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Message-Id: <20250530-b4-v1-amc6821-cooling-device-support-b4-v1-3-7bb98496c969@toradex.com>
Date: Fri, 30 May 2025 14:46:27 -0300
From: João Paulo Gonçalves <jpaulo.silvagoncalves@...il.com>
To: Jean Delvare <jdelvare@...e.com>, Guenter Roeck <linux@...ck-us.net>,
Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
Conor Dooley <conor+dt@...nel.org>,
Farouk Bouabid <farouk.bouabid@...rry.de>,
Quentin Schulz <quentin.schulz@...rry.de>
Cc: linux-hwmon@...r.kernel.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org,
João Paulo Gonçalves <joao.goncalves@...adex.com>
Subject: [PATCH 3/3] hwmon: (amc6821) Add cooling device support
From: João Paulo Gonçalves <joao.goncalves@...adex.com>
Add support for using the AMC6821 as a cooling device. The AMC6821
registers with the thermal framework only if the `cooling-levels`
property is present in the fan device tree child node. Existing behavior
is unchanged, so the AMC6821 can still be used without the thermal
framework (hwmon only).
Signed-off-by: João Paulo Gonçalves <joao.goncalves@...adex.com>
---
drivers/hwmon/amc6821.c | 95 ++++++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 91 insertions(+), 4 deletions(-)
diff --git a/drivers/hwmon/amc6821.c b/drivers/hwmon/amc6821.c
index a969fad803ae1abb05113ce15f2476e83df029d9..f4c2aa71a0e68c071fa4915567327585c20ab5f5 100644
--- a/drivers/hwmon/amc6821.c
+++ b/drivers/hwmon/amc6821.c
@@ -26,6 +26,7 @@
#include <linux/pwm.h>
#include <linux/regmap.h>
#include <linux/slab.h>
+#include <linux/thermal.h>
#include <dt-bindings/pwm/pwm.h>
@@ -126,6 +127,9 @@ module_param(init, int, 0444);
struct amc6821_data {
struct regmap *regmap;
struct mutex update_lock;
+ unsigned long fan_state;
+ unsigned long fan_max_state;
+ unsigned int *fan_cooling_levels;
enum pwm_polarity of_pwm_polarity;
};
@@ -805,6 +809,56 @@ static const struct hwmon_chip_info amc6821_chip_info = {
.info = amc6821_info,
};
+static int amc6821_get_max_state(struct thermal_cooling_device *cdev, unsigned long *state)
+{
+ struct amc6821_data *data = cdev->devdata;
+
+ if (!data)
+ return -EINVAL;
+
+ *state = data->fan_max_state;
+
+ return 0;
+}
+
+static int amc6821_get_cur_state(struct thermal_cooling_device *cdev, unsigned long *state)
+{
+ struct amc6821_data *data = cdev->devdata;
+
+ if (!data)
+ return -EINVAL;
+
+ *state = data->fan_state;
+
+ return 0;
+}
+
+static int amc6821_set_cur_state(struct thermal_cooling_device *cdev, unsigned long state)
+{
+ struct amc6821_data *data = cdev->devdata;
+ int ret;
+
+ if (!data || state > data->fan_max_state)
+ return -EINVAL;
+
+ ret = regmap_write(data->regmap, AMC6821_REG_DCY,
+ data->fan_cooling_levels[state]);
+ if (ret)
+ return ret;
+
+ data->fan_state = state;
+
+ /* Change to manual mode (software DCY) */
+ return regmap_update_bits(data->regmap, AMC6821_REG_CONF1,
+ AMC6821_CONF1_FDRC0 | AMC6821_CONF1_FDRC1, 0);
+}
+
+static const struct thermal_cooling_device_ops amc6821_cooling_ops = {
+ .get_max_state = amc6821_get_max_state,
+ .get_cur_state = amc6821_get_cur_state,
+ .set_cur_state = amc6821_set_cur_state,
+};
+
/* Return 0 if detection is successful, -ENODEV otherwise */
static int amc6821_detect(struct i2c_client *client, struct i2c_board_info *info)
{
@@ -849,10 +903,12 @@ static int amc6821_detect(struct i2c_client *client, struct i2c_board_info *info
return 0;
}
-static void amc6821_of_fan_read_data(struct amc6821_data *data,
- struct device_node *fan_np)
+static int amc6821_of_fan_read_data(struct i2c_client *client,
+ struct amc6821_data *data,
+ struct device_node *fan_np)
{
struct of_phandle_args args;
+ int num;
data->of_pwm_polarity = PWM_POLARITY_NORMAL;
@@ -862,6 +918,22 @@ static void amc6821_of_fan_read_data(struct amc6821_data *data,
of_node_put(args.np);
}
+
+ num = of_property_count_u32_elems(fan_np, "cooling-levels");
+ if (num <= 0)
+ return 0;
+
+ data->fan_max_state = num - 1;
+
+ data->fan_cooling_levels = devm_kcalloc(&client->dev, num,
+ sizeof(u32),
+ GFP_KERNEL);
+
+ if (!data->fan_cooling_levels)
+ return -ENOMEM;
+
+ return of_property_read_u32_array(fan_np, "cooling-levels",
+ data->fan_cooling_levels, num);
}
static enum pwm_polarity amc6821_pwm_polarity(struct amc6821_data *data)
@@ -970,7 +1042,11 @@ static int amc6821_probe(struct i2c_client *client)
"Failed to add fan node release action\n");
if (fan_np)
- amc6821_of_fan_read_data(data, fan_np);
+ err = amc6821_of_fan_read_data(client, data, fan_np);
+
+ if (err)
+ return dev_err_probe(dev, err,
+ "Failed to read fan device tree data\n");
err = amc6821_init_client(client, data);
if (err)
@@ -986,7 +1062,18 @@ static int amc6821_probe(struct i2c_client *client)
hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name,
data, &amc6821_chip_info,
amc6821_groups);
- return PTR_ERR_OR_ZERO(hwmon_dev);
+ if (IS_ERR(hwmon_dev))
+ return dev_err_probe(dev, PTR_ERR(hwmon_dev),
+ "Failed to initialize hwmon\n");
+
+ if (IS_ENABLED(CONFIG_THERMAL) && fan_np && data->fan_cooling_levels)
+ return PTR_ERR_OR_ZERO(devm_thermal_of_cooling_device_register(dev,
+ fan_np,
+ client->name,
+ data,
+ &amc6821_cooling_ops));
+
+ return 0;
}
static const struct i2c_device_id amc6821_id[] = {
--
2.43.0
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