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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 e8fcfcd568 ("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>
This commit is contained in:
Richard Leitner 2017-12-11 13:16:58 +01:00 committed by David S. Miller
parent 3a30ae6ef3
commit a96684914a
2 changed files with 26 additions and 0 deletions
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24
drivers/net/phy/phy_device.c
View File

@ -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 */
/**

2
include/linux/phy.h
View File

@ -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)
{