diff options
| -rw-r--r-- | drivers/platform/chrome/wilco_ec/event.c | 258 |
1 files changed, 149 insertions, 109 deletions
diff --git a/drivers/platform/chrome/wilco_ec/event.c b/drivers/platform/chrome/wilco_ec/event.c index 1eed55681598..dba3d445623f 100644 --- a/drivers/platform/chrome/wilco_ec/event.c +++ b/drivers/platform/chrome/wilco_ec/event.c @@ -39,6 +39,7 @@ #include <linux/list.h> #include <linux/module.h> #include <linux/poll.h> +#include <linux/spinlock.h> #include <linux/uaccess.h> #include <linux/wait.h> @@ -70,11 +71,109 @@ static DEFINE_IDA(event_ida); #define MAX_NUM_EVENTS 64 /** + * struct ec_event - Extended event returned by the EC. + * @size: Number of 16bit words in structure after the size word. + * @type: Extended event type, meaningless for us. + * @event: Event data words. Max count is %EC_ACPI_MAX_EVENT_WORDS. + */ +struct ec_event { + u16 size; + u16 type; + u16 event[0]; +} __packed; + +#define ec_event_num_words(ev) (ev->size - 1) +#define ec_event_size(ev) (sizeof(*ev) + (ec_event_num_words(ev) * sizeof(u16))) + +/** + * struct ec_event_queue - Circular queue for events. + * @capacity: Number of elements the queue can hold. + * @head: Next index to write to. + * @tail: Next index to read from. + * @entries: Array of events. + */ +struct ec_event_queue { + int capacity; + int head; + int tail; + struct ec_event *entries[0]; +}; + +/* Maximum number of events to store in ec_event_queue */ +static int queue_size = 64; +module_param(queue_size, int, 0644); + +static struct ec_event_queue *event_queue_new(int capacity) +{ + struct ec_event_queue *q; + + q = kzalloc(struct_size(q, entries, capacity), GFP_KERNEL); + if (!q) + return NULL; + + q->capacity = capacity; + + return q; +} + +static inline bool event_queue_empty(struct ec_event_queue *q) +{ + /* head==tail when both full and empty, but head==NULL when empty */ + return q->head == q->tail && !q->entries[q->head]; +} + +static inline bool event_queue_full(struct ec_event_queue *q) +{ + /* head==tail when both full and empty, but head!=NULL when full */ + return q->head == q->tail && q->entries[q->head]; +} + +static struct ec_event *event_queue_pop(struct ec_event_queue *q) +{ + struct ec_event *ev; + + if (event_queue_empty(q)) + return NULL; + + ev = q->entries[q->tail]; + q->entries[q->tail] = NULL; + q->tail = (q->tail + 1) % q->capacity; + + return ev; +} + +/* + * If full, overwrite the oldest event and return it so the caller + * can kfree it. If not full, return NULL. + */ +static struct ec_event *event_queue_push(struct ec_event_queue *q, + struct ec_event *ev) +{ + struct ec_event *popped = NULL; + + if (event_queue_full(q)) + popped = event_queue_pop(q); + q->entries[q->head] = ev; + q->head = (q->head + 1) % q->capacity; + + return popped; +} + +static void event_queue_free(struct ec_event_queue *q) +{ + struct ec_event *event; + + while ((event = event_queue_pop(q)) != NULL) + kfree(event); + + kfree(q); +} + +/** * struct event_device_data - Data for a Wilco EC device that responds to ACPI. * @events: Circular queue of EC events to be provided to userspace. - * @num_events: Number of events in the queue. - * @lock: Mutex to guard the queue. - * @wq: Wait queue to notify processes when events or available or the + * @queue_lock: Protect the queue from simultaneous read/writes. + * @wq: Wait queue to notify processes when events are available or the * device has been removed. * @cdev: Char dev that userspace reads() and polls() from. * @dev: Device associated with the %cdev. @@ -84,14 +183,13 @@ static DEFINE_IDA(event_ida); * * There will be one of these structs for each ACPI device registered. This data * is the queue of events received from ACPI that still need to be read from - * userspace (plus a supporting lock and wait queue), as well as the device and - * char device that userspace is using, plus a flag on whether the ACPI device - * has been removed. + * userspace, the device and char device that userspace is using, a wait queue + * used to notify different threads when something has changed, plus a flag + * on whether the ACPI device has been removed. */ struct event_device_data { - struct list_head events; - size_t num_events; - struct mutex lock; + struct ec_event_queue *events; + spinlock_t queue_lock; wait_queue_head_t wq; struct device dev; struct cdev cdev; @@ -100,31 +198,6 @@ struct event_device_data { }; /** - * struct ec_event - Extended