[PATCH 04/10] mtd: spi-nor: aspeed: add support for SPI dual IO read mode

[Cédric Le Goater]

From: Robert Lippert <roblip at gmail.com>

Implements support for the dual IO read mode on aspeed SMC/FMC
controllers which uses both MISO and MOSI lines for data during a read
to double the read bandwidth.

Signed-off-by: Robert Lippert <rlippert at google.com>
[clg: adapted to mainline driver ]
Signed-off-by: Cédric Le Goater <clg at kaod.org>
---
 drivers/mtd/spi-nor/aspeed-smc.c | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/drivers/mtd/spi-nor/aspeed-smc.c b/drivers/mtd/spi-nor/aspeed-smc.c
index 7dfa1ea0a787..b3c8cfe29765 100644
--- a/drivers/mtd/spi-nor/aspeed-smc.c
+++ b/drivers/mtd/spi-nor/aspeed-smc.c
@@ -512,6 +512,7 @@ static ssize_t aspeed_smc_read_user(struct spi_nor *nor, loff_t from,
 	int i;
 	u8 dummy = 0xFF;
 	int ret;
+	u32 ctl;
 
 	if (aspeed_smc_dma_check(chip, from, len)) {
 		ret = aspeed_smc_dma_start(chip, from, read_buf, len, 0);
@@ -525,6 +526,13 @@ static ssize_t aspeed_smc_read_user(struct spi_nor *nor, loff_t from,
 	for (i = 0; i < chip->nor.read_dummy / 8; i++)
 		aspeed_smc_write_to_ahb(chip->ahb_base, &dummy, sizeof(dummy));
 
+	if (chip->nor.flash_read == SPI_NOR_DUAL) {
+		/* Switch to dual I/O mode for data cycle */
+		ctl = readl(chip->ctl) & ~CONTROL_IO_MODE_MASK;
+		ctl |= CONTROL_IO_DUAL_DATA;
+		writel(ctl, chip->ctl);
+	}
+
 	aspeed_smc_read_from_ahb(read_buf, chip->ahb_base, len);
 	aspeed_smc_stop_user(nor);
 out:
@@ -751,6 +759,9 @@ static int aspeed_smc_chip_setup_finish(struct aspeed_smc_chip *chip)
 	case SPI_NOR_FAST:
 		cmd = CONTROL_COMMAND_MODE_FREAD;
 		break;
+	case SPI_NOR_DUAL:
+		cmd = CONTROL_COMMAND_MODE_FREAD | CONTROL_IO_DUAL_DATA;
+		break;
 	default:
 		dev_err(chip->nor.dev, "unsupported SPI read mode\n");
 		return -EINVAL;
@@ -760,7 +771,7 @@ static int aspeed_smc_chip_setup_finish(struct aspeed_smc_chip *chip)
 		chip->nor.read_opcode << CONTROL_COMMAND_SHIFT |
 		CONTROL_IO_DUMMY_SET(chip->nor.read_dummy / 8);
 
-	dev_dbg(controller->dev, "base control register: %08x\n",
+	dev_dbg(controller->dev, "read control register: %08x\n",
 		chip->ctl_val[smc_read]);
 	return 0;
 }
@@ -830,12 +841,7 @@ static int aspeed_smc_setup_flash(struct aspeed_smc_controller *controller,
 		if (ret)
 			break;
 
-		/*
-		 * TODO: Add support for SPI_NOR_QUAD and SPI_NOR_DUAL
-		 * attach when board support is present as determined
-		 * by of property.
-		 */
-		ret = spi_nor_scan(nor, NULL, SPI_NOR_NORMAL);
+		ret = spi_nor_scan(nor, NULL, SPI_NOR_DUAL);
 		if (ret)
 			break;
 
-- 
2.7.4