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
  10 struct iio_kfifo {
  11         struct iio_buffer buffer;
  12         struct kfifo kf;
  13         int update_needed;
  14 };
  15
  16 #define iio_to_kfifo(r) container_of(r, struct iio_kfifo, buffer)
  17
  18 static inline int __iio_allocate_kfifo(struct iio_kfifo *buf,
  19                                 int bytes_per_datum, int length)
  20 {
  21         if ((length == 0) || (bytes_per_datum == 0))
  22                 return -EINVAL;
  23
  24         __iio_update_buffer(&buf->buffer, bytes_per_datum, length);
  25         return kfifo_alloc(&buf->kf, bytes_per_datum*length, GFP_KERNEL);
  26 }
  27
  28 static int iio_request_update_kfifo(struct iio_buffer *r)
  29 {
  30         int ret = 0;
  31         struct iio_kfifo *buf = iio_to_kfifo(r);
  32
  33         if (!buf->update_needed)
  34                 goto error_ret;
  35         kfifo_free(&buf->kf);
  36         ret = __iio_allocate_kfifo(buf, buf->buffer.bytes_per_datum,
  37                                    buf->buffer.length);
  38 error_ret:
  39         return ret;
  40 }
  41
  42 static int iio_get_length_kfifo(struct iio_buffer *r)
  43 {
  44         return r->length;
  45 }
  46
  47 static IIO_BUFFER_ENABLE_ATTR;
  48 static IIO_BUFFER_LENGTH_ATTR;
  49
  50 static struct attribute *iio_kfifo_attributes[] = {
  51         &dev_attr_length.attr,
  52         &dev_attr_enable.attr,
  53         NULL,
  54 };
  55
  56 static struct attribute_group iio_kfifo_attribute_group = {
  57         .attrs = iio_kfifo_attributes,
  58         .name = "buffer",
  59 };
  60
  61 static int iio_get_bytes_per_datum_kfifo(struct iio_buffer *r)
  62 {
  63         return r->bytes_per_datum;
  64 }
  65
  66 static int iio_mark_update_needed_kfifo(struct iio_buffer *r)
  67 {
  68         struct iio_kfifo *kf = iio_to_kfifo(r);
  69         kf->update_needed = true;
  70         return 0;
  71 }
  72
  73 static int iio_set_bytes_per_datum_kfifo(struct iio_buffer *r, size_t bpd)
  74 {
  75         if (r->bytes_per_datum != bpd) {
  76                 r->bytes_per_datum = bpd;
  77                 iio_mark_update_needed_kfifo(r);
  78         }
  79         return 0;
  80 }
  81
  82 static int iio_set_length_kfifo(struct iio_buffer *r, int length)
  83 {
  84         if (r->length != length) {
  85                 r->length = length;
  86                 iio_mark_update_needed_kfifo(r);
  87         }
  88         return 0;
  89 }
  90
  91 static int iio_store_to_kfifo(struct iio_buffer *r,
  92                               u8 *data,
  93                               s64 timestamp)
  94 {
  95         int ret;
  96         struct iio_kfifo *kf = iio_to_kfifo(r);
  97         ret = kfifo_in(&kf->kf, data, r->bytes_per_datum);
  98         if (ret != r->bytes_per_datum)
  99                 return -EBUSY;
 100         return 0;
 101 }
 102
 103 static int iio_read_first_n_kfifo(struct iio_buffer *r,
 104                            size_t n, char __user *buf)
 105 {
 106         int ret, copied;
 107         struct iio_kfifo *kf = iio_to_kfifo(r);
 108
 109         if (n < r->bytes_per_datum)
 110                 return -EINVAL;
 111
 112         n = rounddown(n, r->bytes_per_datum);
 113         ret = kfifo_to_user(&kf->kf, buf, n, &copied);
 114
 115         return copied;
 116 }
 117
 118 static const struct iio_buffer_access_funcs kfifo_access_funcs = {
 119         .store_to = &iio_store_to_kfifo,
 120         .read_first_n = &iio_read_first_n_kfifo,
 121         .request_update = &iio_request_update_kfifo,
 122         .get_bytes_per_datum = &iio_get_bytes_per_datum_kfifo,
 123         .set_bytes_per_datum = &iio_set_bytes_per_datum_kfifo,
 124         .get_length = &iio_get_length_kfifo,
 125         .set_length = &iio_set_length_kfifo,
 126 };
 127
 128 struct iio_buffer *iio_kfifo_allocate(struct iio_dev *indio_dev)
 129 {
 130         struct iio_kfifo *kf;
 131
 132         kf = kzalloc(sizeof *kf, GFP_KERNEL);
 133         if (!kf)
 134                 return NULL;
 135         kf->update_needed = true;
 136         iio_buffer_init(&kf->buffer);
 137         kf->buffer.attrs = &iio_kfifo_attribute_group;
 138         kf->buffer.access = &kfifo_access_funcs;
 139
 140         return &kf->buffer;
 141 }
 142 EXPORT_SYMBOL(iio_kfifo_allocate);
 143
 144 void iio_kfifo_free(struct iio_buffer *r)
 145 {
 146         kfree(iio_to_kfifo(r));
 147 }
 148 EXPORT_SYMBOL(iio_kfifo_free);
 149
 150 MODULE_LICENSE("GPL");