kfifo_buf.c
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#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/workqueue.h>
#include <linux/kfifo.h>
#include <linux/mutex.h>
#include <linux/iio/kfifo_buf.h>
#include <linux/sched.h>
#include <linux/poll.h>
struct iio_kfifo {
struct iio_buffer buffer;
struct kfifo kf;
struct mutex user_lock;
int update_needed;
};
#define iio_to_kfifo(r) container_of(r, struct iio_kfifo, buffer)
static inline int __iio_allocate_kfifo(struct iio_kfifo *buf,
int bytes_per_datum, int length)
{
if ((length == 0) || (bytes_per_datum == 0))
return -EINVAL;
return __kfifo_alloc((struct __kfifo *)&buf->kf, length,
bytes_per_datum, GFP_KERNEL);
}
static int iio_request_update_kfifo(struct iio_buffer *r)
{
int ret = 0;
struct iio_kfifo *buf = iio_to_kfifo(r);
mutex_lock(&buf->user_lock);
if (buf->update_needed) {
kfifo_free(&buf->kf);
ret = __iio_allocate_kfifo(buf, buf->buffer.bytes_per_datum,
buf->buffer.length);
buf->update_needed = false;
} else {
kfifo_reset_out(&buf->kf);
}
mutex_unlock(&buf->user_lock);
return ret;
}
static int iio_get_length_kfifo(struct iio_buffer *r)
{
return r->length;
}
static IIO_BUFFER_ENABLE_ATTR;
static IIO_BUFFER_LENGTH_ATTR;
static struct attribute *iio_kfifo_attributes[] = {
&dev_attr_length.attr,
&dev_attr_enable.attr,
NULL,
};
static struct attribute_group iio_kfifo_attribute_group = {
.attrs = iio_kfifo_attributes,
.name = "buffer",
};
static int iio_get_bytes_per_datum_kfifo(struct iio_buffer *r)
{
return r->bytes_per_datum;
}
static int iio_mark_update_needed_kfifo(struct iio_buffer *r)
{
struct iio_kfifo *kf = iio_to_kfifo(r);
kf->update_needed = true;
return 0;
}
static int iio_set_bytes_per_datum_kfifo(struct iio_buffer *r, size_t bpd)
{
if (r->bytes_per_datum != bpd) {
r->bytes_per_datum = bpd;
iio_mark_update_needed_kfifo(r);
}
return 0;
}
static int iio_set_length_kfifo(struct iio_buffer *r, int length)
{
/* Avoid an invalid state */
if (length < 2)
length = 2;
if (r->length != length) {
r->length = length;
iio_mark_update_needed_kfifo(r);
}
return 0;
}
static int iio_store_to_kfifo(struct iio_buffer *r,
const void *data)
{
int ret;
struct iio_kfifo *kf = iio_to_kfifo(r);
ret = kfifo_in(&kf->kf, data, 1);
if (ret != 1)
return -EBUSY;
wake_up_interruptible_poll(&r->pollq, POLLIN | POLLRDNORM);
return 0;
}
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 (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 bool iio_kfifo_buf_data_available(struct iio_buffer *r)
{
struct iio_kfifo *kf = iio_to_kfifo(r);
bool empty;
mutex_lock(&kf->user_lock);
empty = kfifo_is_empty(&kf->kf);
mutex_unlock(&kf->user_lock);
return !empty;
}
static void iio_kfifo_buffer_release(struct iio_buffer *buffer)
{
struct iio_kfifo *kf = iio_to_kfifo(buffer);
mutex_destroy(&kf->user_lock);
kfifo_free(&kf->kf);
kfree(kf);
}
static const struct iio_buffer_access_funcs kfifo_access_funcs = {
.store_to = &iio_store_to_kfifo,
.read_first_n = &iio_read_first_n_kfifo,
.data_available = iio_kfifo_buf_data_available,
.request_update = &iio_request_update_kfifo,
.get_bytes_per_datum = &iio_get_bytes_per_datum_kfifo,
.set_bytes_per_datum = &iio_set_bytes_per_datum_kfifo,
.get_length = &iio_get_length_kfifo,
.set_length = &iio_set_length_kfifo,
.release = &iio_kfifo_buffer_release,
};
struct iio_buffer *iio_kfifo_allocate(struct iio_dev *indio_dev)
{
struct iio_kfifo *kf;
kf = kzalloc(sizeof *kf, GFP_KERNEL);
if (!kf)
return NULL;
kf->update_needed = true;
iio_buffer_init(&kf->buffer);
kf->buffer.attrs = &iio_kfifo_attribute_group;
kf->buffer.access = &kfifo_access_funcs;
kf->buffer.length = 2;
mutex_init(&kf->user_lock);
return &kf->buffer;
}
EXPORT_SYMBOL(iio_kfifo_allocate);
void iio_kfifo_free(struct iio_buffer *r)
{
iio_buffer_put(r);
}
EXPORT_SYMBOL(iio_kfifo_free);
MODULE_LICENSE("GPL");