On 02/18/2015 02:07 AM, Lukasz Majewski wrote:
This patch provides code for reading PWM FAN configuration data via
device tree. The pwm-fan can work with full speed when configuration
is not provided. However, errors are propagated when wrong DT bindings
are found.
Additionally the struct pwm_fan_ctx has been extended.
Signed-off-by: Lukasz Majewski <l.majewski@xxxxxxxxxxx>
---
Changes for v2:
- Rename pwm_fan_max_states to pwm_fan_cooling_levels
- Moving pwm_fan_of_get_cooling_data() call after setting end enabling PWM FAN
- pwm_fan_of_get_cooling_data() now can fail - preserving old behaviour
- Remove unnecessary dev_err() call
Changes for v3:
- Patch's headline has been reedited
- pwm_fan_of_get_cooling_data() return code is now being checked.
- of_property_count_elems_of_size() is now used instead of_find_property()
- More verbose patch description added
Changes for v4:
- dev_err() has been removed from pwm_fan_of_get_cooling_data()
- Returning -EINVAL when "cooling-levels" are defined in DT, but doesn't
have the value
---
drivers/hwmon/pwm-fan.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 51 insertions(+), 1 deletion(-)
diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
index bd42d39..82cd06a 100644
--- a/drivers/hwmon/pwm-fan.c
+++ b/drivers/hwmon/pwm-fan.c
@@ -30,7 +30,10 @@
struct pwm_fan_ctx {
struct mutex lock;
struct pwm_device *pwm;
- unsigned char pwm_value;
+ unsigned int pwm_value;
+ unsigned int pwm_fan_state;
+ unsigned int pwm_fan_max_state;
+ unsigned int *pwm_fan_cooling_levels;
};
static int __set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm)
@@ -100,6 +103,48 @@ static struct attribute *pwm_fan_attrs[] = {
ATTRIBUTE_GROUPS(pwm_fan);
+int pwm_fan_of_get_cooling_data(struct device *dev, struct pwm_fan_ctx *ctx)
+{
+ struct device_node *np = dev->of_node;
+ int num, i, ret;
+
+ ret = of_property_count_elems_of_size(np, "cooling-levels",
+ sizeof(u32));
+
+ if (ret == -EINVAL)
+ return 0;
The function returns -EINVAL if there is no such property,
but also if prop->length % elem_size != 0. The latter _would_
be an error.
Overall I don't entirely understand why you do not call
of_find_property first. If that returns NULL, you would know for sure
that the property does not exist, and you would not have to second
guess the returned error from of_property_count_elems_of_size.
On a side note, there is of_property_count_u32_elems() to count
properties of size u32.
+
+ if (ret <= 0) {
+ dev_err(dev, "Wrong data!\n");
+ return ret ? ret : -EINVAL;
+ }
If devicetree is not configured, of_property_count_elems_of_size
returns -ENOSYS, which is returned, causing the driver to fail loading.
+
+ num = ret;
+ ctx->pwm_fan_cooling_levels = devm_kzalloc(dev, num * sizeof(u32),
+ GFP_KERNEL);
+ if (!ctx->pwm_fan_cooling_levels)
+ return -ENOMEM;
+
+ ret = of_property_read_u32_array(np, "cooling-levels",
+ ctx->pwm_fan_cooling_levels, num);
+ if (ret) {
+ dev_err(dev, "Property 'cooling-levels' cannot be read!\n");
+ return ret;
+ }
+
+ for (i = 0; i < num; i++) {
+ if (ctx->pwm_fan_cooling_levels[i] > MAX_PWM) {
+ dev_err(dev, "PWM fan state[%d]:%d > %d\n", i,
+ ctx->pwm_fan_cooling_levels[i], MAX_PWM);
+ return -EINVAL;
+ }
+ }
+
+ ctx->pwm_fan_max_state = num - 1;
+
+ return 0;
+}
+
static int pwm_fan_probe(struct platform_device *pdev)
{
struct device *hwmon;
@@ -145,6 +190,11 @@ static int pwm_fan_probe(struct platform_device *pdev)
pwm_disable(ctx->pwm);
return PTR_ERR(hwmon);
}
+
+ ret = pwm_fan_of_get_cooling_data(&pdev->dev, ctx);
+ if (ret)
+ return ret;
+
return 0;
}
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