diff options
Diffstat (limited to 'drivers/iio/buffer/industrialio-buffer-dmaengine.c')
| -rw-r--r-- | drivers/iio/buffer/industrialio-buffer-dmaengine.c | 213 |
1 files changed, 213 insertions, 0 deletions
diff --git a/drivers/iio/buffer/industrialio-buffer-dmaengine.c b/drivers/iio/buffer/industrialio-buffer-dmaengine.c new file mode 100644 index 000000000000..ebdb838d3a1c --- /dev/null +++ b/drivers/iio/buffer/industrialio-buffer-dmaengine.c @@ -0,0 +1,213 @@ +/* + * Copyright 2014-2015 Analog Devices Inc. + * Author: Lars-Peter Clausen <lars@metafoo.de> + * + * Licensed under the GPL-2 or later. + */ + +#include <linux/slab.h> +#include <linux/kernel.h> +#include <linux/dmaengine.h> +#include <linux/dma-mapping.h> +#include <linux/spinlock.h> +#include <linux/err.h> + +#include <linux/iio/iio.h> +#include <linux/iio/buffer.h> +#include <linux/iio/buffer-dma.h> +#include <linux/iio/buffer-dmaengine.h> + +/* + * The IIO DMAengine buffer combines the generic IIO DMA buffer infrastructure + * with the DMAengine framework. The generic IIO DMA buffer infrastructure is + * used to manage the buffer memory and implement the IIO buffer operations + * while the DMAengine framework is used to perform the DMA transfers. Combined + * this results in a device independent fully functional DMA buffer + * implementation that can be used by device drivers for peripherals which are + * connected to a DMA controller which has a DMAengine driver implementation. + */ + +struct dmaengine_buffer { + struct iio_dma_buffer_queue queue; + + struct dma_chan *chan; + struct list_head active; + + size_t align; + size_t max_size; +}; + +static struct dmaengine_buffer *iio_buffer_to_dmaengine_buffer( + struct iio_buffer *buffer) +{ + return container_of(buffer, struct dmaengine_buffer, queue.buffer); +} + +static void iio_dmaengine_buffer_block_done(void *data) +{ + struct iio_dma_buffer_block *block = data; + unsigned long flags; + + spin_lock_irqsave(&block->queue->list_lock, flags); + list_del(&block->head); + spin_unlock_irqrestore(&block->queue->list_lock, flags); + iio_dma_buffer_block_done(block); +} + +static int iio_dmaengine_buffer_submit_block(struct iio_dma_buffer_queue *queue, + struct iio_dma_buffer_block *block) +{ + struct dmaengine_buffer *dmaengine_buffer = + iio_buffer_to_dmaengine_buffer(&queue->buffer); + struct dma_async_tx_descriptor *desc; + dma_cookie_t cookie; + + block->bytes_used = min(block->size, dmaengine_buffer->max_size); + block->bytes_used = rounddown(block->bytes_used, + dmaengine_buffer->align); + + desc = dmaengine_prep_slave_single(dmaengine_buffer->chan, + block->phys_addr, block->bytes_used, DMA_DEV_TO_MEM, + DMA_PREP_INTERRUPT); + if (!desc) + return -ENOMEM; + + desc->callback = iio_dmaengine_buffer_block_done; + desc->callback_param = block; + + cookie = dmaengine_submit(desc); + if (dma_submit_error(cookie)) + return dma_submit_error(cookie); + + spin_lock_irq(&dmaengine_buffer->queue.list_lock); + list_add_tail(&block->head, &dmaengine_buffer->active); + spin_unlock_irq(&dmaengine_buffer->queue.list_lock); + + dma_async_issue_pending(dmaengine_buffer->chan); + + return 0; +} + +static void iio_dmaengine_buffer_abort(struct iio_dma_buffer_queue *queue) +{ + struct dmaengine_buffer *dmaengine_buffer = + iio_buffer_to_dmaengine_buffer(&queue->buffer); + + dmaengine_terminate_all(dmaengine_buffer->chan); + /* FIXME: There is a slight chance of a race condition here. + * dmaengine_terminate_all() does