On 01/03/2019 15:33, Christoph Muellner wrote:
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@xxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Philipp Tomsich <philipp.tomsich@xxxxxxxxxxxxxxxxxxxxx>
---
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);
I think we're aiming to use %pOF for node names now, but here it looks
redundant anyway - dev_info() will already show the device name, which
for an of_platform device is the same thing.
+ rk_phy->drive_impedance = PHYCTRL_DR_50OHM;
+ } else {
+ rk_phy->drive_impedance = convert_drive_impedance_ohm(pdev, val);
+ }
FWIW, if you initialise val to the default (i.e. 50) then you could get
rid of the "else" case and just do the conversion unconditionally.
That's a fairly common idiom for reading optional properties.
Robin.
+
generic_phy = devm_phy_create(dev, dev->of_node, &ops);
if (IS_ERR(generic_phy)) {
dev_err(dev, "failed to create PHY\n");
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