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
  10struct iio_kfifo {
  11        struct iio_buffer buffer;
  12        struct kfifo kf;
  13        int update_needed;
  14};
  15
  16#define iio_to_kfifo(r) container_of(r, struct iio_kfifo, buffer)
  17
  18static inline int __iio_allocate_kfifo(struct iio_kfifo *buf,
  19                                int bytes_per_datum, int length)
  20{
  21        if ((length == 0) || (bytes_per_datum == 0))
  22                return -EINVAL;
  23
  24        __iio_update_buffer(&buf->buffer, bytes_per_datum, length);
  25        return kfifo_alloc(&buf->kf, bytes_per_datum*length, GFP_KERNEL);
  26}
  27
  28static int iio_request_update_kfifo(struct iio_buffer *r)
  29{
  30        int ret = 0;
  31        struct iio_kfifo *buf = iio_to_kfifo(r);
  32
  33        if (!buf->update_needed)
  34                goto error_ret;
  35        kfifo_free(&buf->kf);
  36        ret = __iio_allocate_kfifo(buf, buf->buffer.bytes_per_datum,
  37                                   buf->buffer.length);
  38error_ret:
  39        return ret;
  40}
  41
  42static int iio_get_length_kfifo(struct iio_buffer *r)
  43{
  44        return r->length;
  45}
  46
  47static IIO_BUFFER_ENABLE_ATTR;
  48static IIO_BUFFER_LENGTH_ATTR;
  49
  50static struct attribute *iio_kfifo_attributes[] = {
  51        &dev_attr_length.attr,
  52        &dev_attr_enable.attr,
  53        NULL,
  54};
  55
  56static struct attribute_group iio_kfifo_attribute_group = {
  57        .attrs = iio_kfifo_attributes,
  58        .name = "buffer",
  59};
  60
  61static int iio_get_bytes_per_datum_kfifo(struct iio_buffer *r)
  62{
  63        return r->bytes_per_datum;
  64}
  65
  66static int iio_mark_update_needed_kfifo(struct iio_buffer *r)
  67{
  68        struct iio_kfifo *kf = iio_to_kfifo(r);
  69        kf->update_needed = true;
  70        return 0;
  71}
  72
  73static int iio_set_bytes_per_datum_kfifo(struct iio_buffer *r, size_t bpd)
  74{
  75        if (r->bytes_per_datum != bpd) {
  76                r->bytes_per_datum = bpd;
  77                iio_mark_update_needed_kfifo(r);
  78        }
  79        return 0;
  80}
  81
  82static int iio_set_length_kfifo(struct iio_buffer *r, int length)
  83{
  84        if (r->length != length) {
  85                r->length = length;
  86                iio_mark_update_needed_kfifo(r);
  87        }
  88        return 0;
  89}
  90
  91static int iio_store_to_kfifo(struct iio_buffer *r,
  92                              u8 *data,
  93                              s64 timestamp)
  94{
  95        int ret;
  96        struct iio_kfifo *kf = iio_to_kfifo(r);
  97        ret = kfifo_in(&kf->kf, data, r->bytes_per_datum);
  98        if (ret != r->bytes_per_datum)
  99                return -EBUSY;
 100        return 0;
 101}
 102
 103static int iio_read_first_n_kfifo(struct iio_buffer *r,
 104                           size_t n, char __user *buf)
 105{
 106        int ret, copied;
 107        struct iio_kfifo *kf = iio_to_kfifo(r);
 108
 109        if (n < r->bytes_per_datum)
 110                return -EINVAL;
 111
 112        n = rounddown(n, r->bytes_per_datum);
 113        ret = kfifo_to_user(&kf->kf, buf, n, &copied);
 114
 115        return copied;
 116}
 117
 118static const struct iio_buffer_access_funcs kfifo_access_funcs = {
 119        .store_to = &iio_store_to_kfifo,
 120        .read_first_n = &iio_read_first_n_kfifo,
 121        .request_update = &iio_request_update_kfifo,
 122        .get_bytes_per_datum = &iio_get_bytes_per_datum_kfifo,
 123        .set_bytes_per_datum = &iio_set_bytes_per_datum_kfifo,
 124        .get_length = &iio_get_length_kfifo,
 125        .set_length = &iio_set_length_kfifo,
 126};
 127
 128struct iio_buffer *iio_kfifo_allocate(struct iio_dev *indio_dev)
 129{
 130        struct iio_kfifo *kf;
 131
 132        kf = kzalloc(sizeof *kf, GFP_KERNEL);
 133        if (!kf)
 134                return NULL;
 135        kf->update_needed = true;
 136        iio_buffer_init(&kf->buffer);
 137        kf->buffer.attrs = &iio_kfifo_attribute_group;
 138        kf->buffer.access = &kfifo_access_funcs;
 139
 140        return &kf->buffer;
 141}
 142EXPORT_SYMBOL(iio_kfifo_allocate);
 143
 144void iio_kfifo_free(struct iio_buffer *r)
 145{
 146        kfree(iio_to_kfifo(r));
 147}
 148EXPORT_SYMBOL(iio_kfifo_free);
 149
 150MODULE_LICENSE("GPL");
 151
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