddev->lock); + 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"); |