drivers/iio/buffer/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 #include <linux/iio/iio.h>
   9 #include <linux/iio/buffer.h>
  10 #include <linux/iio/kfifo_buf.h>
  11 #include <linux/iio/buffer_impl.h>
  12 #include <linux/sched.h>
  13 #include <linux/poll.h>
  14
  15 struct iio_kfifo {
  16         struct iio_buffer buffer;
  17         struct kfifo kf;
  18         struct mutex user_lock;
  19         int update_needed;
  20 };
  21
  22 #define iio_to_kfifo(r) container_of(r, struct iio_kfifo, buffer)
  23
  24 static inline int __iio_allocate_kfifo(struct iio_kfifo *buf,
  25                                 int bytes_per_datum, int length)
  26 {
  27         if ((length == 0) || (bytes_per_datum == 0))
  28                 return -EINVAL;
  29
  30         return __kfifo_alloc((struct __kfifo *)&buf->kf, length,
  31                              bytes_per_datum, GFP_KERNEL);
  32 }
  33
  34 static int iio_request_update_kfifo(struct iio_buffer *r)
  35 {
  36         int ret = 0;
  37         struct iio_kfifo *buf = iio_to_kfifo(r);
  38
  39         mutex_lock(&buf->user_lock);
  40         if (buf->update_needed) {
  41                 kfifo_free(&buf->kf);
  42                 ret = __iio_allocate_kfifo(buf, buf->buffer.bytes_per_datum,
  43                                    buf->buffer.length);
  44                 if (ret >= 0)
  45                         buf->update_needed = false;
  46         } else {
  47                 kfifo_reset_out(&buf->kf);
  48         }
  49         mutex_unlock(&buf->user_lock);
  50
  51         return ret;
  52 }
  53
  54 static int iio_mark_update_needed_kfifo(struct iio_buffer *r)
  55 {
  56         struct iio_kfifo *kf = iio_to_kfifo(r);
  57         kf->update_needed = true;
  58         return 0;
  59 }
  60
  61 static int iio_set_bytes_per_datum_kfifo(struct iio_buffer *r, size_t bpd)
  62 {
  63         if (r->bytes_per_datum != bpd) {
  64                 r->bytes_per_datum = bpd;
  65                 iio_mark_update_needed_kfifo(r);
  66         }
  67         return 0;
  68 }
  69
  70 static int iio_set_length_kfifo(struct iio_buffer *r, int length)
  71 {
  72         /* Avoid an invalid state */
  73         if (length < 2)
  74                 length = 2;
  75         if (r->length != length) {
  76                 r->length = length;
  77                 iio_mark_update_needed_kfifo(r);
  78         }
  79         return 0;
  80 }
  81
  82 static int iio_store_to_kfifo(struct iio_buffer *r,
  83                               const void *data)
  84 {
  85         int ret;
  86         struct iio_kfifo *kf = iio_to_kfifo(r);
  87         ret = kfifo_in(&kf->kf, data, 1);
  88         if (ret != 1)
  89                 return -EBUSY;
  90         return 0;
  91 }
  92
  93 static int iio_read_first_n_kfifo(struct iio_buffer *r,
  94                            size_t n, char __user *buf)
  95 {
  96         int ret, copied;
  97         struct iio_kfifo *kf = iio_to_kfifo(r);
  98
  99         if (mutex_lock_interruptible(&kf->user_lock))
 100                 return -ERESTARTSYS;
 101
 102         if (!kfifo_initialized(&kf->kf) || n < kfifo_esize(&kf->kf))
 103                 ret = -EINVAL;
 104         else
 105                 ret = kfifo_to_user(&kf->kf, buf, n, &copied);
 106         mutex_unlock(&kf->user_lock);
 107         if (ret < 0)
 108                 return ret;
 109
 110         return copied;
 111 }
 112
