Commit 69226896 authored by Roger Quadros's avatar Roger Quadros Committed by David S. Miller
Browse files

mdio_bus: Issue GPIO RESET to PHYs. 



Some boards [1] leave the PHYs at an invalid state
during system power-up or reset thus causing unreliability
issues with the PHY which manifests as PHY not being detected
or link not functional. To fix this, these PHYs need to be RESET
via a GPIO connected to the PHY's RESET pin.

Some boards have a single GPIO controlling the PHY RESET pin of all
PHYs on the bus whereas some others have separate GPIOs controlling
individual PHY RESETs.

In both cases, the RESET de-assertion cannot be done in the PHY driver
as the PHY will not probe till its reset is de-asserted.
So do the RESET de-assertion in the MDIO bus driver.

[1] - am572x-idk, am571x-idk, a437x-idk

Signed-off-by: default avatarRoger Quadros <rogerq@ti.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 15769ff8

Documentation/devicetree/bindings/net/mdio.txt

0 → 100644
+33 −0
Original line number Diff line number Diff line 
Common MDIO bus properties.



These are generic properties that can apply to any MDIO bus.



Optional properties:

- reset-gpios: List of one or more GPIOs that control the RESET lines

  of the PHYs on that MDIO bus.

- reset-delay-us: RESET pulse width in microseconds as per PHY datasheet.



A list of child nodes, one per device on the bus is expected. These

should follow the generic phy.txt, or a device specific binding document.



Example :

This example shows these optional properties, plus other properties

required for the TI Davinci MDIO driver.



	davinci_mdio: ethernet@0x5c030000 {

		compatible = "ti,davinci_mdio";

		reg = <0x5c030000 0x1000>;

		#address-cells = <1>;

		#size-cells = <0>;



		reset-gpios = <&gpio2 5 GPIO_ACTIVE_LOW>;

		reset-delay-us = <2>;   /* PHY datasheet states 1us min */



		ethphy0: ethernet-phy@1 {

			reg = <1>;

		};



		ethphy1: ethernet-phy@3 {

			reg = <3>;

		};

	};

drivers/net/phy/mdio_bus.c

+47 −0
Original line number Diff line number Diff line
@@ -22,8 +22,11 @@ 
#include <linux/init.h>

#include <linux/delay.h>

#include <linux/device.h>

#include <linux/gpio.h>

#include <linux/gpio/consumer.h>

#include <linux/of_device.h>

#include <linux/of_mdio.h>

#include <linux/of_gpio.h>

#include <linux/netdevice.h>

#include <linux/etherdevice.h>

#include <linux/skbuff.h>
@@ -337,6 +340,7 @@ int __mdiobus_register(struct mii_bus *bus, struct module *owner) 
{

	struct mdio_device *mdiodev;

	int i, err;

	struct gpio_desc *gpiod;



	if (NULL == bus || NULL == bus->name ||

	    NULL == bus->read || NULL == bus->write)
@@ -363,6 +367,35 @@ int __mdiobus_register(struct mii_bus *bus, struct module *owner) 
	if (bus->reset)

		bus->reset(bus);



	/* de-assert bus level PHY GPIO resets */

	if (bus->num_reset_gpios > 0) {

		bus->reset_gpiod = devm_kcalloc(&bus->dev,

						 bus->num_reset_gpios,

						 sizeof(struct gpio_desc *),

						 GFP_KERNEL);

		if (!bus->reset_gpiod)

			return -ENOMEM;

	}



	for (i = 0; i < bus->num_reset_gpios; i++) {

		gpiod = devm_gpiod_get_index(&bus->dev, "reset", i,

					     GPIOD_OUT_LOW);

		if (IS_ERR(gpiod)) {

			err = PTR_ERR(gpiod);

			if (err != -ENOENT) {

				dev_err(&bus->dev,

					"mii_bus %s couldn't get reset GPIO\n",

					bus->id);

				return err;

			}

		} else {

			bus->reset_gpiod[i] = gpiod;

			gpiod_set_value_cansleep(gpiod, 1);

			udelay(bus->reset_delay_us);

			gpiod_set_value_cansleep(gpiod, 0);

		}

	}



	for (i = 0; i < PHY_MAX_ADDR; i++) {

		if ((bus->phy_mask & (1 << i)) == 0) {

			struct phy_device *phydev;
@@ -390,6 +423,13 @@ error: 
		mdiodev->device_remove(mdiodev);

		mdiodev->device_free(mdiodev);

	}



	/* Put PHYs in RESET to save power */

	for (i = 0; i < bus->num_reset_gpios; i++) {

		if (bus->reset_gpiod[i])

			gpiod_set_value_cansleep(bus->reset_gpiod[i], 1);

	}



	device_del(&bus->dev);

	return err;

}
@@ -411,6 +451,13 @@ void mdiobus_unregister(struct mii_bus *bus) 
		mdiodev->device_remove(mdiodev);

		mdiodev->device_free(mdiodev);

	}



	/* Put PHYs in RESET to save power */

	for (i = 0; i < bus->num_reset_gpios; i++) {

		if (bus->reset_gpiod[i])

			gpiod_set_value_cansleep(bus->reset_gpiod[i], 1);

	}



	device_del(&bus->dev);

}

EXPORT_SYMBOL(mdiobus_unregister);

drivers/of/of_mdio.c

+7 −0
Original line number Diff line number Diff line
@@ -22,6 +22,8 @@ 
#include <linux/of_net.h>

#include <linux/module.h>



#define DEFAULT_GPIO_RESET_DELAY	10	/* in microseconds */



MODULE_AUTHOR("Grant Likely <grant.likely@secretlab.ca>");

MODULE_LICENSE("GPL");
@@ -221,6 +223,11 @@ int of_mdiobus_register(struct mii_bus *mdio, struct device_node *np) 


	mdio->dev.of_node = np;



	/* Get bus level PHY reset GPIO details */

	mdio->reset_delay_us = DEFAULT_GPIO_RESET_DELAY;

	of_property_read_u32(np, "reset-delay-us", &mdio->reset_delay_us);

	mdio->num_reset_gpios = of_gpio_named_count(np, "reset-gpios");



	/* Register the MDIO bus */

	rc = mdiobus_register(mdio);

	if (rc)

include/linux/phy.h

+7 −0
Original line number Diff line number Diff line
@@ -217,6 +217,13 @@ struct mii_bus { 
	 * matching its address

	 */

	int irq[PHY_MAX_ADDR];



	/* GPIO reset pulse width in microseconds */

	int reset_delay_us;

	/* Number of reset GPIOs */

	int num_reset_gpios;

	/* Array of RESET GPIO descriptors */

	struct gpio_desc **reset_gpiod;

};

#define to_mii_bus(d) container_of(d, struct mii_bus, dev)

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