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#include <linux/poll.h>
  11
  12struct iio_kfifo {
  13        struct iio_buffer buffer;
  14        struct kfifo kf;
  15        struct mutex user_lock;
  16        int update_needed;
  17};
  18
  19#define iio_to_kfifo(r) container_of(r, struct iio_kfifo, buffer)
  20
  21static inline int __iio_allocate_kfifo(struct iio_kfifo *buf,
  22                                int bytes_per_datum, int length)
  23{
  24        if ((length == 0) || (bytes_per_datum == 0))
  25                return -EINVAL;
  26
  27        return __kfifo_alloc((struct __kfifo *)&buf->kf, length,
  28                             bytes_per_datum, GFP_KERNEL);
  29}
  30
  31static int iio_request_update_kfifo(struct iio_buffer *r)
  32{
  33        int ret = 0;
  34        struct iio_kfifo *buf = iio_to_kfifo(r);
  35
  36        mutex_lock(&buf->user_lock);
  37        if (buf->update_needed) {
  38                kfifo_free(&buf->kf);
  39                ret = __iio_allocate_kfifo(buf, buf->buffer.bytes_per_datum,
  40                                   buf->buffer.length);
  41                buf->update_needed = false;
  42        } else {
  43                kfifo_reset_out(&buf->kf);
  44        }
  45        mutex_unlock(&buf->user_lock);
  46
  47        return ret;
  48}
  49
  50static int iio_get_length_kfifo(struct iio_buffer *r)
  51{
  52        return r->length;
  53}
  54
  55static IIO_BUFFER_ENABLE_ATTR;
  56static IIO_BUFFER_LENGTH_ATTR;
  57
  58static struct attribute *iio_kfifo_attributes[] = {
  59        &dev_attr_length.attr,
  60        &dev_attr_enable.attr,
  61        NULL,
  62};
  63
  64static struct attribute_group iio_kfifo_attribute_group = {
  65        .attrs = iio_kfifo_attributes,
  66        .name = "buffer",
  67};
  68
  69static int iio_get_bytes_per_datum_kfifo(struct iio_buffer *r)
  70{
  71        return r->bytes_per_datum;
  72}
  73
  74static int iio_mark_update_needed_kfifo(struct iio_buffer *r)
  75{
  76        struct iio_kfifo *kf = iio_to_kfifo(r);
  77        kf->update_needed = true;
  78        return 0;
  79}
  80
  81static int iio_set_bytes_per_datum_kfifo(struct iio_buffer *r, size_t bpd)
  82{
  83        if (r->bytes_per_datum != bpd) {
  84                r->bytes_per_datum = bpd;
  85                iio_mark_update_needed_kfifo(r);
  86        }
  87        return 0;
  88}
  89
  90static int iio_set_length_kfifo(struct iio_buffer *r, int length)
  91{
  92        /* Avoid an invalid state */
  93        if (length < 2)
  94                length = 2;
  95        if (r->length != length) {
  96                r->length = length;
  97                iio_mark_update_needed_kfifo(r);
  98        }
  99        return 0;
 100}
 101
 102static int iio_store_to_kfifo(struct iio_buffer *r,
 103                              const void *data)
 104{
 105        int ret;
 106        struct iio_kfifo *kf = iio_to_kfifo(r);
 107        ret = kfifo_in(&kf->kf, data, 1);
 108        if (ret != 1)
 109                return -EBUSY;
 110
 111        wake_up_interruptible_poll(&r->pollq, POLLIN | POLLRDNORM);
 112
 113        return 0;
 114}
 115
 116static int iio_read_first_n_kfifo(struct iio_buffer *r,
 117                           size_t n, char __user *buf)
 118{
 119        int ret, copied;
 120        struct iio_kfifo *kf = iio_to_kfifo(r);
 121
 122        if (mutex_lock_interruptible(&kf->user_lock))
 123                return -ERESTARTSYS;
 124
 125        if (!kfifo_initialized(&kf->kf) || n < kfifo_esize(&kf->kf))
 126                ret = -EINVAL;
 127        else
 128                ret = kfifo_to_user(&kf->kf, buf, n, &copied);
 129        mutex_unlock(&kf->user_lock);
 130        if (ret < 0)
 131                return ret;
 132
 133        return copied;
 134}
 135
 136static bool iio_kfifo_buf_data_available(struct iio_buffer *r)
 137{
 138        struct iio_kfifo *kf = iio_to_kfifo(r);
 139        bool empty;
 140
 141        mutex_lock(&kf->user_lock);
 142        empty = kfifo_is_empty(&kf->kf);
 143        mutex_unlock(&kf->user_lock);
 144
 145        return !empty;
 146}
 147
 148static void iio_kfifo_buffer_release(struct iio_buffer *buffer)
 149{
 150        struct iio_kfifo *kf = iio_to_kfifo(buffer);
 151
 152        mutex_destroy(&kf->user_lock);
 153        kfifo_free(&kf->kf);
 154        kfree(kf);
 155}
 156
 157static const struct iio_buffer_access_funcs kfifo_access_funcs = {
 158        .store_to = &iio_store_to_kfifo,
 159        .read_first_n = &iio_read_first_n_kfifo,
 160        .data_available = iio_kfifo_buf_data_available,
 161        .request_update = &iio_request_update_kfifo,
 162        .get_bytes_per_datum = &iio_get_bytes_per_datum_kfifo,
 163        .set_bytes_per_datum = &iio_set_bytes_per_datum_kfifo,
 164        .get_length = &iio_get_length_kfifo,
 165        .set_length = &iio_set_length_kfifo,
 166        .release = &iio_kfifo_buffer_release,
 167};
 168
 169struct iio_buffer *iio_kfifo_allocate(struct iio_dev *indio_dev)
 170{
 171        struct iio_kfifo *kf;
 172
 173        kf = kzalloc(sizeof *kf, GFP_KERNEL);
 174        if (!kf)
 175                return NULL;
 176        kf->update_needed = true;
 177        iio_buffer_init(&kf->buffer);
 178        kf->buffer.attrs = &iio_kfifo_attribute_group;
 179        kf->buffer.access = &kfifo_access_funcs;
 180        kf->buffer.length = 2;
 181        mutex_init(&kf->user_lock);
 182        return &kf->buffer;
 183}
 184EXPORT_SYMBOL(iio_kfifo_allocate);
 185
 186void iio_kfifo_free(struct iio_buffer *r)
 187{
 188        iio_buffer_put(r);
 189}
 190EXPORT_SYMBOL(iio_kfifo_free);
 191
 192MODULE_LICENSE("GPL");
 193