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Subject[PATCH v4.1] phylib: Add device reset GPIO support
Date
From: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>

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 -- it made use of the reset GPIO for its own purposes...

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Acked-by: Rob Herring <robh@kernel.org>
[geert: Propagate actual errors from fwnode_get_named_gpiod()]
[geert: Avoid destroying initial setup]
[geert: Consolidate GPIO descriptor acquiring code]
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
v4.1:
- Fix uninitialized variable in mdiobus_register_device(),

v4:
- Remove Florian's Acked-by,
- Add missing #include <linux/gpio/consumer.h>,
- Re-add the gpiod check, as the dummy gpiod_set_value() for !GPIOLIB
does not ignore NULL, and calls WARN_ON(1),
- Do not reassert the reset signal if {mdio,phy}_probe() or
phy_device_register() succeeded, as that may destroy initial setup,
- Do not deassert the reset signal in {mdio,phy}_remove(), as it
should already be deasserted,
- Bring the PHY back into reset state in phy_device_remove(),
- Move/consolidate GPIO descriptor acquiring code from
of_mdiobus_register_phy() and of_mdiobus_register_device() to
mdiobus_register_device().
Note that this changes behavior slightly, in that the reset signal
is now also asserted when called from of_mdiobus_register_device().

v3:
- Fix fwnode_get_named_gpiod() call due to added parameters (which
allowed to eliminate the gpiod_direction_output() call),
- Undelete one blank line in the AT803x driver,
- Resolve rejects, refresh patch,
- Reword/reformat changelog,
- Take over from Sergei,
- Add Acked-by,
- Remove unneeded gpiod check, as gpiod_set_value() handles NULL fine,
- Handle fwnode_get_named_gpiod() errors correctly:
- -ENOENT is ignored (the GPIO is optional), and turned into NULL,
which allowed to remove all later !IS_ERR() checks,
- Other errors (incl. -EPROBE_DEFER) are propagated [*],

v2:
- Reformat changelog,
- Resolve rejects, refresh patch.
---
Documentation/devicetree/bindings/net/phy.txt | 2 ++
drivers/net/phy/at803x.c | 18 +++------------
drivers/net/phy/mdio_bus.c | 21 ++++++++++++++++++
drivers/net/phy/mdio_device.c | 25 +++++++++++++++++++--
drivers/net/phy/phy_device.c | 32 +++++++++++++++++++++++++--
include/linux/mdio.h | 3 +++
include/linux/phy.h | 5 +++++
7 files changed, 87 insertions(+), 19 deletions(-)

diff --git a/Documentation/devicetree/bindings/net/phy.txt b/Documentation/devicetree/bindings/net/phy.txt
index 77d0b2a61ffa96fc..c05479f5ac7cc837 100644
--- a/Documentation/devicetree/bindings/net/phy.txt
+++ b/Documentation/devicetree/bindings/net/phy.txt
@@ -53,6 +53,8 @@ Optional Properties:
to ensure the integrated PHY is used. The absence of this property indicates
the muxers should be configured so that the external PHY is used.

+- reset-gpios: The GPIO phandle and specifier for the PHY reset signal.
+
Example:

ethernet-phy@0 {
diff --git a/drivers/net/phy/at803x.c b/drivers/net/phy/at803x.c
index de7dd6566df7a364..29da7a3c7a3761c0 100644
--- a/drivers/net/phy/at803x.c
+++ b/drivers/net/phy/at803x.c
@@ -71,7 +71,6 @@ MODULE_LICENSE("GPL");

struct at803x_priv {
bool phy_reset:1;
- struct gpio_desc *gpiod_reset;
};

struct at803x_context {
@@ -254,22 +253,11 @@ static int at803x_probe(struct phy_device *phydev)
{
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;
@@ -343,14 +331,14 @@ static void at803x_link_change_notify(struct phy_device *phydev)
* cannot recover from by software.
*/
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);
diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
index 2df7b62c1a36811e..8f8b7747c54bc478 100644
--- a/drivers/net/phy/mdio_bus.c
+++ b/drivers/net/phy/mdio_bus.c
@@ -38,6 +38,7 @@
#include <linux/phy.h>
#include <linux/io.h>
#include <linux/uaccess.h>
+#include <linux/gpio/consumer.h>

#include <asm/irq.h>

@@ -48,9 +49,26 @@

int mdiobus_register_device(struct mdio_device *mdiodev)
{
+ struct gpio_desc *gpiod = NULL;
+
if (mdiodev->bus->mdio_map[mdiodev->addr])
return -EBUSY;

