[PATCH 13/15] net: phy: mdio: add support for PHY supply regulator

[Bartosz Golaszewski <brgl@bgdev.pl>]

From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

Currently many MAC drivers control the regulator supplying the PHY but
this is conceptually wrong. The regulator should be defined as a property
of the PHY node on the MDIO bus and controlled by the MDIO sub-system.

Add support for an optional PHY regulator which will be enabled before
optional deasserting of the reset signal.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
---
 drivers/net/phy/mdio_bus.c    | 21 ++++++++++++++++++++
 drivers/net/phy/mdio_device.c | 36 +++++++++++++++++++++++++++++++++++
 include/linux/mdio.h          |  3 +++
 3 files changed, 60 insertions(+)

diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
index 53e2fb0be7b9..19f0b9664fe3 100644
--- a/drivers/net/phy/mdio_bus.c
+++ b/drivers/net/phy/mdio_bus.c
@@ -27,6 +27,7 @@
 #include <linux/of_gpio.h>
 #include <linux/of_mdio.h>
 #include <linux/phy.h>
+#include <linux/regulator/consumer.h>
 #include <linux/reset.h>
 #include <linux/skbuff.h>
 #include <linux/slab.h>
@@ -67,6 +68,22 @@ static int mdiobus_register_reset(struct mdio_device *mdiodev)
 	return 0;
 }
 
+static int mdiobus_register_regulator(struct mdio_device *mdiodev)
+{
+	struct regulator *phy_supply;
+
+	phy_supply = regulator_get_optional(&mdiodev->dev, "phy");
+	if (IS_ERR(phy_supply)) {
+		if (PTR_ERR(phy_supply) == -EPROBE_DEFER)
+			return -EPROBE_DEFER;
+		phy_supply = NULL;
+	}
+
+	mdiodev->phy_supply = phy_supply;
+
+	return 0;
+}
+
 int mdiobus_register_device(struct mdio_device *mdiodev)
 {
 	int err;
@@ -83,6 +100,10 @@ int mdiobus_register_device(struct mdio_device *mdiodev)
 		if (err)
 			return err;
 
+		err = mdiobus_register_regulator(mdiodev);
+		if (err)
+			return err;
+
 		/* Assert the reset signal */
 		mdio_device_reset(mdiodev, 1);
 	}
diff --git a/drivers/net/phy/mdio_device.c b/drivers/net/phy/mdio_device.c
index be615504b829..0f698d7a770b 100644
--- a/drivers/net/phy/mdio_device.c
+++ b/drivers/net/phy/mdio_device.c
@@ -17,6 +17,7 @@
 #include <linux/mii.h>
 #include <linux/module.h>
 #include <linux/phy.h>
+#include <linux/regulator/consumer.h>
 #include <linux/reset.h>
 #include <linux/slab.h>
 #include <linux/string.h>
@@ -136,6 +137,32 @@ void mdio_device_reset(struct mdio_device *mdiodev, int value)
 }
 EXPORT_SYMBOL(mdio_device_reset);
 
+int mdio_device_power_on(struct mdio_device *mdiodev)
+{
+	int ret = 0;
+
+	if (mdiodev->phy_supply)
+		/* TODO We may need a delay here just like reset_assert_delay
+		 * but since no user currently needs it, I'm not adding it just
+		 * yet.
+		 */
+		ret = regulator_enable(mdiodev->phy_supply);
+
+	return ret;
+}
+EXPORT_SYMBOL(mdio_device_power_on);
+
+int mdio_device_power_off(struct mdio_device *mdiodev)
+{
+	int ret = 0;
+
+	if (mdiodev->phy_supply)
+		ret = regulator_disable(mdiodev->phy_supply);
+
+	return ret;
+}
+EXPORT_SYMBOL(mdio_device_power_off);
+
 /**
  * mdio_probe - probe an MDIO device
  * @dev: device to probe
@@ -150,6 +177,11 @@ static int mdio_probe(struct device *dev)
 	struct mdio_driver *mdiodrv = to_mdio_driver(drv);
 	int err = 0;
 
+	/* Enable the power supply */
+	err = mdio_device_power_on(mdiodev);
+	if (err)
+		return err;
+
 	/* Deassert the reset signal */
 	mdio_device_reset(mdiodev, 0);
 
@@ -158,6 +190,8 @@ static int mdio_probe(struct device *dev)
 		if (err) {
 			/* Assert the reset signal */
 			mdio_device_reset(mdiodev, 1);
+			/* Disable the power supply */
+			mdio_device_power_off(mdiodev);
 		}
 	}
 
@@ -175,6 +209,8 @@ static int mdio_remove(struct device *dev)
 
 	/* Assert the reset signal */
 	mdio_device_reset(mdiodev, 1);
+	/* Disable the power supply */
+	mdio_device_power_off(mdiodev);
 
 	return 0;
 }
diff --git a/include/linux/mdio.h b/include/linux/mdio.h
index 9ac5e7ff6156..0ae07365a6ca 100644
--- a/include/linux/mdio.h
+++ b/include/linux/mdio.h
@@ -46,6 +46,7 @@ struct mdio_device {
 	int flags;
 	struct gpio_desc *reset_gpio;
 	struct reset_control *reset_ctrl;
+	struct regulator *phy_supply;
 	unsigned int reset_assert_delay;
 	unsigned int reset_deassert_delay;
 };
@@ -92,6 +93,8 @@ struct mdio_device *mdio_device_create(struct mii_bus *bus, int addr);
 int mdio_device_register(struct mdio_device *mdiodev);
 void mdio_device_remove(struct mdio_device *mdiodev);
 void mdio_device_reset(struct mdio_device *mdiodev, int value);
+int mdio_device_power_on(struct mdio_device *mdiodev);
+int mdio_device_power_off(struct mdio_device *mdiodev);
 int mdio_driver_register(struct mdio_driver *drv);
 void mdio_driver_unregister(struct mdio_driver *drv);
 int mdio_device_bus_match(struct device *dev, struct device_driver *drv);
-- 
2.26.1