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