phy: rockchip-emmc: Allow to set drive impedance via DTS.

The rockchip-emmc PHY can be configured with different
drive impedance values. Currenlty a value of 50 Ohm is
hard coded into the driver.

This patch introduces the DTS property 'drive-impedance-ohm'
for the rockchip-emmc phy node, which uses the value from the DTS
to setup the drive impedance accordingly.

Signed-off-by: Christoph Muellner <christoph.muellner@theobroma-systems.com>
Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>

diff --git a/drivers/phy/rockchip/phy-rockchip-emmc.c b/drivers/phy/rockchip/phy-rockchip-emmc.c
index 19bf84f0bc67265c0318b4d9d8a7d853c6903975..b804c6bf4b5550ddbd9143bff2c52dca1cab36f0 100644 (file)
--- a/drivers/phy/rockchip/phy-rockchip-emmc.c
+++ b/drivers/phy/rockchip/phy-rockchip-emmc.c
@@ -87,6 +87,7 @@ struct rockchip_emmc_phy {
        unsigned int    reg_offset;
        struct regmap   *reg_base;
        struct clk      *emmcclk;
+       unsigned int drive_impedance;
 };
 
 static int rockchip_emmc_phy_power(struct phy *phy, bool on_off)
@@ -281,10 +282,10 @@ static int rockchip_emmc_phy_power_on(struct phy *phy)
 {
        struct rockchip_emmc_phy *rk_phy = phy_get_drvdata(phy);
 
-       /* Drive impedance: 50 Ohm */
+       /* Drive impedance: from DTS */
        regmap_write(rk_phy->reg_base,
                     rk_phy->reg_offset + GRF_EMMCPHY_CON6,
-                    HIWORD_UPDATE(PHYCTRL_DR_50OHM,
+                    HIWORD_UPDATE(rk_phy->drive_impedance,
                                   PHYCTRL_DR_MASK,
                                   PHYCTRL_DR_SHIFT));
 
@@ -314,6 +315,26 @@ static const struct phy_ops ops = {
        .owner          = THIS_MODULE,
 };
 
+static u32 convert_drive_impedance_ohm(struct platform_device *pdev, u32 dr_ohm)
+{
+       switch (dr_ohm) {
+       case 100:
+               return PHYCTRL_DR_100OHM;
+       case 66:
+               return PHYCTRL_DR_66OHM;
+       case 50:
+               return PHYCTRL_DR_50OHM;
+       case 40:
+               return PHYCTRL_DR_40OHM;
+       case 33:
+               return PHYCTRL_DR_33OHM;
+       }
+
+       dev_warn(&pdev->dev, "Invalid value %u for drive-impedance-ohm.\n",
+                dr_ohm);
+       return PHYCTRL_DR_50OHM;
+}
+
 static int rockchip_emmc_phy_probe(struct platform_device *pdev)
 {
        struct device *dev = &pdev->dev;
@@ -322,6 +343,7 @@ static int rockchip_emmc_phy_probe(struct platform_device *pdev)
        struct phy_provider *phy_provider;
        struct regmap *grf;
        unsigned int reg_offset;
+       u32 val;
 
        if (!dev->parent || !dev->parent->of_node)
                return -ENODEV;
@@ -344,6 +366,10 @@ static int rockchip_emmc_phy_probe(struct platform_device *pdev)
 
        rk_phy->reg_offset = reg_offset;
        rk_phy->reg_base = grf;
+       rk_phy->drive_impedance = PHYCTRL_DR_50OHM;
+
+       if (!of_property_read_u32(dev->of_node, "drive-impedance-ohm", &val))
+               rk_phy->drive_impedance = convert_drive_impedance_ohm(pdev, val);
 
        generic_phy = devm_phy_create(dev, dev->of_node, &ops);
        if (IS_ERR(generic_phy)) {