From fc4618575f79eea062cdc51715040e40cd35b71c Mon Sep 17 00:00:00 2001 From: Guennadi Liakhovetski Date: Tue, 19 Jan 2010 07:24:55 +0000 Subject: [PATCH] sh: prepare the DMA driver for slave functionality Slave DMA functionality uses scatter-gather arrays for data transfers, whereas memcpy just uses a single data buffer. This patch converts the current memcpy implementation in shdma.c to use scatter-gather, making it just a special case with one SG-element. This allows us to isolate descriptor list manipulations and locking into one function, thus reducing error chances. Signed-off-by: Guennadi Liakhovetski Acked-by: Dan Williams Signed-off-by: Paul Mundt --- drivers/dma/shdma.c | 221 ++++++++++++++++++++++++++++++-------------- 1 file changed, 153 insertions(+), 68 deletions(-) diff --git a/drivers/dma/shdma.c b/drivers/dma/shdma.c index d10cc899c46..427c3effc43 100644 --- a/drivers/dma/shdma.c +++ b/drivers/dma/shdma.c @@ -53,12 +53,12 @@ static void sh_dmae_chan_ld_cleanup(struct sh_dmae_chan *sh_chan, bool all); #define SH_DMAC_CHAN_BASE(id) (dma_base_addr[id]) static void sh_dmae_writel(struct sh_dmae_chan *sh_dc, u32 data, u32 reg) { - ctrl_outl(data, (SH_DMAC_CHAN_BASE(sh_dc->id) + reg)); + ctrl_outl(data, SH_DMAC_CHAN_BASE(sh_dc->id) + reg); } static u32 sh_dmae_readl(struct sh_dmae_chan *sh_dc, u32 reg) { - return ctrl_inl((SH_DMAC_CHAN_BASE(sh_dc->id) + reg)); + return ctrl_inl(SH_DMAC_CHAN_BASE(sh_dc->id) + reg); } static void dmae_init(struct sh_dmae_chan *sh_chan) @@ -95,14 +95,14 @@ static int sh_dmae_rst(int id) return 0; } -static int dmae_is_busy(struct sh_dmae_chan *sh_chan) +static bool dmae_is_busy(struct sh_dmae_chan *sh_chan) { u32 chcr = sh_dmae_readl(sh_chan, CHCR); - if (chcr & CHCR_DE) { - if (!(chcr & CHCR_TE)) - return -EBUSY; /* working */ - } - return 0; /* waiting */ + + if ((chcr & (CHCR_DE | CHCR_TE)) == CHCR_DE) + return true; /* working */ + + return false; /* waiting */ } static inline unsigned int calc_xmit_shift(struct sh_dmae_chan *sh_chan) @@ -136,10 +136,9 @@ static void dmae_halt(struct sh_dmae_chan *sh_chan) static int dmae_set_chcr(struct sh_dmae_chan *sh_chan, u32 val) { - int ret = dmae_is_busy(sh_chan); /* When DMA was working, can not set data to CHCR */ - if (ret) - return ret; + if (dmae_is_busy(sh_chan)) + return -EBUSY; sh_dmae_writel(sh_chan, val, CHCR); return 0; @@ -153,9 +152,9 @@ static int dmae_set_dmars(struct sh_dmae_chan *sh_chan, u16 val) { u32 addr; int shift = 0; - int ret = dmae_is_busy(sh_chan); - if (ret) - return ret; + + if (dmae_is_busy(sh_chan)) + return -EBUSY; if (sh_chan->id & DMARS_CHAN_MSK) shift = DMARS_SHIFT; @@ -301,23 +300,95 @@ static void sh_dmae_free_chan_resources(struct dma_chan *chan) kfree(desc); } -static struct dma_async_tx_descriptor *sh_dmae_prep_memcpy( - struct dma_chan *chan, dma_addr_t dma_dest, dma_addr_t dma_src, - size_t len, unsigned long flags) +/* + * sh_dmae_add_desc - get, set up and return one transfer descriptor + * @sh_chan: DMA channel + * @flags: DMA transfer flags + * @dest: destination DMA address, incremented when direction