phylib: add reset after clk enable support

Some PHYs need the refclk to be a continuous clock. Therefore they don't
allow turning it off and on again during operation. Nonetheless such a
clock switching is performed by some ETH drivers (namely FEC [1]) for
power saving reasons. An example for an affected PHY is the
SMSC/Microchip LAN8720 in "REF_CLK In Mode".

In order to provide a uniform method to overcome this problem this patch
adds a new phy_driver flag (PHY_RST_AFTER_CLK_EN) and corresponding
function phy_reset_after_clk_enable() to the phylib. These should be
used to trigger reset of the PHY after the refclk is switched on again.

[1] commit e8fcfcd5684a ("net: fec: optimize the clock management to save power")

Signed-off-by: Richard Leitner <richard.leitner@skidata.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 1de5e24..462c17e 100644 (file)
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -1218,6 +1218,30 @@ out:
 }
 EXPORT_SYMBOL(phy_loopback);
 
+/**
+ * phy_reset_after_clk_enable - perform a PHY reset if needed
+ * @phydev: target phy_device struct
+ *
+ * Description: Some PHYs are known to need a reset after their refclk was
+ *   enabled. This function evaluates the flags and perform the reset if it's
+ *   needed. Returns < 0 on error, 0 if the phy wasn't reset and 1 if the phy
+ *   was reset.
+ */
+int phy_reset_after_clk_enable(struct phy_device *phydev)
+{
+       if (!phydev || !phydev->drv)
+               return -ENODEV;
+
+       if (phydev->drv->flags & PHY_RST_AFTER_CLK_EN) {
+               phy_device_reset(phydev, 1);
+               phy_device_reset(phydev, 0);
+               return 1;
+       }
+
+       return 0;
+}
+EXPORT_SYMBOL(phy_reset_after_clk_enable);
+
 /* Generic PHY support and helper functions */
 
 /**

diff --git a/include/linux/phy.h b/include/linux/phy.h
index d3037e2..c4b4715 100644 (file)
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -59,6 +59,7 @@
 
 #define PHY_HAS_INTERRUPT      0x00000001
 #define PHY_IS_INTERNAL                0x00000002
+#define PHY_RST_AFTER_CLK_EN   0x00000004
 #define MDIO_DEVICE_IS_PHY     0x80000000
 
 /* Interface Mode definitions */
@@ -853,6 +854,7 @@ int phy_aneg_done(struct phy_device *phydev);
 
 int phy_stop_interrupts(struct phy_device *phydev);
 int phy_restart_aneg(struct phy_device *phydev);
+int phy_reset_after_clk_enable(struct phy_device *phydev);
 
 static inline void phy_device_reset(struct phy_device *phydev, int value)
 {