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

---
Changes in version 2:
- reformatted the changelog;
- resolved rejects, refreshed the patch.

Documentation/devicetree/bindings/net/phy.txt | 2 +
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);

@@ -1596,9 +1611,16 @@ 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;
@@ -1612,8 +1634,15 @@ 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 void 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 void of_mdiobus_register_phy(stru
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(phy))
return;

@@ -75,6 +83,9 @@ static void of_mdiobus_register_phy(stru
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);
@@ -92,6 +103,7 @@ static void of_mdiobus_register_device(s
struct device_node *child, u32 addr)
{
struct mdio_device *mdiodev;
+ struct gpio_desc *gpiod;
int rc;

mdiodev = mdio_device_create(mdio, addr);
@@ -104,6 +116,10 @@ static void of_mdiobus_register_device(s
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;

/* Multiple levels of nesting are possible. However typically this is
@@ -37,6 +38,7 @@ 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)

@@ -69,6 +71,7 @@ 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)

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