 113 static size_t iio_kfifo_buf_data_available(struct iio_buffer *r)
 114 {
 115         struct iio_kfifo *kf = iio_to_kfifo(r);
 116         size_t samples;
 117
 118         mutex_lock(&kf->user_lock);
 119         samples = kfifo_len(&kf->kf);
 120         mutex_unlock(&kf->user_lock);
 121
 122         return samples;
 123 }
 124
 125 static void iio_kfifo_buffer_release(struct iio_buffer *buffer)
 126 {
 127         struct iio_kfifo *kf = iio_to_kfifo(buffer);
 128
 129         mutex_destroy(&kf->user_lock);
 130         kfifo_free(&kf->kf);
 131         kfree(kf);
 132 }
 133
 134 static const struct iio_buffer_access_funcs kfifo_access_funcs = {
 135         .store_to = &iio_store_to_kfifo,
 136         .read_first_n = &iio_read_first_n_kfifo,
 137         .data_available = iio_kfifo_buf_data_available,
 138         .request_update = &iio_request_update_kfifo,
 139         .set_bytes_per_datum = &iio_set_bytes_per_datum_kfifo,
 140         .set_length = &iio_set_length_kfifo,
 141         .release = &iio_kfifo_buffer_release,
 142
 143         .modes = INDIO_BUFFER_SOFTWARE | INDIO_BUFFER_TRIGGERED,
 144 };
 145
 146 struct iio_buffer *iio_kfifo_allocate(void)
 147 {
 148         struct iio_kfifo *kf;
 149
 150         kf = kzalloc(sizeof(*kf), GFP_KERNEL);
 151         if (!kf)
 152                 return NULL;
 153
 154         kf->update_needed = true;
 155         iio_buffer_init(&kf->buffer);
 156         kf->buffer.access = &kfifo_access_funcs;
 157         kf->buffer.length = 2;
 158         mutex_init(&kf->user_lock);
 159
 160         return &kf->buffer;
 161 }
 162 EXPORT_SYMBOL(iio_kfifo_allocate);
 163
 164 void iio_kfifo_free(struct iio_buffer *r)
 165 {
 166         iio_buffer_put(r);
 167 }
 168 EXPORT_SYMBOL(iio_kfifo_free);
 169
 170 static void devm_iio_kfifo_release(struct device *dev, void *res)
 171 {
 172         iio_kfifo_free(*(struct iio_buffer **)res);
 173 }
 174
 175 static int devm_iio_kfifo_match(struct device *dev, void *res, void *data)
 176 {
 177         struct iio_buffer **r = res;
 178
 179         if (WARN_ON(!r || !*r))
 180                 return 0;
 181
 182         return *r == data;
 183 }
 184
 185 /**
 186  * devm_iio_fifo_allocate - Resource-managed iio_kfifo_allocate()
 187  * @dev:                Device to allocate kfifo buffer for
 188  *
 189  * RETURNS:
 190  * Pointer to allocated iio_buffer on success, NULL on failure.
 191  */
 192 struct iio_buffer *devm_iio_kfifo_allocate(struct device *dev)
 193 {
 194         struct iio_buffer **ptr, *r;
 195
 196         ptr = devres_alloc(devm_iio_kfifo_release, sizeof(*ptr), GFP_KERNEL);
 197         if (!ptr)
 198                 return NULL;
 199
 200         r = iio_kfifo_allocate();
 201         if (r) {
 202                 *ptr = r;
 203                 devres_add(dev, ptr);
 204         } else {
 205                 devres_free(ptr);
 206         }
 207
 208         return r;
 209 }
 210 EXPORT_SYMBOL(devm_iio_kfifo_allocate);
 211
 212 /**
 213  * devm_iio_fifo_free - Resource-managed iio_kfifo_free()
 214  * @dev:                Device the buffer belongs to
 215  * @r:                  The buffer associated with the device
 216  */
 217 void devm_iio_kfifo_free(struct device *dev, struct iio_buffer *r)
 218 {
 219         WARN_ON(devres_release(dev, devm_iio_kfifo_release,
 220                                devm_iio_kfifo_match, r));
 221 }
 222 EXPORT_SYMBOL(devm_iio_kfifo_free);
 223
 224 MODULE_LICENSE("GPL");