Contrary to the gpio-fan the pwm-fan driver isn't easy to setup
with pwmconfig/fancontrol because of the missing hwmon sysfs entry
for actual revolutions per minute. This series adds this feature.
Changes in V4:
- remove copy & paste artifact in dt-binding example
- switch to u64 for rpm calculation
- drop overflow handling and init atomic
- handle 0 not as valid irq
- reduce range of pulses_per_revolution
- handle probe defer of platform_get_irq
- delete timer properly in bail-out path
Changes in V3:
- rename property interrupt-ratio to pulses-per-revolution
to avoid confusion with interrupt binding
- handle error case pulses-per-revolution = 0
- bail out properly in case we are unable to request the irq
Changes in V2:
- address Guenter's comments:
- improve description of interrupts
- use atomic_t to avoid races of the pulse counter
- measure sample time to make rpm more reliable under load
- make sysfs entry fan1_input conditional
- add dt-property to define interrupts per fan revolution
- example for fan with RPM support
Stefan Wahren (3):
dt-bindings: hwmon: Add tachometer interrupt to pwm-fan
Documentation: pwm-fan: Add description for RPM support
hwmon: pwm-fan: Add RPM support via external interrupt
.../devicetree/bindings/hwmon/pwm-fan.txt | 21 +++-
Documentation/hwmon/pwm-fan | 3 +
drivers/hwmon/pwm-fan.c | 111 ++++++++++++++++++++-
3 files changed, 130 insertions(+), 5 deletions(-)
--
2.7.4
This adds the tachometer interrupt to the pwm-fan binding, which is
necessary for RPM support.
Signed-off-by: Stefan Wahren <[email protected]>
Reviewed-by: Rob Herring <[email protected]>
---
Documentation/devicetree/bindings/hwmon/pwm-fan.txt | 21 ++++++++++++++++++++-
1 file changed, 20 insertions(+), 1 deletion(-)
diff --git a/Documentation/devicetree/bindings/hwmon/pwm-fan.txt b/Documentation/devicetree/bindings/hwmon/pwm-fan.txt
index 49ca5d8..6ced829b 100644
--- a/Documentation/devicetree/bindings/hwmon/pwm-fan.txt
+++ b/Documentation/devicetree/bindings/hwmon/pwm-fan.txt
@@ -7,7 +7,16 @@ Required properties:
which correspond to thermal cooling states
Optional properties:
-- fan-supply : phandle to the regulator that provides power to the fan
+- fan-supply : phandle to the regulator that provides power to the fan
+- interrupts : This contains a single interrupt specifier which
+ describes the tachometer output of the fan as an
+ interrupt source. The output signal must generate a
+ defined number of interrupts per fan revolution, which
+ require that it must be self resetting edge interrupts.
+ See interrupt-controller/interrupts.txt for the format.
+- pulses-per-revolution : define the tachometer pulses per fan revolution as
+ an integer (default is 2 interrupts per revolution).
+ The value must be greater than zero.
Example:
fan0: pwm-fan {
@@ -38,3 +47,13 @@ Example:
};
};
};
+
+Example 2:
+ fan0: pwm-fan {
+ compatible = "pwm-fan";
+ pwms = <&pwm 0 40000 0>;
+ fan-supply = <®_fan>;
+ interrupt-parent = <&gpio5>;
+ interrupts = <1 IRQ_TYPE_EDGE_FALLING>;
+ pulses-per-revolution = <2>;
+ };
--
2.7.4
This adds a short description for the new RPM support of the pwm-fan
driver.
Signed-off-by: Stefan Wahren <[email protected]>
---
Documentation/hwmon/pwm-fan | 3 +++
1 file changed, 3 insertions(+)
diff --git a/Documentation/hwmon/pwm-fan b/Documentation/hwmon/pwm-fan
index 18529d2..82fe967 100644
--- a/Documentation/hwmon/pwm-fan
+++ b/Documentation/hwmon/pwm-fan
@@ -15,3 +15,6 @@ The driver implements a simple interface for driving a fan connected to
a PWM output. It uses the generic PWM interface, thus it can be used with
a range of SoCs. The driver exposes the fan to the user space through
the hwmon's sysfs interface.