not guarantee that all transfer + * callbacks have finished running. Need to introduce a + * dmaengine_terminate_all_sync(). + */ + iio_dma_buffer_block_list_abort(queue, &dmaengine_buffer->active); +} + +static void iio_dmaengine_buffer_release(struct iio_buffer *buf) +{ + struct dmaengine_buffer *dmaengine_buffer = + iio_buffer_to_dmaengine_buffer(buf); + + iio_dma_buffer_release(&dmaengine_buffer->queue); + kfree(dmaengine_buffer); +} + +static const struct iio_buffer_access_funcs iio_dmaengine_buffer_ops = { + .read_first_n = iio_dma_buffer_read, + .set_bytes_per_datum = iio_dma_buffer_set_bytes_per_datum, + .set_length = iio_dma_buffer_set_length, + .request_update = iio_dma_buffer_request_update, + .enable = iio_dma_buffer_enable, + .disable = iio_dma_buffer_disable, + .data_available = iio_dma_buffer_data_available, + .release = iio_dmaengine_buffer_release, + + .modes = INDIO_BUFFER_HARDWARE, + .flags = INDIO_BUFFER_FLAG_FIXED_WATERMARK, +}; + +static const struct iio_dma_buffer_ops iio_dmaengine_default_ops = { + .submit = iio_dmaengine_buffer_submit_block, + .abort = iio_dmaengine_buffer_abort, +}; + +/** + * iio_dmaengine_buffer_alloc() - Allocate new buffer which uses DMAengine + * @dev: Parent device for the buffer + * @channel: DMA channel name, typically "rx". + * + * This allocates a new IIO buffer which internally uses the DMAengine framework + * to perform its transfers. The parent device will be used to request the DMA + * channel. + * + * Once done using the buffer iio_dmaengine_buffer_free() should be used to + * release it. + */ +struct iio_buffer *iio_dmaengine_buffer_alloc(struct device *dev, + const char *channel) +{ + struct dmaengine_buffer *dmaengine_buffer; + unsigned int width, src_width, dest_width; + struct dma_slave_caps caps; + struct dma_chan *chan; + int ret; + + dmaengine_buffer = kzalloc(sizeof(*dmaengine_buffer), GFP_KERNEL); + if (!dmaengine_buffer) + return ERR_PTR(-ENOMEM); + + chan = dma_request_slave_channel_reason(dev, channel); + if (IS_ERR(chan)) { + ret = PTR_ERR(chan); + goto err_free; + } + + ret = dma_get_slave_caps(chan, &caps); + if (ret < 0) + goto err_free; + + /* Needs to be aligned to the maximum of the minimums */ + if (caps.src_addr_widths) + src_width = __ffs(caps.src_addr_widths); + else + src_width = 1; + if (caps.dst_addr_widths) + dest_width = __ffs(caps.dst_addr_widths); + else + dest_width = 1; + width = max(src_width, dest_width); + + INIT_LIST_HEAD(&dmaengine_buffer->active); + dmaengine_buffer->chan = chan; + dmaengine_buffer->align = width; + dmaengine_buffer->max_size = dma_get_max_seg_size(chan->device->dev); + + iio_dma_buffer_init(&dmaengine_buffer->queue, chan->device->dev, + &iio_dmaengine_default_ops); + + dmaengine_buffer->queue.buffer.access = &iio_dmaengine_buffer_ops; + + return &dmaengine_buffer->queue.buffer; + +err_free: + kfree(dmaengine_buffer); + return ERR_PTR(ret); +} +EXPORT_SYMBOL(iio_dmaengine_buffer_alloc); + +/** + * iio_dmaengine_buffer_free() - Free dmaengine buffer + * @buffer: Buffer to free + * + * Frees a buffer previously allocated with iio_dmaengine_buffer_alloc(). + */ +void iio_dmaengine_buffer_free(struct iio_buffer *buffer) +{ + struct dmaengine_buffer *dmaengine_buffer = + iio_buffer_to_dmaengine_buffer(buffer); + + iio_dma_buffer_exit(&dmaengine_buffer->queue); + dma_release_channel(dmaengine_buffer->chan); + + iio_buffer_put(buffer); +} +EXPORT_SYMBOL_GPL(iio_dmaengine_buffer_free); |