[PATCH v2 1/2] net: mdio: Handle bus level GPIO Reset

[Roger Quadros]

Some platforms have bus level Reset controlled
by a GPIO line. If available then handle bus reset
via GPIO.

Signed-off-by: Roger Quadros <rog...@kernel.org>
---
Changelog:
v2:
- Fix build if DM_GPIO not set
- Fix build on platforms that don't have <asm/gpio.h>
  by using <asm-generic/gpio.h>
---
 include/phy.h     |  7 +++++++
 net/mdio-uclass.c | 37 ++++++++++++++++++++++++++++++++++++-
 2 files changed, 43 insertions(+), 1 deletion(-)

diff --git a/include/phy.h b/include/phy.h
index e02cbdb58c..ae23814bbf 100644
--- a/include/phy.h
+++ b/include/phy.h
@@ -9,6 +9,7 @@
 #ifndef _PHY_H
 #define _PHY_H
 
+#include <asm-generic/gpio.h>
 #include <log.h>
 #include <phy_interface.h>
 #include <dm/ofnode.h>
@@ -76,6 +77,12 @@ struct mii_dev {
        int (*reset)(struct mii_dev *bus);
        struct phy_device *phymap[PHY_MAX_ADDR];
        u32 phy_mask;
+       /** @reset_delay_us: Bus GPIO reset pulse width in microseconds */
+       int reset_delay_us;
+       /** @reset_post_delay_us: Bus GPIO reset deassert delay in microseconds 
*/
+       int reset_post_delay_us;
+       /** @reset_gpiod: Bus Reset GPIO descriptor pointer */
+       struct gpio_desc reset_gpiod;
 };
 
 /* struct phy_driver: a structure which defines PHY behavior
diff --git a/net/mdio-uclass.c b/net/mdio-uclass.c
index e758cc66d7..6fc7034111 100644
--- a/net/mdio-uclass.c
+++ b/net/mdio-uclass.c
@@ -14,6 +14,9 @@
 #include <dm/of_extra.h>
 #include <dm/uclass-internal.h>
 #include <linux/compat.h>
+#include <linux/delay.h>
+
+#define DEFAULT_GPIO_RESET_DELAY       10      /* in microseconds */
 
 void dm_mdio_probe_devices(void)
 {
@@ -80,6 +83,16 @@ int dm_mdio_write(struct udevice *mdio_dev, int addr, int 
devad, int reg,
 int dm_mdio_reset(struct udevice *mdio_dev)
 {
        struct mdio_ops *ops = mdio_get_ops(mdio_dev);
+       struct mdio_perdev_priv *pdata = dev_get_uclass_priv(mdio_dev);
+       struct mii_dev *mii_bus = pdata->mii_bus;
+
+       if (CONFIG_IS_ENABLED(DM_GPIO) && 
dm_gpio_is_valid(&mii_bus->reset_gpiod)) {
+               dm_gpio_set_value(&mii_bus->reset_gpiod, 1);
+               udelay(mii_bus->reset_delay_us);
+               dm_gpio_set_value(&mii_bus->reset_gpiod, 0);
+               if (mii_bus->reset_post_delay_us > 0)
+                       udelay(mii_bus->reset_post_delay_us);
+       }
 
        if (!ops->reset)
                return 0;
@@ -111,14 +124,36 @@ static int mdio_reset(struct mii_dev *mii_bus)
 static int dm_mdio_post_probe(struct udevice *dev)
 {
        struct mdio_perdev_priv *pdata = dev_get_uclass_priv(dev);
+       struct mii_dev *mii_bus;
+       int ret;
 
-       pdata->mii_bus = mdio_alloc();
+       mii_bus = mdio_alloc();
+       if (!mii_bus) {
+               dev_err(dev, "couldn't allocate mii_bus\n");
+               return -ENOMEM;
+       }
+       pdata->mii_bus = mii_bus;
        pdata->mii_bus->read = mdio_read;
        pdata->mii_bus->write = mdio_write;
        pdata->mii_bus->reset = mdio_reset;
        pdata->mii_bus->priv = dev;
        strlcpy(pdata->mii_bus->name, dev->name, MDIO_NAME_LEN);
 
+       if (IS_ENABLED(CONFIG_DM_GPIO)) {
+               /* Get bus level PHY reset GPIO details */
+               mii_bus->reset_delay_us = dev_read_u32_default(dev, 
"reset-delay-us",
+                                                              
DEFAULT_GPIO_RESET_DELAY);
+               mii_bus->reset_post_delay_us = dev_read_u32_default(dev,
+                                                                   
"reset-post-delay-us",
+                                                                   0);
+               ret = gpio_request_by_name(dev, "reset-gpios", 0, 
&mii_bus->reset_gpiod,
+                                          GPIOD_IS_OUT | GPIOD_IS_OUT_ACTIVE);
+               if (ret && ret != -ENOENT) {
+                       dev_err(dev, "couldn't get reset-gpios: %d\n", ret);
+                       return ret;
+               }
+       }
+
        return mdio_register(pdata->mii_bus);
 }
 

-- 
2.34.1