[PATCH v2 2/3] phylib: add support for reset-gpios

[Sam Ravnborg <sam@ravnborg.org>]

Add minimal support for reset-gpios.

Example DT that uses this:

	mdio {
		#address-cells = <1>;
		#size-cells = <0>;
		reset-gpios = <&pioE 17 GPIO_ACTIVE_LOW>;
		reset-delay-us = <1000>;
		ethphy0: ethernet-phy@1 {
			reg = <3>;
		};
	};

This was required to get the Davicom PHY operational on
my proprietary board.
I added the minimal mdio_reset() calls.

Another options was to use a bus reset, but then
the net/ driver used should have dedicated reset support.

The reset-gpios solution is general and matches the
binding specification in net/mdio.txt

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
---
 drivers/net/phy/mdio_bus.c | 64 ++++++++++++++++++++++++++++++++++++++++++++--
 include/linux/phy.h        |  5 ++++
 2 files changed, 67 insertions(+), 2 deletions(-)

diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
index d209716a1..ad358192d 100644
--- a/drivers/net/phy/mdio_bus.c
+++ b/drivers/net/phy/mdio_bus.c
@@ -17,6 +17,8 @@
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
 #include <common.h>
+#include <of_gpio.h>
+#include <gpio.h>
 #include <driver.h>
 #include <init.h>
 #include <clock.h>
@@ -25,6 +27,8 @@
 #include <linux/phy.h>
 #include <linux/err.h>
 
+#define DEFAULT_GPIO_RESET_DELAY	10 /* us */
+
 LIST_HEAD(mii_bus_list);
 
 int mdiobus_detect(struct device_d *dev)
@@ -83,6 +87,45 @@ static int of_mdiobus_register_phy(struct mii_bus *mdio, struct device_node *chi
 }
 
 /**
+ * of_mdioibus_register_reset - register optional reset-gpios
+ * @mdio: pointer to mii_bus structure
+ * @np: pointer to device_node of MDIO bus.
+ *
+ * Read optional reset-gpios from mido node in DT
+ */
+static void of_mdiobus_register_reset(struct mii_bus *mdio,
+				      struct device_node *np)
+{
+	enum of_gpio_flags of_flags;
+	u32 reset_delay;
+	int gpio;
+
+	if (!np)
+		return;
+
+	reset_delay = DEFAULT_GPIO_RESET_DELAY;
+	of_property_read_u32(np, "reset-delay-us", &reset_delay);
+
+	gpio = of_get_named_gpio_flags(np, "reset-gpios", 0, &of_flags);
+	if (gpio_is_valid(gpio)) {
+		unsigned long flags;
+		char *name;
+
+		name = basprintf("%s-reset", dev_name(&mdio->dev));
+		flags = GPIOF_OUT_INIT_INACTIVE;
+
+		if (of_flags & OF_GPIO_ACTIVE_LOW)
+			flags |= GPIOF_ACTIVE_LOW;
+
+		if (gpio_request_one(gpio, flags, name) >= 0) {
+			mdio->reset_gpio = gpio;
+			mdio->reset_delay = reset_delay;
+		}
+	}
+
+}
+
+/**
  * of_mdiobus_register - Register mii_bus and create PHYs from the device tree
  * @mdio: pointer to mii_bus structure
  * @np: pointer to device_node of MDIO bus.
@@ -96,6 +139,9 @@ static int of_mdiobus_register(struct mii_bus *mdio, struct device_node *np)
 	u32 addr;
 	int ret;
 
+	if (!np)
+		return -ENODEV;
+
 	/* Loop over the child nodes and register a phy_device for each one */
 	for_each_available_child_of_node(np, child) {
 		ret = of_property_read_u32(child, "reg", &addr);
@@ -128,6 +174,7 @@ static int of_mdiobus_register(struct mii_bus *mdio, struct device_node *np)
  */
 int mdiobus_register(struct mii_bus *bus)
 {
+	struct device_node *np;
 	int err;
 
 	if (NULL == bus ||
@@ -147,6 +194,11 @@ int mdiobus_register(struct mii_bus *bus)
 		return -EINVAL;
 	}
 
+	np = bus->dev.device_node;
+
+	of_mdiobus_register_reset(bus, np);
+
+	mdio_reset(bus);
 	if (bus->reset)
 		bus->reset(bus);
 
@@ -154,8 +206,7 @@ int mdiobus_register(struct mii_bus *bus)
 
 	pr_info("%s: probed\n", dev_name(&bus->dev));
 
-	if (bus->dev.device_node)
-		of_mdiobus_register(bus, bus->dev.device_node);
+	of_mdiobus_register(bus, np);
 
 	return 0;
 }
@@ -190,6 +241,15 @@ struct phy_device *mdiobus_scan(struct mii_bus *bus, int addr)
 }
 EXPORT_SYMBOL(mdiobus_scan);
 
+void mdio_reset(const struct mii_bus *bus)
+{
+	if (gpio_is_valid(bus->reset_gpio)) {
+		gpio_set_active(bus->reset_gpio, 1);
+		udelay(bus->reset_delay);
+		gpio_set_active(bus->reset_gpio, 0);
+	}
+}
+EXPORT_SYMBOL(mdio_reset);
 
 /**
  *
diff --git a/include/linux/phy.h b/include/linux/phy.h
index ac750f5c3..a34f5b20f 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -99,6 +99,10 @@ struct mii_bus {
 	/* PHY addresses to be ignored when probing */
 	u32 phy_mask;
 
+	/* Optional reset of all PHY's on the bus */
+	int reset_gpio;
+	int reset_delay;
+
 	struct list_head list;
 
 	bool is_multiplexed;
@@ -108,6 +112,7 @@ struct mii_bus {
 int mdiobus_register(struct mii_bus *bus);
 void mdiobus_unregister(struct mii_bus *bus);
 struct phy_device *mdiobus_scan(struct mii_bus *bus, int addr);
+void mdio_reset(const struct mii_bus *bus);
 
 extern struct list_head mii_bus_list;
 
-- 
2.12.0


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