// 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); 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");