[PATCH 1/2] mmc: litex_mmc: Set width from linux request

[Inochi Amaoto <inochiama@gmail.com>]

Previously, the litex_mmc driver force the 4 bits bus width.
This means that the gateware with 1 bit bus width is not fit.
However, litesdcard does support setting bus width, which
make the 1 bit bus width gateware possible to be used.

Add logic for setting bus width in the set_ios() function.

Signed-off-by: Inochi Amaoto <inochiama@gmail.com>
---
 drivers/mmc/host/litex_mmc.c | 36 +++++++++++++++++++++++++++++-------
 1 file changed, 29 insertions(+), 7 deletions(-)

diff --git a/drivers/mmc/host/litex_mmc.c b/drivers/mmc/host/litex_mmc.c
index 3655542ca998..affdff8621bf 100644
--- a/drivers/mmc/host/litex_mmc.c
+++ b/drivers/mmc/host/litex_mmc.c
@@ -29,6 +29,7 @@
 #define LITEX_PHY_CLOCKERDIV  0x04
 #define LITEX_PHY_INITIALIZE  0x08
 #define LITEX_PHY_WRITESTATUS 0x0C
+#define LITEX_PHY_SETTINGS    0x18
 #define LITEX_CORE_CMDARG     0x00
 #define LITEX_CORE_CMDCMD     0x04
 #define LITEX_CORE_CMDSND     0x08
@@ -72,6 +73,10 @@
 #define SD_INIT_DELAY_US  1000
 #define SD_INIT_CLK_HZ    400000
 
+#define SD_PHY_SPEED_1X 0
+#define SD_PHY_SPEED_4X 1
+#define SD_PHY_SPEED_8X 2
+
 #define SDIRQ_CARD_DETECT    1
 #define SDIRQ_SD_TO_MEM_DONE 2
 #define SDIRQ_MEM_TO_SD_DONE 4
@@ -96,6 +101,8 @@ struct litex_mmc_host {
 	unsigned int ref_clk;
 	unsigned int sd_clk;
 
+	u8 width;
+
 	u32 resp[4];
 	u16 rca;
 
@@ -451,6 +458,24 @@ static void litex_mmc_setclk(struct litex_mmc_host *host, unsigned int freq)
 static void litex_mmc_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
 {
 	struct litex_mmc_host *host = mmc_priv(mmc);
+	unsigned int bus_width = SD_PHY_SPEED_1X;
+
+	switch (ios->bus_width) {
+	case MMC_BUS_WIDTH_1:
+		bus_width = SD_PHY_SPEED_1X;
+		break;
+	case MMC_BUS_WIDTH_4:
+		bus_width = SD_PHY_SPEED_4X;
+		break;
+	case MMC_BUS_WIDTH_8:
+		bus_width = SD_PHY_SPEED_8X;
+		break;
+	}
+
+	if (host->width != ios->bus_width) {
+		litex_write8(host->sdphy + LITEX_PHY_SETTINGS, bus_width);
+		host->width = ios->bus_width;
+	}
 
 	/*
 	 * The SD specification requires at least 74 idle clocks before CMD0.
@@ -463,13 +488,6 @@ static void litex_mmc_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
 		return;
 	}
 
-	/*
-	 * NOTE: Ignore any ios->bus_width updates; they occur right after
-	 * the mmc core sends its own acmd6 bus-width change notification,
-	 * which is redundant since we snoop on the command flow and inject
-	 * an early acmd6 before the first data transfer command is sent!
-	 */
-
 	/* Update sd_clk */
 	if (ios->clock != host->sd_clk)
 		litex_mmc_setclk(host, ios->clock);
@@ -555,6 +573,7 @@ static int litex_mmc_probe(struct platform_device *pdev)
 	 */
 	host->is_bus_width_set = false;
 	host->app_cmd = false;
+	host->width = MMC_BUS_WIDTH_1;
 
 	/* LiteSDCard can support 64-bit DMA addressing */
 	ret = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(64));
@@ -587,6 +606,9 @@ static int litex_mmc_probe(struct platform_device *pdev)
 	litex_write8(host->sdreader + LITEX_BLK2MEM_ENA, 0);
 	litex_write8(host->sdwriter + LITEX_MEM2BLK_ENA, 0);
 
+	/* Ensure the litex is at bus width x1 */
+	litex_write8(host->sdphy + LITEX_PHY_SETTINGS, SD_PHY_SPEED_1X);
+
 	init_completion(&host->cmd_done);
 	ret = litex_mmc_irq_init(pdev, host);
 	if (ret)
-- 
2.54.0