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Date: Sat, 08 Jun 2024 10:12:45 +0200
From: Thomas Weißschuh <linux@...ssschuh.net>
To: Benson Leung <bleung@...omium.org>, Tzung-Bi Shih <tzungbi@...nel.org>, 
 Guenter Roeck <groeck@...omium.org>, 
 Thomas Weißschuh <thomas@...ssschuh.net>, 
 Jean Delvare <jdelvare@...e.com>, Guenter Roeck <linux@...ck-us.net>
Cc: Dustin Howett <dustin@...ett.net>, 
 Mario Limonciello <mario.limonciello@....com>, 
 Stephen Horvath <s.horvath@...look.com.au>, chrome-platform@...ts.linux.dev, 
 linux-kernel@...r.kernel.org, linux-hwmon@...r.kernel.org, 
 Thomas Weißschuh <linux@...ssschuh.net>
Subject: [PATCH 3/5] hwmon: (cros_ec) Add support for PWM fan control

Implement setting fan duty cycle and automatic management through
EC_CMD_PWM_SET_FAN_DUTY and EC_CMD_THERMAL_AUTO_FAN_CTRL.

The hardware does not support reading back the values again,
so that is emulated in the driver.

Signed-off-by: Thomas Weißschuh <linux@...ssschuh.net>
---
 Documentation/hwmon/cros_ec_hwmon.rst |   1 +
 drivers/hwmon/cros_ec_hwmon.c         | 128 +++++++++++++++++++++++++++++++++-
 2 files changed, 127 insertions(+), 2 deletions(-)

diff --git a/Documentation/hwmon/cros_ec_hwmon.rst b/Documentation/hwmon/cros_ec_hwmon.rst
index 4aede331baeb..3cc345425aac 100644
--- a/Documentation/hwmon/cros_ec_hwmon.rst
+++ b/Documentation/hwmon/cros_ec_hwmon.rst
@@ -27,4 +27,5 @@ Supported features:
 
   - Current fan speed
   - Target fan speed (for fan 1 only)
+  - PWM-based fan control
   - Current temperature
diff --git a/drivers/hwmon/cros_ec_hwmon.c b/drivers/hwmon/cros_ec_hwmon.c
index 09b8057e1223..48b7073a4991 100644
--- a/drivers/hwmon/cros_ec_hwmon.c
+++ b/drivers/hwmon/cros_ec_hwmon.c
@@ -7,6 +7,7 @@
 
 #include <linux/device.h>
 #include <linux/hwmon.h>
+#include <linux/math.h>
 #include <linux/mod_devicetable.h>
 #include <linux/module.h>
 #include <linux/platform_device.h>
@@ -17,10 +18,19 @@
 
 #define DRV_NAME	"cros-ec-hwmon"
 
+enum cros_ec_hwmon_fan_mode {
+	cros_ec_hwmon_fan_mode_full = 0,
+	cros_ec_hwmon_fan_mode_manual = 1,
+	cros_ec_hwmon_fan_mode_auto = 2,
+};
+
 struct cros_ec_hwmon_priv {
 	struct cros_ec_device *cros_ec;
 	const char *temp_sensor_names[EC_TEMP_SENSOR_ENTRIES + EC_TEMP_SENSOR_B_ENTRIES];
 	u8 usable_fans;
+	bool has_fan_pwm;
+	u8 fan_pwm[EC_FAN_SPEED_ENTRIES];
+	enum cros_ec_hwmon_fan_mode fan_mode[EC_FAN_SPEED_ENTRIES];
 };
 
 static int cros_ec_hwmon_read_fan_speed(struct cros_ec_device *cros_ec, u8 index, u16 *speed)
@@ -50,6 +60,27 @@ static int cros_ec_hwmon_read_fan_target(struct cros_ec_device *cros_ec, u16 *sp
 	return 0;
 }
 
+static int cros_ec_hwmon_set_fan_auto(struct cros_ec_device *cros_ec, u8 index)
+{
+	struct ec_params_auto_fan_ctrl_v1 req = {
+		.fan_idx = index,
+	};
+
+	return cros_ec_cmd(cros_ec, 1, EC_CMD_THERMAL_AUTO_FAN_CTRL,
+			   &req, sizeof(req), NULL, 0);
+}
+
+static int cros_ec_hwmon_set_fan_duty_cycle(struct cros_ec_device *cros_ec, u8 index, u8 percent)
+{
+	struct ec_params_pwm_set_fan_duty_v1 req = {
+		.fan_idx = index,
+		.percent = percent,
+	};
+
+	return cros_ec_cmd(cros_ec, 1, EC_CMD_PWM_SET_FAN_DUTY,
+			   &req, sizeof(req), NULL, 0);
+}
+
 static int cros_ec_hwmon_read_temp(struct cros_ec_device *cros_ec, u8 index, u8 *temp)
 {
 	unsigned int offset;
@@ -111,6 +142,17 @@ static int cros_ec_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
 			if (ret == 0)
 				*val = speed;
 		}
+
+	} else if (type == hwmon_pwm) {
+		if (attr == hwmon_pwm_input) {
+			*val = priv->fan_pwm[channel];
+			ret = 0;
+
+		} else if (attr == hwmon_pwm_enable) {
+			*val = priv->fan_mode[channel];
+			ret = 0;
+		}
+
 	} else if (type == hwmon_temp) {
 		if (attr == hwmon_temp_input) {
 			ret = cros_ec_hwmon_read_temp(priv->cros_ec, channel, &temp);
@@ -143,6 +185,61 @@ static int cros_ec_hwmon_read_string(struct device *dev, enum hwmon_sensor_types
 	return -EOPNOTSUPP;
 }
 
