[PATCH RFT 1/2] phylib: add device reset GPIO support

[Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>]

The PHY  devices sometimes do have their reset signal (maybe even power
supply?) tied to some GPIO and sometimes it also does happen that a boot
loader does not leave it deasserted. So far this issue has been attacked
from (as I believe) a wrong angle: by teaching the MAC driver to manipulate
the GPIO in question;  that solution, when  applied to the device trees,
led to adding the PHY reset GPIO properties to the MAC device node, with
one exception: Cadence MACB driver which could handle the "reset-gpios"
prop  in a PHY device  subnode.  I believe that the correct approach is to
teach the 'phylib' to get the MDIO device reset GPIO from the device tree
node corresponding to this device -- which this patch is doing...

Note that I had to modify the  AT803x PHY driver as it would stop working
otherwise as it made use of the reset GPIO for its own purposes...

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>

---
 Documentation/devicetree/bindings/net/phy.txt |    2 +
 drivers/net/phy/at803x.c                      |   19 ++------------
 drivers/net/phy/mdio_bus.c                    |    4 +++
 drivers/net/phy/mdio_device.c                 |   27 +++++++++++++++++++--
 drivers/net/phy/phy_device.c                  |   33 ++++++++++++++++++++++++--
 drivers/of/of_mdio.c                          |   16 ++++++++++++
 include/linux/mdio.h                          |    3 ++
 include/linux/phy.h                           |    5 +++
 8 files changed, 89 insertions(+), 20 deletions(-)

Index: net-next/Documentation/devicetree/bindings/net/phy.txt
===================================================================
--- net-next.orig/Documentation/devicetree/bindings/net/phy.txt
+++ net-next/Documentation/devicetree/bindings/net/phy.txt
@@ -35,6 +35,8 @@ Optional Properties:
 - broken-turn-around: If set, indicates the PHY device does not correctly
   release the turn around line low at the end of a MDIO transaction.
 
+- reset-gpios: The GPIO phandle and specifier for the PHY reset signal.
+
 Example:
 
 ethernet-phy@0 {
Index: net-next/drivers/net/phy/at803x.c
===================================================================
--- net-next.orig/drivers/net/phy/at803x.c
+++ net-next/drivers/net/phy/at803x.c
@@ -65,7 +65,6 @@ MODULE_LICENSE("GPL");
 
 struct at803x_priv {
 	bool phy_reset:1;
-	struct gpio_desc *gpiod_reset;
 };
 
 struct at803x_context {
@@ -271,22 +270,10 @@ static int at803x_probe(struct phy_devic
 {
 	struct device *dev = &phydev->mdio.dev;
 	struct at803x_priv *priv;
-	struct gpio_desc *gpiod_reset;
 
 	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 	if (!priv)
 		return -ENOMEM;
-
-	if (phydev->drv->phy_id != ATH8030_PHY_ID)
-		goto does_not_require_reset_workaround;
-
-	gpiod_reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW);
-	if (IS_ERR(gpiod_reset))
-		return PTR_ERR(gpiod_reset);
-
-	priv->gpiod_reset = gpiod_reset;
-
-does_not_require_reset_workaround:
 	phydev->priv = priv;
 
 	return 0;
@@ -361,14 +348,14 @@ static void at803x_link_change_notify(st
 	 */
 	if (phydev->drv->phy_id == ATH8030_PHY_ID) {
 		if (phydev->state == PHY_NOLINK) {
-			if (priv->gpiod_reset && !priv->phy_reset) {
+			if (phydev->mdio.reset && !priv->phy_reset) {
 				struct at803x_context context;
 
 				at803x_context_save(phydev, &context);
 
-				gpiod_set_value(priv->gpiod_reset, 1);
+				phy_device_reset(phydev, 1);
 				msleep(1);
-				gpiod_set_value(priv->gpiod_reset, 0);
+				phy_device_reset(phydev, 0);
 				msleep(1);
 
 				at803x_context_restore(phydev, &context);
Index: net-next/drivers/net/phy/mdio_bus.c
===================================================================
--- net-next.orig/drivers/net/phy/mdio_bus.c
+++ net-next/drivers/net/phy/mdio_bus.c
@@ -35,6 +35,7 @@
 #include <linux/phy.h>
 #include <linux/io.h>
 #include <linux/uaccess.h>
+#include <linux/gpio/consumer.h>
 
 #include <asm/irq.h>
 
@@ -371,6 +372,9 @@ void mdiobus_unregister(struct mii_bus *
 		if (!mdiodev)
 			continue;
 
