drivers/iio/buffer/industrialio-buffer-dmaengine.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright 2014-2015 Analog Devices Inc.
   4  *  Author: Lars-Peter Clausen <lars@metafoo.de>
   5  */
   6
   7 #include <linux/slab.h>
   8 #include <linux/kernel.h>
   9 #include <linux/dmaengine.h>
  10 #include <linux/dma-mapping.h>
  11 #include <linux/spinlock.h>
  12 #include <linux/err.h>
  13 #include <linux/module.h>
  14
  15 #include <linux/iio/iio.h>
  16 #include <linux/iio/sysfs.h>
  17 #include <linux/iio/buffer.h>
  18 #include <linux/iio/buffer_impl.h>
  19 #include <linux/iio/buffer-dma.h>
  20 #include <linux/iio/buffer-dmaengine.h>
  21
  22 /*
  23  * The IIO DMAengine buffer combines the generic IIO DMA buffer infrastructure
  24  * with the DMAengine framework. The generic IIO DMA buffer infrastructure is
  25  * used to manage the buffer memory and implement the IIO buffer operations
  26  * while the DMAengine framework is used to perform the DMA transfers. Combined
  27  * this results in a device independent fully functional DMA buffer
  28  * implementation that can be used by device drivers for peripherals which are
  29  * connected to a DMA controller which has a DMAengine driver implementation.
  30  */
  31
  32 struct dmaengine_buffer {
  33         struct iio_dma_buffer_queue queue;
  34
  35         struct dma_chan *chan;
  36         struct list_head active;
  37
  38         size_t align;
  39         size_t max_size;
  40 };
  41
  42 static struct dmaengine_buffer *iio_buffer_to_dmaengine_buffer(
  43                 struct iio_buffer *buffer)
  44 {
  45         return container_of(buffer, struct dmaengine_buffer, queue.buffer);
  46 }
  47
  48 static void iio_dmaengine_buffer_block_done(void *data,
  49                 const struct dmaengine_result *result)
  50 {
  51         struct iio_dma_buffer_block *block = data;
  52         unsigned long flags;
  53
  54         spin_lock_irqsave(&block->queue->list_lock, flags);
  55         list_del(&block->head);
  56         spin_unlock_irqrestore(&block->queue->list_lock, flags);
  57         block->bytes_used -= result->residue;
  58         iio_dma_buffer_block_done(block);
  59 }
  60
  61 static int iio_dmaengine_buffer_submit_block(struct iio_dma_buffer_queue *queue,
  62         struct iio_dma_buffer_block *block)
  63 {
  64         struct dmaengine_buffer *dmaengine_buffer =
  65                 iio_buffer_to_dmaengine_buffer(&queue->buffer);
  66         struct dma_async_tx_descriptor *desc;
  67         dma_cookie_t cookie;
  68
  69         block->bytes_used = min(block->size, dmaengine_buffer->max_size);
  70         block->bytes_used = rounddown(block->bytes_used,
  71                         dmaengine_buffer->align);
  72
  73         desc = dmaengine_prep_slave_single(dmaengine_buffer->chan,
  74                 block->phys_addr, block->bytes_used, DMA_DEV_TO_MEM,
  75                 DMA_PREP_INTERRUPT);
  76         if (!desc)
  77                 return -ENOMEM;
  78
  79         desc->callback_result = iio_dmaengine_buffer_block_done;
  80         desc->callback_param = block;
  81
