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