linux/drivers/iio/buffer/kfifo_buf.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2#include <linux/slab.h>
   3#include <linux/kernel.h>
   4#include <linux/module.h>
   5#include <linux/device.h>
   6#include <linux/workqueue.h>
   7#include <linux/kfifo.h>
   8#include <linux/mutex.h>
   9#include <linux/iio/iio.h>
  10#include <linux/iio/buffer.h>
  11#include <linux/iio/kfifo_buf.h>
  12#include <linux/iio/buffer_impl.h>
  13#include <linux/sched.h>
  14#include <linux/poll.h>
  15
  16struct iio_kfifo {
  17        struct iio_buffer buffer;
  18        struct kfifo kf;
  19        struct mutex user_lock;
  20        int update_needed;
  21};
  22
  23#define iio_to_kfifo(r) container_of(r, struct iio_kfifo, buffer)
  24
  25static inline int __iio_allocate_kfifo(struct iio_kfifo *buf,
  26                        size_t bytes_per_datum, unsigned int length)
  27{
  28        if ((length == 0) || (bytes_per_datum == 0))
  29                return -EINVAL;
  30
  31        /*
  32         * Make sure we don't overflow an unsigned int after kfifo rounds up to
  33         * the next power of 2.
  34         */
  35        if (roundup_pow_of_two(length) > UINT_MAX / bytes_per_datum)
  36                return -EINVAL;
  37
  38        return __kfifo_alloc((struct __kfifo *)&buf->kf, length,
  39                             bytes_per_datum, GFP_KERNEL);
  40}
  41
  42static int iio_request_update_kfifo(struct iio_buffer *r)
  43{
  44        int ret = 0;
  45        struct iio_kfifo *buf = iio_to_kfifo(r);
  46
  47        mutex_lock(&buf->user_lock);
  48        if (buf->update_needed) {
  49                kfifo_free(&buf->kf);
  50                ret = __iio_allocate_kfifo(buf, buf->buffer.bytes_per_datum,
  51                                   buf->buffer.length);
  52                if (ret >= 0)
  53                        buf->update_needed = false;
  54        } else {
  55                kfifo_reset_out(&buf->kf);
  56        }
  57        mutex_unlock(&buf->user_lock);
  58
  59        return ret;
  60}
  61
  62static int iio_mark_update_needed_kfifo(struct iio_buffer *r)
  63{
  64        struct iio_kfifo *kf = iio_to_kfifo(r);
  65        kf->update_needed = true;
  66        return 0;
  67}
  68
  69static int iio_set_bytes_per_datum_kfifo(struct iio_buffer *r, size_t bpd)
  70{
  71        if (r->bytes_per_datum != bpd) {
  72                r->bytes_per_datum = bpd;
  73                iio_mark_update_needed_kfifo(r);
  74        }
  75        return 0;
  76}
  77
  78static int iio_set_length_kfifo(struct iio_buffer *r, unsigned int length)
  79{
  80        /* Avoid an invalid state */
  81        if (length < 2)
  82                length = 2;
  83        if (r->length != length) {
  84                r->length = length;
  85                iio_mark_update_needed_kfifo(r);
  86        }
  87        return 0;
  88}
  89
  90static int iio_store_to_kfifo(struct iio_buffer *r,
  91                              const void *data)
  92{
  93        int ret;
  94        struct iio_kfifo *kf = iio_to_kfifo(r);
  95        ret = kfifo_in(&kf->kf, data, 1);
  96        if (ret != 1)
  97                return -EBUSY;
  98        return 0;
  99}
 100
 101static int iio_read_kfifo(struct iio_buffer *r, size_t n, char __user *buf)
 102{
 103        int ret, copied;
 104        struct iio_kfifo *kf = iio_to_kfifo(r);
 105
 106        if (mutex_lock_interruptible(&kf->user_lock))
 107                return -ERESTARTSYS;
 108
 109        if (!kfifo_initialized(&kf->kf) || n < kfifo_esize(&kf->kf))
 110                ret = -EINVAL;
