mtd: rawnand: sunxi: Add MDMA support

This patch enables NAND MDMA (MBUS DMA) mode for
the Allwinner SoCs A23/A33/H3.

The DMA transfer method gets sets now to MBUS DMA as default for
the sun8i-a23-nand-controller (till now DMA transfer was executed
via the shared DMA engine).

The main advantage is more bandwidth for the users of the shared DMA
engine and also that the MBUS DMA setup requires less configuration
effort. For example you don't need to define a dedicated DMA channel
in the device-tree any more.
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Signed-off-by: Manuel Dipolt <manuel.dipolt@robart.cc>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/154840787.280672.1602517282173.JavaMail.zimbra@robart.cc

drivers/mtd/nand/raw/sunxi_nand.c

@@ -51,6 +51,7 @@
 #define NFC_REG_USER_DATA(x)	(0x0050 + ((x) * 4))
 #define NFC_REG_SPARE_AREA	0x00A0
 #define NFC_REG_PAT_ID		0x00A4
+#define NFC_REG_MDMA_ADDR	0x00C0
 #define NFC_REG_MDMA_CNT	0x00C4
 #define NFC_RAM0_BASE		0x0400
 #define NFC_RAM1_BASE		0x0800
@@ -209,13 +210,13 @@ static inline struct sunxi_nand_chip *to_sunxi_nand(struct nand_chip *nand)
  * NAND Controller capabilities structure: stores NAND controller capabilities
  * for distinction between compatible strings.
  *
- * @extra_mbus_conf:	Contrary to A10, A10s and A13, accessing internal RAM
+ * @has_mdma:		Use mbus dma mode, otherwise general dma
  *			through MBUS on A23/A33 needs extra configuration.
  * @reg_io_data:	I/O data register
  * @dma_maxburst:	DMA maxburst
  */
 struct sunxi_nfc_caps {
-	bool extra_mbus_conf;
+	bool has_mdma;
 	unsigned int reg_io_data;
 	unsigned int dma_maxburst;
 };
@@ -365,24 +366,31 @@ static int sunxi_nfc_dma_op_prepare(struct sunxi_nfc *nfc, const void *buf,
 	if (!ret)
 		return -ENOMEM;
 
-	dmad = dmaengine_prep_slave_sg(nfc->dmac, sg, 1, tdir, DMA_CTRL_ACK);
-	if (!dmad) {
-		ret = -EINVAL;
-		goto err_unmap_buf;
+	if (!nfc->caps->has_mdma) {
+		dmad = dmaengine_prep_slave_sg(nfc->dmac, sg, 1, tdir, DMA_CTRL_ACK);
+		if (!dmad) {
+			ret = -EINVAL;
+			goto err_unmap_buf;
+		}
 	}
 
 	writel(readl(nfc->regs + NFC_REG_CTL) | NFC_RAM_METHOD,
 	       nfc->regs + NFC_REG_CTL);
 	writel(nchunks, nfc->regs + NFC_REG_SECTOR_NUM);
 	writel(chunksize, nfc->regs + NFC_REG_CNT);
-	if (nfc->caps->extra_mbus_conf)
-		writel(chunksize * nchunks, nfc->regs + NFC_REG_MDMA_CNT);
 
-	dmat = dmaengine_submit(dmad);
+	if (nfc->caps->has_mdma) {
+		writel(readl(nfc->regs + NFC_REG_CTL) & ~NFC_DMA_TYPE_NORMAL,
+		       nfc->regs + NFC_REG_CTL);
+		writel(chunksize * nchunks, nfc->regs + NFC_REG_MDMA_CNT);
+		writel(sg_dma_address(sg), nfc->regs + NFC_REG_MDMA_ADDR);
+	} else {
+		dmat = dmaengine_submit(dmad);
 
