net: stmmac: restore pinstate in pm resume.

This patch adds code to restore default pinstate of the pins when it
comes back from low power state. Without this patch the state of the
pins would be unknown and the driver would not work.

This patch also adds code to put the pins in to sleep state when the
driver enters low power state.
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@st.com>
Acked-by: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/stmicro/stmmac/stmmac_main.c

@@ -43,6 +43,7 @@
 #include <linux/dma-mapping.h>
 #include <linux/slab.h>
 #include <linux/prefetch.h>
+#include <linux/pinctrl/consumer.h>
 #ifdef CONFIG_STMMAC_DEBUG_FS
 #include <linux/debugfs.h>
 #include <linux/seq_file.h>
@@ -2864,6 +2865,7 @@ int stmmac_suspend(struct net_device *ndev)
 		priv->hw->mac->pmt(priv->ioaddr, priv->wolopts);
 	else {
 		stmmac_set_mac(priv->ioaddr, false);
+		pinctrl_pm_select_sleep_state(priv->device);
 		/* Disable clock in case of PWM is off */
 		clk_disable_unprepare(priv->stmmac_clk);
 	}
@@ -2890,6 +2892,7 @@ int stmmac_resume(struct net_device *ndev)
 	if (device_may_wakeup(priv->device)) {
 		priv->hw->mac->pmt(priv->ioaddr, 0);
 	} else {
+		pinctrl_pm_select_default_state(priv->device);
 		/* enable the clk prevously disabled */
 		clk_prepare_enable(priv->stmmac_clk);
 		/* reset the phy so that it's ready */