net/smsc911x: Check if PHY is in operational mode before software reset

SMSC LAN generation 4 chips integrate an IEEE 802.3 ethernet physical layer.
The PHY driver for this integrated chip enable an energy detect power-down mode.
When the PHY is in a power-down mode, it prevents the MAC portion chip to be
software reseted.

That means that if we compile the kernel with the configuration option SMSC_PHY
enabled and try to bring the network interface up without an cable plug-ed the
PHY will be in a low power mode and the software reset will fail returning -EIO
to user-space:

root@igep00x0:~# ifconfig eth0 up
ifconfig: SIOCSIFFLAGS: Input/output error

This patch disable the energy detect power-down mode before trying to software
reset the LAN chip and re-enables after it was reseted successfully.

Signed-off-by: Javier Martinez Canillas <javier@dowhile0.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 92 insertions, 0 deletions

diff --git a/drivers/net/ethernet/smsc/smsc911x.c b/drivers/net/ethernet/smsc/smsc911x.c
index 06d0df61bee6..9d0b8ced0234 100644
--- a/drivers/net/ethernet/smsc/smsc911x.c
+++ b/drivers/net/ethernet/smsc/smsc911x.c
@@ -1319,10 +1319,92 @@ static void smsc911x_rx_multicast_update_workaround(struct smsc911x_data *pdata)
         spin_unlock(&pdata->mac_lock);
 }
 
+static int smsc911x_phy_disable_energy_detect(struct smsc911x_data *pdata)
+{
+        int rc = 0;
+
+        if (!pdata->phy_dev)
+                return rc;
+
+        rc = phy_read(pdata->phy_dev, MII_LAN83C185_CTRL_STATUS);
+
+        if (rc < 0) {
+                SMSC_WARN(pdata, drv, "Failed reading PHY control reg");
+                return rc;
+        }
+
+        /*
+         * If energy is detected the PHY is already awake so is not necessary
+         * to disable the energy detect power-down mode.
+         */
+        if ((rc & MII_LAN83C185_EDPWRDOWN) &&
+            !(rc & MII_LAN83C185_ENERGYON)) {
+                /* Disable energy detect mode for this SMSC Transceivers */
+                rc = phy_write(pdata->phy_dev, MII_LAN83C185_CTRL_STATUS,
+                               rc & (~MII_LAN83C185_EDPWRDOWN));
+
+                if (rc < 0) {
+                        SMSC_WARN(pdata, drv, "Failed writing PHY control reg");
+                        return rc;
+                }
+
+                mdelay(1);
+        }
+
+        return 0;
+}
+
+static int smsc911x_phy_enable_energy_detect(struct smsc911x_data *pdata)
+{
+        int rc = 0;
+
+        if (!pdata->phy_dev)
+                return rc;
+
+        rc = phy_read(pdata->phy_dev, MII_LAN83C185_CTRL_STATUS);
+
+        if (rc < 0) {
+                SMSC_WARN(pdata, drv, "Failed reading PHY control reg");
+                return rc;
+        }
+
+        /* Only enable if energy detect mode is already disabled */
+        if (!(rc & MII_LAN83C185_EDPWRDOWN)) {
+                mdelay(100);
+                /* Enable energy detect mode for this SMSC Transceivers */
+                rc = phy_write(pdata->phy_dev, MII_LAN83C185_CTRL_STATUS,
+                               rc | MII_LAN83C185_EDPWRDOWN);
+
+                if (rc < 0) {
+                        SMSC_WARN(pdata, drv, "Failed writing PHY control reg");
+                        return rc;
+                }
+
+                mdelay(1);
+        }
+        return 0;
+}
+
 static int smsc911x_soft_reset(struct smsc911x_data *pdata)
 {
         unsigned int timeout;
         unsigned int temp;
+        int ret;
+
+        /*
+         * LAN9210/LAN9211/LAN9220/LAN9221 chips have an internal PHY that
+         * are initialized in a Energy Detect Power-Down mode that prevents
+         * the MAC chip to be software reseted. So we have to wakeup the PHY
+         * before.
+         */
+        if (pdata->generation == 4) {
+                ret = smsc911x_phy_disable_energy_detect(pdata);
+
+                if (ret) {
+                        SMSC_WARN(pdata, drv, "Failed to wakeup the PHY chip");
+                        return ret;
+                }
+        }
 
         /* Reset the LAN911x */
         smsc911x_reg_write(pdata, HW_CFG, HW_CFG_SRST_);
@@ -1336,6 +1418,16 @@ static int smsc911x_soft_reset(struct smsc911x_data *pdata)
                 SMSC_WARN(pdata, drv, "Failed to complete reset");
                 return -EIO;
         }
+
+        if (pdata->generation == 4) {
+                ret = smsc911x_phy_enable_energy_detect(pdata);
+
+                if (ret) {
+                        SMSC_WARN(pdata, drv, "Failed to wakeup the PHY chip");
+                        return ret;
+                }
+        }
+
         return 0;
 }