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                 buf->update_needed = false;
  42         } else {
  43                 kfifo_reset_out(&buf->kf);
  44         }
  45         mutex_unlock(&buf->user_lock);
  46
  47         return ret;
  48 }
  49
  50 static int iio_get_length_kfifo(struct iio_buffer *r)
  51 {
  52         return r->length;
  53 }
  54
  55 static IIO_BUFFER_ENABLE_ATTR;
  56 static IIO_BUFFER_LENGTH_ATTR;
  57
  58 static struct attribute *iio_kfifo_attributes[] = {
  59         &dev_attr_length.attr,
  60         &dev_attr_enable.attr,
  61         NULL,
  62 };
  63
  64 static struct attribute_group iio_kfifo_attribute_group = {
  65         .attrs = iio_kfifo_attributes,
  66         .name = "buffer",
  67 };
  68
  69 static int iio_get_bytes_per_datum_kfifo(struct iio_buffer *r)
  70 {
  71         return r->bytes_per_datum;
  72 }
  73
  74 static int iio_mark_update_needed_kfifo(struct iio_buffer *r)
  75 {
  76         struct iio_kfifo *kf = iio_to_kfifo(r);
  77         kf->update_needed = true;
  78         return 0;
  79 }
  80
  81 static int iio_set_bytes_per_datum_kfifo(struct iio_buffer *r, size_t bpd)
  82 {
  83         if (r->bytes_per_datum != bpd) {
  84                 r->bytes_per_datum = bpd;
  85                 iio_mark_update_needed_kfifo(r);
  86         }
  87         return 0;
  88 }
  89
  90 static int iio_set_length_kfifo(struct iio_buffer *r, int length)
  91 {
  92         /* Avoid an invalid state */
  93         if (length < 2)
  94                 length = 2;
  95         if (r->length != length) {
  96                 r->length = length;
  97                 iio_mark_update_needed_kfifo(r);
  98         }
  99         return 0;
 100 }
 101
 102 static int iio_store_to_kfifo(struct iio_buffer *r,
 103                               const void *data)
 104 {
 105         int ret;
 106         struct iio_kfifo *kf = iio_to_kfifo(r);
 107         ret = kfifo_in(&kf->kf, data, 1);
 108         if (ret != 1)
 109                 return -EBUSY;
 110
 111         wake_up_interruptible_poll(&r->pollq, POLLIN | POLLRDNORM);
 112
 113         return 0;
 114 }
 115
 116 static int iio_read_first_n_kfifo(struct iio_buffer *r,
 117                            size_t n, char __user *buf)
 118 {
 119         int ret, copied;
 120         struct iio_kfifo *kf = iio_to_kfifo(r);
 121
 122         if (mutex_lock_interruptible(&kf->user_lock))
 123                 return -ERESTARTSYS;
 124
 125         if (!kfifo_initialized(&kf->kf) || n < kfifo_esize(&kf->kf))
 126                 ret = -EINVAL;
 127         else
 128                 ret = kfifo_to_user(&kf->kf, buf, n, &copied);
 129         mutex_unlock(&kf->user_lock);
 130         if (ret < 0)
 131                 return ret;
 132
 133         return copied;
 134 }
 135
 136 static bool iio_kfifo_buf_data_available(struct iio_buffer *r)
 137 {
 138         struct iio_kfifo *kf = iio_to_kfifo(r);
 139         bool empty;
 140
 141         mutex_lock(&kf->user_lock);
 142         empty = kfifo_is_empty(&kf->kf);
 143         mutex_unlock(&kf->user_lock);
 144
 145         return !empty;
 146 }
 147
 148 static void iio_kfifo_buffer_release(struct iio_buffer *buffer)
 149 {
 150         struct iio_kfifo *kf = iio_to_kfifo(buffer);
 151
 152         mutex_destroy(&kf->user_lock);
 153         kfifo_free(&kf->kf);
 154         kfree(kf);
 155 }
 156
 157 static const struct iio_buffer_access_funcs kfifo_access_funcs = {
 158         .store_to = &iio_store_to_kfifo,
 159         .read_first_n = &iio_read_first_n_kfifo,
 160         .data_available = iio_kfifo_buf_data_available,
 161         .request_update = &iio_request_update_kfifo,
 162         .get_bytes_per_datum = &iio_get_bytes_per_datum_kfifo,
 163         .set_bytes_per_datum = &iio_set_bytes_per_datum_kfifo,
 164         .get_length = &iio_get_length_kfifo,
 165         .set_length = &iio_set_length_kfifo,
 166         .release = &iio_kfifo_buffer_release,
 167 };
 168
 169 struct iio_buffer *iio_kfifo_allocate(struct iio_dev *indio_dev)
 170 {
 171         struct iio_kfifo *kf;
 172
 173         kf = kzalloc(sizeof *kf, GFP_KERNEL);
 174         if (!kf)
 175                 return NULL;
 176         kf->update_needed = true;
 177         iio_buffer_init(&kf->buffer);
 178         kf->buffer.attrs = &iio_kfifo_attribute_group;
 179         kf->buffer.access = &kfifo_access_funcs;
 180         kf->buffer.length = 2;
 181         mutex_init(&kf->user_lock);
 182         return &kf->buffer;
 183 }
 184 EXPORT_SYMBOL(iio_kfifo_allocate);
 185
 186 void iio_kfifo_free(struct iio_buffer *r)
 187 {
 188         iio_buffer_put(r);
 189 }
 190 EXPORT_SYMBOL(iio_kfifo_free);
 191
 192 MODULE_LICENSE("GPL");