[PATCH 7/9] hwmon: thermal: Code for using PWM FAN as a cooling device

[Lukasz Majewski]

The PWM FAN device can now be used as a thermal cooling device. Necessary
infrastructure has been added in this commit.

Signed-off-by: Lukasz Majewski <l.majew...@samsung.com>
---
 drivers/hwmon/pwm-fan.c | 79 ++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 78 insertions(+), 1 deletion(-)

diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
index 5854bb3..97b77e9 100644
--- a/drivers/hwmon/pwm-fan.c
+++ b/drivers/hwmon/pwm-fan.c
@@ -24,6 +24,7 @@
 #include <linux/platform_device.h>
 #include <linux/pwm.h>
 #include <linux/sysfs.h>
+#include <linux/thermal.h>
 
 #define MAX_PWM 255
 
@@ -68,6 +69,17 @@ exit_set_pwm_err:
        return ret;
 }
 
+static void pwm_fan_update_state(struct pwm_fan_ctx *ctx, unsigned long pwm)
+{
+       int i;
+
+       for (i = 0; i < ctx->pwm_fan_max_state; ++i)
+               if (pwm < ctx->pwm_fan_cooling_states[i + 1])
+                       break;
+
+       ctx->pwm_fan_state = i;
+}
+
 static ssize_t set_pwm(struct device *dev, struct device_attribute *attr,
                       const char *buf, size_t count)
 {
@@ -82,6 +94,7 @@ static ssize_t set_pwm(struct device *dev, struct 
device_attribute *attr,
        if (ret)
                return ret;
 
+       pwm_fan_update_state(ctx, pwm);
        return count;
 }
 
@@ -103,6 +116,59 @@ static struct attribute *pwm_fan_attrs[] = {
 
 ATTRIBUTE_GROUPS(pwm_fan);
 
+/* thermal cooling device callbacks */
+static int pwm_fan_get_max_state(struct thermal_cooling_device *cdev,
+                                unsigned long *state)
+{
+       struct pwm_fan_ctx *ctx = cdev->devdata;
+
+       *state = ctx->pwm_fan_max_state;
+
+       return 0;
+}
+
+static int pwm_fan_get_cur_state(struct thermal_cooling_device *cdev,
+                                unsigned long *state)
+{
+       struct pwm_fan_ctx *ctx = cdev->devdata;
+
+       if (!ctx)
+               return -EINVAL;
+
+       *state = ctx->pwm_fan_state;
+
+       return 0;
+}
+
+static int
+pwm_fan_set_cur_state(struct thermal_cooling_device *cdev, unsigned long state)
+{
+       struct pwm_fan_ctx *ctx = cdev->devdata;
+       int ret;
+
+       if (!ctx || (state > ctx->pwm_fan_max_state))
+               return -EINVAL;
+
+       if (state == ctx->pwm_fan_state)
+               return 0;
+
+       ret = __set_pwm(ctx, ctx->pwm_fan_cooling_states[state]);
+       if (ret) {
+               dev_err(&cdev->device, "Cannot set pwm!\n");
+               return ret;
+       }
+
+       ctx->pwm_fan_state = state;
+
+       return ret;
+}
+
+static const struct thermal_cooling_device_ops pwm_fan_cooling_ops = {
+       .get_max_state = pwm_fan_get_max_state,
+       .get_cur_state = pwm_fan_get_cur_state,
+       .set_cur_state = pwm_fan_set_cur_state,
+};
+
 int pwm_fan_of_get_cooling_data(struct device *dev, struct pwm_fan_ctx *ctx)
 {
        struct device_node *np = dev->of_node;
@@ -148,8 +214,9 @@ int pwm_fan_of_get_cooling_data(struct device *dev, struct 
pwm_fan_ctx *ctx)
 
 static int pwm_fan_probe(struct platform_device *pdev)
 {
-       struct device *hwmon;
+       struct thermal_cooling_device *cdev;
        struct pwm_fan_ctx *ctx;
+       struct device *hwmon;
        int duty_cycle;
        int ret;
 
@@ -194,6 +261,16 @@ static int pwm_fan_probe(struct platform_device *pdev)
                pwm_disable(ctx->pwm);
                return PTR_ERR(hwmon);
        }
+
+       cdev = thermal_of_cooling_device_register(pdev->dev.of_node, "pwm-fan",
+                                                 ctx, &pwm_fan_cooling_ops);
+       if (IS_ERR(cdev)) {
+               dev_err(&pdev->dev,
+                       "Failed to register pwm-fan as thermal cooling device");
+               pwm_disable(ctx->pwm);
+               return PTR_ERR(cdev);
+       }
+
        return 0;
 }
 
-- 
2.0.0.rc2

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