+		if (mdiodev->reset)
+			gpiod_put(mdiodev->reset);
+
 		mdiodev->device_remove(mdiodev);
 		mdiodev->device_free(mdiodev);
 	}
Index: net-next/drivers/net/phy/mdio_device.c
===================================================================
--- net-next.orig/drivers/net/phy/mdio_device.c
+++ net-next/drivers/net/phy/mdio_device.c
@@ -12,6 +12,8 @@
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
 #include <linux/errno.h>
+#include <linux/gpio.h>
+#include <linux/gpio/consumer.h>
 #include <linux/init.h>
 #include <linux/interrupt.h>
 #include <linux/kernel.h>
@@ -103,6 +105,13 @@ void mdio_device_remove(struct mdio_devi
 }
 EXPORT_SYMBOL(mdio_device_remove);
 
+void mdio_device_reset(struct mdio_device *mdiodev, int value)
+{
+	if (mdiodev->reset)
+		gpiod_set_value(mdiodev->reset, value);
+}
+EXPORT_SYMBOL(mdio_device_reset);
+
 /**
  * mdio_probe - probe an MDIO device
  * @dev: device to probe
@@ -117,9 +126,16 @@ static int mdio_probe(struct device *dev
 	struct mdio_driver *mdiodrv = to_mdio_driver(drv);
 	int err = 0;
 
-	if (mdiodrv->probe)
+	if (mdiodrv->probe) {
+		/* Deassert the reset signal */
+		mdio_device_reset(mdiodev, 0);
+
 		err = mdiodrv->probe(mdiodev);
 
+		/* Assert the reset signal */
+		mdio_device_reset(mdiodev, 1);
+	}
+
 	return err;
 }
 
@@ -129,9 +145,16 @@ static int mdio_remove(struct device *de
 	struct device_driver *drv = mdiodev->dev.driver;
 	struct mdio_driver *mdiodrv = to_mdio_driver(drv);
 
-	if (mdiodrv->remove)
+	if (mdiodrv->remove) {
+		/* Deassert the reset signal */
+		mdio_device_reset(mdiodev, 0);
+
 		mdiodrv->remove(mdiodev);
 
+		/* Assert the reset signal */
+		mdio_device_reset(mdiodev, 1);
+	}
+
 	return 0;
 }
 
Index: net-next/drivers/net/phy/phy_device.c
===================================================================
--- net-next.orig/drivers/net/phy/phy_device.c
+++ net-next/drivers/net/phy/phy_device.c
@@ -589,6 +589,9 @@ int phy_device_register(struct phy_devic
 	if (err)
 		return err;
 
+	/* Deassert the reset signal */
+	phy_device_reset(phydev, 0);
+
 	/* Run all of the fixups for this PHY */
 	err = phy_scan_fixups(phydev);
 	if (err) {
@@ -604,9 +607,15 @@ int phy_device_register(struct phy_devic
 		goto out;
 	}
 
+	/* Assert the reset signal */
+	phy_device_reset(phydev, 1);
+
 	return 0;
 
  out:
+	/* Assert the reset signal */
+	phy_device_reset(phydev, 1);
+
 	mdiobus_unregister_device(&phydev->mdio);
 	return err;
 }
@@ -792,6 +801,9 @@ int phy_init_hw(struct phy_device *phyde
 {
 	int ret = 0;
 
+	/* Deassert the reset signal */
+	phy_device_reset(phydev, 0);
+
 	if (!phydev->drv || !phydev->drv->config_init)
 		return 0;
 
@@ -997,6 +1009,9 @@ void phy_detach(struct phy_device *phyde
 
 	put_device(&phydev->mdio.dev);
 	module_put(bus->owner);
+
+	/* Assert the reset signal */
+	phy_device_reset(phydev, 1);
 }
 EXPORT_SYMBOL(phy_detach);
 
@@ -1595,9 +1610,16 @@ static int phy_probe(struct device *dev)
 	/* Set the state to READY by default */
 	phydev->state = PHY_READY;
 
-	if (phydev->drv->probe)
+	if (phydev->drv->probe) {
+		/* Deassert the reset signal */
+		phy_device_reset(phydev, 0);
+
 		err = phydev->drv->probe(phydev);
 