+
+The fan rotation speed returned via the optional 'fan1_input' is extrapolated
+from the sampled interrupts from the tachometer signal within 1 second.
--
2.7.4
This adds RPM support to the pwm-fan driver in order to use with
fancontrol/pwmconfig. This feature is intended for fans with a tachometer
output signal, which generate a defined number of pulses per revolution.
Signed-off-by: Stefan Wahren <[email protected]>
---
drivers/hwmon/pwm-fan.c | 111 ++++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 107 insertions(+), 4 deletions(-)
diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
index 167221c..3245a49 100644
--- a/drivers/hwmon/pwm-fan.c
+++ b/drivers/hwmon/pwm-fan.c
@@ -18,6 +18,7 @@
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
+#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/of.h>
@@ -26,6 +27,7 @@
#include <linux/regulator/consumer.h>
#include <linux/sysfs.h>
#include <linux/thermal.h>
+#include <linux/timer.h>
#define MAX_PWM 255
@@ -33,6 +35,14 @@ struct pwm_fan_ctx {
struct mutex lock;
struct pwm_device *pwm;
struct regulator *reg_en;
+
+ int irq;
+ atomic_t pulses;
+ unsigned int rpm;
+ u8 pulses_per_revolution;
+ ktime_t sample_start;
+ struct timer_list rpm_timer;
+
unsigned int pwm_value;
unsigned int pwm_fan_state;
unsigned int pwm_fan_max_state;
@@ -40,6 +50,32 @@ struct pwm_fan_ctx {
struct thermal_cooling_device *cdev;
};
+/* This handler assumes self resetting edge triggered interrupt. */
+static irqreturn_t pulse_handler(int irq, void *dev_id)
+{
+ struct pwm_fan_ctx *ctx = dev_id;
+
+ atomic_inc(&ctx->pulses);
+
+ return IRQ_HANDLED;
+}
+
+static void sample_timer(struct timer_list *t)
+{
+ struct pwm_fan_ctx *ctx = from_timer(ctx, t, rpm_timer);
+ int pulses;
+ u64 tmp;
+
+ pulses = atomic_read(&ctx->pulses);
+ atomic_sub(pulses, &ctx->pulses);
+ tmp = (u64)pulses * ktime_ms_delta(ktime_get(), ctx->sample_start) * 60;
+ do_div(tmp, ctx->pulses_per_revolution * 1000);
+ ctx->rpm = tmp;
+
+ ctx->sample_start = ktime_get();
+ mod_timer(&ctx->rpm_timer, jiffies + HZ);
+}
+
static int __set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm)
{
unsigned long period;
@@ -100,15 +136,49 @@ static ssize_t pwm_show(struct device *dev, struct device_attribute *attr,
return sprintf(buf, "%u\n", ctx->pwm_value);
}
+static ssize_t rpm_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
+
+ return sprintf(buf, "%u\n", ctx->rpm);
+}
static SENSOR_DEVICE_ATTR_RW(pwm1, pwm, 0);
+static SENSOR_DEVICE_ATTR_RO(fan1_input, rpm, 0);
static struct attribute *pwm_fan_attrs[] = {
&sensor_dev_attr_pwm1.dev_attr.attr,
+ &sensor_dev_attr_fan1_input.dev_attr.attr,
NULL,
};
-ATTRIBUTE_GROUPS(pwm_fan);
+static umode_t pwm_fan_attrs_visible(struct kobject *kobj, struct attribute *a,
+ int n)
+{
+ struct device *dev = container_of(kobj, struct device, kobj);
+ struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
