net: fec: Ensure clocks are enabled while using mdio bus

When a switch is attached to the mdio bus, the mdio bus can be used
while the interface is not open. If the IPG clock is not enabled, MDIO
reads/writes will simply time out.

Add support for runtime PM to control this clock. Enable/disable this
clock using runtime PM, with open()/close() and mdio read()/write()
function triggering runtime PM operations. Since PM is optional, the
IPG clock is enabled at probe and is no longer modified by
fec_enet_clk_enable(), thus if PM is not enabled in the kernel, it is
guaranteed the clock is running when MDIO operations are performed.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Cc: tyler.baker@linaro.org
Cc: fabio.estevam@freescale.com
Cc: shawn.guo@linaro.org
Tested-by: Fabio Estevam <fabio.estevam@freescale.com>
Tested-by: Tyler Baker <tyler.baker@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index 5e8b837..32e3807 100644 (file)
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -24,6 +24,7 @@
 #include <linux/module.h>
 #include <linux/kernel.h>
 #include <linux/string.h>
+#include <linux/pm_runtime.h>
 #include <linux/ptrace.h>
 #include <linux/errno.h>
 #include <linux/ioport.h>
@@ -77,6 +78,7 @@ static void fec_enet_itr_coal_init(struct net_device *ndev);
 #define FEC_ENET_RAEM_V        0x8
 #define FEC_ENET_RAFL_V        0x8
 #define FEC_ENET_OPD_V 0xFFF0
+#define FEC_MDIO_PM_TIMEOUT  100 /* ms */
 
 static struct platform_device_id fec_devtype[] = {
        {
@@ -1767,7 +1769,13 @@ static void fec_enet_adjust_link(struct net_device *ndev)
 static int fec_enet_mdio_read(struct mii_bus *bus, int mii_id, int regnum)
 {
        struct fec_enet_private *fep = bus->priv;
+       struct device *dev = &fep->pdev->dev;
        unsigned long time_left;
+       int ret = 0;
+
+       ret = pm_runtime_get_sync(dev);
+       if (IS_ERR_VALUE(ret))
+               return ret;
 
        fep->mii_timeout = 0;
        init_completion(&fep->mdio_done);
@@ -1783,18 +1791,30 @@ static int fec_enet_mdio_read(struct mii_bus *bus, int mii_id, int regnum)
        if (time_left == 0) {
                fep->mii_timeout = 1;
                netdev_err(fep->netdev, "MDIO read timeout\n");
-               return -ETIMEDOUT;
+               ret = -ETIMEDOUT;
+               goto out;
        }
 
-       /* return value */
-       return FEC_MMFR_DATA(readl(fep->hwp + FEC_MII_DATA));
+       ret = FEC_MMFR_DATA(readl(fep->hwp + FEC_MII_DATA));
+
+out:
+       pm_runtime_mark_last_busy(dev);
+       pm_runtime_put_autosuspend(dev);
+
+       return ret;
 }
 
 static int fec_enet_mdio_write(struct mii_bus *bus, int mii_id, int regnum,
                           u16 value)
 {
        struct fec_enet_private *fep = bus->priv;
+       struct device *dev = &fep->pdev->dev;
        unsigned long time_left;
+       int ret = 0;
+
+       ret = pm_runtime_get_sync(dev);
+       if (IS_ERR_VALUE(ret))
+               return ret;
 
        fep->mii_timeout = 0;
        init_completion(&fep->mdio_done);
@@ -1811,10 +1831,13 @@ static int fec_enet_mdio_write(struct mii_bus *bus, int mii_id, int regnum,
        if (time_left == 0) {
                fep->mii_timeout = 1;
                netdev_err(fep->netdev, "MDIO write timeout\n");
-               return -ETIMEDOUT;
+               ret  = -ETIMEDOUT;
        }
 
-       return 0;
+       pm_runtime_mark_last_busy(dev);
+       pm_runtime_put_autosuspend(dev);
+
+       return ret;
 }
 
 static int fec_enet_clk_enable(struct net_device *ndev, bool enable)
@@ -1826,9 +1849,6 @@ static int fec_enet_clk_enable(struct net_device *ndev, bool enable)
                ret = clk_prepare_enable(fep->clk_ahb);
                if (ret)
                        return ret;
-               ret = clk_prepare_enable(fep->clk_ipg);
-               if (ret)
-                       goto failed_clk_ipg;
                if (fep->clk_enet_out) {
                        ret = clk_prepare_enable(fep->clk_enet_out);
                        if (ret)
@@ -1852,7 +1872,6 @@ static int fec_enet_clk_enable(struct net_device *ndev, bool enable)
                }
        } else {
                clk_disable_unprepare(fep->clk_ahb);
-               clk_disable_unprepare(fep->clk_ipg);
                if (fep->clk_enet_out)
                        clk_disable_unprepare(fep->clk_enet_out);
                if (fep->clk_ptp) {
@@ -1874,8 +1893,6 @@ failed_clk_ptp:
        if (fep->clk_enet_out)
                clk_disable_unprepare(fep->clk_enet_out);
 failed_clk_enet_out:
-               clk_disable_unprepare(fep->clk_ipg);
-failed_clk_ipg:
                clk_disable_unprepare(fep->clk_ahb);
 
        return ret;
@@ -2847,10 +2864,14 @@ fec_enet_open(struct net_device *ndev)
        struct fec_enet_private *fep = netdev_priv(ndev);
        int ret;
 
