[PATCH 06/15] dmaengine: dw-axi-dmac: Support device_prep_slave_sg

[Sia Jee Heng]

Add device_prep_slave_sg() callback function so that DMA_MEM_TO_DEV
and DMA_DEV_TO_MEM operations in single mode can be supported.

Existing AxiDMA driver only support data transfer between
memory to memory. Data transfer between device to memory and
memory to device in single mode would failed if this interface
is not supported by the AxiDMA driver.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Signed-off-by: Sia Jee Heng <jee.heng.sia@xxxxxxxxx>
---
 .../dma/dw-axi-dmac/dw-axi-dmac-platform.c    | 142 ++++++++++++++++++
 drivers/dma/dw-axi-dmac/dw-axi-dmac.h         |   1 +
 2 files changed, 143 insertions(+)

diff --git a/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c b/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
index 16e6934ae9a1..1124c97025f2 100644
--- a/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
+++ b/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
@@ -307,6 +307,22 @@ static void axi_chan_block_xfer_start(struct axi_dma_chan *chan,
 	       priority << CH_CFG_H_PRIORITY_POS |
 	       DWAXIDMAC_HS_SEL_HW << CH_CFG_H_HS_SEL_DST_POS |
 	       DWAXIDMAC_HS_SEL_HW << CH_CFG_H_HS_SEL_SRC_POS);
+	switch (chan->direction) {
+	case DMA_MEM_TO_DEV:
+		reg |= (chan->config.device_fc ?
+			DWAXIDMAC_TT_FC_MEM_TO_PER_DST :
+			DWAXIDMAC_TT_FC_MEM_TO_PER_DMAC)
+			<< CH_CFG_H_TT_FC_POS;
+		break;
+	case DMA_DEV_TO_MEM:
+		reg |= (chan->config.device_fc ?
+			DWAXIDMAC_TT_FC_PER_TO_MEM_SRC :
+			DWAXIDMAC_TT_FC_PER_TO_MEM_DMAC)
+			<< CH_CFG_H_TT_FC_POS;
+		break;
+	default:
+		break;
+	}
 	axi_chan_iowrite32(chan, CH_CFG_H, reg);
 
 	write_chan_llp(chan, first->hw_desc[0].llp | lms);
@@ -559,6 +575,129 @@ dma_chan_prep_dma_memcpy(struct dma_chan *dchan, dma_addr_t dst_adr,
 	return NULL;
 }
 