+		/* Assert the reset signal */
+		phy_device_reset(phydev, 1);
+	}
+
 	mutex_unlock(&phydev->lock);
 
 	return err;
@@ -1611,8 +1633,15 @@ static int phy_remove(struct device *dev
 	phydev->state = PHY_DOWN;
 	mutex_unlock(&phydev->lock);
 
-	if (phydev->drv->remove)
+	if (phydev->drv->remove) {
+		/* Deassert the reset signal */
+		phy_device_reset(phydev, 0);
+
 		phydev->drv->remove(phydev);
+
+		/* Assert the reset signal */
+		phy_device_reset(phydev, 1);
+	}
 	phydev->drv = NULL;
 
 	return 0;
Index: net-next/drivers/of/of_mdio.c
===================================================================
--- net-next.orig/drivers/of/of_mdio.c
+++ net-next/drivers/of/of_mdio.c
@@ -44,6 +44,7 @@ static int of_get_phy_id(struct device_n
 static int of_mdiobus_register_phy(struct mii_bus *mdio, struct device_node *child,
 				   u32 addr)
 {
+	struct gpio_desc *gpiod;
 	struct phy_device *phy;
 	bool is_c45;
 	int rc;
@@ -52,10 +53,17 @@ static int of_mdiobus_register_phy(struc
 	is_c45 = of_device_is_compatible(child,
 					 "ethernet-phy-ieee802.3-c45");
 
+	gpiod = fwnode_get_named_gpiod(&child->fwnode, "reset-gpios");
+	/* Deassert the reset signal */
+	if (!IS_ERR(gpiod))
+		gpiod_direction_output(gpiod, 0);
 	if (!is_c45 && !of_get_phy_id(child, &phy_id))
 		phy = phy_device_create(mdio, addr, phy_id, 0, NULL);
 	else
 		phy = get_phy_device(mdio, addr, is_c45);
+	/* Assert the reset signal again */
+	if (!IS_ERR(gpiod))
+		gpiod_set_value(gpiod, 1);
 	if (IS_ERR_OR_NULL(phy))
 		return 1;
 
@@ -75,6 +83,9 @@ static int of_mdiobus_register_phy(struc
 	of_node_get(child);
 	phy->mdio.dev.of_node = child;
 
+	if (!IS_ERR(gpiod))
+		phy->mdio.reset = gpiod;
+
 	/* All data is now stored in the phy struct;
 	 * register it */
 	rc = phy_device_register(phy);
@@ -95,6 +106,7 @@ static int of_mdiobus_register_device(st
 				      u32 addr)
 {
 	struct mdio_device *mdiodev;
+	struct gpio_desc *gpiod;
 	int rc;
 
 	mdiodev = mdio_device_create(mdio, addr);
@@ -107,6 +119,10 @@ static int of_mdiobus_register_device(st
 	of_node_get(child);
 	mdiodev->dev.of_node = child;
 
+	gpiod = fwnode_get_named_gpiod(&child->fwnode, "reset-gpios");
+	if (!IS_ERR(gpiod))
+		mdiodev->reset = gpiod;
+
 	/* All data is now stored in the mdiodev struct; register it. */
 	rc = mdio_device_register(mdiodev);
 	if (rc) {
Index: net-next/include/linux/mdio.h
===================================================================
--- net-next.orig/include/linux/mdio.h
+++ net-next/include/linux/mdio.h
@@ -11,6 +11,7 @@
 
 #include <uapi/linux/mdio.h>
 
+struct gpio_desc;
 struct mii_bus;
 
 struct mdio_device {
@@ -26,6 +27,7 @@ struct mdio_device {
 	/* Bus address of the MDIO device (0-31) */
 	int addr;
 	int flags;
+	struct gpio_desc *reset;
 };
 #define to_mdio_device(d) container_of(d, struct mdio_device, dev)
 
@@ -58,6 +60,7 @@ void mdio_device_free(struct mdio_device
 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_driver_register(struct mdio_driver *drv);
 void mdio_driver_unregister(struct mdio_driver *drv);
 
Index: net-next/include/linux/phy.h
===================================================================
--- net-next.orig/include/linux/phy.h
+++ net-next/include/linux/phy.h
@@ -769,6 +769,11 @@ static inline int phy_read_status(struct
 	return phydev->drv->read_status(phydev);
 }
 
+static inline void phy_device_reset(struct phy_device *phydev, int value)
+{
+	mdio_device_reset(&phydev->mdio, value);
+}
+
 #define phydev_err(_phydev, format, args...)	\
 	dev_err(&_phydev->mdio.dev, format, ##args)