drivers/staging/iio/kfifo_buf.c

   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
   9 #include "kfifo_buf.h"
  10
  11 struct iio_kfifo {
  12         struct iio_ring_buffer ring;
  13         struct kfifo kf;
  14         int use_count;
  15         int update_needed;
  16         struct mutex use_lock;
  17 };
  18
  19 #define iio_to_kfifo(r) container_of(r, struct iio_kfifo, ring)
  20
  21 static 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         __iio_update_ring_buffer(&buf->ring, bytes_per_datum, length);
  28         return kfifo_alloc(&buf->kf, bytes_per_datum*length, GFP_KERNEL);
  29 }
  30
  31 static int iio_request_update_kfifo(struct iio_ring_buffer *r)
  32 {
  33         int ret = 0;
  34         struct iio_kfifo *buf = iio_to_kfifo(r);
  35
  36         mutex_lock(&buf->use_lock);
  37         if (!buf->update_needed)
  38                 goto error_ret;
  39         if (buf->use_count) {
  40                 ret = -EAGAIN;
  41                 goto error_ret;
  42         }
  43         kfifo_free(&buf->kf);
  44         ret = __iio_allocate_kfifo(buf, buf->ring.bytes_per_datum,
  45                                 buf->ring.length);
  46 error_ret:
  47         mutex_unlock(&buf->use_lock);
  48         return ret;
  49 }
  50
  51 static void iio_mark_kfifo_in_use(struct iio_ring_buffer *r)
  52 {
  53         struct iio_kfifo *buf = iio_to_kfifo(r);
  54         mutex_lock(&buf->use_lock);
  55         buf->use_count++;
  56         mutex_unlock(&buf->use_lock);
  57 }
  58
  59 static void iio_unmark_kfifo_in_use(struct iio_ring_buffer *r)
  60 {
  61         struct iio_kfifo *buf = iio_to_kfifo(r);
  62         mutex_lock(&buf->use_lock);
  63         buf->use_count--;
  64         mutex_unlock(&buf->use_lock);
  65 }
  66
  67 static int iio_get_length_kfifo(struct iio_ring_buffer *r)
  68 {
  69         return r->length;
  70 }
  71
  72 static inline void __iio_init_kfifo(struct iio_kfifo *kf)
  73 {
  74         mutex_init(&kf->use_lock);
  75 }
  76
  77 static IIO_RING_ENABLE_ATTR;
  78 static IIO_RING_BYTES_PER_DATUM_ATTR;
  79 static IIO_RING_LENGTH_ATTR;
  80
  81 static struct attribute *iio_kfifo_attributes[] = {
  82         &dev_attr_length.attr,
  83         &dev_attr_bytes_per_datum.attr,
  84         &dev_attr_enable.attr,
  85         NULL,
  86 };
  87
  88 static struct attribute_group iio_kfifo_attribute_group = {
  89         .attrs = iio_kfifo_attributes,
  90         .name = "buffer",
  91 };
  92
  93 struct iio_ring_buffer *iio_kfifo_allocate(struct iio_dev *indio_dev)
  94 {
  95         struct iio_kfifo *kf;
  96
  97         kf = kzalloc(sizeof *kf, GFP_KERNEL);
  98         if (!kf)
  99                 return NULL;
 100         kf->update_needed = true;
 101         iio_ring_buffer_init(&kf->ring, indio_dev);
 102         kf->ring.attrs = &iio_kfifo_attribute_group;
 103         __iio_init_kfifo(kf);
 104
 105         return &kf->ring;
 106 }
 107 EXPORT_SYMBOL(iio_kfifo_allocate);
 108
 109 static int iio_get_bytes_per_datum_kfifo(struct iio_ring_buffer *r)
 110 {
 111         return r->bytes_per_datum;
 112 }
 113
 114 static int iio_set_bytes_per_datum_kfifo(struct iio_ring_buffer *r, size_t bpd)
 115 {
 116         if (r->bytes_per_datum != bpd) {
 117                 r->bytes_per_datum = bpd;
 118                 if (r->access->mark_param_change)
 119                         r->access->mark_param_change(r);
 120         }
 121         return 0;
 122 }
 123
 124 static int iio_mark_update_needed_kfifo(struct iio_ring_buffer *r)
 125 {
 126         struct iio_kfifo *kf = iio_to_kfifo(r);
 127         kf->update_needed = true;
 128         return 0;
 129 }
 130
 131 static int iio_set_length_kfifo(struct iio_ring_buffer *r, int length)
 132 {
 133         if (r->length != length) {
 134                 r->length = length;
 135                 if (r->access->mark_param_change)
 136                         r->access->mark_param_change(r);
 137         }
 138         return 0;
 139 }
 140
 141 void iio_kfifo_free(struct iio_ring_buffer *r)
 142 {
 143         kfree(iio_to_kfifo(r));
 144 }
 145 EXPORT_SYMBOL(iio_kfifo_free);
 146
 147 static int iio_store_to_kfifo(struct iio_ring_buffer *r,
 148                               u8 *data,
 149                               s64 timestamp)
 150 {
 151         int ret;
 152         struct iio_kfifo *kf = iio_to_kfifo(r);
 153         u8 *datal = kmalloc(r->bytes_per_datum, GFP_KERNEL);
 154         memcpy(datal, data, r->bytes_per_datum - sizeof(timestamp));
 155         memcpy(datal + r->bytes_per_datum - sizeof(timestamp),
 156                 &timestamp, sizeof(timestamp));
 157         ret = kfifo_in(&kf->kf, data, r->bytes_per_datum);
 158         if (ret != r->bytes_per_datum) {
 159                 kfree(datal);
 160                 return -EBUSY;
 161         }
 162         kfree(datal);
 163         return 0;
 164 }
 165
 166 static int iio_read_first_n_kfifo(struct iio_ring_buffer *r,
 167                            size_t n, char __user *buf)
 168 {
 169         int ret, copied;
 170         struct iio_kfifo *kf = iio_to_kfifo(r);
 171
 172         ret = kfifo_to_user(&kf->kf, buf, r->bytes_per_datum*n, &copied);
 173
 174         return copied;
 175 }
 176
 177 const struct iio_ring_access_funcs kfifo_access_funcs = {
 178         .mark_in_use = &iio_mark_kfifo_in_use,
 179         .unmark_in_use = &iio_unmark_kfifo_in_use,
 180         .store_to = &iio_store_to_kfifo,
 181         .read_first_n = &iio_read_first_n_kfifo,
 182         .mark_param_change = &iio_mark_update_needed_kfifo,
 183         .request_update = &iio_request_update_kfifo,
 184         .get_bytes_per_datum = &iio_get_bytes_per_datum_kfifo,
 185         .set_bytes_per_datum = &iio_set_bytes_per_datum_kfifo,
 186         .get_length = &iio_get_length_kfifo,
 187         .set_length = &iio_set_length_kfifo,
 188 };
 189 EXPORT_SYMBOL(kfifo_access_funcs);
 190
 191 MODULE_LICENSE("GPL");