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
  11 struct iio_kfifo {
  12         struct iio_buffer buffer;
  13         struct kfifo kf;
  14         int update_needed;
  15 };
  16
  17 #define iio_to_kfifo(r) container_of(r, struct iio_kfifo, buffer)
  18
  19 static inline int __iio_allocate_kfifo(struct iio_kfifo *buf,
  20                                 int bytes_per_datum, int length)
  21 {
  22         if ((length == 0) || (bytes_per_datum == 0))
  23                 return -EINVAL;
  24
  25         __iio_update_buffer(&buf->buffer, bytes_per_datum, length);
  26         return __kfifo_alloc((struct __kfifo *)&buf->kf, length,
  27                              bytes_per_datum, GFP_KERNEL);
  28 }
  29
  30 static int iio_request_update_kfifo(struct iio_buffer *r)
  31 {
  32         int ret = 0;
  33         struct iio_kfifo *buf = iio_to_kfifo(r);
  34
  35         if (!buf->update_needed)
  36                 goto error_ret;
  37         kfifo_free(&buf->kf);
  38         ret = __iio_allocate_kfifo(buf, buf->buffer.bytes_per_datum,
  39                                    buf->buffer.length);
  40         r->stufftoread = false;
  41 error_ret:
  42         return ret;
  43 }
  44
  45 static int iio_get_length_kfifo(struct iio_buffer *r)
  46 {
  47         return r->length;
  48 }
  49
  50 static IIO_BUFFER_ENABLE_ATTR;
  51 static IIO_BUFFER_LENGTH_ATTR;
  52
  53 static struct attribute *iio_kfifo_attributes[] = {
  54         &dev_attr_length.attr,
  55         &dev_attr_enable.attr,
  56         NULL,
  57 };
  58
  59 static struct attribute_group iio_kfifo_attribute_group = {
  60         .attrs = iio_kfifo_attributes,
  61         .name = "buffer",
  62 };
  63
  64 static int iio_get_bytes_per_datum_kfifo(struct iio_buffer *r)
  65 {
  66         return r->bytes_per_datum;
  67 }
  68
  69 static int iio_mark_update_needed_kfifo(struct iio_buffer *r)
  70 {
  71         struct iio_kfifo *kf = iio_to_kfifo(r);
  72         kf->update_needed = true;
  73         return 0;
  74 }
  75
  76 static int iio_set_bytes_per_datum_kfifo(struct iio_buffer *r, size_t bpd)
  77 {
  78         if (r->bytes_per_datum != bpd) {
  79                 r->bytes_per_datum = bpd;
  80                 iio_mark_update_needed_kfifo(r);
  81         }
  82         return 0;
  83 }
  84
  85 static int iio_set_length_kfifo(struct iio_buffer *r, int length)
  86 {
  87         /* Avoid an invalid state */
  88         if (length < 2)
  89                 length = 2;
  90         if (r->length != length) {
  91                 r->length = length;
  92                 iio_mark_update_needed_kfifo(r);
  93         }
  94         return 0;
  95 }
  96
  97 static int iio_store_to_kfifo(struct iio_buffer *r,
  98                               u8 *data)
  99 {
 100         int ret;
 101         struct iio_kfifo *kf = iio_to_kfifo(r);
 102         ret = kfifo_in(&kf->kf, data, 1);
 103         if (ret != 1)
 104                 return -EBUSY;
 105         r->stufftoread = true;
 106         wake_up_interruptible(&r->pollq);
 107
 108         return 0;
 109 }
 110
 111 static int iio_read_first_n_kfifo(struct iio_buffer *r,
 112                            size_t n, char __user *buf)
 113 {
 114         int ret, copied;
 115         struct iio_kfifo *kf = iio_to_kfifo(r);
 116
 117         if (n < r->bytes_per_datum || r->bytes_per_datum == 0)
 118                 return -EINVAL;
 119
 120         ret = kfifo_to_user(&kf->kf, buf, n, &copied);
 121         if (ret < 0)
 122                 return ret;
 123
 124         if (kfifo_is_empty(&kf->kf))
 125                 r->stufftoread = false;
 126         /* verify it is still empty to avoid race */
 127         if (!kfifo_is_empty(&kf->kf))
 128                 r->stufftoread = true;
 129
 130         return copied;
 131 }
 132
 133 static const struct iio_buffer_access_funcs kfifo_access_funcs = {
 134         .store_to = &iio_store_to_kfifo,
 135         .read_first_n = &iio_read_first_n_kfifo,
 136         .request_update = &iio_request_update_kfifo,
 137         .get_bytes_per_datum = &iio_get_bytes_per_datum_kfifo,
 138         .set_bytes_per_datum = &iio_set_bytes_per_datum_kfifo,
 139         .get_length = &iio_get_length_kfifo,
 140         .set_length = &iio_set_length_kfifo,
 141 };
 142
 143 struct iio_buffer *iio_kfifo_allocate(struct iio_dev *indio_dev)
 144 {
 145         struct iio_kfifo *kf;
 146
 147         kf = kzalloc(sizeof *kf, GFP_KERNEL);
 148         if (!kf)
 149                 return NULL;
 150         kf->update_needed = true;
 151         iio_buffer_init(&kf->buffer);
 152         kf->buffer.attrs = &iio_kfifo_attribute_group;
 153         kf->buffer.access = &kfifo_access_funcs;
 154         kf->buffer.length = 2;
 155         return &kf->buffer;
 156 }
 157 EXPORT_SYMBOL(iio_kfifo_allocate);
 158
 159 void iio_kfifo_free(struct iio_buffer *r)
 160 {
 161         kfree(iio_to_kfifo(r));
 162 }
 163 EXPORT_SYMBOL(iio_kfifo_free);
 164
 165 MODULE_LICENSE("GPL");