From: Biju Das Date: Mon, 16 Mar 2026 13:32:51 +0000 (+0200) Subject: dmaengine: sh: rz-dmac: Add device_tx_status() callback X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=21323b118c16d287355e6497e1098ce1ca348bd6;p=thirdparty%2Fkernel%2Flinux.git dmaengine: sh: rz-dmac: Add device_tx_status() callback The RZ/G2L SCIFA driver uses dmaengine_prep_slave_sg() to enqueue DMA transfers and implements a timeout mechanism on RX to handle cases where a DMA transfer does not complete. The timeout is implemented using an hrtimer. In the hrtimer callback, dmaengine_tx_status() is called (along with dmaengine_pause()) to retrieve the transfer residue and handle incomplete DMA transfers. Add support for the device_tx_status() callback. Co-developed-by: Long Luu Signed-off-by: Long Luu Signed-off-by: Biju Das Co-developed-by: Claudiu Beznea Signed-off-by: Claudiu Beznea Reviewed-by: Frank Li Link: https://patch.msgid.link/20260316133252.240348-8-claudiu.beznea.uj@bp.renesas.com Signed-off-by: Vinod Koul --- diff --git a/drivers/dma/sh/rz-dmac.c b/drivers/dma/sh/rz-dmac.c index 6bfa77844e02a..4f6f9f4bacca2 100644 --- a/drivers/dma/sh/rz-dmac.c +++ b/drivers/dma/sh/rz-dmac.c @@ -124,10 +124,12 @@ struct rz_dmac { * Registers */ +#define CRTB 0x0020 #define CHSTAT 0x0024 #define CHCTRL 0x0028 #define CHCFG 0x002c #define NXLA 0x0038 +#define CRLA 0x003c #define DCTRL 0x0000 @@ -676,6 +678,145 @@ static void rz_dmac_device_synchronize(struct dma_chan *chan) rz_dmac_set_dma_req_no(dmac, channel->index, dmac->info->default_dma_req_no); } +static struct rz_lmdesc * +rz_dmac_get_next_lmdesc(struct rz_lmdesc *base, struct rz_lmdesc *lmdesc) +{ + struct rz_lmdesc *next = ++lmdesc; + + if (next >= base + DMAC_NR_LMDESC) + next = base; + + return next; +} + +static u32 rz_dmac_calculate_residue_bytes_in_vd(struct rz_dmac_chan *channel, u32 crla) +{ + struct rz_lmdesc *lmdesc = channel->lmdesc.head; + struct dma_chan *chan = &channel->vc.chan; + struct rz_dmac *dmac = to_rz_dmac(chan->device); + u32 residue = 0, i = 0; + + while (lmdesc->nxla != crla) { + lmdesc = rz_dmac_get_next_lmdesc(channel->lmdesc.base, lmdesc); + if (++i >= DMAC_NR_LMDESC) + return 0; + } + + /* Calculate residue from next lmdesc to end of virtual desc */ + while (lmdesc->chcfg & CHCFG_DEM) { + residue += lmdesc->tb; + lmdesc = rz_dmac_get_next_lmdesc(channel->lmdesc.base, lmdesc); + } + + dev_dbg(dmac->dev, "%s: VD residue is %u\n", __func__, residue); + + return residue; +} + +static u32 rz_dmac_chan_get_residue(struct rz_dmac_chan *channel, + dma_cookie_t cookie) +{ + struct rz_dmac_desc *current_desc, *desc; + enum dma_status status; + u32 crla, crtb, i; + + /* Get current processing virtual descriptor */ + current_desc = list_first_entry(&channel->ld_active, + struct rz_dmac_desc, node); + if (!current_desc) + return 0; + + /* + * If the cookie corresponds to a descriptor that has been completed + * there is no residue. The same check has already been performed by the + * caller but without holding the channel lock, so the descriptor could + * now be complete. + */ + status = dma_cookie_status(&channel->vc.chan, cookie, NULL); + if (status == DMA_COMPLETE) + return 0; + + /* + * If the cookie doesn't correspond to the currently processing virtual + * descriptor