From ace3d8614ab0e6544f5f85921085b55b915fe9aa Mon Sep 17 00:00:00 2001 From: David Herrmann Date: Sun, 10 Jun 2012 15:16:14 +0200 Subject: HID: uhid: add internal message buffer When receiving messages from the HID subsystem, we need to process them and store them in an internal buffer so user-space can read() on the char device to retrieve the messages. This adds a static buffer for 32 messages to each uhid device. Each message is dynamically allocated so the uhid_device structure does not get too big. uhid_queue() adds a message to the buffer. If the buffer is full, the message is discarded. uhid_queue_event() is an helper for messages without payload. This also adds a public header: uhid.h. It contains the declarations for the user-space API. It is built around "struct uhid_event" which contains a type field which specifies the event type and each event can then add a variable-length payload. For now, there is only a dummy event but later patches will add new event types and payloads. Signed-off-by: David Herrmann Signed-off-by: Jiri Kosina --- drivers/hid/uhid.c | 65 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 65 insertions(+) (limited to 'drivers/hid') diff --git a/drivers/hid/uhid.c b/drivers/hid/uhid.c index 5b02d6cb0e60..05ef4b05a63e 100644 --- a/drivers/hid/uhid.c +++ b/drivers/hid/uhid.c @@ -25,16 +25,81 @@ #include #define UHID_NAME "uhid" +#define UHID_BUFSIZE 32 + +struct uhid_device { + struct hid_device *hid; + + wait_queue_head_t waitq; + spinlock_t qlock; + __u8 head; + __u8 tail; + struct uhid_event *outq[UHID_BUFSIZE]; +}; static struct miscdevice uhid_misc; +static void uhid_queue(struct uhid_device *uhid, struct uhid_event *ev) +{ + __u8 newhead; + + newhead = (uhid->head + 1) % UHID_BUFSIZE; + + if (newhead != uhid->tail) { + uhid->outq[uhid->head] = ev; + uhid->head = newhead; + wake_up_interruptible(&uhid->waitq); + } else { + hid_warn(uhid->hid, "Output queue is full\n"); + kfree(ev); + } +} + +static int uhid_queue_event(struct uhid_device *uhid, __u32 event) +{ + unsigned long flags; + struct uhid_event *ev; + + ev = kzalloc(sizeof(*ev), GFP_KERNEL); + if (!ev) + return -ENOMEM; + + ev->type = event; + + spin_lock_irqsave(&uhid->qlock, flags); + uhid_queue(uhid, ev); + spin_unlock_irqrestore(&uhid->qlock, flags); + + return 0; +} + static int uhid_char_open(struct inode *inode, struct file *file) { + struct uhid_device *uhid; + + uhid = kzalloc(sizeof(*uhid), GFP_KERNEL); + if (!uhid) + return -ENOMEM; + + spin_lock_init(&uhid->qlock); + init_waitqueue_head(&uhid->waitq); + + file->private_data = uhid; + nonseekable_open(inode, file); + return 0; } static int uhid_char_release(struct inode *inode, struct file *file) { + struct uhid_device *uhid = file->private_data; + unsigned int i; + + for (i = 0; i < UHID_BUFSIZE; ++i) + kfree(uhid->outq[i]); + + kfree(uhid); + return 0; } -- cgit v1.2.3-55-g7522