+ struct device_attribute *devattr;
+
+ /* Hide fan_input in case no interrupt is available */
+ devattr = container_of(a, struct device_attribute, attr);
+ if (devattr == &sensor_dev_attr_fan1_input.dev_attr) {
+ if (ctx->irq <= 0)
+ return 0;
+ }
+
+ return a->mode;
+}
+
+static const struct attribute_group pwm_fan_group = {
+ .attrs = pwm_fan_attrs,
+ .is_visible = pwm_fan_attrs_visible,
+};
+
+static const struct attribute_group *pwm_fan_groups[] = {
+ &pwm_fan_group,
+ NULL,
+};
/* thermal cooling device callbacks */
static int pwm_fan_get_max_state(struct thermal_cooling_device *cdev,
@@ -261,17 +331,45 @@ static int pwm_fan_probe(struct platform_device *pdev)
goto err_reg_disable;
}
+ timer_setup(&ctx->rpm_timer, sample_timer, 0);
+
+ if (of_property_read_u8(pdev->dev.of_node, "pulses-per-revolution",
+ &ctx->pulses_per_revolution)) {
+ ctx->pulses_per_revolution = 2;
+ }
+
+ if (!ctx->pulses_per_revolution) {
+ dev_err(&pdev->dev, "pulses-per-revolution can't be zero.\n");
+ ret = -EINVAL;
+ goto err_pwm_disable;
+ }
+
+ ctx->irq = platform_get_irq(pdev, 0);
+ if (ctx->irq == -EPROBE_DEFER) {
+ ret = ctx->irq;
+ goto err_pwm_disable;
+ } else if (ctx->irq > 0) {
+ ret = devm_request_irq(&pdev->dev, ctx->irq, pulse_handler, 0,
+ pdev->name, ctx);
+ if (ret) {
+ dev_err(&pdev->dev, "Can't get interrupt working.\n");
+ goto err_pwm_disable;
+ }
+ ctx->sample_start = ktime_get();
+ mod_timer(&ctx->rpm_timer, jiffies + HZ);
+ }
+
hwmon = devm_hwmon_device_register_with_groups(&pdev->dev, "pwmfan",
ctx, pwm_fan_groups);
if (IS_ERR(hwmon)) {
dev_err(&pdev->dev, "Failed to register hwmon device\n");
ret = PTR_ERR(hwmon);
- goto err_pwm_disable;
+ goto err_del_timer;
}
ret = pwm_fan_of_get_cooling_data(&pdev->dev, ctx);
if (ret)
- return ret;
+ goto err_del_timer;
ctx->pwm_fan_state = ctx->pwm_fan_max_state;
if (IS_ENABLED(CONFIG_THERMAL)) {
@@ -282,7 +380,7 @@ static int pwm_fan_probe(struct platform_device *pdev)
dev_err(&pdev->dev,
"Failed to register pwm-fan as cooling device");
ret = PTR_ERR(cdev);
- goto err_pwm_disable;
+ goto err_del_timer;
}
ctx->cdev = cdev;
thermal_cdev_update(cdev);
@@ -290,6 +388,9 @@ static int pwm_fan_probe(struct platform_device *pdev)
return 0;
+err_del_timer:
+ del_timer_sync(&ctx->rpm_timer);
+
err_pwm_disable:
state.enabled = false;
pwm_apply_state(ctx->pwm, &state);
@@ -306,6 +407,8 @@ static int pwm_fan_remove(struct platform_device *pdev)
struct pwm_fan_ctx *ctx = platform_get_drvdata(pdev);
thermal_cooling_device_unregister(ctx->cdev);
+ del_timer_sync(&ctx->rpm_timer);
+
if (ctx->pwm_value)
pwm_disable(ctx->pwm);
--
2.7.4
On Tue, Apr 02, 2019 at 04:21:50PM +0200, Stefan Wahren wrote:
> This adds RPM support to the pwm-fan driver in order to use with
> fancontrol/pwmconfig. This feature is intended for fans with a tachometer
> output signal, which generate a defined number of pulses per revolution.
