[PATCH 2/5] net: phy: mxl-gpy: add MxL86211C MDIO I/O regulator

[Robert Marko]

The MxL86211C can configure its MDIO, MDC, and MDINT pads for
1.8 V or 3.3 V signaling through VSPEC1_PM_CTRL.MDIO_VOL.

MxL86211C is a bit weird in the sense that it power the MDIO pins via
the VDPP pad, so you must provide it with 1.8V or 3.3V there.

However, it does not automatically configure the VSPEC1_PM_CTRL.MDIO_VOL
bit and defaults to 3.3V, so if you are using 1.8V in order to have
reliable MDIO communication you must set that bit.

So, model the MDIO I/O voltage setting as a regulator.

Signed-off-by: Robert Marko <robert.marko@xxxxxxxxxx>
---
 drivers/net/phy/Kconfig   |  1 +
 drivers/net/phy/mxl-gpy.c | 74 ++++++++++++++++++++++++++++++++++++++-
 2 files changed, 74 insertions(+), 1 deletion(-)

diff --git a/drivers/net/phy/Kconfig b/drivers/net/phy/Kconfig
index d3835597e3795..bdaee0cb4829d 100644
--- a/drivers/net/phy/Kconfig
+++ b/drivers/net/phy/Kconfig
@@ -302,6 +302,7 @@ config MAXLINEAR_GPHY
 	tristate "Maxlinear Ethernet PHYs"
 	select POLYNOMIAL if HWMON
 	depends on HWMON || HWMON=n
+	depends on REGULATOR
 	help
 	  Support for the Maxlinear GPY115, GPY211, GPY212, GPY215,
 	  GPY241, GPY245 PHYs.
diff --git a/drivers/net/phy/mxl-gpy.c b/drivers/net/phy/mxl-gpy.c
index 089a1a9e5bc61..4cbbfae046317 100644
--- a/drivers/net/phy/mxl-gpy.c
+++ b/drivers/net/phy/mxl-gpy.c
@@ -14,6 +14,8 @@
 #include <linux/polynomial.h>
 #include <linux/property.h>
 #include <linux/netdevice.h>
+#include <linux/regulator/driver.h>
+#include <linux/of.h>
 
 /* PHY ID */
 #define PHY_ID_GPYx15B_MASK	0xFFFFFFFC
@@ -110,6 +112,10 @@
 #define VSPEC1_SGMII_ANEN_ANRS	(VSPEC1_SGMII_CTRL_ANEN | \
 				 VSPEC1_SGMII_CTRL_ANRS)
 
+/* Packet Manager Control */
+#define VSPEC1_PM_CTRL		0x0c
+#define VSPEC1_PM_CTRL_MDIO_VOL	BIT(14)
+
 /* Temperature sensor */
 #define VSPEC1_TEMP_STA	0x0E
 #define VSPEC1_TEMP_STA_DATA	GENMASK(9, 0)
@@ -390,6 +396,72 @@ static int gpy_probe(struct phy_device *phydev)
 	return 0;
 }
 
+static int mxl86211c_mdio_reg_set_voltage_sel(struct regulator_dev *rdev,
+					      unsigned int selector)
+{
+	struct phy_device *phydev = rdev_get_drvdata(rdev);
+
+	return phy_modify_mmd(phydev, MDIO_MMD_VEND1, VSPEC1_PM_CTRL,
+			      VSPEC1_PM_CTRL_MDIO_VOL,
+			      selector ? 0 : VSPEC1_PM_CTRL_MDIO_VOL);
+}
+
+static int mxl86211c_mdio_reg_get_voltage_sel(struct regulator_dev *rdev)
+{
+	struct phy_device *phydev = rdev_get_drvdata(rdev);
+	int val;
+
+	val = phy_read_mmd(phydev, MDIO_MMD_VEND1, VSPEC1_PM_CTRL);
+	if (val < 0)
+		return val;
+
+	return (val & VSPEC1_PM_CTRL_MDIO_VOL) ? 0 : 1;
+}
+
+static const struct regulator_ops mxl86211c_mdio_regulator_ops = {
+	.list_voltage = regulator_list_voltage_table,
+	.set_voltage_sel = mxl86211c_mdio_reg_set_voltage_sel,
+	.get_voltage_sel = mxl86211c_mdio_reg_get_voltage_sel,
+};
+
+static const unsigned int mxl86211c_mdio_voltage_table[] = {
+	1800000,
+	3300000,
+};
+
+static const struct regulator_desc mxl86211c_mdio_desc = {
+	.name = "mdio",
+	.of_match = of_match_ptr("mdio-regulator"),
+	.n_voltages = ARRAY_SIZE(mxl86211c_mdio_voltage_table),
+	.volt_table = mxl86211c_mdio_voltage_table,
+	.ops = &mxl86211c_mdio_regulator_ops,
+	.type = REGULATOR_VOLTAGE,
+	.owner = THIS_MODULE,
+};
+
+static int mxl86211c_probe(struct phy_device *phydev)
+{
+	struct device *dev = &phydev->mdio.dev;
+	struct regulator_config config = { };
+	struct regulator_dev *rdev;
+	int ret;
+
+	ret = gpy_probe(phydev);
+	if (ret)
+		return ret;
+
+	config.dev = dev;
+	config.driver_data = phydev;
+
+	rdev = devm_regulator_register(dev, &mxl86211c_mdio_desc, &config);
+	if (IS_ERR(rdev)) {
+		phydev_err(phydev, "failed to register MDIO regulator\n");
+		return PTR_ERR(rdev);
+	}
+
+	return 0;
+}
+
 static bool gpy_sgmii_need_reaneg(struct phy_device *phydev)
 {
 	struct gpy_priv *priv = phydev->priv;
@@ -1406,7 +1478,7 @@ static struct phy_driver gpy_drivers[] = {
 		.name		= "Maxlinear Ethernet MxL86211C",
 		.get_features	= genphy_c45_pma_read_abilities,
 		.config_init	= gpy21x_config_init,
-		.probe		= gpy_probe,
+		.probe		= mxl86211c_probe,
 		.inband_caps	= gpy_inband_caps,
 		.config_inband	= gpy_config_inband,
 		.suspend	= genphy_suspend,
-- 
2.55.0