[PATCH v3 1/4] phy: rockchip-emmc: Allow to set drive impedance via DTS.

Christoph Muellner
2019-03-22T11:34:50Z

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>
---
drivers/phy/rockchip/phy-rockchip-emmc.c | 30 ++++++++++++++++++++++++++++--
1 file changed, 28 insertions(+), 2 deletions(-)

diff --git a/drivers/phy/rockchip/phy-rockchip-emmc.c b/drivers/phy/rockchip/phy-rockchip-emmc.c
index 19bf84f0bc67..b804c6bf4b55 100644
--- 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)) {
--
2.11.0