[PATCH v2 10/11] net: phy: at803x: add disable hibernation mode support

[Marco Felsch <m.felsch@pengutronix.de>]

This commit is based on Linux commit:

| commit 9ecf04016c87bcb33b44e24489d33618e2592f41
| Author: Wei Fang <wei.fang@nxp.com>
| Date:   Thu Aug 18 11:00:54 2022 +0800
|
|     net: phy: at803x: add disable hibernation mode support
|
|     When the cable is unplugged, the Atheros AR803x PHYs will enter
|     hibernation mode after about 10 seconds if the hibernation mode
|     is enabled and will not provide any clock to the MAC. But for
|     some MACs, this feature might cause unexpected issues due to the
|     logic of MACs.
|     Taking SYNP MAC (stmmac) as an example, if the cable is unplugged
|     and the "eth0" interface is down, the AR803x PHY will enter
|     hibernation mode. Then perform the "ifconfig eth0 up" operation,
|     the stmmac can't be able to complete the software reset operation
|     and fail to init it's own DMA. Therefore, the "eth0" interface is
|     failed to ifconfig up. Why does it cause this issue? The truth is
|     that the software reset operation of the stmmac is designed to
|     depend on the RX_CLK of PHY.
|     So, this patch offers an option for the user to determine whether
|     to disable the hibernation mode of AR803x PHYs.
|
|     Signed-off-by: Wei Fang <wei.fang@nxp.com>
|     Reviewed-by: Andrew Lunn <andrew@lunn.ch>
|     Signed-off-by: Jakub Kicinski <kuba@kernel.org>

The commit is adapted to always disable the hibernation mode instead of
making it optional since bootloaders require no special power
optimization.

Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
---
v2:
- adapt the commit message
- unconditional disable the hibernation mode (afa)

 drivers/net/phy/at803x.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/net/phy/at803x.c b/drivers/net/phy/at803x.c
index 2e3e57b27ee6..b9e11025b86c 100644
--- a/drivers/net/phy/at803x.c
+++ b/drivers/net/phy/at803x.c
@@ -32,6 +32,9 @@
 #define AT803X_DEBUG_REG_5			0x05
 #define AT803X_DEBUG_TX_CLK_DLY_EN		BIT(8)
 
+#define AT803X_DEBUG_REG_HIB_CTRL		0x0b
+#define   AT803X_DEBUG_HIB_CTRL_PS_HIB_EN	BIT(15)
+
 /* AT803x supports either the XTAL input pad, an internal PLL or the
  * DSP as clock reference for the clock output pad. The XTAL reference
  * is only used for 25 MHz output, all other frequencies need the PLL.
@@ -131,6 +134,15 @@ static int at803x_disable_tx_delay(struct phy_device *phydev)
 				     AT803X_DEBUG_TX_CLK_DLY_EN, 0);
 }
 
+static int at803x_hibernation_mode_config(struct phy_device *phydev)
+{
+	/* The default after hardware reset is hibernation mode enabled. After
+	 * software reset, the value is retained.
+	 */
+	return at803x_debug_reg_mask(phydev, AT803X_DEBUG_REG_HIB_CTRL,
+				     AT803X_DEBUG_HIB_CTRL_PS_HIB_EN, 0);
+}
+
 static bool at803x_match_phy_id(struct phy_device *phydev, u32 phy_id)
 {
 	struct phy_driver *drv = to_phy_driver(phydev->dev.driver);
@@ -287,6 +299,10 @@ static int at803x_config_init(struct phy_device *phydev)
 	if (ret < 0)
 		return ret;
 
+	ret = at803x_hibernation_mode_config(phydev);
+	if (ret < 0)
+		return ret;
+
 	return 0;
 }
 
-- 
2.39.2