From ccadee9b1e90dc6d3d97a20ac96cb1a82e0d5a1d Mon Sep 17 00:00:00 2001 From: Laurent Pinchart Date: Wed, 16 Jul 2014 23:15:48 +0200 Subject: dmaengine: rcar-dmac: Implement support for hardware descriptor lists The DMAC supports hardware-based auto-configuration from descriptor lists. This reduces the number of interrupts required for processing a DMA transfer. Support that mode in the driver. Signed-off-by: Laurent Pinchart Tested-by: Wolfram Sang diff --git a/drivers/dma/sh/rcar-dmac.c b/drivers/dma/sh/rcar-dmac.c index 89d40f9..6e7cdab 100644 --- a/drivers/dma/sh/rcar-dmac.c +++ b/drivers/dma/sh/rcar-dmac.c @@ -10,6 +10,7 @@ * published by the Free Software Foundation. */ +#include #include #include #include @@ -41,6 +42,19 @@ struct rcar_dmac_xfer_chunk { }; /* + * struct rcar_dmac_hw_desc - Hardware descriptor for a transfer chunk + * @sar: value of the SAR register (source address) + * @dar: value of the DAR register (destination address) + * @tcr: value of the TCR register (transfer count) + */ +struct rcar_dmac_hw_desc { + u32 sar; + u32 dar; + u32 tcr; + u32 reserved; +} __attribute__((__packed__)); + +/* * struct rcar_dmac_desc - R-Car Gen2 DMA Transfer Descriptor * @async_tx: base DMA asynchronous transaction descriptor * @direction: direction of the DMA transfer @@ -49,6 +63,10 @@ struct rcar_dmac_xfer_chunk { * @node: entry in the channel's descriptors lists * @chunks: list of transfer chunks for this transfer * @running: the transfer chunk being currently processed + * @nchunks: number of transfer chunks for this transfer + * @hwdescs.mem: hardware descriptors memory for the transfer + * @hwdescs.dma: device address of the hardware descriptors memory + * @hwdescs.size: size of the hardware descriptors in bytes * @size: transfer size in bytes * @cyclic: when set indicates that the DMA transfer is cyclic */ @@ -61,6 +79,13 @@ struct rcar_dmac_desc { struct list_head node; struct list_head chunks; struct rcar_dmac_xfer_chunk *running; + unsigned int nchunks; + + struct { + struct rcar_dmac_hw_desc *mem; + dma_addr_t dma; + size_t size; + } hwdescs; unsigned int size; bool cyclic; @@ -217,7 +242,8 @@ struct rcar_dmac { #define RCAR_DMATSRB 0x0038 #define RCAR_DMACHCRB 0x001c #define RCAR_DMACHCRB_DCNT(n) ((n) << 24) -#define RCAR_DMACHCRB_DPTR(n) ((n) << 16) +#define RCAR_DMACHCRB_DPTR_MASK (0xff << 16) +#define RCAR_DMACHCRB_DPTR_SHIFT 16 #define RCAR_DMACHCRB_DRST (1 << 15) #define RCAR_DMACHCRB_DTS (1 << 8) #define RCAR_DMACHCRB_SLM_NORMAL (0 << 4) @@ -289,30 +315,81 @@ static bool rcar_dmac_chan_is_busy(struct rcar_dmac_chan *chan) static void rcar_dmac_chan_start_xfer(struct rcar_dmac_chan *chan) { struct rcar_dmac_desc *desc = chan->desc.running; - struct rcar_dmac_xfer_chunk *chunk = desc->running; - - dev_dbg(chan->chan.device->dev, - "chan%u: queue chunk %p: %u@%pad -> %pad\n", - chan->index, chunk, chunk->size, &chunk->src_addr, - &chunk->dst_addr); + u32 chcr = desc->chcr; WARN_ON_ONCE(rcar_dmac_chan_is_busy(chan)); + if (chan->mid_rid >= 0) + rcar_dmac_chan_write(chan, RCAR_DMARS, chan->mid_rid); + + if (desc->hwdescs.mem) { + dev_dbg(chan->chan.device->dev, + "chan%u: queue