From 4d6d74e22096543cb3b35e717cf1b9aea3655f37 Mon Sep 17 00:00:00 2001 From: Robin Murphy Date: Fri, 19 May 2017 15:06:44 +0100 Subject: [PATCH] dmaengine: pl330: Add IOMMU support to slave tranfers Wire up dma_map_resource() for slave transfers, so that we can let the PL330 use IOMMU-backed DMA mapping ops on systems with an appropriate IOMMU and RAM above 4GB, to avoid CPU bounce buffering. Signed-off-by: Robin Murphy Signed-off-by: Vinod Koul --- drivers/dma/pl330.c | 75 +++++++++++++++++++++++++++++++++++++++------ 1 file changed, 66 insertions(+), 9 deletions(-) diff --git a/drivers/dma/pl330.c b/drivers/dma/pl330.c index 8b0da7fa520d..a9451a14ad07 100644 --- a/drivers/dma/pl330.c +++ b/drivers/dma/pl330.c @@ -443,7 +443,10 @@ struct dma_pl330_chan { /* For D-to-M and M-to-D channels */ int burst_sz; /* the peripheral fifo width */ int burst_len; /* the number of burst */ - dma_addr_t fifo_addr; + phys_addr_t fifo_addr; + /* DMA-mapped view of the FIFO; may differ if an IOMMU is present */ + dma_addr_t fifo_dma; + enum dma_data_direction dir; /* for cyclic capability */ bool cyclic; @@ -2120,11 +2123,60 @@ static int pl330_alloc_chan_resources(struct dma_chan *chan) return 1; } +/* + * We need the data direction between the DMAC (the dma-mapping "device") and + * the FIFO (the dmaengine "dev"), from the FIFO's point of view. Confusing! + */ +static enum dma_data_direction +pl330_dma_slave_map_dir(enum dma_transfer_direction dir) +{ + switch (dir) { + case DMA_MEM_TO_DEV: + return DMA_FROM_DEVICE; + case DMA_DEV_TO_MEM: + return DMA_TO_DEVICE; + case DMA_DEV_TO_DEV: + return DMA_BIDIRECTIONAL; + default: + return DMA_NONE; + } +} + +static void pl330_unprep_slave_fifo(struct dma_pl330_chan *pch) +{ + if (pch->dir != DMA_NONE) + dma_unmap_resource(pch->chan.device->dev, pch->fifo_dma, + 1 << pch->burst_sz, pch->dir, 0); + pch->dir = DMA_NONE; +} + + +static bool pl330_prep_slave_fifo(struct dma_pl330_chan *pch, + enum dma_transfer_direction dir) +{ + struct device *dev = pch->chan.device->dev; + enum dma_data_direction dma_dir = pl330_dma_slave_map_dir(dir); + + /* Already mapped for this config? */ + if (pch->dir == dma_dir) + return true; + + pl330_unprep_slave_fifo(pch); + pch->fifo_dma = dma_map_resource(dev, pch->fifo_addr, + 1 << pch->burst_sz, dma_dir, 0); + if (dma_mapping_error(dev, pch->fifo_dma)) + return false; + + pch->dir = dma_dir; + return true; +} + static int pl330_config(struct dma_chan *chan, struct dma_slave_config *slave_config) { struct dma_pl330_chan *pch = to_pchan(chan); + pl330_unprep_slave_fifo(pch); if (slave_config->direction == DMA_MEM_TO_DEV) { if (slave_config->dst_addr) pch->fifo_addr = slave_config->dst_addr; @@ -2235,6 +2287,7 @@ static void pl330_free_chan_resources(struct dma_chan *chan) spin_unlock_irqrestore(&pl330->lock, flags); pm_runtime_mark_last_busy(pch->dmac->ddma.dev); pm_runtime_put_autosuspend(pch->dmac->ddma.dev); + pl330_unprep_slave_fifo(pch); } static int pl330_get_current_xferred_count(struct dma_pl330_chan *pch, @@ -2564,6 +2617,9 @@ static struct dma_async_tx_descriptor *pl330_prep_dma_cyclic( return NULL; } + if (!pl330_prep_slave_fifo(pch, direction)) + return NULL; + for (i = 0; i < len / period_len; i++) { desc = pl330_get_desc(pch); if (!desc) { @@ -2593,12 +2649,12 @@ static struct dma_async_tx_descriptor *pl330_prep_dma_cyclic( desc->rqcfg.src_inc = 1; desc->rqcfg.dst_inc = 0; src = dma_addr; - dst = pch->fifo_addr; + dst = pch->fifo_dma; break; case DMA_DEV_TO_MEM: desc->rqcfg.src_inc = 0; desc->rqcfg.dst_inc = 1; - src = pch->fifo_addr; + src = pch->fifo_dma; dst = dma_addr; break; default: @@ -2711,12 +2767,12 @@ pl330_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl, struct dma_pl330_chan *pch = to_pchan(chan); struct scatterlist *sg; int i; - dma_addr_t addr; if (unlikely(!pch || !sgl || !sg_len)) return NULL; - addr = pch->fifo_addr; + if (!pl330_prep_slave_fifo(pch, direction)) + return NULL; first = NULL; @@ -2742,13 +2798,13 @@ pl330_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl, if (direction == DMA_MEM_TO_DEV) { desc->rqcfg.src_inc = 1; desc->rqcfg.dst_inc = 0; - fill_px(&desc->px, - addr, sg_dma_address(sg), sg_dma_len(sg)); + fill_px(&desc->px, pch->fifo_dma, sg_dma_address(sg), + sg_dma_len(sg)); } else { desc->rqcfg.src_inc = 0; desc->rqcfg.dst_inc = 1; - fill_px(&desc->px, - sg_dma_address(sg), addr, sg_dma_len(sg)); + fill_px(&desc->px, sg_dma_address(sg), pch->fifo_dma, + sg_dma_len(sg)); } desc->rqcfg.brst_size = pch->burst_sz; @@ -2906,6 +2962,7 @@ pl330_probe(struct amba_device *adev, const struct amba_id *id) pch->thread = NULL; pch->chan.device = pd; pch->dmac = pl330; + pch->dir = DMA_NONE; /* Add the channel to the DMAC list */ list_add_tail(&pch->chan.device_node, &pd->channels); -- 2.20.1