>
> Signed-off-by: Stefan Wahren <[email protected]>
> ---
> drivers/hwmon/pwm-fan.c | 111 ++++++++++++++++++++++++++++++++++++++++++++++--
> 1 file changed, 107 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
> index 167221c..3245a49 100644
> --- a/drivers/hwmon/pwm-fan.c
> +++ b/drivers/hwmon/pwm-fan.c
> @@ -18,6 +18,7 @@
>
> #include <linux/hwmon.h>
> #include <linux/hwmon-sysfs.h>
> +#include <linux/interrupt.h>
> #include <linux/module.h>
> #include <linux/mutex.h>
> #include <linux/of.h>
> @@ -26,6 +27,7 @@
> #include <linux/regulator/consumer.h>
> #include <linux/sysfs.h>
> #include <linux/thermal.h>
> +#include <linux/timer.h>
>
> #define MAX_PWM 255
>
> @@ -33,6 +35,14 @@ struct pwm_fan_ctx {
> struct mutex lock;
> struct pwm_device *pwm;
> struct regulator *reg_en;
> +
> + int irq;
> + atomic_t pulses;
> + unsigned int rpm;
> + u8 pulses_per_revolution;
> + ktime_t sample_start;
> + struct timer_list rpm_timer;
> +
> unsigned int pwm_value;
> unsigned int pwm_fan_state;
> unsigned int pwm_fan_max_state;
> @@ -40,6 +50,32 @@ struct pwm_fan_ctx {
> struct thermal_cooling_device *cdev;
> };
>
> +/* This handler assumes self resetting edge triggered interrupt. */
> +static irqreturn_t pulse_handler(int irq, void *dev_id)
> +{
> + struct pwm_fan_ctx *ctx = dev_id;
> +
> + atomic_inc(&ctx->pulses);
> +
> + return IRQ_HANDLED;
> +}
> +
> +static void sample_timer(struct timer_list *t)
> +{
> + struct pwm_fan_ctx *ctx = from_timer(ctx, t, rpm_timer);
> + int pulses;
> + u64 tmp;
> +
> + pulses = atomic_read(&ctx->pulses);
> + atomic_sub(pulses, &ctx->pulses);
> + tmp = (u64)pulses * ktime_ms_delta(ktime_get(), ctx->sample_start) * 60;
> + do_div(tmp, ctx->pulses_per_revolution * 1000);
> + ctx->rpm = tmp;
> +
> + ctx->sample_start = ktime_get();
> + mod_timer(&ctx->rpm_timer, jiffies + HZ);
> +}
> +
> static int __set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm)
> {
> unsigned long period;
> @@ -100,15 +136,49 @@ static ssize_t pwm_show(struct device *dev, struct device_attribute *attr,
> return sprintf(buf, "%u\n", ctx->pwm_value);
> }
>
> +static ssize_t rpm_show(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
> +
> + return sprintf(buf, "%u\n", ctx->rpm);
> +}
>
> static SENSOR_DEVICE_ATTR_RW(pwm1, pwm, 0);
> +static SENSOR_DEVICE_ATTR_RO(fan1_input, rpm, 0);
>
> static struct attribute *pwm_fan_attrs[] = {
> &sensor_dev_attr_pwm1.dev_attr.attr,
> + &sensor_dev_attr_fan1_input.dev_attr.attr,
> NULL,
> };
>
> -ATTRIBUTE_GROUPS(pwm_fan);
> +static umode_t pwm_fan_attrs_visible(struct kobject *kobj, struct attribute *a,
> + int n)
> +{
> + struct device *dev = container_of(kobj, struct device, kobj);
> + struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
> + struct device_attribute *devattr;
> +
> + /* Hide fan_input in case no interrupt is available */
> + devattr = container_of(a, struct device_attribute, attr);
> + if (devattr == &sensor_dev_attr_fan1_input.dev_attr) {
> + if (ctx->irq <= 0)
> + return 0;
> + }
Side note: This can be easier written as
if (n == 1 && ctx->irq <= 0)
return 0;
Not that it matters much.
