From 7406ffc54e986b006993220da8d1c298efb9ddb7 Mon Sep 17 00:00:00 2001
From: Kevin Hao <haokexin@gmail.com>
Date: Tue, 20 Mar 2018 09:44:52 +0800
Subject: [PATCH 0554/1795] net: phy: Add general dummy stubs for MMD register
 access

For some phy devices, even though they don't support the MMD extended
register access, it does have some side effect if we are trying to
read/write the MMD registers via indirect method. So introduce general
dummy stubs for MMD register access which these devices can use to avoid
such side effect.

Fixes: b6b5e8a69118 ("gianfar: Disable EEE autoneg by default")
Signed-off-by: Kevin Hao <haokexin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit 5df7af85ecd88e8b5f1f31d6456c3cf38a8bbdda)
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
 drivers/net/phy/phy_device.c | 17 +++++++++++++++++
 include/linux/phy.h          |  4 ++++
 2 files changed, 21 insertions(+)

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index a174d05a9752..fe76e2c4022a 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -1641,6 +1641,23 @@ int genphy_config_init(struct phy_device *phydev)
 }
 EXPORT_SYMBOL(genphy_config_init);
 
+/* This is used for the phy device which doesn't support the MMD extended
+ * register access, but it does have side effect when we are trying to access
+ * the MMD register via indirect method.
+ */
+int genphy_read_mmd_unsupported(struct phy_device *phdev, int devad, u16 regnum)
+{
+	return -EOPNOTSUPP;
+}
+EXPORT_SYMBOL(genphy_read_mmd_unsupported);
+
+int genphy_write_mmd_unsupported(struct phy_device *phdev, int devnum,
+				 u16 regnum, u16 val)
+{
+	return -EOPNOTSUPP;
+}
+EXPORT_SYMBOL(genphy_write_mmd_unsupported);
+
 int genphy_suspend(struct phy_device *phydev)
 {
 	int value;
diff --git a/include/linux/phy.h b/include/linux/phy.h
index dca9e926b88f..efc04c2d92c9 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -879,6 +879,10 @@ static inline int genphy_no_soft_reset(struct phy_device *phydev)
 {
 	return 0;
 }
+int genphy_read_mmd_unsupported(struct phy_device *phdev, int devad,
+				u16 regnum);
+int genphy_write_mmd_unsupported(struct phy_device *phdev, int devnum,
+				 u16 regnum, u16 val);
 
 /* Clause 45 PHY */
 int genphy_c45_restart_aneg(struct phy_device *phydev);
-- 
2.19.0