+static struct dma_async_tx_descriptor *
+dw_axi_dma_chan_prep_slave_sg(struct dma_chan *dchan, struct scatterlist *sgl,
+			      unsigned int sg_len,
+			      enum dma_transfer_direction direction,
+			      unsigned long flags, void *context)
+{
+	struct axi_dma_chan *chan = dchan_to_axi_dma_chan(dchan);
+	unsigned int data_width = BIT(chan->chip->dw->hdata->m_data_width);
+	struct axi_dma_hw_desc *hw_desc = NULL;
+	struct axi_dma_desc *desc = NULL;
+	struct scatterlist *sg;
+	unsigned int reg_width;
+	unsigned int mem_width;
+	dma_addr_t reg;
+	unsigned int i;
+	u32 ctllo, ctlhi;
+	size_t block_ts;
+	u32 mem, len;
+	u64 llp = 0;
+	u8 lms = 0; /* Select AXI0 master for LLI fetching */
+
+	if (unlikely(!is_slave_direction(direction) || !sg_len))
+		return NULL;
+
+	chan->direction = direction;
+
+	desc = axi_desc_alloc(sg_len);
+	if (unlikely(!desc))
+		goto err_desc_get;
+
+	switch (direction) {
+	case DMA_MEM_TO_DEV:
+		reg_width = __ffs(chan->config.dst_addr_width);
+		reg = chan->config.dst_addr;
+		ctllo = reg_width << CH_CTL_L_DST_WIDTH_POS |
+			DWAXIDMAC_CH_CTL_L_NOINC << CH_CTL_L_DST_INC_POS |
+			DWAXIDMAC_CH_CTL_L_INC << CH_CTL_L_SRC_INC_POS;
+		break;
+	case DMA_DEV_TO_MEM:
+		reg_width = __ffs(chan->config.src_addr_width);
+		reg = chan->config.src_addr;
+		ctllo = reg_width << CH_CTL_L_SRC_WIDTH_POS |
+			DWAXIDMAC_CH_CTL_L_INC << CH_CTL_L_DST_INC_POS |
+			DWAXIDMAC_CH_CTL_L_NOINC << CH_CTL_L_SRC_INC_POS;
+		break;
+	default:
+		return NULL;
+	}
+
+	desc->chan = chan;
+
+	for_each_sg(sgl, sg, sg_len, i) {
+		mem = sg_dma_address(sg);
+		len = sg_dma_len(sg);
+		hw_desc = &desc->hw_desc[i];
+		mem_width = __ffs(data_width | mem | len);
+		if (mem_width > DWAXIDMAC_TRANS_WIDTH_32)
+			mem_width = DWAXIDMAC_TRANS_WIDTH_32;
+
+		hw_desc->lli = axi_desc_get(chan, &hw_desc->llp);
+		if (unlikely(!hw_desc->lli))
+			goto err_desc_get;
+
+		if (direction == DMA_MEM_TO_DEV)
+			block_ts = len >> mem_width;
+		else
+			block_ts = len >> reg_width;
+
+		ctlhi = CH_CTL_H_LLI_VALID;
+		if (chan->chip->dw->hdata->restrict_axi_burst_len) {
+			u32 burst_len = chan->chip->dw->hdata->axi_rw_burst_len;
+
+			ctlhi |= (CH_CTL_H_ARLEN_EN |
+				burst_len << CH_CTL_H_ARLEN_POS |
+				CH_CTL_H_AWLEN_EN |
+				burst_len << CH_CTL_H_AWLEN_POS);
+		}
+
+		hw_desc->lli->ctl_hi = cpu_to_le32(ctlhi);
+
+		if (direction == DMA_MEM_TO_DEV)
+			ctllo |= mem_width << CH_CTL_L_SRC_WIDTH_POS;
+		else
+			ctllo |= mem_width << CH_CTL_L_DST_WIDTH_POS;
+
+		if (direction == DMA_MEM_TO_DEV) {
+			write_desc_sar(hw_desc, mem);
+			write_desc_dar(hw_desc, reg);
+		} else {
+			write_desc_sar(hw_desc, reg);
+			write_desc_dar(hw_desc, mem);
+		}
+
+		hw_desc->lli->block_ts_lo = cpu_to_le32(block_ts - 1);
+		ctllo |= (DWAXIDMAC_BURST_TRANS_LEN_4 << CH_CTL_L_DST_MSIZE_POS |
+				 DWAXIDMAC_BURST_TRANS_LEN_4 << CH_CTL_L_SRC_MSIZE_POS);
+		hw_desc->lli->ctl_lo = cpu_to_le32(ctllo);
+
+		set_desc_src_master(hw_desc);
+	}
+
+	if (unlikely(!desc))
+		return NULL;
+
+	/* Set end-of-link to the last link descriptor of list */
+	set_desc_last(&desc->hw_desc[sg_len - 1]);
+
+	/* Managed transfer list */
+	do {
+		hw_desc = &desc->hw_desc[--sg_len];
+		write_desc_llp(hw_desc, llp | lms);
+		llp = hw_desc->llp;
+	} while (sg_len);
+
+	return vchan_tx_prep(&chan->vc, &desc->vd, flags);
+
+err_desc_get:
+	if (desc)
+		axi_desc_put(desc);
+
+	return NULL;
+}
+
 static int dw_axi_dma_chan_slave_config(struct dma_chan *dchan,
 					struct dma_slave_config *config)
 {
@@ -938,12 +1077,14 @@ static int dw_probe(struct platform_device *pdev)
 
 	/* Set capabilities */
 	dma_cap_set(DMA_MEMCPY, dw->dma.cap_mask);
+	dma_cap_set(DMA_SLAVE, dw->dma.cap_mask);
 
 	/* DMA capabilities */
 	dw->dma.chancnt = hdata->nr_channels;
 	dw->dma.src_addr_widths = AXI_DMA_BUSWIDTHS;
 	dw->dma.dst_addr_widths = AXI_DMA_BUSWIDTHS;
 	dw->dma.directions = BIT(DMA_MEM_TO_MEM);
+	dw->dma.directions |= BIT(DMA_MEM_TO_DEV) | BIT(DMA_DEV_TO_MEM);
 	dw->dma.residue_granularity = DMA_RESIDUE_GRANULARITY_DESCRIPTOR;
 
 	dw->dma.dev = chip->dev;
@@ -959,6 +1100,7 @@ static int dw_probe(struct platform_device *pdev)
 	dw->dma.device_prep_dma_memcpy = dma_chan_prep_dma_memcpy;
 	dw->dma.device_synchronize = dw_axi_dma_synchronize;
 	dw->dma.device_config = dw_axi_dma_chan_slave_config;
+	dw->dma.device_prep_slave_sg = dw_axi_dma_chan_prep_slave_sg;
 
 	platform_set_drvdata(pdev, chip);
 
diff --git a/drivers/dma/dw-axi-dmac/dw-axi-dmac.h b/drivers/dma/dw-axi-dmac/dw-axi-dmac.h
index a75b921d6b1a..ac49f2e14b0c 100644
--- a/drivers/dma/dw-axi-dmac/dw-axi-dmac.h
+++ b/drivers/dma/dw-axi-dmac/dw-axi-dmac.h
@@ -44,6 +44,7 @@ struct axi_dma_chan {
 
 	struct axi_dma_desc		*desc;
 	struct dma_slave_config		config;
+	enum dma_transfer_direction	direction;
 	/* these other elements are all protected by vc.lock */
 	bool				is_paused;
 };
-- 
2.18.0