[PATCH 1/2] phy: rockchip: set pulldown for strobe line in dts

[Chris Ruehl]

This patch add support to set the internal pulldown via dt property
and allow simplify the board design for the trace from emmc-phy to
the eMMC chipset.
Default to not set the pull-down.

This patch was inspired from the 4.4 tree of the
Rockchip SDK, where it is enabled unconditional.
The patch had been tested with our rk3399 customized board.

Signed-off-by: Chris Ruehl <chris.ru...@gtsys.com.hk>
---
 drivers/phy/rockchip/phy-rockchip-emmc.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/phy/rockchip/phy-rockchip-emmc.c 
b/drivers/phy/rockchip/phy-rockchip-emmc.c
index 2dc19ddd120f..d9bc45828f74 100644
--- a/drivers/phy/rockchip/phy-rockchip-emmc.c
+++ b/drivers/phy/rockchip/phy-rockchip-emmc.c
@@ -67,6 +67,10 @@
 #define PHYCTRL_OTAPDLYENA_SHIFT       0xb
 #define PHYCTRL_OTAPDLYSEL_MASK                0xf
 #define PHYCTRL_OTAPDLYSEL_SHIFT       0x7
+#define PHYCTRL_REN_STRB_DISABLE       0x0
+#define PHYCTRL_REN_STRB_ENABLE        0x1
+#define PHYCTRL_REN_STRB_MASK  0x1
+#define PHYCTRL_REN_STRB_SHIFT 0x9
 
 #define PHYCTRL_IS_CALDONE(x) \
        ((((x) >> PHYCTRL_CALDONE_SHIFT) & \
@@ -80,6 +84,7 @@ struct rockchip_emmc_phy {
        struct regmap   *reg_base;
        struct clk      *emmcclk;
        unsigned int drive_impedance;
+       unsigned int enable_strobe_pulldown;
 };
 
 static int rockchip_emmc_phy_power(struct phy *phy, bool on_off)
@@ -295,6 +300,13 @@ static int rockchip_emmc_phy_power_on(struct phy *phy)
                                   PHYCTRL_OTAPDLYSEL_MASK,
                                   PHYCTRL_OTAPDLYSEL_SHIFT));
 
+       /* Internal pull-down for strobe line */
+       regmap_write(rk_phy->reg_base,
+                       rk_phy->reg_offset + GRF_EMMCPHY_CON2,
+                       HIWORD_UPDATE(rk_phy->enable_strobe_pulldown,
+                               PHYCTRL_REN_STRB_MASK,
+                               PHYCTRL_REN_STRB_SHIFT));
+
        /* Power up emmc phy analog blocks */
        return rockchip_emmc_phy_power(phy, PHYCTRL_PDB_PWR_ON);
 }
@@ -359,10 +371,14 @@ 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;
+       rk_phy->enable_strobe_pulldown = PHYCTRL_REN_STRB_DISABLE;
 
        if (!of_property_read_u32(dev->of_node, "drive-impedance-ohm", &val))
                rk_phy->drive_impedance = convert_drive_impedance_ohm(pdev, 
val);
 
+       if (of_property_read_bool(dev->of_node, "enable-strobe-pulldown"))
+               rk_phy->enable_strobe_pulldown = PHYCTRL_REN_STRB_ENABLE;
+
        generic_phy = devm_phy_create(dev, dev->of_node, &ops);
        if (IS_ERR(generic_phy)) {
                dev_err(dev, "failed to create PHY\n");
-- 
2.20.1