dt:net:stmmac: Add dt specific phy reset callback support.

This patch adds phy reset callback support for stmmac driver via device
trees. It adds three new properties to gmac device tree bindings to
define the reset signal via gpio.

With this patch users can conveniently pass reset gpio number with pre,
pulse and post delay in micro secs via DTs.

 active low:
		_________		 ____________
	<pre-delay>	|<pulse-delay>	|<post-delay>
		 	|		|
		 	|_______________|

 active high:
 			 ________________
	<pre-delay>	|<pulse-delay>	|<post-delay>
			|		|
		________|		|___________

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@st.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 56 insertions, 2 deletions

diff --git a/Documentation/devicetree/bindings/net/stmmac.txt b/Documentation/devicetree/bindings/net/stmmac.txt
index e1ddfcc46a4e..261c563b5f06 100644
--- a/Documentation/devicetree/bindings/net/stmmac.txt
+++ b/Documentation/devicetree/bindings/net/stmmac.txt
@@ -13,6 +13,12 @@ Required properties:
 - phy-mode: String, operation mode of the PHY interface.
   Supported values are: "mii", "rmii", "gmii", "rgmii".
 - snps,phy-addr         phy address to connect to.
+- snps,reset-gpio       gpio number for phy reset.
+- snps,reset-active-low boolean flag to indicate if phy reset is active low.
+- snps,reset-delays-us  is triplet of delays
+        The 1st cell is reset pre-delay in micro seconds.
+        The 2nd cell is reset pulse in micro seconds.
+        The 3rd cell is reset post-delay in micro seconds.
 - snps,pbl              Programmable Burst Length
 - snps,fixed-burst      Program the DMA to use the fixed burst mode
 - snps,mixed-burst      Program the DMA to use the mixed burst mode
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c
index cc15039eaa47..fe7bc9903867 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c
@@ -27,6 +27,9 @@
 #include <linux/mii.h>
 #include <linux/phy.h>
 #include <linux/slab.h>
+#include <linux/of.h>
+#include <linux/of_gpio.h>
+
 #include <asm/io.h>
 
 #include "stmmac.h"
@@ -131,10 +134,46 @@ static int stmmac_mdio_reset(struct mii_bus *bus)
         struct net_device *ndev = bus->priv;
         struct stmmac_priv *priv = netdev_priv(ndev);
         unsigned int mii_address = priv->hw->mii.addr;
+        struct stmmac_mdio_bus_data *data = priv->plat->mdio_bus_data;
+
+#ifdef CONFIG_OF
+        if (priv->device->of_node) {
+                int reset_gpio, active_low;
+
+                if (data->reset_gpio < 0) {
+                        struct device_node *np = priv->device->of_node;
+                        if (!np)
+                                return 0;
+
+                        data->reset_gpio = of_get_named_gpio(np,
+                                                "snps,reset-gpio", 0);
+                        if (data->reset_gpio < 0)
+                                return 0;
+
+                        data->active_low = of_property_read_bool(np,
+                                                "snps,reset-active-low");
+                        of_property_read_u32_array(np,
+                                "snps,reset-delays-us", data->delays, 3);
+                }
+
+                reset_gpio = data->reset_gpio;
+                active_low = data->active_low;
+
+                if (!gpio_request(reset_gpio, "mdio-reset")) {
+                        gpio_direction_output(reset_gpio, active_low ? 1 : 0);
+                        udelay(data->delays[0]);
+                        gpio_set_value(reset_gpio, active_low ? 0 : 1);
+                        udelay(data->delays[1]);
+                        gpio_set_value(reset_gpio, active_low ? 1 : 0);
+                        udelay(data->delays[2]);
+                        gpio_free(reset_gpio);
+                }
+        }
+#endif
 
-        if (priv->plat->mdio_bus_data->phy_reset) {
+        if (data->phy_reset) {
                 pr_debug("stmmac_mdio_reset: calling phy_reset\n");
-                priv->plat->mdio_bus_data->phy_reset(priv->plat->bsp_priv);
+                data->phy_reset(priv->plat->bsp_priv);
         }
 
         /* This is a workaround for problems with the STE101P PHY.
@@ -172,6 +211,11 @@ int stmmac_mdio_register(struct net_device *ndev)
         else
                 irqlist = priv->mii_irq;
 
+#ifdef CONFIG_OF
+        if (priv->device->of_node)
+                mdio_bus_data->reset_gpio = -1;
+#endif
+
         new_bus->name = "stmmac";
         new_bus->read = &stmmac_mdio_read;
         new_bus->write = &stmmac_mdio_write;
diff --git a/include/linux/stmmac.h b/include/linux/stmmac.h
index c1b3ed3fb787..9e495d31516e 100644
--- a/include/linux/stmmac.h
+++ b/include/linux/stmmac.h
@@ -80,6 +80,10 @@ struct stmmac_mdio_bus_data {
         unsigned int phy_mask;
         int *irqs;
         int probed_phy_irq;
+#ifdef CONFIG_OF
+        int reset_gpio, active_low;
+        u32 delays[3];
+#endif
 };
 
 struct stmmac_dma_cfg {