+static int cros_ec_hwmon_write_pwm_input(struct cros_ec_hwmon_priv *priv, int channel, long val)
+{
+	u8 percent;
+	int ret;
+
+	if (val < 0 || val > 255)
+		return -EINVAL;
+
+	percent = DIV_ROUND_CLOSEST(val * 100, 255);
+
+	if (priv->fan_mode[channel] == cros_ec_hwmon_fan_mode_manual) {
+		ret = cros_ec_hwmon_set_fan_duty_cycle(priv->cros_ec, channel, percent);
+		if (ret < 0)
+			return ret;
+	}
+
+	priv->fan_pwm[channel] = percent;
+	return 0;
+}
+
+static int cros_ec_hwmon_write_pwm_enable(struct cros_ec_hwmon_priv *priv, int channel, long val)
+{
+	int ret;
+
+	if (val == cros_ec_hwmon_fan_mode_full)
+		ret = cros_ec_hwmon_set_fan_duty_cycle(priv->cros_ec, channel, 100);
+	else if (val == cros_ec_hwmon_fan_mode_manual)
+		ret = cros_ec_hwmon_set_fan_duty_cycle(priv->cros_ec, channel,
+						       priv->fan_pwm[channel]);
+	else if (val == cros_ec_hwmon_fan_mode_auto)
+		ret = cros_ec_hwmon_set_fan_auto(priv->cros_ec, channel);
+	else
+		return -EINVAL;
+
+	priv->fan_mode[channel] = val;
+	return ret;
+}
+
+static int cros_ec_hwmon_write(struct device *dev, enum hwmon_sensor_types type,
+			       u32 attr, int channel, long val)
+{
+	struct cros_ec_hwmon_priv *priv = dev_get_drvdata(dev);
+	int ret = -EOPNOTSUPP;
+
+	if (type == hwmon_pwm) {
+		if (attr == hwmon_pwm_input)
+			ret = cros_ec_hwmon_write_pwm_input(priv, channel, val);
+
+		else if (attr == hwmon_pwm_enable)
+			ret = cros_ec_hwmon_write_pwm_enable(priv, channel, val);
+	}
+
+	return ret;
+}
+
 static umode_t cros_ec_hwmon_is_visible(const void *data, enum hwmon_sensor_types type,
 					u32 attr, int channel)
 {
@@ -156,6 +253,11 @@ static umode_t cros_ec_hwmon_is_visible(const void *data, enum hwmon_sensor_type
 
 		if (priv->usable_fans & BIT(channel))
 			return 0444;
+
+	} else if (type == hwmon_pwm) {
+		if (priv->has_fan_pwm && priv->usable_fans & BIT(channel))
+			return 0644;
+
 	} else if (type == hwmon_temp) {
 		if (priv->temp_sensor_names[channel])
 			return 0444;
@@ -170,6 +272,11 @@ static const struct hwmon_channel_info * const cros_ec_hwmon_info[] = {
 			   HWMON_F_INPUT | HWMON_F_FAULT,
 			   HWMON_F_INPUT | HWMON_F_FAULT,
 			   HWMON_F_INPUT | HWMON_F_FAULT),
+	HWMON_CHANNEL_INFO(pwm,
+			   HWMON_PWM_INPUT | HWMON_PWM_ENABLE,
+			   HWMON_PWM_INPUT | HWMON_PWM_ENABLE,
+			   HWMON_PWM_INPUT | HWMON_PWM_ENABLE,
+			   HWMON_PWM_INPUT | HWMON_PWM_ENABLE),
 	HWMON_CHANNEL_INFO(temp,
 			   HWMON_T_INPUT | HWMON_T_FAULT | HWMON_T_LABEL,
 			   HWMON_T_INPUT | HWMON_T_FAULT | HWMON_T_LABEL,
@@ -201,6 +308,7 @@ static const struct hwmon_channel_info * const cros_ec_hwmon_info[] = {
 static const struct hwmon_ops cros_ec_hwmon_ops = {
 	.read = cros_ec_hwmon_read,
 	.read_string = cros_ec_hwmon_read_string,
+	.write = cros_ec_hwmon_write,
 	.is_visible = cros_ec_hwmon_is_visible,
 };
 
@@ -249,10 +357,26 @@ static void cros_ec_hwmon_probe_fans(struct cros_ec_hwmon_priv *priv)
 	size_t i;
 	int ret;
 
+	ret = cros_ec_cmd_versions(priv->cros_ec, EC_CMD_PWM_SET_FAN_DUTY);
+	if (ret >= 0 && ret & EC_VER_MASK(1))
+		priv->has_fan_pwm = 1;
+
 	for (i = 0; i < EC_FAN_SPEED_ENTRIES; i++) {
 		ret = cros_ec_hwmon_read_fan_speed(priv->cros_ec, i, &speed);
-		if (ret == 0 && speed != EC_FAN_SPEED_NOT_PRESENT)
-			priv->usable_fans |= BIT(i);
+		if (ret < 0)
+			continue;
+		if (speed == EC_FAN_SPEED_NOT_PRESENT)
+			continue;
+
+		priv->usable_fans |= BIT(i);
+
+		if (priv->has_fan_pwm) {
+			priv->fan_mode[i] = cros_ec_hwmon_fan_mode_auto;
+			ret = cros_ec_hwmon_set_fan_auto(priv->cros_ec, i);
+			if (ret != 0)
+				priv->has_fan_pwm = 0;
+		}
+
 	}
 }
 

-- 
2.45.2


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