[PATCH 3/3] mmc: esdhc i.MX: Support 8bit mode

[Sascha Hauer]

The i.MX esdhc has a nonstandard bit layout for the SDHCI_HOST_CONTROL
register. To support 8bit bus width on i.MX populate the platform_bus_width
callback. This is tested on an i.MX25, but should according to the datasheets
work on the other i.MX using this hardware aswell. The i.MX6, while having
a SDHCI_SPEC_300 controller, still uses the same nonstandard register layout.

Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
---
 .../devicetree/bindings/mmc/fsl-imx-esdhc.txt      |    1 +
 arch/arm/plat-mxc/include/mach/esdhc.h             |    1 +
 drivers/mmc/host/sdhci-esdhc-imx.c                 |   56 ++++++++++++++++++--
 3 files changed, 55 insertions(+), 3 deletions(-)

diff --git a/Documentation/devicetree/bindings/mmc/fsl-imx-esdhc.txt b/Documentation/devicetree/bindings/mmc/fsl-imx-esdhc.txt
index 1dd6225..c989994 100644
--- a/Documentation/devicetree/bindings/mmc/fsl-imx-esdhc.txt
+++ b/Documentation/devicetree/bindings/mmc/fsl-imx-esdhc.txt
@@ -12,6 +12,7 @@ Required properties:
 Optional properties:
 - fsl,cd-controller : Indicate to use controller internal card detection
 - fsl,wp-controller : Indicate to use controller internal write protection
+- bus-width : Maximum supported bus width. Defaults to 4 if omitted
 
 Examples:
 
diff --git a/arch/arm/plat-mxc/include/mach/esdhc.h b/arch/arm/plat-mxc/include/mach/esdhc.h
index aaf9748..b4a0521 100644
--- a/arch/arm/plat-mxc/include/mach/esdhc.h
+++ b/arch/arm/plat-mxc/include/mach/esdhc.h
@@ -39,5 +39,6 @@ struct esdhc_platform_data {
 	unsigned int cd_gpio;
 	enum wp_types wp_type;
 	enum cd_types cd_type;
+	int max_bus_width;
 };
 #endif /* __ASM_ARCH_IMX_ESDHC_H */
diff --git a/drivers/mmc/host/sdhci-esdhc-imx.c b/drivers/mmc/host/sdhci-esdhc-imx.c
index 4fe7312..b205fe9 100644
--- a/drivers/mmc/host/sdhci-esdhc-imx.c
+++ b/drivers/mmc/host/sdhci-esdhc-imx.c
@@ -57,6 +57,13 @@
  */
 #define ESDHC_FLAG_MULTIBLK_NO_INT	(1 << 1)
 
+/*
+ * Freescale interpretation of the SDHCI_HOST_CONTROL register
+ */
+#define FSL_SDHCI_CTRL_4BITBUS			(0x1 << 1)
+#define FSL_SDHCI_CTRL_8BITBUS			(0x2 << 1)
+#define FSL_SDHCI_CTRL_BUSWIDTH_MASK		(0x3 << 1)
+
 enum imx_esdhc_type {
 	IMX25_ESDHC,
 	IMX35_ESDHC,
@@ -307,6 +314,7 @@ static void esdhc_writeb_le(struct sdhci_host *host, u8 val, int reg)
 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
 	struct pltfm_imx_data *imx_data = pltfm_host->priv;
 	u32 new_val;
+	u32 mask;
 
 	switch (reg) {
 	case SDHCI_POWER_CONTROL:
@@ -318,7 +326,6 @@ static void esdhc_writeb_le(struct sdhci_host *host, u8 val, int reg)
 	case SDHCI_HOST_CONTROL:
 		/* FSL messed up here, so we can just keep those three */
 		new_val = val & (SDHCI_CTRL_LED | \
-				SDHCI_CTRL_4BITBUS | \
 				SDHCI_CTRL_D3CD);
 		/* ensure the endianess */
 		new_val |= ESDHC_HOST_CONTROL_LE;
@@ -328,7 +335,13 @@ static void esdhc_writeb_le(struct sdhci_host *host, u8 val, int reg)
 			new_val |= (val & SDHCI_CTRL_DMA_MASK) << 5;
 		}
 