event returned by the EC. - * @size: Number of words in structure after the size word. - * @type: Extended event type from &enum ec_event_type. - * @event: Event data words. Max count is %EC_ACPI_MAX_EVENT_WORDS. - */ -struct ec_event { - u16 size; - u16 type; - u16 event[0]; -} __packed; - -/** - * struct ec_event_entry - Event queue entry. - * @list: List node. - * @size: Number of bytes in event structure. - * @event: Extended event returned by the EC. This should be the last - * element because &struct ec_event includes a zero length array. - */ -struct ec_event_entry { - struct list_head list; - size_t size; - struct ec_event event; -}; - -/** * enqueue_events() - Place EC events in queue to be read by userspace. * @adev: Device the events came from. * @buf: Buffer of event data. @@ -132,7 +205,7 @@ struct ec_event_entry { * * %buf contains a number of ec_event's, packed one after the other. * Each ec_event is of variable length. Start with the first event, copy it - * into a containing ev_event_entry, store that entry in a list, move on + * into a persistent ec_event, store that entry in the queue, move on * to the next ec_event in buf, and repeat. * * Return: 0 on success or negative error code on failure. @@ -140,25 +213,20 @@ struct ec_event_entry { static int enqueue_events(struct acpi_device *adev, const u8 *buf, u32 length) { struct event_device_data *dev_data = adev->driver_data; - struct ec_event *event; - struct ec_event_entry *entry, *oldest_entry; - size_t event_size, num_words, word_size; + struct ec_event *event, *queue_event, *old_event; + size_t num_words, event_size; u32 offset = 0; while (offset < length) { event = (struct ec_event *)(buf + offset); - if (!event) - return -EINVAL; - /* Number of 16bit event data words is size - 1 */ - num_words = event->size - 1; - word_size = num_words * sizeof(u16); - event_size = sizeof(*event) + word_size; + num_words = ec_event_num_words(event); + event_size = ec_event_size(event); if (num_words > EC_ACPI_MAX_EVENT_WORDS) { dev_err(&adev->dev, "Too many event words: %zu > %d\n", num_words, EC_ACPI_MAX_EVENT_WORDS); return -EOVERFLOW; - }; + } /* Ensure event does not overflow the available buffer */ if ((offset + event_size) > length) { @@ -170,31 +238,15 @@ static int enqueue_events(struct acpi_device *adev, const u8 *buf, u32 length) /* Point to the next event in the buffer */ offset += event_size; - /* Create event entry for the queue */ - entry = kzalloc(sizeof(struct ec_event_entry) + word_size, - GFP_KERNEL); - if (!entry) + /* Copy event into the queue */ + queue_event = kmemdup(event, event_size, GFP_KERNEL); + if (!queue_event) return -ENOMEM; - entry->size = event_size; - memcpy(&entry->event, event, entry->size); - - mutex_lock(&dev_data->lock); - - /* If the queue is full, delete the oldest event */ - if (dev_data->num_events >= MAX_NUM_EVENTS) { - oldest_entry = list_first_entry(&dev_data->events, - struct ec_event_entry, - list); - list_del(&oldest_entry->list); - kfree(oldest_entry); - dev_data->num_events--; - } - - /* Add this event to the queue */ - list_add_tail(&entry->list, &dev_data->events); - dev_data->num_events++; - - mutex_unlock(&dev_data->lock); + spin_lock(&dev_data->queue_lock); + old_event = event_queue_push(dev_data->events, queue_event); + spin_unlock(&dev_data->queue_lock); + kfree(old_event); + wake_up_interruptible(&dev_data->wq); } return 0; @@ -210,7 +262,6 @@ static int enqueue_events(struct acpi_device *adev, const u8 *buf, u32 length) static void event_device_notify(struct acpi_device *adev, u32 value) { struct acpi_buffer event_buffer = { ACPI_ALLOCATE_BUFFER, NULL }; - struct event_device_data *dev_data = adev->driver_data; union acpi_object *obj; acpi_status status; @@ -249,9 +300,6 @@ static void event_device_notify(struct acpi_device *adev, u32 value) enqueue_events(adev, obj->buffer.pointer, obj->buffer.length); kfree(obj); - - if (dev_data->num_events) - wake_up_interruptible(&dev_data->wq); } static int event_open(struct inode *inode, struct file *filp) @@ -267,7 +315,7 @@ static int event_open(struct inode *inode, struct file *filp) /* Increase refcount on device so dev_data is not freed */ get_device(&dev_data->dev); - nonseekable_open(inode, filp); + stream_open(inode, filp); filp->private_data = dev_data; return 0; @@ -281,7 +329,7 @@ static __poll_t event_poll(struct file *filp, poll_table *wait) poll_wait(filp, &dev_data->wq, wait); if (!dev_data->exist) return EPOLLHUP; - if (dev_data->num_events) + if (!event_queue_empty(dev_data->events)) mask |= EPOLLIN | EPOLLRDNORM | EPOLLPRI; return mask; } @@ -293,8 +341,7 @@ static __poll_t event_poll(struct file *filp, poll_table *wait) * @count: Number of bytes requested. Must be at least EC_ACPI_MAX_EVENT_SIZE. * @pos: File position pointer, irrelevant since we don't support seeking. * - * Fills the passed buffer with the data from the first event in the queue, - * removes that event from the queue. On error, the event remains in the queue. + * Removes the first event from the queue, places it in the passed buffer. * * If there are no events in the the queue, then one of two things happens, * depending on if the file was opened in nonblocking mode: If in nonblocking @@ -307,7 +354,7 @@ static ssize_t event_read(struct file *filp, char __user *buf, size_t count, loff_t *pos) { struct event_device_data *dev_data = filp->private_data; - struct ec_event_entry *entry; + struct ec_event *event; ssize_t n_bytes_written = 0; int err; @@ -315,39 +362,29 @@ static ssize_t event_read(struct file *filp, char __user *buf, size_t count, if (count != 0 && count < EC_ACPI_MAX_EVENT_SIZE) return -EINVAL; - mutex_lock(&dev_data->lock); - - while (dev_data->num_events == 0) { - if (filp->f_flags & O_NONBLOCK) { - mutex_unlock(&dev_data->lock); + spin_lock(&dev_data->queue_lock); + while (event_queue_empty(dev_data->events)) { + spin_unlock(&dev_data->queue_lock); + if (filp->f_flags & O_NONBLOCK) return -EAGAIN; - } - /* Need to unlock so that data can actually get added to the - * queue, and since we recheck before use and it's just - * comparing pointers, this is safe unlocked. - */ - mutex_unlock(&dev_data->lock); + err = wait_event_interruptible(dev_data->wq, - dev_data->num_events); + !event_queue_empty(dev_data->events) || + !dev_data->exist); if (err) return err; /* Device was removed as we waited? */ if (!dev_data->exist) return -ENODEV; - mutex_lock(&dev_data->lock); + spin_lock(&dev_data->queue_lock); } - - entry = list_first_entry(&dev_data->events, - struct ec_event_entry, list); - n_bytes_written = entry->size; - if (copy_to_user(buf, &entry->event, n_bytes_written)) + event = event_queue_pop(dev_data->events); + spin_unlock(&dev_data->queue_lock); + n_bytes_written = ec_event_size(event); + if (copy_to_user(buf, event, n_bytes_written)) n_bytes_written = -EFAULT; - list_del(&entry->list); - kfree(entry); - dev_data->num_events--; - - mutex_unlock(&dev_data->lock); + kfree(event); return n_bytes_written; } @@ -384,15 +421,13 @@ static void free_device_data(struct device *d) struct event_device_data *dev_data; dev_data = container_of(d, struct event_device_data, dev); + event_queue_free(dev_data->events); kfree(dev_data); } static void hangup_device(struct event_device_data *dev_data) { - mutex_lock(&dev_data->lock); dev_data->exist = false; - mutex_unlock(&dev_data->lock); - /* Wake up the waiting processes so they can close. */ wake_up_interruptible(&dev_data->wq); put_device(&dev_data->dev); @@ -420,7 +455,7 @@ static int event_device_add(struct acpi_device *adev) minor = ida_alloc_max(&event_ida, EVENT_MAX_DEV-1, GFP_KERNEL); if (minor < 0) { error = minor; - dev_err(&adev->dev, "Failed to find minor number: %d", error); + dev_err(&adev->dev, "Failed to find minor number: %d\n", error); return error; } @@ -432,8 +467,13 @@ static int event_device_add(struct acpi_device *adev) /* Initialize the device data. */ adev->driver_data = dev_data; - INIT_LIST_HEAD(&dev_data->events); - mutex_init(&dev_data->lock); + dev_data->events = event_queue_new(queue_size); + if (!dev_data->events) { + kfree(dev_data); + error = -ENOMEM; + goto free_minor; + } + spin_lock_init(&dev_data->queue_lock); init_waitqueue_head(&dev_data->wq); dev_data->exist = true; atomic_set(&dev_data->available, 1); @@ -496,14 +536,14 @@ static int __init event_module_init(void) ret = class_register(&event_class); if (ret) { - pr_err(DRV_NAME ": Failed registering class: %d", ret); + pr_err(DRV_NAME ": Failed registering class: %d\n", ret); return ret; } /* Request device numbers, starting with minor=0. Save the major num. */ ret = alloc_chrdev_region(&dev_num, 0, EVENT_MAX_DEV, EVENT_DEV_NAME); if (ret) { - pr_err(DRV_NAME ": Failed allocating dev numbers: %d", ret); + pr_err(DRV_NAME ": Failed allocating dev numbers: %d\n", ret); goto destroy_class; } event_major = MAJOR(dev_num); |