  82         cookie = dmaengine_submit(desc);
  83         if (dma_submit_error(cookie))
  84                 return dma_submit_error(cookie);
  85
  86         spin_lock_irq(&dmaengine_buffer->queue.list_lock);
  87         list_add_tail(&block->head, &dmaengine_buffer->active);
  88         spin_unlock_irq(&dmaengine_buffer->queue.list_lock);
  89
  90         dma_async_issue_pending(dmaengine_buffer->chan);
  91
  92         return 0;
  93 }
  94
  95 static void iio_dmaengine_buffer_abort(struct iio_dma_buffer_queue *queue)
  96 {
  97         struct dmaengine_buffer *dmaengine_buffer =
  98                 iio_buffer_to_dmaengine_buffer(&queue->buffer);
  99
 100         dmaengine_terminate_sync(dmaengine_buffer->chan);
 101         iio_dma_buffer_block_list_abort(queue, &dmaengine_buffer->active);
 102 }
 103
 104 static void iio_dmaengine_buffer_release(struct iio_buffer *buf)
 105 {
 106         struct dmaengine_buffer *dmaengine_buffer =
 107                 iio_buffer_to_dmaengine_buffer(buf);
 108
 109         iio_dma_buffer_release(&dmaengine_buffer->queue);
 110         kfree(dmaengine_buffer);
 111 }
 112
 113 static const struct iio_buffer_access_funcs iio_dmaengine_buffer_ops = {
 114         .read = iio_dma_buffer_read,
 115         .set_bytes_per_datum = iio_dma_buffer_set_bytes_per_datum,
 116         .set_length = iio_dma_buffer_set_length,
 117         .request_update = iio_dma_buffer_request_update,
 118         .enable = iio_dma_buffer_enable,
 119         .disable = iio_dma_buffer_disable,
 120         .data_available = iio_dma_buffer_data_available,
 121         .release = iio_dmaengine_buffer_release,
 122
 123         .modes = INDIO_BUFFER_HARDWARE,
 124         .flags = INDIO_BUFFER_FLAG_FIXED_WATERMARK,
 125 };
 126
 127 static const struct iio_dma_buffer_ops iio_dmaengine_default_ops = {
 128         .submit = iio_dmaengine_buffer_submit_block,
 129         .abort = iio_dmaengine_buffer_abort,
 130 };
 131
 132 static ssize_t iio_dmaengine_buffer_get_length_align(struct device *dev,
 133         struct device_attribute *attr, char *buf)
 134 {
 135         struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 136         struct dmaengine_buffer *dmaengine_buffer =
 137                 iio_buffer_to_dmaengine_buffer(indio_dev->buffer);
 138
 139         return sprintf(buf, "%zu\n", dmaengine_buffer->align);
 140 }
 141
 142 static IIO_DEVICE_ATTR(length_align_bytes, 0444,
 143                        iio_dmaengine_buffer_get_length_align, NULL, 0);
 144
 145 static const struct attribute *iio_dmaengine_buffer_attrs[] = {
 146         &iio_dev_attr_length_align_bytes.dev_attr.attr,
 147         NULL,
 148 };
 149
 150 /**
 151  * iio_dmaengine_buffer_alloc() - Allocate new buffer which uses DMAengine
 152  * @dev: Parent device for the buffer
 153  * @channel: DMA channel name, typically "rx".
 154  *
 155  * This allocates a new IIO buffer which internally uses the DMAengine framework
 156  * to perform its transfers. The parent device will be used to request the DMA
 157  * channel.
 158  *
 159  * Once done using the buffer iio_dmaengine_buffer_free() should be used to
 160  * release it.
