stmmac: add clk management support

this patch adds the way to enable/disable the MAC
clock when call the open/close and resume/restore
functions.
This has been tested on ST platforms and SPEAr; thanks
to Francesco and Deepak.

Signed-off-by: Deepak Sikri <deepak.sikri@st.com>
Tested-by: Francesco Virlinzi <francesco.virlinzi@st.com>
Signed-off-by: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/stmicro/stmmac/stmmac.h

@@ -22,6 +22,8 @@
 
 #define STMMAC_RESOURCE_NAME   "stmmaceth"
 #define DRV_MODULE_VERSION	"Feb_2012"
+
+#include <linux/clk.h>
 #include <linux/stmmac.h>
 #include <linux/phy.h>
 #include "common.h"
@@ -79,6 +81,9 @@ struct stmmac_priv {
 	struct stmmac_counters mmc;
 	struct dma_features dma_cap;
 	int hw_cap_support;
+#ifdef CONFIG_HAVE_CLK
+	struct clk *stmmac_clk;
+#endif
 };
 
 extern int phyaddr;
@@ -97,3 +102,41 @@ int stmmac_dvr_remove(struct net_device *ndev);
 struct stmmac_priv *stmmac_dvr_probe(struct device *device,
 				     struct plat_stmmacenet_data *plat_dat,
 				     void __iomem *addr);
+
+#ifdef CONFIG_HAVE_CLK
+static inline int stmmac_clk_enable(struct stmmac_priv *priv)
+{
+	if (priv->stmmac_clk)
+		return clk_enable(priv->stmmac_clk);
+
+	return 0;
+}
+
+static inline void stmmac_clk_disable(struct stmmac_priv *priv)
+{
+	if (priv->stmmac_clk)
+		clk_disable(priv->stmmac_clk);
+}
+static inline int stmmac_clk_get(struct stmmac_priv *priv)
+{
+	priv->stmmac_clk = clk_get(priv->device, NULL);
+
+	if (IS_ERR(priv->stmmac_clk)) {
+		pr_err("%s: ERROR clk_get failed\n", __func__);
+		return PTR_ERR(priv->stmmac_clk);
+	}
+	return 0;
+}
+#else
+static inline int stmmac_clk_enable(struct stmmac_priv *priv)
+{
+	return 0;
+}
+static inline void stmmac_clk_disable(struct stmmac_priv *priv)
+{
+}
+static inline int stmmac_clk_get(struct stmmac_priv *priv)
+{
+	return 0;
+}
+#endif /* CONFIG_HAVE_CLK */

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

@@ -904,6 +904,8 @@ static int stmmac_open(struct net_device *dev)
 	struct stmmac_priv *priv = netdev_priv(dev);
 	int ret;
 
+	stmmac_clk_enable(priv);
+
 	stmmac_check_ether_addr(priv);
 
 	/* MDIO bus Registration */
@@ -911,13 +913,15 @@ static int stmmac_open(struct net_device *dev)
 	if (ret < 0) {
 		pr_debug("%s: MDIO bus (id: %d) registration failed",
 			 __func__, priv->plat->bus_id);
-		return ret;
+		goto open_clk_dis;
 	}
 
 #ifdef CONFIG_STMMAC_TIMER
 	priv->tm = kzalloc(sizeof(struct stmmac_timer *), GFP_KERNEL);
-	if (unlikely(priv->tm == NULL))
+	if (unlikely(priv->tm == NULL)) {
-		return -ENOMEM;
+		ret = -ENOMEM;
+		goto open_clk_dis;
+	}
 
 	priv->tm->freq = tmrate;
 
@@ -1034,6 +1038,8 @@ open_error:
 	if (priv->phydev)
 		phy_disconnect(priv->phydev);
 
+open_clk_dis:
+	stmmac_clk_disable(priv);
 	return ret;
 }
 
@@ -1086,6 +1092,7 @@ static int stmmac_release(struct net_device *dev)
 	stmmac_exit_fs();
 #endif
 	stmmac_mdio_unregister(dev);
+	stmmac_clk_disable(priv);
 
 	return 0;
 }
@@ -1880,6 +1887,9 @@ struct stmmac_priv *stmmac_dvr_probe(struct device *device,
 		goto error;
 	}
 
+	if (stmmac_clk_get(priv))
+		goto error;
+
 	return priv;
 
 error:
@@ -1949,9 +1959,11 @@ int stmmac_suspend(struct net_device *ndev)
 	/* Enable Power down mode by programming the PMT regs */
 	if (device_may_wakeup(priv->device))
 		priv->hw->mac->pmt(priv->ioaddr, priv->wolopts);
-	else
+	else {
 		stmmac_set_mac(priv->ioaddr, false);
-
+		/* Disable clock in case of PWM is off */
+		stmmac_clk_disable(priv);
+	}
 	spin_unlock(&priv->lock);
 	return 0;
 }
@@ -1972,6 +1984,9 @@ int stmmac_resume(struct net_device *ndev)
 	 * from another devices (e.g. serial console). */
 	if (device_may_wakeup(priv->device))
 		priv->hw->mac->pmt(priv->ioaddr, 0);
+	else
+		/* enable the clk prevously disabled */
+		stmmac_clk_enable(priv);
 
 	netif_device_attach(ndev);