net/cadence_gem: Set PHY autonegotiation restart status

The Linux kernel PHY driver sets AN_RESTART in the BMCR of the
PHY when autonegotiation is started.
Recently the kernel started to read back the PHY's AN_RESTART
bit and now checks whether the autonegotiation is complete and
the bit was cleared [1]. Otherwise the link status is down.

The emulated PHY needs to clear AN_RESTART immediately to inform
the kernel driver about the completion of autonegotiation phase.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c36757eb9dee

Signed-off-by: Linus Ziegert <linus.ziegert+qemu@holoplot.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: 20191104181604.21943-1-linus.ziegert+qemu@holoplot.com
Cc: qemu-stable@nongnu.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

diff --git a/hw/net/cadence_gem.c b/hw/net/cadence_gem.c
index 7f9cb5ab955f9dfcc6daff5e05bf00756b5a303c..b8be73dc558071f907cf5a6d1c5330a1831757ea 100644 (file)
--- a/hw/net/cadence_gem.c
+++ b/hw/net/cadence_gem.c
@@ -271,9 +271,10 @@
 #define PHY_REG_EXT_PHYSPCFC_ST   27
 #define PHY_REG_CABLE_DIAG   28
 
-#define PHY_REG_CONTROL_RST  0x8000
-#define PHY_REG_CONTROL_LOOP 0x4000
-#define PHY_REG_CONTROL_ANEG 0x1000
+#define PHY_REG_CONTROL_RST       0x8000
+#define PHY_REG_CONTROL_LOOP      0x4000
+#define PHY_REG_CONTROL_ANEG      0x1000
+#define PHY_REG_CONTROL_ANRESTART 0x0200
 
 #define PHY_REG_STATUS_LINK     0x0004
 #define PHY_REG_STATUS_ANEGCMPL 0x0020
@@ -1345,7 +1346,7 @@ static void gem_phy_write(CadenceGEMState *s, unsigned reg_num, uint16_t val)
         }
         if (val & PHY_REG_CONTROL_ANEG) {
             /* Complete autonegotiation immediately */
-            val &= ~PHY_REG_CONTROL_ANEG;
+            val &= ~(PHY_REG_CONTROL_ANEG | PHY_REG_CONTROL_ANRESTART);
             s->phy_regs[PHY_REG_STATUS] |= PHY_REG_STATUS_ANEGCMPL;
         }
         if (val & PHY_REG_CONTROL_LOOP) {