drivers/iio/buffer/kfifo_buf.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 #include <linux/slab.h>
   3 #include <linux/kernel.h>
   4 #include <linux/module.h>
   5 #include <linux/device.h>
   6 #include <linux/workqueue.h>
   7 #include <linux/kfifo.h>
   8 #include <linux/mutex.h>
   9 #include <linux/iio/iio.h>
  10 #include <linux/iio/buffer.h>
  11 #include <linux/iio/kfifo_buf.h>
  12 #include <linux/iio/buffer_impl.h>
  13 #include <linux/sched.h>
  14 #include <linux/poll.h>
  15
  16 struct iio_kfifo {
  17         struct iio_buffer buffer;
  18         struct kfifo kf;
  19         struct mutex user_lock;
  20         int update_needed;
  21 };
  22
  23 #define iio_to_kfifo(r) container_of(r, struct iio_kfifo, buffer)
  24
  25 static inline int __iio_allocate_kfifo(struct iio_kfifo *buf,
  26                         size_t bytes_per_datum, unsigned int length)
  27 {
  28         if ((length == 0) || (bytes_per_datum == 0))
  29                 return -EINVAL;
  30
  31         /*
  32          * Make sure we don't overflow an unsigned int after kfifo rounds up to
  33          * the next power of 2.
  34          */
  35         if (roundup_pow_of_two(length) > UINT_MAX / bytes_per_datum)
  36                 return -EINVAL;
  37
  38         return __kfifo_alloc((struct __kfifo *)&buf->kf, length,
  39                              bytes_per_datum, GFP_KERNEL);
  40 }
  41
  42 static int iio_request_update_kfifo(struct iio_buffer *r)
  43 {
  44         int ret = 0;
  45         struct iio_kfifo *buf = iio_to_kfifo(r);
  46
  47         mutex_lock(&buf->user_lock);
  48         if (buf->update_needed) {
  49                 kfifo_free(&buf->kf);
  50                 ret = __iio_allocate_kfifo(buf, buf->buffer.bytes_per_datum,
  51                                    buf->buffer.length);
  52                 if (ret >= 0)
  53                         buf->update_needed = false;
  54         } else {
  55                 kfifo_reset_out(&buf->kf);
  56         }
  57         mutex_unlock(&buf->user_lock);
  58
  59         return ret;
  60 }
  61
  62 static int iio_mark_update_needed_kfifo(struct iio_buffer *r)
  63 {
  64         struct iio_kfifo *kf = iio_to_kfifo(r);
  65         kf->update_needed = true;
  66         return 0;
  67 }
  68
  69 static int iio_set_bytes_per_datum_kfifo(struct iio_buffer *r, size_t bpd)
  70 {
  71         if (r->bytes_per_datum != bpd) {
  72                 r->bytes_per_datum = bpd;
  73                 iio_mark_update_needed_kfifo(r);
  74         }
  75         return 0;
  76 }
  77
  78 static int iio_set_length_kfifo(struct iio_buffer *r, unsigned int length)
  79 {
  80         /* Avoid an invalid state */
  81         if (length < 2)
  82                 length = 2;
  83         if (r->length != length) {
  84                 r->length = length;
  85                 iio_mark_update_needed_kfifo(r);
  86         }
  87         return 0;
  88 }
  89
  90 static int iio_store_to_kfifo(struct iio_buffer *r,
  91                               const void *data)
  92 {
  93         int ret;
  94         struct iio_kfifo *kf = iio_to_kfifo(r);
  95         ret = kfifo_in(&kf->kf, data, 1);
  96         if (ret != 1)
  97                 return -EBUSY;
  98         return 0;
  99 }
 100
