[PATCH v3 3/3] platform/x86: hp-wmi: implement fan keep-alive

[Krishna Chomal <krishna.chomal108@gmail.com>]

The firmware on some HP laptops automatically reverts the fan speed
control to "Auto" mode after a 120 second timeout window.

To ensure that the user-selected fan profile (Max/Manual) persists,
implement a keep-alive mechanism that periodically refreshes the fan
mode trigger before the timeout occurs.

- Introduce a delayed workqueue to trigger the fan mode refresh every 90
  seconds, ensuring the system maintains the correct fan mode setting.
- Integrate the refresh mechanism into hp_wmi_hwmon_enforce_ctx() to
  start, update or cancel the keep-alive process based on the current
  fan mode.

This ensures that the driver stays in sync with the hardware.

Tested on: HP Omen 16-wf1xxx (board ID 8C78)

Signed-off-by: Krishna Chomal <krishna.chomal108@gmail.com>
---
Changes in v3:
- Rename "ctx" to "priv" for drvdata
Changes in v2:
- Explicitly specify time unit in KEEP_ALIVE_DELAY macro
- Handle work rescheduling directly in switch/case
---
 drivers/platform/x86/hp/hp-wmi.c | 46 +++++++++++++++++++++++++++++---
 1 file changed, 43 insertions(+), 3 deletions(-)

diff --git a/drivers/platform/x86/hp/hp-wmi.c b/drivers/platform/x86/hp/hp-wmi.c
index d04e53ae1803..45ab644ff10e 100644
--- a/drivers/platform/x86/hp/hp-wmi.c
+++ b/drivers/platform/x86/hp/hp-wmi.c
@@ -34,6 +34,7 @@
 #include <linux/slab.h>
 #include <linux/string.h>
 #include <linux/types.h>
+#include <linux/workqueue.h>
 
 MODULE_AUTHOR("Matthew Garrett <mjg59@srcf.ucam.org>");
 MODULE_DESCRIPTION("HP laptop WMI driver");
@@ -368,6 +369,7 @@ struct hp_wmi_hwmon_priv {
 	u8 gpu_delta;
 	u8 mode;
 	u8 pwm;
+	struct delayed_work keep_alive_dwork;
 };
 
 struct victus_s_fan_table_header {
@@ -386,6 +388,12 @@ struct victus_s_fan_table {
 	struct victus_s_fan_table_entry entries[];
 } __packed;
 
+/*
+ * 90s delay to prevent the firmware from resetting fan mode after fixed
+ * 120s timeout
+ */
+#define KEEP_ALIVE_DELAY_SECS     90
+
 static inline u8 rpm_to_pwm(u8 rpm, struct hp_wmi_hwmon_priv *priv)
 {
 	return fixp_linear_interpolate(0, 0, priv->max_rpm, U8_MAX,
@@ -2093,6 +2101,7 @@ static int __init hp_wmi_bios_setup(struct platform_device *device)
 static void __exit hp_wmi_bios_remove(struct platform_device *device)
 {
 	int i;
+	struct hp_wmi_hwmon_priv *priv;
 
 	for (i = 0; i < rfkill2_count; i++) {
 		rfkill_unregister(rfkill2[i].rfkill);
@@ -2111,6 +2120,10 @@ static void __exit hp_wmi_bios_remove(struct platform_device *device)
 		rfkill_unregister(wwan_rfkill);
 		rfkill_destroy(wwan_rfkill);
 	}
+
+	priv = platform_get_drvdata(device);
+	if (priv)
+		cancel_delayed_work_sync(&priv->keep_alive_dwork);
 }
 
 static int hp_wmi_resume_handler(struct device *device)
@@ -2179,12 +2192,20 @@ static int hp_wmi_apply_fan_settings(struct hp_wmi_hwmon_priv *priv)
 		if (is_victus_s_thermal_profile())
 			hp_wmi_get_fan_count_userdefine_trigger();
 		ret = hp_wmi_fan_speed_max_set(1);
-		return ret;
+		if (ret < 0)
+			return ret;
+		schedule_delayed_work(&priv->keep_alive_dwork,
+				      secs_to_jiffies(KEEP_ALIVE_DELAY_SECS));
+		return 0;
 	case PWM_MODE_MANUAL:
 		if (!is_victus_s_thermal_profile())
 			return -EOPNOTSUPP;
 		ret = hp_wmi_fan_speed_set(priv, pwm_to_rpm(priv->pwm, priv));
-		return ret;
+		if (ret < 0)
+			return ret;
+		schedule_delayed_work(&priv->keep_alive_dwork,
+				      secs_to_jiffies(KEEP_ALIVE_DELAY_SECS));
+		return 0;
 	case PWM_MODE_AUTO:
 		if (is_victus_s_thermal_profile()) {
 			hp_wmi_get_fan_count_userdefine_trigger();
@@ -2192,7 +2213,10 @@ static int hp_wmi_apply_fan_settings(struct hp_wmi_hwmon_priv *priv)
 		} else {
 			ret = hp_wmi_fan_speed_max_set(0);
 		}
-		return ret;
+		if (ret < 0)
+			return ret;
+		cancel_delayed_work_sync(&priv->keep_alive_dwork);
+		return 0;
 	default:
 		/* shouldn't happen */
 		return -EINVAL;
@@ -2336,6 +2360,20 @@ static const struct hwmon_chip_info chip_info = {
 	.info = info,
 };
 
+static void hp_wmi_hwmon_keep_alive_handler(struct work_struct *work)
+{
+	struct delayed_work *dwork;
+	struct hp_wmi_hwmon_priv *priv;
+
+	dwork = to_delayed_work(work);
+	priv = container_of(dwork, struct hp_wmi_hwmon_priv, keep_alive_dwork);
+	/*
+	 * Re-apply the current hwmon context settings.
+	 * NOTE: hp_wmi_apply_fan_settings will handle the re-scheduling.
+	 */
+	hp_wmi_apply_fan_settings(priv);
+}
+
 static int hp_wmi_setup_fan_settings(struct hp_wmi_hwmon_priv *priv)
 {
 	u8 fan_data[128] = { 0 };
@@ -2393,6 +2431,8 @@ static int hp_wmi_hwmon_init(void)
 		return PTR_ERR(hwmon);
 	}
 
+	INIT_DELAYED_WORK(&priv->keep_alive_dwork, hp_wmi_hwmon_keep_alive_handler);
+	platform_set_drvdata(hp_wmi_platform_dev, priv);
 	hp_wmi_apply_fan_settings(priv);
 
 	return 0;
-- 
2.52.0