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: Roger Quadros <rogerq@xxxxxx>
---
drivers/net/phy/mdio_bus.c | 26 ++++++++++++++++++++++++++
drivers/of/of_mdio.c | 4 ++++
include/linux/phy.h | 5 +++++
3 files changed, 35 insertions(+)
diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
index fa7d51f..25fda2b 100644
--- a/drivers/net/phy/mdio_bus.c
+++ b/drivers/net/phy/mdio_bus.c
@@ -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>
@@ -43,6 +46,8 @@
#include "mdio-boardinfo.h"
+#define DEFAULT_GPIO_RESET_DELAY 10 /* in microseconds */
+
int mdiobus_register_device(struct mdio_device *mdiodev)
{
if (mdiodev->bus->mdio_map[mdiodev->addr])
@@ -307,6 +312,7 @@ 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)
@@ -333,6 +339,26 @@ int __mdiobus_register(struct mii_bus *bus, struct module *owner)
if (bus->reset)
bus->reset(bus);
+ /* de-assert bus level PHY GPIO resets */
+ 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) {
+ pr_err("mii_bus %s couldn't get reset GPIO\n",
+ bus->id);
+ return err;
+ }
+ } else {
+ gpiod_set_value_cansleep(gpiod, 1);
+ if (!bus->reset_delay_us)
+ bus->reset_delay_us = DEFAULT_GPIO_RESET_DELAY;
+ 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;
diff --git a/drivers/of/of_mdio.c b/drivers/of/of_mdio.c
index 0b29798..83a62e4 100644
--- a/drivers/of/of_mdio.c
+++ b/drivers/of/of_mdio.c
@@ -221,6 +221,10 @@ int of_mdiobus_register(struct mii_bus *mdio, struct device_node *np)
mdio->dev.of_node = np;
+ /* Get bus level PHY reset GPIO details */
+ 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)
diff --git a/include/linux/phy.h b/include/linux/phy.h
index 43a7748..80a6574 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -217,6 +217,11 @@ struct mii_bus {
* matching its address
*/
int irq[PHY_MAX_ADDR];
+
+ /* GPIO reset pulse width in uS */
+ int reset_delay_us;
+ /* Number of reset GPIOs */
+ int num_reset_gpios;
};
#define to_mii_bus(d) container_of(d, struct mii_bus, dev)
--
2.7.4
--
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