 161  */
 162 static struct iio_buffer *iio_dmaengine_buffer_alloc(struct device *dev,
 163         const char *channel)
 164 {
 165         struct dmaengine_buffer *dmaengine_buffer;
 166         unsigned int width, src_width, dest_width;
 167         struct dma_slave_caps caps;
 168         struct dma_chan *chan;
 169         int ret;
 170
 171         dmaengine_buffer = kzalloc(sizeof(*dmaengine_buffer), GFP_KERNEL);
 172         if (!dmaengine_buffer)
 173                 return ERR_PTR(-ENOMEM);
 174
 175         chan = dma_request_chan(dev, channel);
 176         if (IS_ERR(chan)) {
 177                 ret = PTR_ERR(chan);
 178                 goto err_free;
 179         }
 180
 181         ret = dma_get_slave_caps(chan, &caps);
 182         if (ret < 0)
 183                 goto err_free;
 184
 185         /* Needs to be aligned to the maximum of the minimums */
 186         if (caps.src_addr_widths)
 187                 src_width = __ffs(caps.src_addr_widths);
 188         else
 189                 src_width = 1;
 190         if (caps.dst_addr_widths)
 191                 dest_width = __ffs(caps.dst_addr_widths);
 192         else
 193                 dest_width = 1;
 194         width = max(src_width, dest_width);
 195
 196         INIT_LIST_HEAD(&dmaengine_buffer->active);
 197         dmaengine_buffer->chan = chan;
 198         dmaengine_buffer->align = width;
 199         dmaengine_buffer->max_size = dma_get_max_seg_size(chan->device->dev);
 200
 201         iio_dma_buffer_init(&dmaengine_buffer->queue, chan->device->dev,
 202                 &iio_dmaengine_default_ops);
 203
 204         dmaengine_buffer->queue.buffer.attrs = iio_dmaengine_buffer_attrs;
 205         dmaengine_buffer->queue.buffer.access = &iio_dmaengine_buffer_ops;
 206
 207         return &dmaengine_buffer->queue.buffer;
 208
 209 err_free:
 210         kfree(dmaengine_buffer);
 211         return ERR_PTR(ret);
 212 }
 213
 214 /**
 215  * iio_dmaengine_buffer_free() - Free dmaengine buffer
 216  * @buffer: Buffer to free
 217  *
 218  * Frees a buffer previously allocated with iio_dmaengine_buffer_alloc().
 219  */
 220 static void iio_dmaengine_buffer_free(struct iio_buffer *buffer)
 221 {
 222         struct dmaengine_buffer *dmaengine_buffer =
 223                 iio_buffer_to_dmaengine_buffer(buffer);
 224
 225         iio_dma_buffer_exit(&dmaengine_buffer->queue);
 226         dma_release_channel(dmaengine_buffer->chan);
 227
 228         iio_buffer_put(buffer);
 229 }
 230
 231 static void __devm_iio_dmaengine_buffer_free(struct device *dev, void *res)
 232 {
 233         iio_dmaengine_buffer_free(*(struct iio_buffer **)res);
 234 }
 235
 236 /**
 237  * devm_iio_dmaengine_buffer_alloc() - Resource-managed iio_dmaengine_buffer_alloc()
 238  * @dev: Parent device for the buffer
 239  * @channel: DMA channel name, typically "rx".
 240  *
 241  * This allocates a new IIO buffer which internally uses the DMAengine framework
 242  * to perform its transfers. The parent device will be used to request the DMA
 243  * channel.
 244  *
 245  * The buffer will be automatically de-allocated once the device gets destroyed.
 246  */
 247 struct iio_buffer *devm_iio_dmaengine_buffer_alloc(struct device *dev,
 248         const char *channel)
 249 {
 250         struct iio_buffer **bufferp, *buffer;
 251
 252         bufferp = devres_alloc(__devm_iio_dmaengine_buffer_free,
 253                                sizeof(*bufferp), GFP_KERNEL);
 254         if (!bufferp)
 255                 return ERR_PTR(-ENOMEM);
 256
 257         buffer = iio_dmaengine_buffer_alloc(dev, channel);
 258         if (IS_ERR(buffer)) {
 259                 devres_free(bufferp);
 260                 return buffer;
 261         }
 262
 263         *bufferp = buffer;
 264         devres_add(dev, bufferp);
 265
 266         return buffer;
 267 }
 268 EXPORT_SYMBOL_GPL(devm_iio_dmaengine_buffer_alloc);
 269
 270 MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
 271 MODULE_DESCRIPTION("DMA buffer for the IIO framework");
 272 MODULE_LICENSE("GPL");