[PATCH] net: dsa: ksz: Add reset GPIO handling

[Marek Vasut]

Add code to handle optional reset GPIO in the KSZ switch driver. The switch
has a reset GPIO line which can be controlled by the CPU, so make sure it is
configured correctly in such setups.

Signed-off-by: Marek Vasut <ma...@denx.de>
Cc: Vivien Didelot <vivien.dide...@savoirfairelinux.com>
Cc: Woojung Huh <woojung....@microchip.com>
Cc: David S. Miller <da...@davemloft.net>
Cc: Tristram Ha <tristram...@microchip.com>
---
 drivers/net/dsa/microchip/ksz_common.c | 26 ++++++++++++++++++++++++++
 drivers/net/dsa/microchip/ksz_priv.h   |  2 ++
 2 files changed, 28 insertions(+)

diff --git a/drivers/net/dsa/microchip/ksz_common.c 
b/drivers/net/dsa/microchip/ksz_common.c
index 9705808c3af7a..1f50b31722958 100644
--- a/drivers/net/dsa/microchip/ksz_common.c
+++ b/drivers/net/dsa/microchip/ksz_common.c
@@ -8,12 +8,14 @@
 #include <linux/delay.h>
 #include <linux/export.h>
 #include <linux/gpio.h>
+#include <linux/gpio/consumer.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/platform_data/microchip-ksz.h>
 #include <linux/phy.h>
 #include <linux/etherdevice.h>
 #include <linux/if_bridge.h>
+#include <linux/of_gpio.h>
 #include <linux/of_net.h>
 #include <net/dsa.h>
 #include <net/switchdev.h>
@@ -289,11 +291,31 @@ EXPORT_SYMBOL(ksz_switch_alloc);
 int ksz_switch_register(struct ksz_device *dev,
                        const struct ksz_dev_ops *ops)
 {
+       struct device_node *np = dev->dev->of_node;
+       enum of_gpio_flags reset_gpio_flags;
+       unsigned long flags;
+       int reset_gpio;
        int ret;
 
        if (dev->pdata)
                dev->chip_id = dev->pdata->chip_id;
 
+       dev->reset_gpio = -1;
+       reset_gpio = of_get_named_gpio_flags(np, "reset-gpios", 0,
+                                            &reset_gpio_flags);
+       if (reset_gpio >= 0) {
+               flags = (reset_gpio_flags == OF_GPIO_ACTIVE_LOW) ?
+                       GPIOF_ACTIVE_LOW : 0;
+               ret = devm_gpio_request_one(dev->dev, reset_gpio, flags,
+                                           "switch-reset");
+               if (ret) {
+                       dev_err(dev->dev, "failed to get reset-gpios: %d\n", 
ret);
+                       return -EIO;
+               }
+               dev->reset_gpio = reset_gpio;
+               gpiod_set_value(gpio_to_desc(reset_gpio), 0);
+       }
+
        mutex_init(&dev->reg_mutex);
        mutex_init(&dev->stats_mutex);
        mutex_init(&dev->alu_mutex);
@@ -329,6 +351,10 @@ void ksz_switch_remove(struct ksz_device *dev)
 {
        dev->dev_ops->exit(dev);
        dsa_unregister_switch(dev->ds);
+
+       if (dev->reset_gpio >= 0)
+               gpiod_set_value(gpio_to_desc(dev->reset_gpio), 1);
+
 }
 EXPORT_SYMBOL(ksz_switch_remove);
 
diff --git a/drivers/net/dsa/microchip/ksz_priv.h 
b/drivers/net/dsa/microchip/ksz_priv.h
index a38ff0841ed4e..6dd2ebfd6e12f 100644
--- a/drivers/net/dsa/microchip/ksz_priv.h
+++ b/drivers/net/dsa/microchip/ksz_priv.h
@@ -59,6 +59,8 @@ struct ksz_device {
 
        void *priv;
 
+       int reset_gpio;                 /* Optional reset GPIO */
+
        /* chip specific data */
        u32 chip_id;
        int num_vlans;
-- 
2.18.0