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
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>;
};
};
......@@ -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);
......
......@@ -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)
......
......@@ -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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