rockchip: sdhci: Add HS400 Enhanced Strobe support for RK3399

On RK3399, a register bit must be set to enable Enhanced Strobe.
Let the Rockchip SDHCI driver set it when Enhanced Strobe configuration
is requested. However, having it set makes the lower-speed modes stop
working and makes reinitialization fail, so let it be unset as needed in
set_control_reg().

This is mostly ported from Linux's Arasan SDHCI driver which happens
to be the underlying IP. (drivers/mmc/host/sdhci-of-arasan.c in Linux
tree).

Signed-off-by: Alper Nebi Yasak <alpernebiyasak@gmail.com>
Reviewed-by: Jaehoon Chung <jh80.chung@samsung.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>

diff --git a/drivers/mmc/rockchip_sdhci.c b/drivers/mmc/rockchip_sdhci.c
index b91df05de4ffd4a67bc0b0404c479728b137dba0..f4d5a59036a22457ab9f25f68d4f6b998be1739f 100644 (file)
--- a/drivers/mmc/rockchip_sdhci.c
+++ b/drivers/mmc/rockchip_sdhci.c
@@ -42,6 +42,9 @@
        ((((x) >> PHYCTRL_DLLRDY_SHIFT) & PHYCTRL_DLLRDY_MASK) ==\
        PHYCTRL_DLLRDY_DONE)
 
+#define ARASAN_VENDOR_REGISTER         0x78
+#define ARASAN_VENDOR_ENHANCED_STROBE  BIT(0)
+
 /* Rockchip specific Registers */
 #define DWCMSHC_EMMC_DLL_CTRL          0x800
 #define DWCMSHC_EMMC_DLL_CTRL_RESET    BIT(1)
@@ -117,6 +120,19 @@ struct sdhci_data {
         * Return: 0 if successful, -ve on error
         */
        int (*set_ios_post)(struct sdhci_host *host);
+
+       /**
+        * set_enhanced_strobe() - Set HS400 Enhanced Strobe config
+        *
+        * This is the set_enhanced_strobe() SDHCI operation that should
+        * be used for the hardware this driver data is associated with.
+        * Normally, this is used to set any host-specific configuration
+        * necessary for HS400 ES.
+        *
+        * @host: SDHCI host structure
+        * Return: 0 if successful, -ve on error
+        */
+       int (*set_enhanced_strobe)(struct sdhci_host *host);
 };
 
 static int rk3399_emmc_phy_init(struct udevice *dev)
@@ -206,6 +222,21 @@ static int rk3399_emmc_get_phy(struct udevice *dev)
        return 0;
 }
 
+static int rk3399_sdhci_set_enhanced_strobe(struct sdhci_host *host)
+{
+       struct mmc *mmc = host->mmc;
+       u32 vendor;
+
+       vendor = sdhci_readl(host, ARASAN_VENDOR_REGISTER);
+       if (mmc->selected_mode == MMC_HS_400_ES)
+               vendor |= ARASAN_VENDOR_ENHANCED_STROBE;
+       else
+               vendor &= ~ARASAN_VENDOR_ENHANCED_STROBE;
+       sdhci_writel(host, vendor, ARASAN_VENDOR_REGISTER);
+
+       return 0;
+}
+
 static void rk3399_sdhci_set_control_reg(struct sdhci_host *host)
 {
        struct rockchip_sdhc *priv = container_of(host, struct rockchip_sdhc, host);
@@ -217,6 +248,15 @@ static void rk3399_sdhci_set_control_reg(struct sdhci_host *host)
                rk3399_emmc_phy_power_off(priv->phy);
 
        sdhci_set_control_reg(host);
+
+       /*
+        * Reinitializing the device tries to set it to lower-speed modes
+        * first, which fails if the Enhanced Strobe bit is set, making
+        * the device impossible to use. Set the correct value here to
+        * let reinitialization attempts succeed.
+        */
+       if (CONFIG_IS_ENABLED(MMC_HS400_ES_SUPPORT))
+               rk3399_sdhci_set_enhanced_strobe(host);
 };
 
 static int rk3399_sdhci_set_ios_post(struct sdhci_host *host)
@@ -409,10 +449,22 @@ static int rockchip_sdhci_execute_tuning(struct mmc *mmc, u8 opcode)
        return ret;
 }
 
+static int rockchip_sdhci_set_enhanced_strobe(struct sdhci_host *host)
+{
+       struct rockchip_sdhc *priv = container_of(host, struct rockchip_sdhc, host);
+       struct sdhci_data *data = (struct sdhci_data *)dev_get_driver_data(priv->dev);
+
+       if (data->set_enhanced_strobe)
+               return data->set_enhanced_strobe(host);
+
+       return -ENOTSUPP;
+}
+
 static struct sdhci_ops rockchip_sdhci_ops = {
        .set_ios_post   = rockchip_sdhci_set_ios_post,
        .platform_execute_tuning = &rockchip_sdhci_execute_tuning,
        .set_control_reg = rockchip_sdhci_set_control_reg,
+       .set_enhanced_strobe = rockchip_sdhci_set_enhanced_strobe,
 };
 
 static int rockchip_sdhci_probe(struct udevice *dev)
@@ -495,6 +547,7 @@ static const struct sdhci_data rk3399_data = {
        .emmc_phy_init = rk3399_emmc_phy_init,
        .set_control_reg = rk3399_sdhci_set_control_reg,
        .set_ios_post = rk3399_sdhci_set_ios_post,
+       .set_enhanced_strobe = rk3399_sdhci_set_enhanced_strobe,
 };
 
 static const struct sdhci_data rk3568_data = {