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Subject[PATCH 2/5] Input: serio_raw - extract queue interface
Date
serio_raw operates on an internal data queue that buffers input packets
from device interrupt. As a queue is a generic data structure, it is
useful for implementing debugging facilities. This patch extracts its
interface in preparation for implementing debugging facilities.

Signed-off-by: Che-Liang Chiou <clchiou@chromium.org>
---
drivers/input/serio/serio_raw.c | 175 +++++++++++++++++++++++++++------------
1 files changed, 121 insertions(+), 54 deletions(-)
diff --git a/drivers/input/serio/serio_raw.c b/drivers/input/serio/serio_raw.c
index 4494233..bc2a8c7 100644
--- a/drivers/input/serio/serio_raw.c
+++ b/drivers/input/serio/serio_raw.c
@@ -29,15 +29,19 @@ MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL");

#define SERIO_RAW_QUEUE_LEN 64
-struct serio_raw {
+struct queue {
unsigned char queue[SERIO_RAW_QUEUE_LEN];
unsigned int tail, head;
+ wait_queue_head_t wait;
+};
+
+struct serio_raw {
+ struct queue queue;

char name[16];
struct kref kref;
struct serio *serio;
struct miscdevice dev;
- wait_queue_head_t wait;
struct list_head client_list;
struct list_head node;
bool dead;
@@ -53,6 +57,105 @@ static DEFINE_MUTEX(serio_raw_mutex);
static LIST_HEAD(serio_raw_list);

/*********************************************************************
+ * Interface with queue *
+ *********************************************************************/
+
+static void queue_init(struct queue *queue)
+{
+ init_waitqueue_head(&queue->wait);
+}
+
+static void queue_clear(struct queue *queue)
+{
+ queue->head = queue->tail = 0;
+}
+
+static bool queue_available(struct queue *queue)
+{
+ return queue->head != queue->tail;
+}
+
+static void queue_wakeup(struct queue *queue)
+{
+ wake_up_interruptible(&queue->wait);
+}
+
+static bool queue_fetch_byte(struct queue *queue, char *c)
+{
+ bool available;
+
+ available = queue_available(queue);
+ if (available) {
+ *c = queue->queue[queue->tail];
+ queue->tail = (queue->tail + 1) % SERIO_RAW_QUEUE_LEN;
+ }
+
+ return available;
+}
+
+static ssize_t queue_read(struct queue *queue,
+ char __user *buffer, size_t count, bool *dead, bool nonblock,
+ bool (*fetch_byte)(struct queue *, char *))
+{
+ char uninitialized_var(c);
+ ssize_t read = 0;
+ int retval;
+
+ if (*dead)
+ return -ENODEV;
+
+ if (!queue_available(queue) && nonblock)
+ return -EAGAIN;
+
+ retval = wait_event_interruptible(queue->wait,
+ queue_available(queue) || *dead);
+ if (retval)
+ return retval;
+
+ if (*dead)
+ return -ENODEV;
+
+ while (read < count && fetch_byte(queue, &c)) {
+ if (put_user(c, buffer++)) {
+ retval = -EFAULT;
+ break;
+ }
+ read++;
+ }
+
+ return read ?: retval;
+}
+
+static bool queue_write_byte(struct queue *queue, char c)
+{
+ unsigned int head;
+ bool may_write;
+
+ queue->queue[queue->head] = c;
+ head = (queue->head + 1) % SERIO_RAW_QUEUE_LEN;
+ may_write = head != queue->tail;
+ if (may_write)
+ queue->head = head;
+
+ return may_write;
+}
+
+static unsigned int queue_poll(struct queue *queue, struct file *file,
+ poll_table *wait, bool *dead)
+{
+ unsigned int mask;
+
+ poll_wait(file, &queue->wait, wait);
+
+ mask = *dead ? POLLHUP | POLLERR : POLLOUT | POLLWRNORM;
+ if (queue_available(queue))
+ mask |= POLLIN | POLLRDNORM;
+
+ return mask;
+}
+
+
+/*********************************************************************
* Interface with userspace (file operations) *
*********************************************************************/

@@ -141,21 +244,17 @@ static int serio_raw_release(struct inode *inode, struct file *file)
return 0;
}

-static bool serio_raw_fetch_byte(struct serio_raw *serio_raw, char *c)
+static bool serio_raw_fetch_byte(struct queue *queue, char *c)
{
- bool empty;
+ struct serio_raw *serio_raw;
+ bool available;