-		esdhc_clrset_le(host, 0xffff, new_val, reg);
+		/*
+		 * Do not touch buswidth bits here. This is done in
+		 * esdhc_pltfm_buswidth.
+		 */
+		mask = 0xffff & ~FSL_SDHCI_CTRL_BUSWIDTH_MASK;
+
+		esdhc_clrset_le(host, mask, new_val, reg);
 		return;
 	}
 	esdhc_clrset_le(host, 0xff, val, reg);
@@ -379,6 +392,27 @@ static unsigned int esdhc_pltfm_get_ro(struct sdhci_host *host)
 	return -ENOSYS;
 }
 
+static int esdhc_pltfm_bus_width(struct sdhci_host *host, int width)
+{
+	u32 ctrl;
+
+	switch (width) {
+	case MMC_BUS_WIDTH_8:
+		ctrl = FSL_SDHCI_CTRL_8BITBUS;
+		break;
+	case MMC_BUS_WIDTH_4:
+		ctrl = FSL_SDHCI_CTRL_4BITBUS;
+		break;
+	default:
+		ctrl = 0;
+		break;
+	}
+
+	esdhc_clrset_le(host, FSL_SDHCI_CTRL_BUSWIDTH_MASK, ctrl, SDHCI_HOST_CONTROL);
+
+	return 0;
+}
+
 static struct sdhci_ops sdhci_esdhc_ops = {
 	.read_l = esdhc_readl_le,
 	.read_w = esdhc_readw_le,
@@ -389,6 +423,7 @@ static struct sdhci_ops sdhci_esdhc_ops = {
 	.get_max_clock = esdhc_pltfm_get_max_clock,
 	.get_min_clock = esdhc_pltfm_get_min_clock,
 	.get_ro = esdhc_pltfm_get_ro,
+	.platform_bus_width = esdhc_pltfm_bus_width,
 };
 
 static struct sdhci_pltfm_data sdhci_esdhc_imx_pdata = {
@@ -434,6 +469,8 @@ sdhci_esdhc_imx_probe_dt(struct platform_device *pdev,
 	if (gpio_is_valid(boarddata->wp_gpio))
 		boarddata->wp_type = ESDHC_WP_GPIO;
 
+	of_property_read_u32(np, "bus-width", &boarddata->max_bus_width);
+
 	return 0;
 }
 #else
@@ -507,7 +544,7 @@ static int __devinit sdhci_esdhc_imx_probe(struct platform_device *pdev)
 	if (is_imx25_esdhc(imx_data) || is_imx35_esdhc(imx_data))
 		/* Fix errata ENGcm07207 present on i.MX25 and i.MX35 */
 		host->quirks |= SDHCI_QUIRK_NO_MULTIBLOCK
-			| SDHCI_QUIRK_BROKEN_ADMA;
+			 | SDHCI_QUIRK_BROKEN_ADMA;
 
 	if (is_imx53_esdhc(imx_data))
 		imx_data->flags |= ESDHC_FLAG_MULTIBLK_NO_INT;
@@ -577,6 +614,19 @@ static int __devinit sdhci_esdhc_imx_probe(struct platform_device *pdev)
 		break;
 	}
 
+	switch (boarddata->max_bus_width) {
+	case 8:
+		host->mmc->caps |= MMC_CAP_8_BIT_DATA | MMC_CAP_4_BIT_DATA;
+		break;
+	case 4:
+	default:
+		host->mmc->caps |= MMC_CAP_4_BIT_DATA;
+		break;
+	case 1:
+		host->quirks |= SDHCI_QUIRK_FORCE_1_BIT_DATA;
+		break;
+	}
+
 	err = sdhci_add_host(host);
 	if (err)
 		goto err_add_host;
-- 
1.7.10.4