+       ret = pm_runtime_get_sync(&fep->pdev->dev);
+       if (IS_ERR_VALUE(ret))
+               return ret;
+
        pinctrl_pm_select_default_state(&fep->pdev->dev);
        ret = fec_enet_clk_enable(ndev, true);
        if (ret)
-               return ret;
+               goto clk_enable;
 
        /* I should reset the ring buffers here, but I don't yet know
         * a simple way to do that.
@@ -2881,6 +2902,9 @@ err_enet_mii_probe:
        fec_enet_free_buffers(ndev);
 err_enet_alloc:
        fec_enet_clk_enable(ndev, false);
+clk_enable:
+       pm_runtime_mark_last_busy(&fep->pdev->dev);
+       pm_runtime_put_autosuspend(&fep->pdev->dev);
        pinctrl_pm_select_sleep_state(&fep->pdev->dev);
        return ret;
 }
@@ -2903,6 +2927,9 @@ fec_enet_close(struct net_device *ndev)
 
        fec_enet_clk_enable(ndev, false);
        pinctrl_pm_select_sleep_state(&fep->pdev->dev);
+       pm_runtime_mark_last_busy(&fep->pdev->dev);
+       pm_runtime_put_autosuspend(&fep->pdev->dev);
+
        fec_enet_free_buffers(ndev);
 
        return 0;
@@ -3388,6 +3415,10 @@ fec_probe(struct platform_device *pdev)
        if (ret)
                goto failed_clk;
 
+       ret = clk_prepare_enable(fep->clk_ipg);
+       if (ret)
+               goto failed_clk_ipg;
+
        fep->reg_phy = devm_regulator_get(&pdev->dev, "phy");
        if (!IS_ERR(fep->reg_phy)) {
                ret = regulator_enable(fep->reg_phy);
@@ -3400,6 +3431,11 @@ fec_probe(struct platform_device *pdev)
                fep->reg_phy = NULL;
        }
 
+       pm_runtime_set_autosuspend_delay(&pdev->dev, FEC_MDIO_PM_TIMEOUT);
+       pm_runtime_use_autosuspend(&pdev->dev);
+       pm_runtime_set_active(&pdev->dev);
+       pm_runtime_enable(&pdev->dev);
+
        fec_reset_phy(pdev);
 
        if (fep->bufdesc_ex)
@@ -3447,6 +3483,10 @@ fec_probe(struct platform_device *pdev)
 
        fep->rx_copybreak = COPYBREAK_DEFAULT;
        INIT_WORK(&fep->tx_timeout_work, fec_enet_timeout_work);
+
+       pm_runtime_mark_last_busy(&pdev->dev);
+       pm_runtime_put_autosuspend(&pdev->dev);
+
        return 0;
 
 failed_register:
@@ -3458,6 +3498,8 @@ failed_init:
        if (fep->reg_phy)
                regulator_disable(fep->reg_phy);
 failed_regulator:
+       clk_disable_unprepare(fep->clk_ipg);
+failed_clk_ipg:
        fec_enet_clk_enable(ndev, false);
 failed_clk:
 failed_phy:
@@ -3567,7 +3609,28 @@ failed_clk:
        return ret;
 }
 
-static SIMPLE_DEV_PM_OPS(fec_pm_ops, fec_suspend, fec_resume);
+static int __maybe_unused fec_runtime_suspend(struct device *dev)
+{
+       struct net_device *ndev = dev_get_drvdata(dev);
+       struct fec_enet_private *fep = netdev_priv(ndev);
+
+       clk_disable_unprepare(fep->clk_ipg);
+
+       return 0;
+}
+
+static int __maybe_unused fec_runtime_resume(struct device *dev)
+{
+       struct net_device *ndev = dev_get_drvdata(dev);
+       struct fec_enet_private *fep = netdev_priv(ndev);
+
+       return clk_prepare_enable(fep->clk_ipg);
+}
+
+static const struct dev_pm_ops fec_pm_ops = {
+       SET_SYSTEM_SLEEP_PM_OPS(fec_suspend, fec_resume)
+       SET_RUNTIME_PM_OPS(fec_runtime_suspend, fec_runtime_resume, NULL)
+};
 
 static struct platform_driver fec_driver = {
        .driver = {