linux/drivers/iio/kfifo_buf.c
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   1#include <linux/slab.h>
   2#include <linux/kernel.h>
   3#include <linux/module.h>
   4#include <linux/device.h>
   5#include <linux/workqueue.h>
   6#include <linux/kfifo.h>
   7#include <linux/mutex.h>
   8#include <linux/iio/kfifo_buf.h>
   9#include <linux/sched.h>
  10
  11struct iio_kfifo {
  12        struct iio_buffer buffer;
  13        struct kfifo kf;
  14        int update_needed;
  15};
  16
  17#define iio_to_kfifo(r) container_of(r, struct iio_kfifo, buffer)
  18
  19static inline int __iio_allocate_kfifo(struct iio_kfifo *buf,
  20                                int bytes_per_datum, int length)
  21{
  22        if ((length == 0) || (bytes_per_datum == 0))
  23                return -EINVAL;
  24
  25        return __kfifo_alloc((struct __kfifo *)&buf->kf, length,
  26                             bytes_per_datum, GFP_KERNEL);
  27}
  28
  29static int iio_request_update_kfifo(struct iio_buffer *r)
  30{
  31        int ret = 0;
  32        struct iio_kfifo *buf = iio_to_kfifo(r);
  33
  34        if (!buf->update_needed)
  35                goto error_ret;
  36        kfifo_free(&buf->kf);
  37        ret = __iio_allocate_kfifo(buf, buf->buffer.bytes_per_datum,
  38                                   buf->buffer.length);
  39        r->stufftoread = false;
  40error_ret:
  41        return ret;
  42}
  43
  44static int iio_get_length_kfifo(struct iio_buffer *r)
  45{
  46        return r->length;
  47}
  48
  49static IIO_BUFFER_ENABLE_ATTR;
  50static IIO_BUFFER_LENGTH_ATTR;
  51
  52static struct attribute *iio_kfifo_attributes[] = {
  53        &dev_attr_length.attr,
  54        &dev_attr_enable.attr,
  55        NULL,
  56};
  57
  58static struct attribute_group iio_kfifo_attribute_group = {
  59        .attrs = iio_kfifo_attributes,
  60        .name = "buffer",
  61};
  62
  63static int iio_get_bytes_per_datum_kfifo(struct iio_buffer *r)
  64{
  65        return r->bytes_per_datum;
  66}
  67
  68static int iio_mark_update_needed_kfifo(struct iio_buffer *r)
  69{
  70        struct iio_kfifo *kf = iio_to_kfifo(r);
  71        kf->update_needed = true;
  72        return 0;
  73}
  74
  75static int iio_set_bytes_per_datum_kfifo(struct iio_buffer *r, size_t bpd)
  76{
  77        if (r->bytes_per_datum != bpd) {
  78                r->bytes_per_datum = bpd;
  79                iio_mark_update_needed_kfifo(r);
  80        }
  81        return 0;
  82}
  83
  84static int iio_set_length_kfifo(struct iio_buffer *r, int length)
  85{
  86        /* Avoid an invalid state */
  87        if (length < 2)
  88                length = 2;
  89        if (r->length != length) {
  90                r->length = length;
  91                iio_mark_update_needed_kfifo(r);
  92        }
  93        return 0;
  94}
  95
  96static int iio_store_to_kfifo(struct iio_buffer *r,
  97                              u8 *data)
  98{
  99        int ret;
 100        struct iio_kfifo *kf = iio_to_kfifo(r);
 101        ret = kfifo_in(&kf->kf, data, 1);
 102        if (ret != 1)
 103                return -EBUSY;
 104        r->stufftoread = true;
 105        wake_up_interruptible(&r->pollq);
 106
 107        return 0;
 108}
 109
 110static int iio_read_first_n_kfifo(struct iio_buffer *r,
 111                           size_t n, char __user *buf)
 112{
 113        int ret, copied;
 114        struct iio_kfifo *kf = iio_to_kfifo(r);
 115
 116        if (n < r->bytes_per_datum || r->bytes_per_datum == 0)
 117                return -EINVAL;
 118
 119        ret = kfifo_to_user(&kf->kf, buf, n, &copied);
 120        if (ret < 0)
 121                return ret;
 122
 123        if (kfifo_is_empty(&kf->kf))
 124                r->stufftoread = false;
 125        /* verify it is still empty to avoid race */
 126        if (!kfifo_is_empty(&kf->kf))
 127                r->stufftoread = true;
 128
 129        return copied;
 130}
 131
 132static const struct iio_buffer_access_funcs kfifo_access_funcs = {
 133        .store_to = &iio_store_to_kfifo,
 134        .read_first_n = &iio_read_first_n_kfifo,
 135        .request_update = &iio_request_update_kfifo,
 136        .get_bytes_per_datum = &iio_get_bytes_per_datum_kfifo,
 137        .set_bytes_per_datum = &iio_set_bytes_per_datum_kfifo,
 138        .get_length = &iio_get_length_kfifo,
 139        .set_length = &iio_set_length_kfifo,
 140};
 141
 142struct iio_buffer *iio_kfifo_allocate(struct iio_dev *indio_dev)
 143{
 144        struct iio_kfifo *kf;
 145
 146        kf = kzalloc(sizeof *kf, GFP_KERNEL);
 147        if (!kf)
 148                return NULL;
 149        kf->update_needed = true;
 150        iio_buffer_init(&kf->buffer);
 151        kf->buffer.attrs = &iio_kfifo_attribute_group;
 152        kf->buffer.access = &kfifo_access_funcs;
 153        kf->buffer.length = 2;
 154        return &kf->buffer;
 155}
 156EXPORT_SYMBOL(iio_kfifo_allocate);
 157
 158void iio_kfifo_free(struct iio_buffer *r)
 159{
 160        kfree(iio_to_kfifo(r));
 161}
 162EXPORT_SYMBOL(iio_kfifo_free);
 163
 164MODULE_LICENSE("GPL");
 165
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