desc %p: %u@%pad\n", + chan->index, desc, desc->nchunks, &desc->hwdescs.dma); + #ifdef CONFIG_ARCH_DMA_ADDR_T_64BIT - rcar_dmac_chan_write(chan, RCAR_DMAFIXSAR, chunk->src_addr >> 32); - rcar_dmac_chan_write(chan, RCAR_DMAFIXDAR, chunk->dst_addr >> 32); + rcar_dmac_chan_write(chan, RCAR_DMAFIXDPBASE, + desc->hwdescs.dma >> 32); #endif - rcar_dmac_chan_write(chan, RCAR_DMASAR, chunk->src_addr & 0xffffffff); - rcar_dmac_chan_write(chan, RCAR_DMADAR, chunk->dst_addr & 0xffffffff); + rcar_dmac_chan_write(chan, RCAR_DMADPBASE, + (desc->hwdescs.dma & 0xfffffff0) | + RCAR_DMADPBASE_SEL); + rcar_dmac_chan_write(chan, RCAR_DMACHCRB, + RCAR_DMACHCRB_DCNT(desc->nchunks - 1) | + RCAR_DMACHCRB_DRST); - if (chan->mid_rid >= 0) - rcar_dmac_chan_write(chan, RCAR_DMARS, chan->mid_rid); + /* + * Program the descriptor stage interrupt to occur after the end + * of the first stage. + */ + rcar_dmac_chan_write(chan, RCAR_DMADPCR, RCAR_DMADPCR_DIPT(1)); + + chcr |= RCAR_DMACHCR_RPT_SAR | RCAR_DMACHCR_RPT_DAR + | RCAR_DMACHCR_RPT_TCR | RCAR_DMACHCR_DPB; + + /* + * If the descriptor isn't cyclic enable normal descriptor mode + * and the transfer completion interrupt. + */ + if (!desc->cyclic) + chcr |= RCAR_DMACHCR_DPM_ENABLED | RCAR_DMACHCR_IE; + /* + * If the descriptor is cyclic and has a callback enable the + * descriptor stage interrupt in infinite repeat mode. + */ + else if (desc->async_tx.callback) + chcr |= RCAR_DMACHCR_DPM_INFINITE | RCAR_DMACHCR_DSIE; + /* + * Otherwise just select infinite repeat mode without any + * interrupt. + */ + else + chcr |= RCAR_DMACHCR_DPM_INFINITE; + } else { + struct rcar_dmac_xfer_chunk *chunk = desc->running; - rcar_dmac_chan_write(chan, RCAR_DMATCR, - chunk->size >> desc->xfer_shift); + dev_dbg(chan->chan.device->dev, + "chan%u: queue chunk %p: %u@%pad -> %pad\n", + chan->index, chunk, chunk->size, &chunk->src_addr, + &chunk->dst_addr); - rcar_dmac_chan_write(chan, RCAR_DMACHCR, desc->chcr | RCAR_DMACHCR_DE | - RCAR_DMACHCR_IE); +#ifdef CONFIG_ARCH_DMA_ADDR_T_64BIT + rcar_dmac_chan_write(chan, RCAR_DMAFIXSAR, + chunk->src_addr >> 32); + rcar_dmac_chan_write(chan, RCAR_DMAFIXDAR, + chunk->dst_addr >> 32); +#endif + rcar_dmac_chan_write(chan, RCAR_DMASAR, + chunk->src_addr & 0xffffffff); + rcar_dmac_chan_write(chan, RCAR_DMADAR, + chunk->dst_addr & 0xffffffff); + rcar_dmac_chan_write(chan, RCAR_DMATCR, + chunk->size >> desc->xfer_shift); + + chcr |= RCAR_DMACHCR_DPM_DISABLED | RCAR_DMACHCR_IE; + } + + rcar_dmac_chan_write(chan, RCAR_DMACHCR, chcr | RCAR_DMACHCR_DE); } static int rcar_dmac_init(struct rcar_dmac *dmac) @@ -403,31 +480,58 @@ static int rcar_dmac_desc_alloc(struct rcar_dmac_chan *chan, gfp_t gfp) * @desc: the descriptor * * Put the descriptor and its transfer chunk descriptors back in the channel's - * free descriptors lists. The descriptor's chunk will be reinitialized to an - * empty list as a result. + * free descriptors lists, and free the hardware descriptors list memory. The + * descriptor's chunks list will be reinitialized to an empty list as a result. * - * The descriptor must have been removed from the channel's done list before - * calling this function. + * The