From bbea0b6e0d214ef1511b9c6ccf3af26b38f0af7d Mon Sep 17 00:00:00 2001 From: Ira Snyder Date: Tue, 8 Sep 2009 17:53:04 -0700 Subject: fsldma: Add DMA_SLAVE support Use the DMA_SLAVE capability of the DMAEngine API to copy/from a scatterlist into an arbitrary list of hardware address/length pairs. This allows a single DMA transaction to copy data from several different devices into a scatterlist at the same time. This also adds support to enable some controller-specific features such as external start and external pause for a DMA transaction. [dan.j.williams@intel.com: rebased on tx_list movement] Signed-off-by: Ira W. Snyder Acked-by: Li Yang Acked-by: Kumar Gala Signed-off-by: Dan Williams --- drivers/dma/fsldma.c | 227 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 227 insertions(+) (limited to 'drivers/dma') diff --git a/drivers/dma/fsldma.c b/drivers/dma/fsldma.c index 7a0cb6064f83..296f9e747fac 100644 --- a/drivers/dma/fsldma.c +++ b/drivers/dma/fsldma.c @@ -34,6 +34,7 @@ #include #include +#include #include "fsldma.h" static void dma_init(struct fsl_dma_chan *fsl_chan) @@ -551,6 +552,229 @@ fail: return NULL; } +/** + * fsl_dma_prep_slave_sg - prepare descriptors for a DMA_SLAVE transaction + * @chan: DMA channel + * @sgl: scatterlist to transfer to/from + * @sg_len: number of entries in @scatterlist + * @direction: DMA direction + * @flags: DMAEngine flags + * + * Prepare a set of descriptors for a DMA_SLAVE transaction. Following the + * DMA_SLAVE API, this gets the device-specific information from the + * chan->private variable. + */ +static struct dma_async_tx_descriptor *fsl_dma_prep_slave_sg( + struct dma_chan *chan, struct scatterlist *sgl, unsigned int sg_len, + enum dma_data_direction direction, unsigned long flags) +{ + struct fsl_dma_chan *fsl_chan; + struct fsl_desc_sw *first = NULL, *prev = NULL, *new = NULL; + struct fsl_dma_slave *slave; + struct list_head *tx_list; + size_t copy; + + int i; + struct scatterlist *sg; + size_t sg_used; + size_t hw_used; + struct fsl_dma_hw_addr *hw; + dma_addr_t dma_dst, dma_src; + + if (!chan) + return NULL; + + if (!chan->private) + return NULL; + + fsl_chan = to_fsl_chan(chan); + slave = chan->private; + + if (list_empty(&slave->addresses)) + return NULL; + + hw = list_first_entry(&slave->addresses, struct fsl_dma_hw_addr, entry); + hw_used = 0; + + /* + * Build the hardware transaction to copy from the scatterlist to + * the hardware, or from the hardware to the scatterlist + * + * If you are copying from the hardware to the scatterlist and it + * takes two hardware entries to fill an entire page, then both + * hardware entries will be coalesced into the same page + * + * If you are copying from the scatterlist to the hardware and a + * single page can fill two hardware entries, then the data will + * be read out of the page into the first hardware entry, and so on + */ + for_each_sg(sgl, sg, sg_len, i) { + sg_used = 0; + + /* Loop until the entire scatterlist entry is used */ + while (sg_used < sg_dma_len(sg)) { + + /* + * If we've used up the current hardware address/length + * pair, we need to load a new one + * + * This is done in a while loop so that descriptors with + * length == 0 will be skipped + */ + while (hw_used >= hw->length) { + + /* + * If the current hardware entry is the last + * entry in the list, we're finished + */ + if (list_is_last(&hw->entry, &slave->addresses)) + goto finished; + + /* Get the next hardware address/length pair */ + hw = list_entry(hw->entry.next, + struct fsl_dma_hw_addr, entry); + hw_used = 0; + } + + /* Allocate the link descriptor from DMA pool */ + new = fsl_dma_alloc_descriptor(fsl_chan); + if (!new) { + dev_err(fsl_chan->dev, "No free memory for " + "link descriptor\n"); + goto fail; + } +#ifdef FSL_DMA_LD_DEBUG + dev_dbg(fsl_chan->dev, "new link desc alloc %p\n", new); +#endif + + /* + * Calculate the maximum number of bytes to transfer, + * making sure it is less than the DMA controller limit + */ + copy = min_t(size_t, sg_dma_len(sg) - sg_used, + hw->length - hw_used); + copy = min_t(size_t, copy, FSL_DMA_BCR_MAX_CNT); + + /* + * DMA_FROM_DEVICE + * from the hardware to the scatterlist + * + * DMA_TO_DEVICE + * from the scatterlist to the hardware + */ + if (direction == DMA_FROM_DEVICE) { + dma_src = hw->address + hw_used; + dma_dst = sg_dma_address(sg) + sg_used; + } else { + dma_src = sg_dma_address(sg) + sg_used; + dma_dst = hw->address + hw_used; + } + + /* Fill in the descriptor */ + set_desc_cnt(fsl_chan, &new->hw, copy); + set_desc_src(fsl_chan, &new->hw, dma_src); + set_desc_dest(fsl_chan, &new->hw, dma_dst); + + /* + * If this is not the first descriptor, chain the + * current descriptor after the previous descriptor + */ + if (!first) { + first = new; + } else { + set_desc_next(fsl_chan, &prev->hw, + new->async_tx.phys); + } + + new->async_tx.cookie = 0; + async_tx_ack(&new->async_tx); + + prev = new; + sg_used += copy; + hw_used += copy; + + /* Insert the link descriptor into the LD ring */ + list_add_tail(&new->node, &first->tx_list); + } + } + +finished: + + /* All of the hardware address/length pairs had length == 0 */ + if (!first || !new) + return NULL; + + new->async_tx.flags = flags; + new->async_tx.cookie = -EBUSY; + + /* Set End-of-link to the last link descriptor of new list */ + set_ld_eol(fsl_chan, new); + + /* Enable extra controller features */ + if (fsl_chan->set_src_loop_size) + fsl_chan->set_src_loop_size(fsl_chan, slave->src_loop_size); + + if (fsl_chan->set_dest_loop_size) + fsl_chan->set_dest_loop_size(fsl_chan, slave->dst_loop_size); + + if (fsl_chan->toggle_ext_start) + fsl_chan->toggle_ext_start(fsl_chan, slave->external_start); + + if (fsl_chan->toggle_ext_pause) + fsl_chan->toggle_ext_pause(fsl_chan, slave->external_pause); + + if (fsl_chan->set_request_count) + fsl_chan->set_request_count(fsl_chan, slave->request_count); + + return &first->async_tx; + +fail: + /* If first was not set, then we failed to allocate the very first + * descriptor, and we're done */ + if (!first) + return NULL; + + /* + * First is set, so all of the descriptors we allocated have been added + * to first->tx_list, INCLUDING "first" itself. Therefore we + * must traverse the list backwards freeing each descriptor in turn + * + * We're re-using variables for the loop, oh well + */ + tx_list = &first->tx_list; + list_for_each_entry_safe_reverse(new, prev, tx_list, node) { + list_del_init(&new->node); + dma_pool_free(fsl_chan->desc_pool, new, new->async_tx.phys); + } + + return NULL; +} + +static void fsl_dma_device_terminate_all(struct dma_chan *chan) +{ + struct fsl_dma_chan *fsl_chan; + struct fsl_desc_sw *desc, *tmp; + unsigned long flags; + + if (!chan) + return; + + fsl_chan = to_fsl_chan(chan); + + /* Halt the DMA engine */ + dma_halt(fsl_chan); + + spin_lock_irqsave(&fsl_chan->desc_lock, flags); + + /* Remove and free all of the descriptors in the LD queue */ + list_for_each_entry_safe(desc, tmp, &fsl_chan->ld_queue, node) { + list_del(&desc->node); + dma_pool_free(fsl_chan->desc_pool, desc, desc->async_tx.phys); + } + + spin_unlock_irqrestore(&fsl_chan->desc_lock, flags); +} + /** * fsl_dma_update_completed_cookie - Update the completed cookie. * @fsl_chan : Freescale DMA channel @@ -977,12 +1201,15 @@ static int __devinit of_fsl_dma_probe(struct of_device *dev, dma_cap_set(DMA_MEMCPY, fdev->common.cap_mask); dma_cap_set(DMA_INTERRUPT, fdev->common.cap_mask); + dma_cap_set(DMA_SLAVE, fdev->common.cap_mask); fdev->common.device_alloc_chan_resources = fsl_dma_alloc_chan_resources; fdev->common.device_free_chan_resources = fsl_dma_free_chan_resources; fdev->common.device_prep_dma_interrupt = fsl_dma_prep_interrupt; fdev->common.device_prep_dma_memcpy = fsl_dma_prep_memcpy; fdev->common.device_is_tx_complete = fsl_dma_is_complete; fdev->common.device_issue_pending = fsl_dma_memcpy_issue_pending; + fdev->common.device_prep_slave_sg = fsl_dma_prep_slave_sg; + fdev->common.device_terminate_all = fsl_dma_device_terminate_all; fdev->common.dev = &dev->dev; fdev->irq = irq_of_parse_and_map(dev->node, 0); -- cgit v1.2.3