+ serio_raw = container_of(queue, struct serio_raw, queue);
serio_pause_rx(serio_raw->serio);
-
- empty = serio_raw->head == serio_raw->tail;
- if (!empty) {
- *c = serio_raw->queue[serio_raw->tail];
- serio_raw->tail = (serio_raw->tail + 1) % SERIO_RAW_QUEUE_LEN;
- }
-
+ available = queue_fetch_byte(queue, c);
serio_continue_rx(serio_raw->serio);

- return !empty;
+ return available;
}

static ssize_t serio_raw_read(struct file *file, char __user *buffer,
@@ -163,33 +262,11 @@ static ssize_t serio_raw_read(struct file *file, char __user *buffer,
{
struct serio_raw_client *client = file->private_data;
struct serio_raw *serio_raw = client->serio_raw;
- char uninitialized_var(c);
- ssize_t read = 0;
- int retval;
-
- if (serio_raw->dead)
- return -ENODEV;
-
- if (serio_raw->head == serio_raw->tail && (file->f_flags & O_NONBLOCK))
- return -EAGAIN;
-
- retval = wait_event_interruptible(serio_raw->wait,
- serio_raw->head != serio_raw->tail || serio_raw->dead);
- if (retval)
- return retval;
-
- if (serio_raw->dead)
- return -ENODEV;
+ struct queue *queue = &serio_raw->queue;

- while (read < count && serio_raw_fetch_byte(serio_raw, &c)) {
- if (put_user(c, buffer++)) {
- retval = -EFAULT;
- break;
- }
- read++;
- }
-
- return read ?: retval;
+ return queue_read(queue, buffer, count,
+ &serio_raw->dead, file->f_flags & O_NONBLOCK,
+ serio_raw_fetch_byte);
}

static ssize_t serio_raw_write(struct file *file, const char __user *buffer,
@@ -234,15 +311,9 @@ static unsigned int serio_raw_poll(struct file *file, poll_table *wait)
{
struct serio_raw_client *client = file->private_data;
struct serio_raw *serio_raw = client->serio_raw;
- unsigned int mask;
-
- poll_wait(file, &serio_raw->wait, wait);
+ struct queue *queue = &serio_raw->queue;

- mask = serio_raw->dead ? POLLHUP | POLLERR : POLLOUT | POLLWRNORM;
- if (serio_raw->head != serio_raw->tail)
- mask |= POLLIN | POLLRDNORM;
-
- return mask;
+ return queue_poll(queue, file, wait, &serio_raw->dead);
}

static const struct file_operations serio_raw_fops = {
@@ -266,16 +337,12 @@ static irqreturn_t serio_raw_interrupt(struct serio *serio, unsigned char data,
{
struct serio_raw *serio_raw = serio_get_drvdata(serio);
struct serio_raw_client *client;
- unsigned int head = serio_raw->head;

/* we are holding serio->lock here so we are protected */
- serio_raw->queue[head] = data;
- head = (head + 1) % SERIO_RAW_QUEUE_LEN;
- if (likely(head != serio_raw->tail)) {
- serio_raw->head = head;
+ if (queue_write_byte(&serio_raw->queue, data)) {
list_for_each_entry(client, &serio_raw->client_list, node)
kill_fasync(&client->fasync, SIGIO, POLL_IN);
- wake_up_interruptible(&serio_raw->wait);
+ queue_wakeup(&serio_raw->queue);
}

return IRQ_HANDLED;
@@ -297,7 +364,7 @@ static int serio_raw_connect(struct serio *serio, struct serio_driver *drv)
"serio_raw%ld", (long)atomic_inc_return(&serio_raw_no) - 1);
kref_init(&serio_raw->kref);
INIT_LIST_HEAD(&serio_raw->client_list);
- init_waitqueue_head(&serio_raw->wait);
+ queue_init(&serio_raw->queue);

serio_raw->serio = serio;
get_device(&serio->dev);
@@ -378,7 +445,7 @@ static void serio_raw_hangup(struct serio_raw *serio_raw)
kill_fasync(&client->fasync, SIGIO, POLL_HUP);
serio_continue_rx(serio_raw->serio);

- wake_up_interruptible(&serio_raw->wait);
+ queue_wakeup(&serio_raw->queue);
}


--
1.7.7.3


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