[PATCH 1/3] phy: rockchip-emmc: Allow to set drive impedance via DTS.
From: Christoph Muellner <hidden>
Date: 2019-03-01 15:56:20
Also in:
linux-arm-kernel, linux-rockchip, lkml
Subsystem:
arm/rockchip soc support, generic phy framework, the rest · Maintainers:
Heiko Stuebner, Vinod Koul, Linus Torvalds
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 <redacted> Signed-off-by: Philipp Tomsich <redacted> --- drivers/phy/rockchip/phy-rockchip-emmc.c | 38 ++++++++++++++++++++++++++++++-- 1 file changed, 36 insertions(+), 2 deletions(-)
diff --git a/drivers/phy/rockchip/phy-rockchip-emmc.c b/drivers/phy/rockchip/phy-rockchip-emmc.c
index 19bf84f0bc67..5413fa73dd45 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 +315,28 @@ 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. " + "Falling back to 50 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 +345,7 @@ 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;
@@ -345,6 +369,16 @@ static int rockchip_emmc_phy_probe(struct platform_device *pdev) rk_phy->reg_offset = reg_offset; rk_phy->reg_base = grf; + if (of_property_read_u32(dev->of_node, "drive-impedance-ohm", &val)) { + dev_info(dev, + "Missing drive-impedance-ohm property in node %s " + "Falling back to 50 Ohm.\n", + dev->of_node->name); + rk_phy->drive_impedance = PHYCTRL_DR_50OHM; + } else { + 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)) { dev_err(dev, "failed to create PHY\n");
--
2.11.0