#include <linux/kernel.h>
#include <linux/wait.h>
-#include <linux/spinlock_types.h>
+#include <linux/mutex.h>
#include <linux/device.h>
#include <linux/cdev.h>
#include <linux/init.h>
int has_tx_fifo; /* whether the IP has the tx fifo enabled */
wait_queue_head_t read_queue; /* wait queue for asynchronos read */
- spinlock_t read_queue_lock; /* lock for reading waitqueue */
+ struct mutex read_lock; /* lock for reading */
wait_queue_head_t write_queue; /* wait queue for asynchronos write */
- spinlock_t write_queue_lock; /* lock for writing waitqueue */
+ struct mutex write_lock; /* lock for writing */
unsigned int write_flags; /* write file flags */
unsigned int read_flags; /* read file flags */
iowrite32(XLLF_INT_ALL_MASK, fifo->base_addr + XLLF_ISR_OFFSET);
}
-/* reads a single packet from the fifo as dictated by the tlast signal */
+/**
+ * axis_fifo_write() - Read a packet from AXIS-FIFO character device.
+ * @f Open file.
+ * @buf User space buffer to read to.
+ * @len User space buffer length.
+ * @off Buffer offset.
+ *
+ * As defined by the device's documentation, we need to check the device's
+ * occupancy before reading the length register and then the data. All these
+ * operations must be executed atomically, in order and one after the other
+ * without missing any.
+ *
+ * Returns the number of bytes read from the device or negative error code
+ * on failure.
+ */
static ssize_t axis_fifo_read(struct file *f, char __user *buf,
size_t len, loff_t *off)
{
u32 tmp_buf[READ_BUF_SIZE];
if (fifo->read_flags & O_NONBLOCK) {
- /* opened in non-blocking mode
- * return if there are no packets available
+ /*
+ * Device opened in non-blocking mode. Try to lock it and then
+ * check if any packet is available.
*/
- if (!ioread32(fifo->base_addr + XLLF_RDFO_OFFSET))
+ if (!mutex_trylock(&fifo->read_lock))
return -EAGAIN;
+
+ if (!ioread32(fifo->base_addr + XLLF_RDFO_OFFSET)) {
+ ret = -EAGAIN;
+ goto end_unlock;
+ }
} else {
/* opened in blocking mode
* wait for a packet available interrupt (or timeout)
* if nothing is currently available
*/
- spin_lock_irq(&fifo->read_queue_lock);
- ret = wait_event_interruptible_lock_irq_timeout
- (fifo->read_queue,
- ioread32(fifo->base_addr + XLLF_RDFO_OFFSET),
- fifo->read_queue_lock,
- (read_timeout >= 0) ? msecs_to_jiffies(read_timeout) :
+ mutex_lock(&fifo->read_lock);
+ ret = wait_event_interruptible_timeout(fifo->read_queue,
+ ioread32(fifo->base_addr + XLLF_RDFO_OFFSET),
+ (read_timeout >= 0) ? msecs_to_jiffies(read_timeout) :
MAX_SCHEDULE_TIMEOUT);
- spin_unlock_irq(&fifo->read_queue_lock);
- if (ret == 0) {
- /* timeout occurred */
- dev_dbg(fifo->dt_device, "read timeout");
- return -EAGAIN;
- } else if (ret == -ERESTARTSYS) {
- /* signal received */
- return -ERESTARTSYS;
- } else if (ret < 0) {
- dev_err(fifo->dt_device, "wait_event_interruptible_timeout() error in read (ret=%i)\n",
- ret);
- return ret;
+ if (ret <= 0) {
+ if (ret == 0) {
+ ret = -EAGAIN;
+ } else if (ret != -ERESTARTSYS) {
+ dev_err(fifo->dt_device, "wait_event_interruptible_timeout() error in read (ret=%i)\n",
+ ret);
+ }
+
+ goto end_unlock;
}
}
if (!bytes_available) {
dev_err(fifo->dt_device, "received a packet of length 0 - fifo core will be reset\n");
reset_ip_core(fifo);
- return -EIO;
+ ret = -EIO;
+ goto end_unlock;
}
if (bytes_available > len) {
dev_err(fifo->dt_device, "user read buffer too small (available bytes=%zu user buffer bytes=%zu) - fifo core will be reset\n",
bytes_available, len);
reset_ip_core(fifo);
- return -EINVAL;
+ ret = -EINVAL;
+ goto end_unlock;
}
if (bytes_available % sizeof(u32)) {
*/
dev_err(fifo->dt_device, "received a packet that isn't word-aligned - fifo core will be reset\n");
reset_ip_core(fifo);
- return -EIO;
+ ret = -EIO;
+ goto end_unlock;
}
words_available = bytes_available / sizeof(u32);
if (copy_to_user(buf + copied * sizeof(u32), tmp_buf,
copy * sizeof(u32))) {
reset_ip_core(fifo);
- return -EFAULT;
+ ret = -EFAULT;
+ goto end_unlock;
}
copied += copy;
words_available -= copy;
}
- return bytes_available;
+ ret = bytes_available;
+
+end_unlock:
+ mutex_unlock(&fifo->read_lock);
+
+ return ret;
}
+/**
+ * axis_fifo_write() - Write buffer to AXIS-FIFO character device.