 111        else
 112                ret = kfifo_to_user(&kf->kf, buf, n, &copied);
 113        mutex_unlock(&kf->user_lock);
 114        if (ret < 0)
 115                return ret;
 116
 117        return copied;
 118}
 119
 120static size_t iio_kfifo_buf_data_available(struct iio_buffer *r)
 121{
 122        struct iio_kfifo *kf = iio_to_kfifo(r);
 123        size_t samples;
 124
 125        mutex_lock(&kf->user_lock);
 126        samples = kfifo_len(&kf->kf);
 127        mutex_unlock(&kf->user_lock);
 128
 129        return samples;
 130}
 131
 132static void iio_kfifo_buffer_release(struct iio_buffer *buffer)
 133{
 134        struct iio_kfifo *kf = iio_to_kfifo(buffer);
 135
 136        mutex_destroy(&kf->user_lock);
 137        kfifo_free(&kf->kf);
 138        kfree(kf);
 139}
 140
 141static const struct iio_buffer_access_funcs kfifo_access_funcs = {
 142        .store_to = &iio_store_to_kfifo,
 143        .read = &iio_read_kfifo,
 144        .data_available = iio_kfifo_buf_data_available,
 145        .request_update = &iio_request_update_kfifo,
 146        .set_bytes_per_datum = &iio_set_bytes_per_datum_kfifo,
 147        .set_length = &iio_set_length_kfifo,
 148        .release = &iio_kfifo_buffer_release,
 149
 150        .modes = INDIO_BUFFER_SOFTWARE | INDIO_BUFFER_TRIGGERED,
 151};
 152
 153struct iio_buffer *iio_kfifo_allocate(void)
 154{
 155        struct iio_kfifo *kf;
 156
 157        kf = kzalloc(sizeof(*kf), GFP_KERNEL);
 158        if (!kf)
 159                return NULL;
 160
 161        kf->update_needed = true;
 162        iio_buffer_init(&kf->buffer);
 163        kf->buffer.access = &kfifo_access_funcs;
 164        kf->buffer.length = 2;
 165        mutex_init(&kf->user_lock);
 166
 167        return &kf->buffer;
 168}
 169EXPORT_SYMBOL(iio_kfifo_allocate);
 170
 171void iio_kfifo_free(struct iio_buffer *r)
 172{
 173        iio_buffer_put(r);
 174}
 175EXPORT_SYMBOL(iio_kfifo_free);
 176
 177static void devm_iio_kfifo_release(struct device *dev, void *res)
 178{
 179        iio_kfifo_free(*(struct iio_buffer **)res);
 180}
 181
 182static int devm_iio_kfifo_match(struct device *dev, void *res, void *data)
 183{
 184        struct iio_buffer **r = res;
 185
 186        if (WARN_ON(!r || !*r))
 187                return 0;
 188
 189        return *r == data;
 190}
 191
 192/**
 193 * devm_iio_fifo_allocate - Resource-managed iio_kfifo_allocate()
 194 * @dev:                Device to allocate kfifo buffer for
 195 *
 196 * RETURNS:
 197 * Pointer to allocated iio_buffer on success, NULL on failure.
 198 */
 199struct iio_buffer *devm_iio_kfifo_allocate(struct device *dev)
 200{
 201        struct iio_buffer **ptr, *r;
 202
 203        ptr = devres_alloc(devm_iio_kfifo_release, sizeof(*ptr), GFP_KERNEL);
 204        if (!ptr)
 205                return NULL;
 206
 207        r = iio_kfifo_allocate();
 208        if (r) {
 209                *ptr = r;
 210                devres_add(dev, ptr);
 211        } else {
 212                devres_free(ptr);
 213        }
 214
 215        return r;
 216}
 217EXPORT_SYMBOL(devm_iio_kfifo_allocate);
 218
 219/**
 220 * devm_iio_fifo_free - Resource-managed iio_kfifo_free()
 221 * @dev:                Device the buffer belongs to
 222 * @r:                  The buffer associated with the device
 223 */
 224void devm_iio_kfifo_free(struct device *dev, struct iio_buffer *r)
 225{
 226        WARN_ON(devres_release(dev, devm_iio_kfifo_release,
 227                               devm_iio_kfifo_match, r));
 228}
 229EXPORT_SYMBOL(devm_iio_kfifo_free);
 230
 231MODULE_LICENSE("GPL");
 232