equals + * DMA_FROM_DEVICE or DMA_BIDIRECTIONAL + * @src: source DMA address, incremented when direction equals + * DMA_TO_DEVICE or DMA_BIDIRECTIONAL + * @len: DMA transfer length + * @first: if NULL, set to the current descriptor and cookie set to -EBUSY + * @direction: needed for slave DMA to decide which address to keep constant, + * equals DMA_BIDIRECTIONAL for MEMCPY + * Returns 0 or an error + * Locks: called with desc_lock held + */ +static struct sh_desc *sh_dmae_add_desc(struct sh_dmae_chan *sh_chan, + unsigned long flags, dma_addr_t *dest, dma_addr_t *src, size_t *len, + struct sh_desc **first, enum dma_data_direction direction) { - struct sh_dmae_chan *sh_chan; - struct sh_desc *first = NULL, *prev = NULL, *new; + struct sh_desc *new; size_t copy_size; - LIST_HEAD(tx_list); - int chunks = (len + SH_DMA_TCR_MAX) / (SH_DMA_TCR_MAX + 1); - if (!chan) + if (!*len) return NULL; - if (!len) + /* Allocate the link descriptor from the free list */ + new = sh_dmae_get_desc(sh_chan); + if (!new) { + dev_err(sh_chan->dev, "No free link descriptor available\n"); return NULL; + } - sh_chan = to_sh_chan(chan); + copy_size = min(*len, (size_t)SH_DMA_TCR_MAX + 1); + + new->hw.sar = *src; + new->hw.dar = *dest; + new->hw.tcr = copy_size; + + if (!*first) { + /* First desc */ + new->async_tx.cookie = -EBUSY; + *first = new; + } else { + /* Other desc - invisible to the user */ + new->async_tx.cookie = -EINVAL; + } + + dev_dbg(sh_chan->dev, "chaining (%u/%u)@%x -> %x with %p, cookie %d\n", + copy_size, *len, *src, *dest, &new->async_tx, + new->async_tx.cookie); + + new->mark = DESC_PREPARED; + new->async_tx.flags = flags; + + *len -= copy_size; + if (direction == DMA_BIDIRECTIONAL || direction == DMA_TO_DEVICE) + *src += copy_size; + if (direction == DMA_BIDIRECTIONAL || direction == DMA_FROM_DEVICE) + *dest += copy_size; + + return new; +} + +/* + * sh_dmae_prep_sg - prepare transfer descriptors from an SG list + * + * Common routine for public (MEMCPY) and slave DMA. The MEMCPY case is also + * converted to scatter-gather to guarantee consistent locking and a correct + * list manipulation. For slave DMA direction carries the usual meaning, and, + * logically, the SG list is RAM and the addr variable contains slave address, + * e.g., the FIFO I/O register. For MEMCPY direction equals DMA_BIDIRECTIONAL + * and the SG list contains only one element and points at the source buffer. + */ +static struct dma_async_tx_descriptor *sh_dmae_prep_sg(struct sh_dmae_chan *sh_chan, + struct scatterlist *sgl, unsigned int sg_len, dma_addr_t *addr, + enum dma_data_direction direction, unsigned long flags) +{ + struct scatterlist *sg; + struct sh_desc *first = NULL, *new = NULL /* compiler... */; + LIST_HEAD(tx_list); + int chunks = 0; + int i; + + if (!sg_len) + return NULL; + + for_each_sg(sgl, sg, sg_len, i) + chunks += (sg_dma_len(sg) + SH_DMA_TCR_MAX) / + (SH_DMA_TCR_MAX + 1); /* Have to lock the whole loop to protect against concurrent release */ spin_lock_bh(&sh_chan->desc_lock); @@ -333,49 +404,32 @@ static struct dma_async_tx_descriptor *sh_dmae_prep_memcpy( * only during this function, then they are immediately spliced * back onto the free list in form of a chain */ - do { - /* Allocate the link descriptor from the free list */ - new = sh_dmae_get_desc(sh_chan); - if (!new) { - dev_err(sh_chan->dev, - "No free memory for link descriptor\n"); - list_for_each_entry(new, &tx_list, node) - new->mark = DESC_IDLE; - list_splice(&tx_list, &sh_chan->ld_free); - spin_unlock_bh(&sh_chan->desc_lock); - return NULL; - } - - copy_size = min(len, (size_t)SH_DMA_TCR_MAX + 1); - - new->hw.sar = dma_src; - new->hw.dar = dma_dest; - new->hw.tcr = copy_size; - if (!first) { - /* First desc */ - new->async_tx.cookie = -EBUSY; - first = new; - } else { - /* Other desc - invisible to the user */ - new->async_tx.cookie = -EINVAL; - } - - dev_dbg(sh_chan->dev, - "chaining %u of %u with %p, dst %x, cookie %d\n", - copy_size, len, &new->async_tx, dma_dest, - new->async_tx.cookie); - - new->mark = DESC_PREPARED; - new->async_tx.flags = flags; - new->chunks = chunks--; - - prev = new; - len -= copy_size; - dma_src += copy_size; - dma_dest += copy_size; - /* Insert the link descriptor to the LD ring */ - list_add_tail(&new->node, &tx_list); - } while (len); + for_each_sg(sgl, sg, sg_len, i) { + dma_addr_t sg_addr = sg_dma_address(sg); + size_t len = sg_dma_len(sg); + + if (!len) + goto err_get_desc; + + do { + dev_dbg(sh_chan->dev, "Add SG #%d@%p[%d], dma %llx\n", + i, sg, len, (unsigned long long)sg_addr); + + if (direction == DMA_FROM_DEVICE) + new = sh_dmae_add_desc(sh_chan, flags, + &sg_addr, addr, &len, &first, + direction); + else + new = sh_dmae_add_desc(sh_chan, flags, + addr, &sg_addr, &len, &first, + direction); + if (!new) + goto err_get_desc; + + new->chunks = chunks--; + list_add_tail(&new->node, &tx_list); + } while (len); + } if (new != first) new->async_tx.cookie = -ENOSPC; @@ -386,6 +440,37 @@ static struct dma_async_tx_descriptor *sh_dmae_prep_memcpy( spin_unlock_bh(&sh_chan->desc_lock); return &first->async_tx; + +err_get_desc: + list_for_each_entry(new, &tx_list, node) + new->mark = DESC_IDLE; + list_splice(&tx_list, &sh_chan->ld_free); + + spin_unlock_bh(&sh_chan->desc_lock); + + return NULL; +} + +static struct dma_async_tx_descriptor *sh_dmae_prep_memcpy( + struct dma_chan *chan, dma_addr_t dma_dest, dma_addr_t dma_src, + size_t len, unsigned long flags) +{ + struct sh_dmae_chan *sh_chan; + struct scatterlist sg; + + if (!chan || !len) + return NULL; + + sh_chan = to_sh_chan(chan); + + sg_init_table(&sg, 1); + sg_set_page(&sg, pfn_to_page(PFN_DOWN(dma_src)), len, + offset_in_page(dma_src)); + sg_dma_address(&sg) = dma_src; + sg_dma_len(&sg) = len; + + return sh_dmae_prep_sg(sh_chan, &sg, 1, &dma_dest, DMA_BIDIRECTIONAL, + flags); } static dma_async_tx_callback __ld_cleanup(struct sh_dmae_chan *sh_chan, bool all) @@ -559,7 +644,7 @@ static irqreturn_t sh_dmae_err(int irq, void *data) /* IRQ Multi */ if (shdev->pdata.mode & SHDMA_MIX_IRQ) { - int cnt = 0; + int __maybe_unused cnt = 0; switch (irq) { #if defined(DMTE6_IRQ) && defined(DMAE1_IRQ) case DMTE6_IRQ: -- 2.39.2