-	ret = dma_submit_error(dmat);
-	if (ret)
-		goto err_clr_dma_flag;
+		ret = dma_submit_error(dmat);
+		if (ret)
+			goto err_clr_dma_flag;
+	}
 
 	return 0;
 
@@ -913,7 +921,7 @@ static int sunxi_nfc_hw_ecc_read_chunks_dma(struct nand_chip *nand, uint8_t *buf
 	unsigned int max_bitflips = 0;
 	int ret, i, raw_mode = 0;
 	struct scatterlist sg;
-	u32 status;
+	u32 status, wait;
 
 	ret = sunxi_nfc_wait_cmd_fifo_empty(nfc);
 	if (ret)
@@ -931,13 +939,18 @@ static int sunxi_nfc_hw_ecc_read_chunks_dma(struct nand_chip *nand, uint8_t *buf
 	writel((NAND_CMD_RNDOUTSTART << 16) | (NAND_CMD_RNDOUT << 8) |
 	       NAND_CMD_READSTART, nfc->regs + NFC_REG_RCMD_SET);
 
-	dma_async_issue_pending(nfc->dmac);
+	wait = NFC_CMD_INT_FLAG;
+
+	if (nfc->caps->has_mdma)
+		wait |= NFC_DMA_INT_FLAG;
+	else
+		dma_async_issue_pending(nfc->dmac);
 
 	writel(NFC_PAGE_OP | NFC_DATA_SWAP_METHOD | NFC_DATA_TRANS,
 	       nfc->regs + NFC_REG_CMD);
 
-	ret = sunxi_nfc_wait_events(nfc, NFC_CMD_INT_FLAG, false, 0);
-	if (ret)
+	ret = sunxi_nfc_wait_events(nfc, wait, false, 0);
+	if (ret && !nfc->caps->has_mdma)
 		dmaengine_terminate_all(nfc->dmac);
 
 	sunxi_nfc_randomizer_disable(nand);
@@ -1278,6 +1291,7 @@ static int sunxi_nfc_hw_ecc_write_page_dma(struct nand_chip *nand,
 	struct sunxi_nfc *nfc = to_sunxi_nfc(nand->controller);
 	struct nand_ecc_ctrl *ecc = &nand->ecc;
 	struct scatterlist sg;
+	u32 wait;
 	int ret, i;
 
 	sunxi_nfc_select_chip(nand, nand->cur_cs);
@@ -1306,14 +1320,19 @@ static int sunxi_nfc_hw_ecc_write_page_dma(struct nand_chip *nand,
 	writel((NAND_CMD_RNDIN << 8) | NAND_CMD_PAGEPROG,
 	       nfc->regs + NFC_REG_WCMD_SET);
 
-	dma_async_issue_pending(nfc->dmac);
+	wait = NFC_CMD_INT_FLAG;
+
+	if (nfc->caps->has_mdma)
+		wait |= NFC_DMA_INT_FLAG;
+	else
+		dma_async_issue_pending(nfc->dmac);
 
 	writel(NFC_PAGE_OP | NFC_DATA_SWAP_METHOD |
 	       NFC_DATA_TRANS | NFC_ACCESS_DIR,
 	       nfc->regs + NFC_REG_CMD);
 
-	ret = sunxi_nfc_wait_events(nfc, NFC_CMD_INT_FLAG, false, 0);
-	if (ret)
+	ret = sunxi_nfc_wait_events(nfc, wait, false, 0);
+	if (ret && !nfc->caps->has_mdma)
 		dmaengine_terminate_all(nfc->dmac);
 
 	sunxi_nfc_randomizer_disable(nand);
@@ -1696,7 +1715,7 @@ static int sunxi_nand_hw_ecc_ctrl_init(struct nand_chip *nand,
 	ecc->write_oob = sunxi_nfc_hw_ecc_write_oob;
 	mtd_set_ooblayout(mtd, &sunxi_nand_ooblayout_ops);
 
