mmc: tegra: Set calibration pad voltage reference

Configure the voltage reference used by the automatic pad drive strength
calibration procedure. The value is a magic number from the TRM.
Signed-off-by: Aapo Vienamo <avienamo@nvidia.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/sdhci-tegra.c

@@ -51,6 +51,10 @@
 #define SDHCI_AUTO_CAL_START				BIT(31)
 #define SDHCI_AUTO_CAL_ENABLE				BIT(29)
 
+#define SDHCI_TEGRA_SDMEM_COMP_PADCTRL			0x1e0
+#define SDHCI_TEGRA_SDMEM_COMP_PADCTRL_VREF_SEL_MASK	0x0000000f
+#define SDHCI_TEGRA_SDMEM_COMP_PADCTRL_VREF_SEL_VAL	0x7
+
 #define SDHCI_TEGRA_AUTO_CAL_STATUS			0x1ec
 #define SDHCI_TEGRA_AUTO_CAL_ACTIVE			BIT(31)
 
@@ -187,7 +191,7 @@ static void tegra_sdhci_reset(struct sdhci_host *host, u8 mask)
 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
 	struct sdhci_tegra *tegra_host = sdhci_pltfm_priv(pltfm_host);
 	const struct sdhci_tegra_soc_data *soc_data = tegra_host->soc_data;
-	u32 misc_ctrl, clk_ctrl;
+	u32 misc_ctrl, clk_ctrl, pad_ctrl;
 
 	sdhci_reset(host, mask);
 
@@ -222,8 +226,14 @@ static void tegra_sdhci_reset(struct sdhci_host *host, u8 mask)
 	sdhci_writel(host, misc_ctrl, SDHCI_TEGRA_VENDOR_MISC_CTRL);
 	sdhci_writel(host, clk_ctrl, SDHCI_TEGRA_VENDOR_CLOCK_CTRL);
 
-	if (soc_data->nvquirks & NVQUIRK_HAS_PADCALIB)
+	if (soc_data->nvquirks & NVQUIRK_HAS_PADCALIB) {
+		pad_ctrl = sdhci_readl(host, SDHCI_TEGRA_SDMEM_COMP_PADCTRL);
+		pad_ctrl &= ~SDHCI_TEGRA_SDMEM_COMP_PADCTRL_VREF_SEL_MASK;
+		pad_ctrl |= SDHCI_TEGRA_SDMEM_COMP_PADCTRL_VREF_SEL_VAL;
+		sdhci_writel(host, pad_ctrl, SDHCI_TEGRA_SDMEM_COMP_PADCTRL);
+
 		tegra_host->pad_calib_required = true;
+	}
 
 	tegra_host->ddr_signaling = false;
 }