+ /* Deassert the optional reset signal */
+ if (mdiodev->dev.of_node)
+ gpiod = fwnode_get_named_gpiod(&mdiodev->dev.of_node->fwnode,
+ "reset-gpios", 0, GPIOD_OUT_LOW,
+ "PHY reset");
+ if (PTR_ERR(gpiod) == -ENOENT)
+ gpiod = NULL;
+ else if (IS_ERR(gpiod))
+ return PTR_ERR(gpiod);
+
+ mdiodev->reset = gpiod;
+
+ /* Assert the reset signal again */
+ mdio_device_reset(mdiodev, 1);
+
mdiodev->bus->mdio_map[mdiodev->addr] = mdiodev;

return 0;
@@ -420,6 +438,9 @@ void mdiobus_unregister(struct mii_bus *bus)
if (!mdiodev)
continue;

+ if (mdiodev->reset)
+ gpiod_put(mdiodev->reset);
+
mdiodev->device_remove(mdiodev);
mdiodev->device_free(mdiodev);
}
diff --git a/drivers/net/phy/mdio_device.c b/drivers/net/phy/mdio_device.c
index e24f28924af8953d..75d97dd9fb281704 100644
--- a/drivers/net/phy/mdio_device.c
+++ b/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>
@@ -114,6 +116,13 @@ void mdio_device_remove(struct mdio_device *mdiodev)
}
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
@@ -128,8 +137,16 @@ 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);
+ if (err) {
+ /* Assert the reset signal */
+ mdio_device_reset(mdiodev, 1);
+ }
+ }

return err;
}
@@ -140,9 +157,13 @@ static int mdio_remove(struct device *dev)
struct device_driver *drv = mdiodev->dev.driver;
struct mdio_driver *mdiodrv = to_mdio_driver(drv);

- if (mdiodrv->remove)
+ if (mdiodrv->remove) {
mdiodrv->remove(mdiodev);

+ /* Assert the reset signal */
+ mdio_device_reset(mdiodev, 1);
+ }
+
return 0;
}

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 8154fb706751e8ad..1de5e242b8b4cda3 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -632,6 +632,9 @@ int phy_device_register(struct phy_device *phydev)
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) {
@@ -650,6 +653,9 @@ int phy_device_register(struct phy_device *phydev)
return 0;

out:
+ /* Assert the reset signal */
+ phy_device_reset(phydev, 1);
+
mdiobus_unregister_device(&phydev->mdio);
return err;
}
@@ -666,6 +672,10 @@ EXPORT_SYMBOL(phy_device_register);
void phy_device_remove(struct phy_device *phydev)
{
device_del(&phydev->mdio.dev);
+
+ /* Assert the reset signal */
+ phy_device_reset(phydev, 1);
+
mdiobus_unregister_device(&phydev->mdio);
}
EXPORT_SYMBOL(phy_device_remove);
@@ -849,6 +859,9 @@ int phy_init_hw(struct phy_device *phydev)
{
int ret = 0;

+ /* Deassert the reset signal */
+ phy_device_reset(phydev, 0);
+
if (!phydev->drv || !phydev->drv->config_init)
return 0;

@@ -1126,6 +1139,9 @@ void phy_detach(struct phy_device *phydev)
put_device(&phydev->mdio.dev);
if (ndev_owner != bus->owner)
module_put(bus->owner);
+
+ /* Assert the reset signal */
+ phy_device_reset(phydev, 1);
}
EXPORT_SYMBOL(phy_detach);

@@ -1811,8 +1827,16 @@ 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);
+ if (err) {
+ /* Assert the reset signal */
+ phy_device_reset(phydev, 1);
+ }
+ }

mutex_unlock(&phydev->lock);

@@ -1829,8 +1853,12 @@ static int phy_remove(struct device *dev)
phydev->state = PHY_DOWN;
mutex_unlock(&phydev->lock);

- if (phydev->drv && phydev->drv->remove)
+ if (phydev->drv && phydev->drv->remove) {
phydev->drv->remove(phydev);
+
+ /* Assert the reset signal */
+ phy_device_reset(phydev, 1);
+ }
phydev->drv = NULL;

return 0;
diff --git a/include/linux/mdio.h b/include/linux/mdio.h
index ca08ab16ecdc9b78..92d4e55ffe675637 100644
--- a/include/linux/mdio.h
+++ b/include/linux/mdio.h
@@ -12,6 +12,7 @@
#include <uapi/linux/mdio.h>
#include <linux/mod_devicetable.h>

+struct gpio_desc;
struct mii_bus;

/* Multiple levels of nesting are possible. However typically this is
@@ -39,6 +40,7 @@ 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)

@@ -71,6 +73,7 @@ void mdio_device_free(struct mdio_device *mdiodev);
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);
int mdio_device_bus_match(struct device *dev, struct device_driver *drv);
diff --git a/include/linux/phy.h b/include/linux/phy.h
index 4962af37722ac2ea..6106ed915841c97e 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -841,6 +841,11 @@ int phy_aneg_done(struct phy_device *phydev);
int phy_stop_interrupts(struct phy_device *phydev);
int phy_restart_aneg(struct phy_device *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)

--
2.7.4
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