mmc: tegra: Implement HS400 enhanced strobe

Implement eMMC HS400 enhanced strobe. Enhanced strobe is an alternative
mechanism to the HS400 tuning procedure.

Signed-off-by: Aapo Vienamo <avienamo@nvidia.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

diff --git a/drivers/mmc/host/sdhci-tegra.c b/drivers/mmc/host/sdhci-tegra.c
index b102edc..a3f4452 100644 (file)
--- a/drivers/mmc/host/sdhci-tegra.c
+++ b/drivers/mmc/host/sdhci-tegra.c
@@ -43,6 +43,9 @@
 #define SDHCI_CLOCK_CTRL_PADPIPE_CLKEN_OVERRIDE                BIT(3)
 #define SDHCI_CLOCK_CTRL_SPI_MODE_CLKEN_OVERRIDE       BIT(2)
 
+#define SDHCI_TEGRA_VENDOR_SYS_SW_CTRL                 0x104
+#define SDHCI_TEGRA_SYS_SW_CTRL_ENHANCED_STROBE                BIT(31)
+
 #define SDHCI_TEGRA_VENDOR_CAP_OVERRIDES               0x10c
 #define SDHCI_TEGRA_CAP_OVERRIDES_DQS_TRIM_MASK                0x00003f00
 #define SDHCI_TEGRA_CAP_OVERRIDES_DQS_TRIM_SHIFT       8
@@ -294,6 +297,23 @@ static void tegra_sdhci_set_tap(struct sdhci_host *host, unsigned int tap)
        }
 }
 
+static void tegra_sdhci_hs400_enhanced_strobe(struct mmc_host *mmc,
+                                             struct mmc_ios *ios)
+{
+       struct sdhci_host *host = mmc_priv(mmc);
+       u32 val;
+
+       val = sdhci_readl(host, SDHCI_TEGRA_VENDOR_SYS_SW_CTRL);
+
+       if (ios->enhanced_strobe)
+               val |= SDHCI_TEGRA_SYS_SW_CTRL_ENHANCED_STROBE;
+       else
+               val &= ~SDHCI_TEGRA_SYS_SW_CTRL_ENHANCED_STROBE;
+
+       sdhci_writel(host, val, SDHCI_TEGRA_VENDOR_SYS_SW_CTRL);
+
+}
+
 static void tegra_sdhci_reset(struct sdhci_host *host, u8 mask)
 {
        struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
@@ -996,6 +1016,9 @@ static int sdhci_tegra_probe(struct platform_device *pdev)
                                sdhci_tegra_start_signal_voltage_switch;
        }
 
+       host->mmc_host_ops.hs400_enhanced_strobe =
+                       tegra_sdhci_hs400_enhanced_strobe;
+
        rc = mmc_of_parse(host->mmc);
        if (rc)
                goto err_parse_dt;