descriptor must have been removed from the channel's lists before calling + * this function. * - * Locking: Must be called with the channel lock held. + * Locking: Must be called in non-atomic context. */ static void rcar_dmac_desc_put(struct rcar_dmac_chan *chan, struct rcar_dmac_desc *desc) { + if (desc->hwdescs.mem) { + dma_free_coherent(NULL, desc->hwdescs.size, desc->hwdescs.mem, + desc->hwdescs.dma); + desc->hwdescs.mem = NULL; + } + + spin_lock_irq(&chan->lock); list_splice_tail_init(&desc->chunks, &chan->desc.chunks_free); list_add_tail(&desc->node, &chan->desc.free); + spin_unlock_irq(&chan->lock); } static void rcar_dmac_desc_recycle_acked(struct rcar_dmac_chan *chan) { struct rcar_dmac_desc *desc, *_desc; + LIST_HEAD(list); - list_for_each_entry_safe(desc, _desc, &chan->desc.wait, node) { + /* + * We have to temporarily move all descriptors from the wait list to a + * local list as iterating over the wait list, even with + * list_for_each_entry_safe, isn't safe if we release the channel lock + * around the rcar_dmac_desc_put() call. + */ + spin_lock_irq(&chan->lock); + list_splice_init(&chan->desc.wait, &list); + spin_unlock_irq(&chan->lock); + + list_for_each_entry_safe(desc, _desc, &list, node) { if (async_tx_test_ack(&desc->async_tx)) { list_del(&desc->node); rcar_dmac_desc_put(chan, desc); } } + + if (list_empty(&list)) + return; + + /* Put the remaining descriptors back in the wait list. */ + spin_lock_irq(&chan->lock); + list_splice(&list, &chan->desc.wait); + spin_unlock_irq(&chan->lock); } /* @@ -444,11 +548,11 @@ static struct rcar_dmac_desc *rcar_dmac_desc_get(struct rcar_dmac_chan *chan) struct rcar_dmac_desc *desc; int ret; - spin_lock_irq(&chan->lock); - /* Recycle acked descriptors before attempting allocation. */ rcar_dmac_desc_recycle_acked(chan); + spin_lock_irq(&chan->lock); + do { if (list_empty(&chan->desc.free)) { /* @@ -547,6 +651,28 @@ rcar_dmac_xfer_chunk_get(struct rcar_dmac_chan *chan) return chunk; } +static void rcar_dmac_alloc_hwdesc(struct rcar_dmac_chan *chan, + struct rcar_dmac_desc *desc) +{ + struct rcar_dmac_xfer_chunk *chunk; + struct rcar_dmac_hw_desc *hwdesc; + size_t size = desc->nchunks * sizeof(*hwdesc); + + hwdesc = dma_alloc_coherent(NULL, size, &desc->hwdescs.dma, GFP_NOWAIT); + if (!hwdesc) + return; + + desc->hwdescs.mem = hwdesc; + desc->hwdescs.size = size; + + list_for_each_entry(chunk, &desc->chunks, node) { + hwdesc->sar = chunk->src_addr; + hwdesc->dar = chunk->dst_addr; + hwdesc->tcr = chunk->size >> desc->xfer_shift; + hwdesc++; + } +} + /* ----------------------------------------------------------------------------- * Stop and reset */ @@ -555,7 +681,8 @@ static void rcar_dmac_chan_halt(struct rcar_dmac_chan *chan) { u32 chcr = rcar_dmac_chan_read(chan, RCAR_DMACHCR); - chcr &= ~(RCAR_DMACHCR_IE | RCAR_DMACHCR_TE | RCAR_DMACHCR_DE); + chcr &= ~(RCAR_DMACHCR_DSE | RCAR_DMACHCR_DSIE | RCAR_DMACHCR_IE | + RCAR_DMACHCR_TE | RCAR_DMACHCR_DE); rcar_dmac_chan_write(chan, RCAR_DMACHCR, chcr); } @@ -666,8 +793,10 @@ rcar_dmac_chan_prep_sg(struct rcar_dmac_chan *chan, struct scatterlist *sgl, struct rcar_dmac_xfer_chunk *chunk; struct