> +
> + return a->mode;
> +}
> +
> +static const struct attribute_group pwm_fan_group = {
> + .attrs = pwm_fan_attrs,
> + .is_visible = pwm_fan_attrs_visible,
> +};
> +
> +static const struct attribute_group *pwm_fan_groups[] = {
> + &pwm_fan_group,
> + NULL,
> +};
>
> /* thermal cooling device callbacks */
> static int pwm_fan_get_max_state(struct thermal_cooling_device *cdev,
> @@ -261,17 +331,45 @@ static int pwm_fan_probe(struct platform_device *pdev)
> goto err_reg_disable;
> }
>
> + timer_setup(&ctx->rpm_timer, sample_timer, 0);
> +
> + if (of_property_read_u8(pdev->dev.of_node, "pulses-per-revolution",
This does not work: The property is not defined as u8. You have to either
use of_property_read_u32() or declare the property as u8.
[ Sorry, I didn't know until recently that this is necessary ]
> + &ctx->pulses_per_revolution)) {
> + ctx->pulses_per_revolution = 2;
> + }
> +
> + if (!ctx->pulses_per_revolution) {
> + dev_err(&pdev->dev, "pulses-per-revolution can't be zero.\n");
> + ret = -EINVAL;
> + goto err_pwm_disable;
> + }
> +
> + ctx->irq = platform_get_irq(pdev, 0);
> + if (ctx->irq == -EPROBE_DEFER) {
> + ret = ctx->irq;
> + goto err_pwm_disable;
It might be better to call platform_get_irq() and to do do this check
first, before enabling the regulator (in practice before calling
devm_regulator_get_optional). It doesn't make sense to enable the
regulator only to disable it because the irq is not yet available.
> + } else if (ctx->irq > 0) {
As written, this else is unnecessary, and static checkers will complain
about it.
> + ret = devm_request_irq(&pdev->dev, ctx->irq, pulse_handler, 0,
> + pdev->name, ctx);
> + if (ret) {
> + dev_err(&pdev->dev, "Can't get interrupt working.\n");
> + goto err_pwm_disable;
> + }
> + ctx->sample_start = ktime_get();
> + mod_timer(&ctx->rpm_timer, jiffies + HZ);
> + }
> +
> hwmon = devm_hwmon_device_register_with_groups(&pdev->dev, "pwmfan",
> ctx, pwm_fan_groups);
> if (IS_ERR(hwmon)) {
> dev_err(&pdev->dev, "Failed to register hwmon device\n");
> ret = PTR_ERR(hwmon);
> - goto err_pwm_disable;
> + goto err_del_timer;
> }
>
> ret = pwm_fan_of_get_cooling_data(&pdev->dev, ctx);
> if (ret)
> - return ret;
> + goto err_del_timer;
Outch. This is buggy and should have been "goto err_pwm_disable;".
It needs to be fixed with a separate patch, and first, so we can
backport it. Can you do that ?
>
> ctx->pwm_fan_state = ctx->pwm_fan_max_state;
> if (IS_ENABLED(CONFIG_THERMAL)) {
> @@ -282,7 +380,7 @@ static int pwm_fan_probe(struct platform_device *pdev)
> dev_err(&pdev->dev,
> "Failed to register pwm-fan as cooling device");
> ret = PTR_ERR(cdev);
> - goto err_pwm_disable;
> + goto err_del_timer;
> }
> ctx->cdev = cdev;
> thermal_cdev_update(cdev);
> @@ -290,6 +388,9 @@ static int pwm_fan_probe(struct platform_device *pdev)
>
> return 0;
>
> +err_del_timer:
> + del_timer_sync(&ctx->rpm_timer);
> +
> err_pwm_disable:
> state.enabled = false;
> pwm_apply_state(ctx->pwm, &state);
> @@ -306,6 +407,8 @@ static int pwm_fan_remove(struct platform_device *pdev)
> struct pwm_fan_ctx *ctx = platform_get_drvdata(pdev);
>
> thermal_cooling_device_unregister(ctx->cdev);
> + del_timer_sync(&ctx->rpm_timer);
> +
> if (ctx->pwm_value)
> pwm_disable(ctx->pwm);
>
> --
> 2.7.4
>
Hi Guenter,
Am 02.04.19 um 22:55 schrieb Guenter Roeck:
> On Tue, Apr 02, 2019 at 04:21:50PM +0200, Stefan Wahren wrote:
>> This adds RPM support to the pwm-fan driver in order to use with
>> fancontrol/pwmconfig. This feature is intended for fans with a tachometer
>> output signal, which generate a defined number of pulses per revolution.
