[PATCH v2 net-next] net: phy: disregard "Clause 22 registers present" bit in get_phy_c45_devs_in_pkg

[Heiner Kallweit <hkallweit1@gmail.com>]

Bit 0 in register 1.5 doesn't represent a device but is a flag that
Clause 22 registers are present. Therefore disregard this bit when
populating the device list. If code needs this information it
should read register 1.5 directly instead of accessing the device
list.
Because this bit doesn't represent a device don't define a
MDIO_MMD_XYZ constant, just define a MDIO_DEVS_XYZ constant for
the flag in the device list bitmap.

v2:
- make masking of bit 0 more explicit
- improve commit message

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
---
 drivers/net/phy/phy_device.c | 3 +++
 include/uapi/linux/mdio.h    | 1 +
 2 files changed, 4 insertions(+)

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 9369e1323..d4fc1fd8a 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -684,6 +684,9 @@ static int get_phy_c45_devs_in_pkg(struct mii_bus *bus, int addr, int dev_addr,
 		return -EIO;
 	*devices_in_package |= (phy_reg & 0xffff);
 
+	/* Bit 0 doesn't represent a device, it indicates c22 regs presence */
+	*devices_in_package &= ~BIT(0);
+
 	return 0;
 }
 
diff --git a/include/uapi/linux/mdio.h b/include/uapi/linux/mdio.h
index 2e6e309f0..0e012b168 100644
--- a/include/uapi/linux/mdio.h
+++ b/include/uapi/linux/mdio.h
@@ -115,6 +115,7 @@
 
 /* Device present registers. */
 #define MDIO_DEVS_PRESENT(devad)	(1 << (devad))
+#define MDIO_DEVS_C22PRESENT		MDIO_DEVS_PRESENT(0)
 #define MDIO_DEVS_PMAPMD		MDIO_DEVS_PRESENT(MDIO_MMD_PMAPMD)
 #define MDIO_DEVS_WIS			MDIO_DEVS_PRESENT(MDIO_MMD_WIS)
 #define MDIO_DEVS_PCS			MDIO_DEVS_PRESENT(MDIO_MMD_PCS)
-- 
2.20.1