+ * @f Open file.
+ * @buf User space buffer to write to the device.
+ * @len User space buffer length.
+ * @off Buffer offset.
+ *
+ * As defined by the device's documentation, we need to write to the device's
+ * data buffer then to the device's packet length register atomically. Also,
+ * we need to lock before checking if the device has available space to avoid
+ * any concurrency issue.
+ *
+ * Returns the number of bytes written to the device or negative error code
+ * on failure.
+ */
static ssize_t axis_fifo_write(struct file *f, const char __user *buf,
size_t len, loff_t *off)
{
}
if (fifo->write_flags & O_NONBLOCK) {
- /* opened in non-blocking mode
- * return if there is not enough room available in the fifo
+ /*
+ * Device opened in non-blocking mode. Try to lock it and then
+ * check if there is any room to write the given buffer.
*/
+ if (!mutex_trylock(&fifo->write_lock))
+ return -EAGAIN;
+
if (words_to_write > ioread32(fifo->base_addr +
XLLF_TDFV_OFFSET)) {
- return -EAGAIN;
+ ret = -EAGAIN;
+ goto end_unlock;
}
} else {
/* opened in blocking mode */
/* wait for an interrupt (or timeout) if there isn't
* currently enough room in the fifo
*/
- spin_lock_irq(&fifo->write_queue_lock);
- ret = wait_event_interruptible_lock_irq_timeout
- (fifo->write_queue,
- ioread32(fifo->base_addr + XLLF_TDFV_OFFSET)
+ mutex_lock(&fifo->write_lock);
+ ret = wait_event_interruptible_timeout(fifo->write_queue,
+ ioread32(fifo->base_addr + XLLF_TDFV_OFFSET)
>= words_to_write,
- fifo->write_queue_lock,
- (write_timeout >= 0) ?
- msecs_to_jiffies(write_timeout) :
+ (write_timeout >= 0) ? msecs_to_jiffies(write_timeout) :
MAX_SCHEDULE_TIMEOUT);
- spin_unlock_irq(&fifo->write_queue_lock);
- if (ret == 0) {
- /* timeout occurred */
- dev_dbg(fifo->dt_device, "write timeout\n");
- return -EAGAIN;
- } else if (ret == -ERESTARTSYS) {
- /* signal received */
- return -ERESTARTSYS;
- } else if (ret < 0) {
- /* unknown error */
- dev_err(fifo->dt_device,
- "wait_event_interruptible_timeout() error in write (ret=%i)\n",
- ret);
- return ret;
+ if (ret <= 0) {
+ if (ret == 0) {
+ ret = -EAGAIN;
+ } else if (ret != -ERESTARTSYS) {
+ dev_err(fifo->dt_device, "wait_event_interruptible_timeout() error in write (ret=%i)\n",
+ ret);
+ }
+
+ goto end_unlock;
}
}
if (copy_from_user(tmp_buf, buf + copied * sizeof(u32),
copy * sizeof(u32))) {
reset_ip_core(fifo);
- return -EFAULT;
+ ret = -EFAULT;
+ goto end_unlock;
}
for (i = 0; i < copy; i++)
words_to_write -= copy;
}
+ ret = copied * sizeof(u32);
+
/* write packet size to fifo */
- iowrite32(copied * sizeof(u32), fifo->base_addr + XLLF_TLR_OFFSET);
+ iowrite32(ret, fifo->base_addr + XLLF_TLR_OFFSET);
+
+end_unlock:
+ mutex_unlock(&fifo->write_lock);
- return (ssize_t)copied * sizeof(u32);
+ return ret;
}
static irqreturn_t axis_fifo_irq(int irq, void *dw)
init_waitqueue_head(&fifo->read_queue);
init_waitqueue_head(&fifo->write_queue);
- spin_lock_init(&fifo->read_queue_lock);
- spin_lock_init(&fifo->write_queue_lock);
+ mutex_init(&fifo->read_lock);
+ mutex_init(&fifo->write_lock);
/* ----------------------------
* init device memory space
projects / linux-2.6-microblaze.git / blobdiff