rcar_dmac_desc *desc; struct scatterlist *sg; + unsigned int nchunks = 0; unsigned int max_chunk_size; unsigned int full_size = 0; + bool highmem = false; unsigned int i; desc = rcar_dmac_desc_get(chan); @@ -706,6 +835,14 @@ rcar_dmac_chan_prep_sg(struct rcar_dmac_chan *chan, struct scatterlist *sgl, size = ALIGN(dev_addr, 1ULL << 32) - dev_addr; if (mem_addr >> 32 != (mem_addr + size - 1) >> 32) size = ALIGN(mem_addr, 1ULL << 32) - mem_addr; + + /* + * Check if either of the source or destination address + * can't be expressed in 32 bits. If so we can't use + * hardware descriptor lists. + */ + if (dev_addr >> 32 || mem_addr >> 32) + highmem = true; #endif chunk = rcar_dmac_xfer_chunk_get(chan); @@ -736,11 +873,26 @@ rcar_dmac_chan_prep_sg(struct rcar_dmac_chan *chan, struct scatterlist *sgl, len -= size; list_add_tail(&chunk->node, &desc->chunks); + nchunks++; } } + desc->nchunks = nchunks; desc->size = full_size; + /* + * Use hardware descriptor lists if possible when more than one chunk + * needs to be transferred (otherwise they don't make much sense). + * + * The highmem check currently covers the whole transfer. As an + * optimization we could use descriptor lists for consecutive lowmem + * chunks and direct manual mode for highmem chunks. Whether the + * performance improvement would be significant enough compared to the + * additional complexity remains to be investigated. + */ + if (!highmem && nchunks > 1) + rcar_dmac_alloc_hwdesc(chan, desc); + return &desc->async_tx; } @@ -940,8 +1092,10 @@ static unsigned int rcar_dmac_chan_get_residue(struct rcar_dmac_chan *chan, dma_cookie_t cookie) { struct rcar_dmac_desc *desc = chan->desc.running; + struct rcar_dmac_xfer_chunk *running = NULL; struct rcar_dmac_xfer_chunk *chunk; unsigned int residue = 0; + unsigned int dptr = 0; if (!desc) return 0; @@ -954,9 +1108,23 @@ static unsigned int rcar_dmac_chan_get_residue(struct rcar_dmac_chan *chan, if (cookie != desc->async_tx.cookie) return desc->size; + /* + * In descriptor mode the descriptor running pointer is not maintained + * by the interrupt handler, find the running descriptor from the + * descriptor pointer field in the CHCRB register. In non-descriptor + * mode just use the running descriptor pointer. + */ + if (desc->hwdescs.mem) { + dptr = (rcar_dmac_chan_read(chan, RCAR_DMACHCRB) & + RCAR_DMACHCRB_DPTR_MASK) >> RCAR_DMACHCRB_DPTR_SHIFT; + WARN_ON(dptr >= desc->nchunks); + } else { + running = desc->running; + } + /* Compute the size of all chunks still to be transferred. */ list_for_each_entry_reverse(chunk, &desc->chunks, node) { - if (chunk == desc->running) + if (chunk == running || ++dptr == desc->nchunks) break; residue += chunk->size; @@ -1025,42 +1193,71 @@ done: * IRQ handling */ +static irqreturn_t rcar_dmac_isr_desc_stage_end(struct rcar_dmac_chan *chan) +{ + struct rcar_dmac_desc *desc = chan->desc.running; + unsigned int stage; + + if (WARN_ON(!desc || !desc->cyclic)) { + /* + * This should never happen, there should always be a running + * cyclic descriptor when a descriptor stage end interrupt is + * triggered. Warn and return. + */ + return IRQ_NONE; + } + + /* Program