net: phy: mxl-gpy: add MDINT workaround

[platform/kernel/linux-starfive.git] / drivers / net / phy / mxl-gpy.c

diff --git a/drivers/net/phy/mxl-gpy.c b/drivers/net/phy/mxl-gpy.c
index 24bae27..cae2409 100644 (file)
--- a/drivers/net/phy/mxl-gpy.c
+++ b/drivers/net/phy/mxl-gpy.c
@@ -9,6 +9,7 @@
 #include <linux/module.h>
 #include <linux/bitfield.h>
 #include <linux/hwmon.h>
+#include <linux/mutex.h>
 #include <linux/phy.h>
 #include <linux/polynomial.h>
 #include <linux/netdevice.h>
@@ -70,6 +71,14 @@
 #define VPSPEC1_TEMP_STA       0x0E
 #define VPSPEC1_TEMP_STA_DATA  GENMASK(9, 0)
 
+/* Mailbox */
+#define VSPEC1_MBOX_DATA       0x5
+#define VSPEC1_MBOX_ADDRLO     0x6
+#define VSPEC1_MBOX_CMD                0x7
+#define VSPEC1_MBOX_CMD_ADDRHI GENMASK(7, 0)
+#define VSPEC1_MBOX_CMD_RD     (0 << 8)
+#define VSPEC1_MBOX_CMD_READY  BIT(15)
+
 /* WoL */
 #define VPSPEC2_WOL_CTL                0x0E06
 #define VPSPEC2_WOL_AD01       0x0E08
@@ -77,7 +86,13 @@
 #define VPSPEC2_WOL_AD45       0x0E0A
 #define WOL_EN                 BIT(0)
 
+/* Internal registers, access via mbox */
+#define REG_GPIO0_OUT          0xd3ce00
+
 struct gpy_priv {
+       /* serialize mailbox acesses */
+       struct mutex mbox_lock;
+
        u8 fw_major;
        u8 fw_minor;
 };
@@ -187,6 +202,45 @@ static int gpy_hwmon_register(struct phy_device *phydev)
 }
 #endif
 
+static int gpy_mbox_read(struct phy_device *phydev, u32 addr)
+{
+       struct gpy_priv *priv = phydev->priv;
+       int val, ret;
+       u16 cmd;
+
+       mutex_lock(&priv->mbox_lock);
+
+       ret = phy_write_mmd(phydev, MDIO_MMD_VEND1, VSPEC1_MBOX_ADDRLO,
+                           addr);
+       if (ret)
+               goto out;
+
+       cmd = VSPEC1_MBOX_CMD_RD;
+       cmd |= FIELD_PREP(VSPEC1_MBOX_CMD_ADDRHI, addr >> 16);
+
+       ret = phy_write_mmd(phydev, MDIO_MMD_VEND1, VSPEC1_MBOX_CMD, cmd);
+       if (ret)
+               goto out;
+
+       /* The mbox read is used in the interrupt workaround. It was observed
+        * that a read might take up to 2.5ms. This is also the time for which
+        * the interrupt line is stuck low. To be on the safe side, poll the
+        * ready bit for 10ms.
+        */
+       ret = phy_read_mmd_poll_timeout(phydev, MDIO_MMD_VEND1,
+                                       VSPEC1_MBOX_CMD, val,
+                                       (val & VSPEC1_MBOX_CMD_READY),
+                                       500, 10000, false);
+       if (ret)
+               goto out;
+
+       ret = phy_read_mmd(phydev, MDIO_MMD_VEND1, VSPEC1_MBOX_DATA);
+
+out:
+       mutex_unlock(&priv->mbox_lock);
+       return ret;
+}
+
 static int gpy_config_init(struct phy_device *phydev)
 {
        int ret;
@@ -201,6 +255,13 @@ static int gpy_config_init(struct phy_device *phydev)
        return ret < 0 ? ret : 0;
 }
 
+static bool gpy_has_broken_mdint(struct phy_device *phydev)
+{
+       /* At least these PHYs are known to have broken interrupt handling */
+       return phydev->drv->phy_id == PHY_ID_GPY215B ||
+              phydev->drv->phy_id == PHY_ID_GPY215C;
+}
+
 static int gpy_probe(struct phy_device *phydev)
 {
        struct device *dev = &phydev->mdio.dev;
@@ -218,6 +279,7 @@ static int gpy_probe(struct phy_device *phydev)
        if (!priv)
                return -ENOMEM;
        phydev->priv = priv;
+       mutex_init(&priv->mbox_lock);
 
        fw_version = phy_read(phydev, PHY_FWV);
        if (fw_version < 0)
@@ -492,6 +554,29 @@ static irqreturn_t gpy_handle_interrupt(struct phy_device *phydev)
        if (!(reg & PHY_IMASK_MASK))
                return IRQ_NONE;
 
+       /* The PHY might leave the interrupt line asserted even after PHY_ISTAT
+        * is read. To avoid interrupt storms, delay the interrupt handling as
+        * long as the PHY drives the interrupt line. An internal bus read will
+        * stall as long as the interrupt line is asserted, thus just read a
+        * random register here.
+        * Because we cannot access the internal bus at all while the interrupt
+        * is driven by the PHY, there is no way to make the interrupt line
+        * unstuck (e.g. by changing the pinmux to GPIO input) during that time
+        * frame. Therefore, polling is the best we can do and won't do any more
+        * harm.
+        * It was observed that this bug happens on link state and link speed
+        * changes on a GPY215B and GYP215C independent of the firmware version
+        * (which doesn't mean that this list is exhaustive).
+        */
+       if (gpy_has_broken_mdint(phydev) &&
+           (reg & (PHY_IMASK_LSTC | PHY_IMASK_LSPC))) {
+               reg = gpy_mbox_read(phydev, REG_GPIO0_OUT);
+               if (reg < 0) {
+                       phy_error(phydev);
+                       return IRQ_NONE;
+               }
+       }
+
        phy_trigger_machine(phydev);
 
        return IRQ_HANDLED;