net: libphy: Add phy specific function to access mmd phy registers

libphy was originally written assuming all phy devices support clause 45
access extensions to the mmd registers through the indirection registers
located within the first 16 phy registers. This assumption is not true
in all cases, and one specific example is the Micrel ksz9021 10/100/1000
Mbps phy. Using the stmmac driver, accessing the mmd registers to query
and configure energy efficient Ethernet (EEE) features yielded unexpected
behavior.

This patch adds mmd access functions to the phy driver that can be
overriden by the phy specific driver if the phy does not support this
mechanism or uses it's own non-standard access mechanism. By default,
the IEEE Compatible clause 45 access mechanism described in clause 22
is used. With this patch, EEE query/configure functions as expected
using the stmmac and the Micrel ksz9021 phy.

Signed-off-by: Vince Bridgers <vbridgers2013@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 18 insertions, 0 deletions

diff --git a/include/linux/phy.h b/include/linux/phy.h
index 68041446c450..ed39956b5613 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -545,6 +545,24 @@ struct phy_driver {
 	 */
 	void (*link_change_notify)(struct phy_device *dev);
 
+	/* A function provided by a phy specific driver to override the
+	 * the PHY driver framework support for reading a MMD register
+	 * from the PHY. If not supported, return -1. This function is
+	 * optional for PHY specific drivers, if not provided then the
+	 * default MMD read function is used by the PHY framework.
+	 */
+	int (*read_mmd_indirect)(struct phy_device *dev, int ptrad,
+				 int devnum, int regnum);
+
+	/* A function provided by a phy specific driver to override the
+	 * the PHY driver framework support for writing a MMD register
+	 * from the PHY. This function is optional for PHY specific drivers,
+	 * if not provided then the default MMD read function is used by
+	 * the PHY framework.
+	 */
+	void (*write_mmd_indirect)(struct phy_device *dev, int ptrad,
+				   int devnum, int regnum, u32 val);
+
 	struct device_driver driver;
 };
 #define to_phy_driver(d) container_of(d, struct phy_driver, driver)