![Josselin Costanzi](/assets/img/avatar_default.png)
Currently the IIO buffer blocking read only wait until at least one data element is available. This patch makes the reader sleep until enough data is collected before returning to userspace. This should limit the read() calls count when trying to get data in batches. Co-author: Yannick Bedhomme <yannick.bedhomme@mobile-devices.fr> Signed-off-by: Josselin Costanzi <josselin.costanzi@mobile-devices.fr> [rebased and remove buffer timeout] Signed-off-by: Octavian Purdila <octavian.purdila@intel.com> Reviewed-by: Lars-Peter Clausen <lars@metafoo.de> Signed-off-by: Jonathan Cameron <jic23@kernel.org>
219 lines
4.7 KiB
C
219 lines
4.7 KiB
C
#include <linux/slab.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/device.h>
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#include <linux/workqueue.h>
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#include <linux/kfifo.h>
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#include <linux/mutex.h>
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#include <linux/iio/kfifo_buf.h>
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#include <linux/sched.h>
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#include <linux/poll.h>
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struct iio_kfifo {
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struct iio_buffer buffer;
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struct kfifo kf;
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struct mutex user_lock;
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int update_needed;
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};
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#define iio_to_kfifo(r) container_of(r, struct iio_kfifo, buffer)
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static inline int __iio_allocate_kfifo(struct iio_kfifo *buf,
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int bytes_per_datum, int length)
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{
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if ((length == 0) || (bytes_per_datum == 0))
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return -EINVAL;
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return __kfifo_alloc((struct __kfifo *)&buf->kf, length,
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bytes_per_datum, GFP_KERNEL);
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}
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static int iio_request_update_kfifo(struct iio_buffer *r)
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{
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int ret = 0;
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struct iio_kfifo *buf = iio_to_kfifo(r);
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mutex_lock(&buf->user_lock);
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if (buf->update_needed) {
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kfifo_free(&buf->kf);
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ret = __iio_allocate_kfifo(buf, buf->buffer.bytes_per_datum,
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buf->buffer.length);
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buf->update_needed = false;
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} else {
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kfifo_reset_out(&buf->kf);
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}
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mutex_unlock(&buf->user_lock);
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return ret;
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}
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static int iio_mark_update_needed_kfifo(struct iio_buffer *r)
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{
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struct iio_kfifo *kf = iio_to_kfifo(r);
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kf->update_needed = true;
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return 0;
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}
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static int iio_set_bytes_per_datum_kfifo(struct iio_buffer *r, size_t bpd)
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{
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if (r->bytes_per_datum != bpd) {
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r->bytes_per_datum = bpd;
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iio_mark_update_needed_kfifo(r);
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}
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return 0;
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}
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static int iio_set_length_kfifo(struct iio_buffer *r, int length)
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{
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/* Avoid an invalid state */
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if (length < 2)
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length = 2;
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if (r->length != length) {
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r->length = length;
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iio_mark_update_needed_kfifo(r);
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}
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return 0;
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}
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static int iio_store_to_kfifo(struct iio_buffer *r,
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const void *data)
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{
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int ret;
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struct iio_kfifo *kf = iio_to_kfifo(r);
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ret = kfifo_in(&kf->kf, data, 1);
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if (ret != 1)
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return -EBUSY;
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return 0;
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}
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static int iio_read_first_n_kfifo(struct iio_buffer *r,
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size_t n, char __user *buf)
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{
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int ret, copied;
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struct iio_kfifo *kf = iio_to_kfifo(r);
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if (mutex_lock_interruptible(&kf->user_lock))
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return -ERESTARTSYS;
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if (!kfifo_initialized(&kf->kf) || n < kfifo_esize(&kf->kf))
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ret = -EINVAL;
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else
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ret = kfifo_to_user(&kf->kf, buf, n, &copied);
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mutex_unlock(&kf->user_lock);
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if (ret < 0)
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return ret;
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return copied;
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}
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static size_t iio_kfifo_buf_data_available(struct iio_buffer *r)
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{
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struct iio_kfifo *kf = iio_to_kfifo(r);
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size_t samples;
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mutex_lock(&kf->user_lock);
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samples = kfifo_len(&kf->kf);
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mutex_unlock(&kf->user_lock);
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return samples;
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}
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static void iio_kfifo_buffer_release(struct iio_buffer *buffer)
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{
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struct iio_kfifo *kf = iio_to_kfifo(buffer);
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mutex_destroy(&kf->user_lock);
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kfifo_free(&kf->kf);
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kfree(kf);
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}
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static const struct iio_buffer_access_funcs kfifo_access_funcs = {
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.store_to = &iio_store_to_kfifo,
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.read_first_n = &iio_read_first_n_kfifo,
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.data_available = iio_kfifo_buf_data_available,
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.request_update = &iio_request_update_kfifo,
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.set_bytes_per_datum = &iio_set_bytes_per_datum_kfifo,
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.set_length = &iio_set_length_kfifo,
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.release = &iio_kfifo_buffer_release,
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};
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struct iio_buffer *iio_kfifo_allocate(void)
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{
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struct iio_kfifo *kf;
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kf = kzalloc(sizeof(*kf), GFP_KERNEL);
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if (!kf)
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return NULL;
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kf->update_needed = true;
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iio_buffer_init(&kf->buffer);
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kf->buffer.access = &kfifo_access_funcs;
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kf->buffer.length = 2;
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mutex_init(&kf->user_lock);
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return &kf->buffer;
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}
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EXPORT_SYMBOL(iio_kfifo_allocate);
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void iio_kfifo_free(struct iio_buffer *r)
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{
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iio_buffer_put(r);
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}
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EXPORT_SYMBOL(iio_kfifo_free);
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static void devm_iio_kfifo_release(struct device *dev, void *res)
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{
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iio_kfifo_free(*(struct iio_buffer **)res);
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}
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static int devm_iio_kfifo_match(struct device *dev, void *res, void *data)
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{
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struct iio_buffer **r = res;
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if (WARN_ON(!r || !*r))
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return 0;
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return *r == data;
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}
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/**
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* devm_iio_fifo_allocate - Resource-managed iio_kfifo_allocate()
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* @dev: Device to allocate kfifo buffer for
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*
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* RETURNS:
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* Pointer to allocated iio_buffer on success, NULL on failure.
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*/
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struct iio_buffer *devm_iio_kfifo_allocate(struct device *dev)
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{
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struct iio_buffer **ptr, *r;
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ptr = devres_alloc(devm_iio_kfifo_release, sizeof(*ptr), GFP_KERNEL);
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if (!ptr)
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return NULL;
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r = iio_kfifo_allocate();
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if (r) {
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*ptr = r;
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devres_add(dev, ptr);
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} else {
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devres_free(ptr);
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}
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return r;
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}
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EXPORT_SYMBOL(devm_iio_kfifo_allocate);
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/**
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* devm_iio_fifo_free - Resource-managed iio_kfifo_free()
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* @dev: Device the buffer belongs to
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* @r: The buffer associated with the device
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*/
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void devm_iio_kfifo_free(struct device *dev, struct iio_buffer *r)
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{
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WARN_ON(devres_release(dev, devm_iio_kfifo_release,
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devm_iio_kfifo_match, r));
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}
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EXPORT_SYMBOL(devm_iio_kfifo_free);
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MODULE_LICENSE("GPL");
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