phy: rockchip-emmc: output tap delay dt property

Update the rockchip-emmc phy to set the otapdlysec register with
a dt property. This was mentioned from Brian Norris when he sent
the path to set the default value in the driver.
This patch add a dt property 'output-tapdelay-select' u32 and allow
to set the 0x0-0xf. If not set in dts, the old default 0x4 applies.

Tested with our customized rk3399 to tune the eMMC.

Signed-off-by: Chris Ruehl <chris.ruehl@gtsys.com.hk>
Link: https://lore.kernel.org/r/20201202082507.3536-2-chris.ruehl@gtsys.com.hk
Signed-off-by: Vinod Koul <vkoul@kernel.org>

diff --git a/drivers/phy/rockchip/phy-rockchip-emmc.c b/drivers/phy/rockchip/phy-rockchip-emmc.c
index 48e2d75..1e424f2 100644 (file)
--- a/drivers/phy/rockchip/phy-rockchip-emmc.c
+++ b/drivers/phy/rockchip/phy-rockchip-emmc.c
@@ -65,6 +65,8 @@
 #define PHYCTRL_OTAPDLYENA             0x1
 #define PHYCTRL_OTAPDLYENA_MASK                0x1
 #define PHYCTRL_OTAPDLYENA_SHIFT       0xb
+#define PHYCTRL_OTAPDLYSEL_DEFAULT     0x4
+#define PHYCTRL_OTAPDLYSEL_MAXVALUE    0xf
 #define PHYCTRL_OTAPDLYSEL_MASK                0xf
 #define PHYCTRL_OTAPDLYSEL_SHIFT       0x7
 #define PHYCTRL_REN_STRB_DISABLE       0x0
@@ -85,6 +87,7 @@ struct rockchip_emmc_phy {
        struct clk      *emmcclk;
        unsigned int drive_impedance;
        unsigned int enable_strobe_pulldown;
+       unsigned int output_tapdelay_select;
 };
 
 static int rockchip_emmc_phy_power(struct phy *phy, bool on_off)
@@ -296,7 +299,7 @@ static int rockchip_emmc_phy_power_on(struct phy *phy)
        /* Output tap delay */
        regmap_write(rk_phy->reg_base,
                     rk_phy->reg_offset + GRF_EMMCPHY_CON0,
-                    HIWORD_UPDATE(4,
+                    HIWORD_UPDATE(rk_phy->output_tapdelay_select,
                                   PHYCTRL_OTAPDLYSEL_MASK,
                                   PHYCTRL_OTAPDLYSEL_SHIFT));
 
@@ -372,6 +375,7 @@ static int rockchip_emmc_phy_probe(struct platform_device *pdev)
        rk_phy->reg_base = grf;
        rk_phy->drive_impedance = PHYCTRL_DR_50OHM;
        rk_phy->enable_strobe_pulldown = PHYCTRL_REN_STRB_DISABLE;
+       rk_phy->output_tapdelay_select = PHYCTRL_OTAPDLYSEL_DEFAULT;
 
        if (!of_property_read_u32(dev->of_node, "drive-impedance-ohm", &val))
                rk_phy->drive_impedance = convert_drive_impedance_ohm(pdev, val);
@@ -379,6 +383,13 @@ static int rockchip_emmc_phy_probe(struct platform_device *pdev)
        if (of_property_read_bool(dev->of_node, "enable-strobe-pulldown"))
                rk_phy->enable_strobe_pulldown = PHYCTRL_REN_STRB_ENABLE;
 
+       if (!of_property_read_u32(dev->of_node, "output-tapdelay-select", &val)) {
+               if (val <= PHYCTRL_OTAPDLYSEL_MAXVALUE)
+                       rk_phy->output_tapdelay_select = val;
+               else
+                       dev_err(dev, "output-tapdelay-select exceeds limit, apply default\n");
+       }
+
        generic_phy = devm_phy_create(dev, dev->of_node, &ops);
        if (IS_ERR(generic_phy)) {
                dev_err(dev, "failed to create PHY\n");