-	if (nfc->dmac) {
+	if (nfc->dmac || nfc->caps->has_mdma) {
 		ecc->read_page = sunxi_nfc_hw_ecc_read_page_dma;
 		ecc->read_subpage = sunxi_nfc_hw_ecc_read_subpage_dma;
 		ecc->write_page = sunxi_nfc_hw_ecc_write_page_dma;
@@ -2061,6 +2080,36 @@ static void sunxi_nand_chips_cleanup(struct sunxi_nfc *nfc)
 	}
 }
 
+static int sunxi_nfc_dma_init(struct sunxi_nfc *nfc, struct resource *r)
+{
+	int ret;
+
+	if (nfc->caps->has_mdma)
+		return 0;
+
+	nfc->dmac = dma_request_chan(nfc->dev, "rxtx");
+	if (IS_ERR(nfc->dmac)) {
+		ret = PTR_ERR(nfc->dmac);
+		if (ret == -EPROBE_DEFER)
+			return ret;
+
+		/* Ignore errors to fall back to PIO mode */
+		dev_warn(nfc->dev, "failed to request rxtx DMA channel: %d\n", ret);
+		nfc->dmac = NULL;
+	} else {
+		struct dma_slave_config dmac_cfg = { };
+
+		dmac_cfg.src_addr = r->start + nfc->caps->reg_io_data;
+		dmac_cfg.dst_addr = dmac_cfg.src_addr;
+		dmac_cfg.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
+		dmac_cfg.dst_addr_width = dmac_cfg.src_addr_width;
+		dmac_cfg.src_maxburst = nfc->caps->dma_maxburst;
+		dmac_cfg.dst_maxburst = nfc->caps->dma_maxburst;
+		dmaengine_slave_config(nfc->dmac, &dmac_cfg);
+	}
+	return 0;
+}
+
 static int sunxi_nfc_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
@@ -2135,30 +2184,10 @@ static int sunxi_nfc_probe(struct platform_device *pdev)
 	if (ret)
 		goto out_ahb_reset_reassert;
 
-	nfc->dmac = dma_request_chan(dev, "rxtx");
-	if (IS_ERR(nfc->dmac)) {
-		ret = PTR_ERR(nfc->dmac);
-		if (ret == -EPROBE_DEFER)
-			goto out_ahb_reset_reassert;
+	ret = sunxi_nfc_dma_init(nfc, r);
 
-		/* Ignore errors to fall back to PIO mode */
-		dev_warn(dev, "failed to request rxtx DMA channel: %d\n", ret);
-		nfc->dmac = NULL;
-	} else {
-		struct dma_slave_config dmac_cfg = { };
-
-		dmac_cfg.src_addr = r->start + nfc->caps->reg_io_data;
-		dmac_cfg.dst_addr = dmac_cfg.src_addr;
-		dmac_cfg.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
-		dmac_cfg.dst_addr_width = dmac_cfg.src_addr_width;
-		dmac_cfg.src_maxburst = nfc->caps->dma_maxburst;
-		dmac_cfg.dst_maxburst = nfc->caps->dma_maxburst;
-		dmaengine_slave_config(nfc->dmac, &dmac_cfg);
-
-		if (nfc->caps->extra_mbus_conf)
-			writel(readl(nfc->regs + NFC_REG_CTL) |
-			       NFC_DMA_TYPE_NORMAL, nfc->regs + NFC_REG_CTL);
-	}
+	if (ret)
+		goto out_ahb_reset_reassert;
 
 	platform_set_drvdata(pdev, nfc);
 
@@ -2205,7 +2234,7 @@ static const struct sunxi_nfc_caps sunxi_nfc_a10_caps = {
 };
 
 static const struct sunxi_nfc_caps sunxi_nfc_a23_caps = {
-	.extra_mbus_conf = true,
+	.has_mdma = true,
 	.reg_io_data = NFC_REG_A23_IO_DATA,
 	.dma_maxburst = 8,
 };