>>
>> Signed-off-by: Stefan Wahren <[email protected]>
>> ---
>> drivers/hwmon/pwm-fan.c | 111 ++++++++++++++++++++++++++++++++++++++++++++++--
>> 1 file changed, 107 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
>> index 167221c..3245a49 100644
>> --- a/drivers/hwmon/pwm-fan.c
>> +++ b/drivers/hwmon/pwm-fan.c
>> @@ -18,6 +18,7 @@
>>
>> #include <linux/hwmon.h>
>> #include <linux/hwmon-sysfs.h>
>> +#include <linux/interrupt.h>
>> #include <linux/module.h>
>> #include <linux/mutex.h>
>> #include <linux/of.h>
>> @@ -26,6 +27,7 @@
>> #include <linux/regulator/consumer.h>
>> #include <linux/sysfs.h>
>> #include <linux/thermal.h>
>> +#include <linux/timer.h>
>>
>> #define MAX_PWM 255
>>
>> @@ -33,6 +35,14 @@ struct pwm_fan_ctx {
>> struct mutex lock;
>> struct pwm_device *pwm;
>> struct regulator *reg_en;
>> +
>> + int irq;
>> + atomic_t pulses;
>> + unsigned int rpm;
>> + u8 pulses_per_revolution;
>> + ktime_t sample_start;
>> + struct timer_list rpm_timer;
>> +
>> unsigned int pwm_value;
>> unsigned int pwm_fan_state;
>> unsigned int pwm_fan_max_state;
>> @@ -40,6 +50,32 @@ struct pwm_fan_ctx {
>> struct thermal_cooling_device *cdev;
>> };
>>
>> +/* This handler assumes self resetting edge triggered interrupt. */
>> +static irqreturn_t pulse_handler(int irq, void *dev_id)
>> +{
>> + struct pwm_fan_ctx *ctx = dev_id;
>> +
>> + atomic_inc(&ctx->pulses);
>> +
>> + return IRQ_HANDLED;
>> +}
>> +
>> +static void sample_timer(struct timer_list *t)
>> +{
>> + struct pwm_fan_ctx *ctx = from_timer(ctx, t, rpm_timer);
>> + int pulses;
>> + u64 tmp;
>> +
>> + pulses = atomic_read(&ctx->pulses);
>> + atomic_sub(pulses, &ctx->pulses);
>> + tmp = (u64)pulses * ktime_ms_delta(ktime_get(), ctx->sample_start) * 60;
>> + do_div(tmp, ctx->pulses_per_revolution * 1000);
>> + ctx->rpm = tmp;
>> +
>> + ctx->sample_start = ktime_get();
>> + mod_timer(&ctx->rpm_timer, jiffies + HZ);
>> +}
>> +
>> static int __set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm)
>> {
>> unsigned long period;
>> @@ -100,15 +136,49 @@ static ssize_t pwm_show(struct device *dev, struct device_attribute *attr,
>> return sprintf(buf, "%u\n", ctx->pwm_value);
>> }
>>
>> +static ssize_t rpm_show(struct device *dev,
>> + struct device_attribute *attr, char *buf)
>> +{
>> + struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
>> +
>> + return sprintf(buf, "%u\n", ctx->rpm);
>> +}
>>
>> static SENSOR_DEVICE_ATTR_RW(pwm1, pwm, 0);
>> +static SENSOR_DEVICE_ATTR_RO(fan1_input, rpm, 0);
>>
>> static struct attribute *pwm_fan_attrs[] = {
>> &sensor_dev_attr_pwm1.dev_attr.attr,
>> + &sensor_dev_attr_fan1_input.dev_attr.attr,
>> NULL,
>> };
>>
>> -ATTRIBUTE_GROUPS(pwm_fan);
>> +static umode_t pwm_fan_attrs_visible(struct kobject *kobj, struct attribute *a,
>> + int n)
>> +{
>> + struct device *dev = container_of(kobj, struct device, kobj);
>> + struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
>> + struct device_attribute *devattr;
>> +
>> + /* Hide fan_input in case no interrupt is available */
>> + devattr = container_of(a, struct device_attribute, attr);
>> + if (devattr == &sensor_dev_attr_fan1_input.dev_attr) {
>> + if (ctx->irq <= 0)
>> + return 0;
>> + }
> Side note: This can be easier written as
> if (n == 1 && ctx->irq <= 0)
> return 0;
>
> Not that it matters much.
>
>> +
>> + return a->mode;
>> +}
>> +
>> +static const struct attribute_group pwm_fan_group = {
>> + .attrs = pwm_fan_attrs,
>> + .is_visible = pwm_fan_attrs_visible,
>> +};
>> +
>> +static const struct attribute_group *pwm_fan_groups[] = {
>> + &pwm_fan_group,
>> + NULL,
>> +};
>>
>> /* thermal cooling device callbacks */
>> static int pwm_fan_get_max_state(struct thermal_cooling_device *cdev,
>> @@ -261,17 +331,45 @@ static int pwm_fan_probe(struct platform_device *pdev)
>> goto err_reg_disable;
>> }
>>
>> + timer_setup(&ctx->rpm_timer, sample_timer, 0);
>> +
>> + if (of_property_read_u8(pdev->dev.of_node, "pulses-per-revolution",
> This does not work: The property is not defined as u8. You have to either
> use of_property_read_u32() or declare the property as u8.
pulses_per_revolution is defined as u8 since this version
>
> [ Sorry, I didn't know until recently that this is necessary ]
>
>> + &ctx->pulses_per_revolution)) {
>> + ctx->pulses_per_revolution = 2;
>> + }
>> +
>> + if (!ctx->pulses_per_revolution) {
>> + dev_err(&pdev->dev, "pulses-per-revolution can't be zero.\n");
>> + ret = -EINVAL;
>> + goto err_pwm_disable;
>> + }
>> +
>> + ctx->irq = platform_get_irq(pdev, 0);
>> + if (ctx->irq == -EPROBE_DEFER) {
>> + ret = ctx->irq;
>> + goto err_pwm_disable;
> It might be better to call platform_get_irq() and to do do this check
> first, before enabling the regulator (in practice before calling
> devm_regulator_get_optional). It doesn't make sense to enable the
> regulator only to disable it because the irq is not yet available.
>
>> + } else if (ctx->irq > 0) {
> As written, this else is unnecessary, and static checkers will complain
> about it.
>
>> + ret = devm_request_irq(&pdev->dev, ctx->irq, pulse_handler, 0,
>> + pdev->name, ctx);
>> + if (ret) {
>> + dev_err(&pdev->dev, "Can't get interrupt working.\n");
>> + goto err_pwm_disable;
>> + }
>> + ctx->sample_start = ktime_get();
>> + mod_timer(&ctx->rpm_timer, jiffies + HZ);
>> + }
>> +
>> hwmon = devm_hwmon_device_register_with_groups(&pdev->dev, "pwmfan",
>> ctx, pwm_fan_groups);
>> if (IS_ERR(hwmon)) {
>> dev_err(&pdev->dev, "Failed to register hwmon device\n");
>> ret = PTR_ERR(hwmon);
>> - goto err_pwm_disable;
>> + goto err_del_timer;
>> }
>>
>> ret = pwm_fan_of_get_cooling_data(&pdev->dev, ctx);
>> if (ret)
>> - return ret;
>> + goto err_del_timer;
> Outch. This is buggy and should have been "goto err_pwm_disable;".