the interrupt pointer to the next stage. */ + stage = (rcar_dmac_chan_read(chan, RCAR_DMACHCRB) & + RCAR_DMACHCRB_DPTR_MASK) >> RCAR_DMACHCRB_DPTR_SHIFT; + rcar_dmac_chan_write(chan, RCAR_DMADPCR, RCAR_DMADPCR_DIPT(stage)); + + return IRQ_WAKE_THREAD; +} + static irqreturn_t rcar_dmac_isr_transfer_end(struct rcar_dmac_chan *chan) { struct rcar_dmac_desc *desc = chan->desc.running; - struct rcar_dmac_xfer_chunk *chunk; irqreturn_t ret = IRQ_WAKE_THREAD; if (WARN_ON_ONCE(!desc)) { /* - * This should never happen, there should always be - * a running descriptor when a transfer ends. Warn and - * return. + * This should never happen, there should always be a running + * descriptor when a transfer end interrupt is triggered. Warn + * and return. */ return IRQ_NONE; } /* - * If we haven't completed the last transfer chunk simply move to the - * next one. Only wake the IRQ thread if the transfer is cyclic. + * The transfer end interrupt isn't generated for each chunk when using + * descriptor mode. Only update the running chunk pointer in + * non-descriptor mode. */ - chunk = desc->running; - if (!list_is_last(&chunk->node, &desc->chunks)) { - desc->running = list_next_entry(chunk, node); - if (!desc->cyclic) - ret = IRQ_HANDLED; - goto done; - } + if (!desc->hwdescs.mem) { + /* + * If we haven't completed the last transfer chunk simply move + * to the next one. Only wake the IRQ thread if the transfer is + * cyclic. + */ + if (!list_is_last(&desc->running->node, &desc->chunks)) { + desc->running = list_next_entry(desc->running, node); + if (!desc->cyclic) + ret = IRQ_HANDLED; + goto done; + } - /* - * We've completed the last transfer chunk. If the transfer is cyclic, - * move back to the first one. - */ - if (desc->cyclic) { - desc->running = list_first_entry(&desc->chunks, + /* + * We've completed the last transfer chunk. If the transfer is + * cyclic, move back to the first one. + */ + if (desc->cyclic) { + desc->running = + list_first_entry(&desc->chunks, struct rcar_dmac_xfer_chunk, node); - goto done; + goto done; + } } /* The descriptor is complete, move it to the done list. */ @@ -1083,6 +1280,7 @@ done: static irqreturn_t rcar_dmac_isr_channel(int irq, void *dev) { + u32 mask = RCAR_DMACHCR_DSE | RCAR_DMACHCR_TE; struct rcar_dmac_chan *chan = dev; irqreturn_t ret = IRQ_NONE; u32 chcr; @@ -1090,8 +1288,12 @@ static irqreturn_t rcar_dmac_isr_channel(int irq, void *dev) spin_lock(&chan->lock); chcr = rcar_dmac_chan_read(chan, RCAR_DMACHCR); - rcar_dmac_chan_write(chan, RCAR_DMACHCR, - chcr & ~(RCAR_DMACHCR_TE | RCAR_DMACHCR_DE)); + if (chcr & RCAR_DMACHCR_TE) + mask |= RCAR_DMACHCR_DE; + rcar_dmac_chan_write(chan, RCAR_DMACHCR, chcr & ~mask); + + if (chcr & RCAR_DMACHCR_DSE) + ret |= rcar_dmac_isr_desc_stage_end(chan); if (chcr & RCAR_DMACHCR_TE) ret |= rcar_dmac_isr_transfer_end(chan); @@ -1148,11 +1350,11 @@ static irqreturn_t rcar_dmac_isr_channel_thread(int irq, void *dev) list_add_tail(&desc->node, &chan->desc.wait); } + spin_unlock_irq(&chan->lock); + /* Recycle all acked descriptors. */ rcar_dmac_desc_recycle_acked(chan); - spin_unlock_irq(&chan->lock); - return IRQ_HANDLED; } -- cgit v0.10.2