static ssize_t parrot_device_read(struct file* filp, char __user *buffer, size_t length, loff_t* offset)
{
int retval;
unsigned int copied;
/* The default from 'cat' is to issue multiple reads until the FIFO is depleted
* one_shot avoids that */
if (one_shot && message_read) return 0;
dbg("");
if (kfifo_is_empty(&parrot_msg_fifo)) {
dbg("no message in fifo\n");
return 0;
}
retval = kfifo_to_user(&parrot_msg_fifo, buffer, parrot_msg_len[parrot_msg_idx_rd], &copied);
/* Ignore short reads (but warn about them) */
if (parrot_msg_len[parrot_msg_idx_rd] != copied) {
warn("short read detected\n");
}
/* loop into the message length table */
parrot_msg_idx_rd = (parrot_msg_idx_rd+1)%PARROT_MSG_FIFO_MAX;
message_read = true;
return retval ? retval : copied;
}
static ssize_t pfsRead(struct file *file, char __user *buffer, size_t count, loff_t *pffset) {
int ret;
unsigned int copied;
if(!strcmp(PDE_DATA(file_inode(file)),"procEntry")) {
ret = kfifo_to_user(&myfifo, buffer, 32, &copied);
rc+=1;
return ret?ret:copied;
}
else if(!strcmp(PDE_DATA(file_inode(file)),"rwCount")) {
if(flag>0) {
flag=0;
ret=0;
}
else {
ret = sprintf(buffer, "Number of Reads : %d\nNumber of Writes : %d\n", rc, wc);
flag = 1;
}
return ret;
}
else {
printk(KERN_ALERT "Invalid Data\n");
return 0;
}
return 0;
}
static ssize_t rpmsg_dev_read(struct file *filp, char __user *ubuff,
size_t len, loff_t *p_off)
{
struct _rpmsg_device *_prpmsg_device = (struct _rpmsg_device *)filp->private_data;
struct _rpmsg_params *local = ( struct _rpmsg_params *)&_prpmsg_device->rpmsg_params;
int retval;
unsigned int data_available, data_used, bytes_copied;
/* Acquire lock to access rpmsg kfifo */
static int count = 0;
while (mutex_lock_interruptible(&local->sync_lock))
{
if (!count)
{
pr_info("%s: error = %d.\n", __func__,mutex_lock_interruptible(&local->sync_lock));
count++;
}
}
data_available = kfifo_len(&local->rpmsg_kfifo);
if (data_available == 0)
{
/* Release lock */
mutex_unlock(&local->sync_lock);
/* if non-blocking read is requested return error */
if (filp->f_flags & O_NONBLOCK)
return -EAGAIN;
/* Block the calling context till data becomes available */
wait_event_interruptible(local->usr_wait_q,
local->block_flag != 0);
while (mutex_lock_interruptible(&local->sync_lock));
}
/* reset block flag */
local->block_flag = 0;
/* Provide requested data size to user space */
data_available = kfifo_len(&local->rpmsg_kfifo);
data_used = (data_available > len) ? len : data_available;
retval = kfifo_to_user(&local->rpmsg_kfifo, ubuff, data_used, &bytes_copied);
/* Release lock on rpmsg kfifo */
mutex_unlock(&local->sync_lock);
return retval ? retval : bytes_copied;
}
static int iio_read_first_n_kfifo(struct iio_buffer *r,
size_t n, char __user *buf)
{
int ret, copied;
struct iio_kfifo *kf = iio_to_kfifo(r);
if (n < r->bytes_per_datum)
return -EINVAL;
n = rounddown(n, r->bytes_per_datum);
ret = kfifo_to_user(&kf->kf, buf, n, &copied);
return copied;
}
static ssize_t fifo_read(struct file *file, char __user *buf,
size_t count, loff_t *ppos)
{
int ret;
unsigned int copied;
if (mutex_lock_interruptible(&read_lock))
return -ERESTARTSYS;
ret = kfifo_to_user(&test, buf, count, &copied);
mutex_unlock(&read_lock);
return ret ? ret : copied;
}
static ssize_t ami_read(struct file *file, char *buf, size_t count, loff_t *ptr)
{
struct ami306_dev_data *pdev = container_of(file->private_data, struct ami306_dev_data, dev);
u32 iRead = 0;
int res;
wait_event_interruptible(pdev->waitq, (kfifo_len(&(pdev->ebuff))> 0));
/* copy to user */
res = kfifo_to_user(&pdev->ebuff, buf, count, &iRead);
if (res < 0) {
printk("ami_read failed to copy\n");
return -EFAULT;
}
return iRead;
}
static int iio_read_kfifo(struct iio_buffer *r, size_t n, char __user *buf)
{
int ret, copied;
struct iio_kfifo *kf = iio_to_kfifo(r);
if (mutex_lock_interruptible(&kf->user_lock))
return -ERESTARTSYS;
if (!kfifo_initialized(&kf->kf) || n < kfifo_esize(&kf->kf))
ret = -EINVAL;
else
ret = kfifo_to_user(&kf->kf, buf, n, &copied);
mutex_unlock(&kf->user_lock);
if (ret < 0)
return ret;
return copied;
}
static int iio_read_first_n_kfifo(struct iio_buffer *r,
size_t n, char __user *buf)
{
int ret, copied;
struct iio_kfifo *kf = iio_to_kfifo(r);
if (n < r->bytes_per_datum)
return -EINVAL;
n = rounddown(n, r->bytes_per_datum);
ret = kfifo_to_user(&kf->kf, buf, n, &copied);
if (kfifo_is_empty(&kf->kf))
r->stufftoread = false;
/* verify it is still empty to avoid race */
if (!kfifo_is_empty(&kf->kf))
r->stufftoread = true;
return copied;
}
ssize_t cons_read(struct file *filp, char __user *buf, size_t count,
loff_t *f_pos)
{
int ret;
int copied;
pr_info("%s() : FIFO size = %d, count = %d\n", __func__,
(int)kfifo_len(&fifo), (int)count);
if (down_interruptible(&cons_sem))
return -ERESTARTSYS;
while (kfifo_len(&fifo) <= 0) { /* nothing to read */
up(&cons_sem); /* release the lock */
if (filp->f_flags & O_NONBLOCK)
return -EAGAIN;
pr_info("%s () : \"%s\" going to sleep\n", __func__,
current->comm);
if (wait_event_interruptible(cons_que, kfifo_len(&fifo) > 0)) {
pr_info("%s() wait_event_interruptible() : signal: "
"tell the fs layer to handle it\n", __func__);
return -ERESTARTSYS;
/* signal: inform the fs layer to handle it */
}
if (down_interruptible(&cons_sem))
return -ERESTARTSYS;
}
/* ok, data is there, return something */
count = min((long)count, (long)kfifo_len(&fifo));
pr_info("%s() : \"%s\" data to copy = %li bytes\n",
__func__, current->comm, (long)count);
ret = kfifo_to_user(&fifo, buf, count, &copied);
up(&cons_sem);
if (ret < 0)
return -EFAULT;
pr_info("%s() : \"%s\" read %li bytes. FIFO new Size = %d\n",
__func__, current->comm, (long)count, (int)kfifo_len(&fifo));
pr_info("%s() : \"%s\" waking up producer processes\n", __func__,
current->comm);
wake_up_interruptible(&prod_que);
return copied;
}