then the descriptor hasn't been processed yet, and the + * residue is equal to the full descriptor size. Also, a client driver + * is possible to call this function before rz_dmac_irq_handler_thread() + * runs. In this case, the running descriptor will be the next + * descriptor, and will appear in the done list. So, if the argument + * cookie matches the done list's cookie, we can assume the residue is + * zero. + */ + if (cookie != current_desc->vd.tx.cookie) { + list_for_each_entry(desc, &channel->ld_free, node) { + if (cookie == desc->vd.tx.cookie) + return 0; + } + + list_for_each_entry(desc, &channel->ld_queue, node) { + if (cookie == desc->vd.tx.cookie) + return desc->len; + } + + list_for_each_entry(desc, &channel->ld_active, node) { + if (cookie == desc->vd.tx.cookie) + return desc->len; + } + + /* + * No descriptor found for the cookie, there's thus no residue. + * This shouldn't happen if the calling driver passes a correct + * cookie value. + */ + WARN(1, "No descriptor for cookie!"); + return 0; + } + + /* + * We need to read two registers. Make sure the hardware does not move + * to next lmdesc while reading the current lmdesc. Trying it 3 times + * should be enough: initial read, retry, retry for the paranoid. + */ + for (i = 0; i < 3; i++) { + crla = rz_dmac_ch_readl(channel, CRLA, 1); + crtb = rz_dmac_ch_readl(channel, CRTB, 1); + /* Still the same? */ + if (crla == rz_dmac_ch_readl(channel, CRLA, 1)) + break; + } + + WARN_ONCE(i >= 3, "residue might not be continuous!"); + + /* + * Calculate number of bytes transferred in processing virtual descriptor. + * One virtual descriptor can have many lmdesc. + */ + return crtb + rz_dmac_calculate_residue_bytes_in_vd(channel, crla); +} + +static enum dma_status rz_dmac_tx_status(struct dma_chan *chan, + dma_cookie_t cookie, + struct dma_tx_state *txstate) +{ + struct rz_dmac_chan *channel = to_rz_dmac_chan(chan); + enum dma_status status; + u32 residue; + + status = dma_cookie_status(chan, cookie, txstate); + if (status == DMA_COMPLETE || !txstate) + return status; + + scoped_guard(spinlock_irqsave, &channel->vc.lock) + residue = rz_dmac_chan_get_residue(channel, cookie); + + /* if there's no residue, the cookie is complete */ + if (!residue) + return DMA_COMPLETE; + + dma_set_residue(txstate, residue); + + return status; +} + /* * ----------------------------------------------------------------------------- * IRQ handling @@ -997,6 +1138,7 @@ static int rz_dmac_probe(struct platform_device *pdev) engine = &dmac->engine; dma_cap_set(DMA_SLAVE, engine->cap_mask); dma_cap_set(DMA_MEMCPY, engine->cap_mask); + engine->residue_granularity = DMA_RESIDUE_GRANULARITY_BURST; rz_dmac_writel(dmac, DCTRL_DEFAULT, CHANNEL_0_7_COMMON_BASE + DCTRL); rz_dmac_writel(dmac, DCTRL_DEFAULT, CHANNEL_8_15_COMMON_BASE + DCTRL); @@ -1004,7 +1146,7 @@ static int rz_dmac_probe(struct platform_device *pdev) engine->device_alloc_chan_resources = rz_dmac_alloc_chan_resources; engine->device_free_chan_resources = rz_dmac_free_chan_resources; - engine->device_tx_status = dma_cookie_status; + engine->device_tx_status = rz_dmac_tx_status; engine->device_prep_slave_sg = rz_dmac_prep_slave_sg; engine->device_prep_dma_memcpy = rz_dmac_prep_dma_memcpy; engine->device_config = rz_dmac_config;