diff options
Diffstat (limited to 'drivers/iio/kfifo_buf.c')
| -rw-r--r-- | drivers/iio/kfifo_buf.c | 192 |
1 files changed, 192 insertions, 0 deletions
diff --git a/drivers/iio/kfifo_buf.c b/drivers/iio/kfifo_buf.c new file mode 100644 index 00000000000..7134e8ada09 --- /dev/null +++ b/drivers/iio/kfifo_buf.c @@ -0,0 +1,192 @@ +#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"); |