 101 static int iio_read_kfifo(struct iio_buffer *r, size_t n, char __user *buf)
 102 {
 103         int ret, copied;
 104         struct iio_kfifo *kf = iio_to_kfifo(r);
 105
 106         if (mutex_lock_interruptible(&kf->user_lock))
 107                 return -ERESTARTSYS;
 108
 109         if (!kfifo_initialized(&kf->kf) || n < kfifo_esize(&kf->kf))
 110                 ret = -EINVAL;
 111         else
 112                 ret = kfifo_to_user(&kf->kf, buf, n, &copied);
 113         mutex_unlock(&kf->user_lock);
 114         if (ret < 0)
 115                 return ret;
 116
 117         return copied;
 118 }
 119
 120 static size_t iio_kfifo_buf_data_available(struct iio_buffer *r)
 121 {
 122         struct iio_kfifo *kf = iio_to_kfifo(r);
 123         size_t samples;
 124
 125         mutex_lock(&kf->user_lock);
 126         samples = kfifo_len(&kf->kf);
 127         mutex_unlock(&kf->user_lock);
 128
 129         return samples;
 130 }
 131
 132 static void iio_kfifo_buffer_release(struct iio_buffer *buffer)
 133 {
 134         struct iio_kfifo *kf = iio_to_kfifo(buffer);
 135
 136         mutex_destroy(&kf->user_lock);
 137         kfifo_free(&kf->kf);
 138         kfree(kf);
 139 }
 140
 141 static const struct iio_buffer_access_funcs kfifo_access_funcs = {
 142         .store_to = &iio_store_to_kfifo,
 143         .read = &iio_read_kfifo,
 144         .data_available = iio_kfifo_buf_data_available,
 145         .request_update = &iio_request_update_kfifo,
 146         .set_bytes_per_datum = &iio_set_bytes_per_datum_kfifo,
 147         .set_length = &iio_set_length_kfifo,
 148         .release = &iio_kfifo_buffer_release,
 149
 150         .modes = INDIO_BUFFER_SOFTWARE | INDIO_BUFFER_TRIGGERED,
 151 };
 152
 153 struct iio_buffer *iio_kfifo_allocate(void)
 154 {
 155         struct iio_kfifo *kf;
 156
 157         kf = kzalloc(sizeof(*kf), GFP_KERNEL);
 158         if (!kf)
 159                 return NULL;
 160
 161         kf->update_needed = true;
 162         iio_buffer_init(&kf->buffer);
 163         kf->buffer.access = &kfifo_access_funcs;
 164         kf->buffer.length = 2;
 165         mutex_init(&kf->user_lock);
 166
 167         return &kf->buffer;
 168 }
 169 EXPORT_SYMBOL(iio_kfifo_allocate);
 170
 171 void iio_kfifo_free(struct iio_buffer *r)
 172 {
 173         iio_buffer_put(r);
 174 }
 175 EXPORT_SYMBOL(iio_kfifo_free);
 176
 177 static void devm_iio_kfifo_release(struct device *dev, void *res)
 178 {
 179         iio_kfifo_free(*(struct iio_buffer **)res);
 180 }
 181
 182 /**
 183  * devm_iio_fifo_allocate - Resource-managed iio_kfifo_allocate()
 184  * @dev:                Device to allocate kfifo buffer for
 185  *
 186  * RETURNS:
 187  * Pointer to allocated iio_buffer on success, NULL on failure.
 188  */
 189 struct iio_buffer *devm_iio_kfifo_allocate(struct device *dev)
 190 {
 191         struct iio_buffer **ptr, *r;
 192
 193         ptr = devres_alloc(devm_iio_kfifo_release, sizeof(*ptr), GFP_KERNEL);
 194         if (!ptr)
 195                 return NULL;
 196
 197         r = iio_kfifo_allocate();
 198         if (r) {
 199                 *ptr = r;
 200                 devres_add(dev, ptr);
 201         } else {
 202                 devres_free(ptr);
 203         }
 204
 205         return r;
 206 }
 207 EXPORT_SYMBOL(devm_iio_kfifo_allocate);
 208
 209 MODULE_LICENSE("GPL");