[PATCH v2 net-next PATCH 1/1] net: phy: air_en8811h: Introduce resume/suspend and clk_restore_context to ensure correct CKO settings after network interface reinitialization.

[Lucien.Jheng]

If the user reinitializes the network interface, the PHY will reinitialize,
and the CKO settings will revert to their initial configuration(be enabled).
To prevent CKO from being re-enabled,
en8811h_clk_restore_context and en8811h_resume were added
to ensure the CKO settings remain correct.

Signed-off-by: Lucien.Jheng <lucienzx159@xxxxxxxxx>
---
Change in PATCH v2:
air_en8811h.c:
 * Fix: build errors about using __ functions.
 * Add clk_save_context to handle CKO state.
 * Add cko_is_enabled to track CKO state.

 drivers/net/phy/air_en8811h.c | 45 +++++++++++++++++++++++++++++++----
 1 file changed, 41 insertions(+), 4 deletions(-)

diff --git a/drivers/net/phy/air_en8811h.c b/drivers/net/phy/air_en8811h.c
index 57fbd8df9438..badd65f0ccee 100644
--- a/drivers/net/phy/air_en8811h.c
+++ b/drivers/net/phy/air_en8811h.c
@@ -11,6 +11,7 @@
  * Copyright (C) 2023 Airoha Technology Corp.
  */

+#include <linux/clk.h>
 #include <linux/clk-provider.h>
 #include <linux/phy.h>
 #include <linux/firmware.h>
@@ -157,6 +158,7 @@ struct en8811h_priv {
 	struct led		led[EN8811H_LED_COUNT];
 	struct clk_hw		hw;
 	struct phy_device	*phydev;
+	unsigned int		cko_is_enabled;
 };

 enum {
@@ -865,11 +867,30 @@ static int en8811h_clk_is_enabled(struct clk_hw *hw)
 	return (pbus_value & EN8811H_CLK_CGM_CKO);
 }

+static int en8811h_clk_save_context(struct clk_hw *hw)
+{
+	struct en8811h_priv *priv = clk_hw_to_en8811h_priv(hw);
+
+	priv->cko_is_enabled = en8811h_clk_is_enabled(hw);
+
+	return 0;
+}
+
+static void en8811h_clk_restore_context(struct clk_hw *hw)
+{
+	struct en8811h_priv *priv = clk_hw_to_en8811h_priv(hw);
+
+	if (!priv->cko_is_enabled)
+		en8811h_clk_disable(hw);
+}
+
 static const struct clk_ops en8811h_clk_ops = {
-	.recalc_rate	= en8811h_clk_recalc_rate,
-	.enable		= en8811h_clk_enable,
-	.disable	= en8811h_clk_disable,
-	.is_enabled	= en8811h_clk_is_enabled,
+	.recalc_rate		= en8811h_clk_recalc_rate,
+	.enable			= en8811h_clk_enable,
+	.disable		= en8811h_clk_disable,
+	.is_enabled		= en8811h_clk_is_enabled,
+	.save_context		= en8811h_clk_save_context,
+	.restore_context	= en8811h_clk_restore_context,
 };

 static int en8811h_clk_provider_setup(struct device *dev, struct clk_hw *hw)
@@ -1149,6 +1170,20 @@ static irqreturn_t en8811h_handle_interrupt(struct phy_device *phydev)
 	return IRQ_HANDLED;
 }

+static int en8811h_resume(struct phy_device *phydev)
+{
+	clk_restore_context();
+
+	return genphy_resume(phydev);
+}
+
+static int en8811h_suspend(struct phy_device *phydev)
+{
+	clk_save_context();
+
+	return genphy_suspend(phydev);
+}
+
 static struct phy_driver en8811h_driver[] = {
 {
 	PHY_ID_MATCH_MODEL(EN8811H_PHY_ID),
@@ -1159,6 +1194,8 @@ static struct phy_driver en8811h_driver[] = {
 	.get_rate_matching	= en8811h_get_rate_matching,
 	.config_aneg		= en8811h_config_aneg,
 	.read_status		= en8811h_read_status,
+	.resume			= en8811h_resume,
+	.suspend		= en8811h_suspend,
 	.config_intr		= en8811h_clear_intr,
 	.handle_interrupt	= en8811h_handle_interrupt,
 	.led_hw_is_supported	= en8811h_led_hw_is_supported,
--
2.34.1