> It needs to be fixed with a separate patch, and first, so we can
> backport it. Can you do that ?
Sure
Stefan
On 03/04/2019 10:55, Stefan Wahren wrote:
> Hi Guenter,
>
> Am 02.04.19 um 22:55 schrieb Guenter Roeck:
>> On Tue, Apr 02, 2019 at 04:21:50PM +0200, Stefan Wahren wrote:
>>> This adds RPM support to the pwm-fan driver in order to use with
>>> fancontrol/pwmconfig. This feature is intended for fans with a tachometer
>>> output signal, which generate a defined number of pulses per revolution.
>>>
>>> Signed-off-by: Stefan Wahren <[email protected]>
>>> ---
>>> drivers/hwmon/pwm-fan.c | 111 ++++++++++++++++++++++++++++++++++++++++++++++--
>>> 1 file changed, 107 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
>>> index 167221c..3245a49 100644
>>> --- a/drivers/hwmon/pwm-fan.c
>>> +++ b/drivers/hwmon/pwm-fan.c
>>> @@ -18,6 +18,7 @@
>>>
>>> #include <linux/hwmon.h>
>>> #include <linux/hwmon-sysfs.h>
>>> +#include <linux/interrupt.h>
>>> #include <linux/module.h>
>>> #include <linux/mutex.h>
>>> #include <linux/of.h>
>>> @@ -26,6 +27,7 @@
>>> #include <linux/regulator/consumer.h>
>>> #include <linux/sysfs.h>
>>> #include <linux/thermal.h>
>>> +#include <linux/timer.h>
>>>
>>> #define MAX_PWM 255
>>>
>>> @@ -33,6 +35,14 @@ struct pwm_fan_ctx {
>>> struct mutex lock;
>>> struct pwm_device *pwm;
>>> struct regulator *reg_en;
>>> +
>>> + int irq;
>>> + atomic_t pulses;
>>> + unsigned int rpm;
>>> + u8 pulses_per_revolution;
>>> + ktime_t sample_start;
>>> + struct timer_list rpm_timer;
>>> +
>>> unsigned int pwm_value;
>>> unsigned int pwm_fan_state;
>>> unsigned int pwm_fan_max_state;
>>> @@ -40,6 +50,32 @@ struct pwm_fan_ctx {
>>> struct thermal_cooling_device *cdev;
>>> };
>>>
>>> +/* This handler assumes self resetting edge triggered interrupt. */
>>> +static irqreturn_t pulse_handler(int irq, void *dev_id)
>>> +{
>>> + struct pwm_fan_ctx *ctx = dev_id;
>>> +
>>> + atomic_inc(&ctx->pulses);
>>> +
>>> + return IRQ_HANDLED;
>>> +}
>>> +
>>> +static void sample_timer(struct timer_list *t)
>>> +{
>>> + struct pwm_fan_ctx *ctx = from_timer(ctx, t, rpm_timer);
>>> + int pulses;
>>> + u64 tmp;
>>> +
>>> + pulses = atomic_read(&ctx->pulses);
>>> + atomic_sub(pulses, &ctx->pulses);
>>> + tmp = (u64)pulses * ktime_ms_delta(ktime_get(), ctx->sample_start) * 60;
>>> + do_div(tmp, ctx->pulses_per_revolution * 1000);
>>> + ctx->rpm = tmp;
>>> +
>>> + ctx->sample_start = ktime_get();
>>> + mod_timer(&ctx->rpm_timer, jiffies + HZ);
>>> +}
>>> +
>>> static int __set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm)
>>> {
>>> unsigned long period;
>>> @@ -100,15 +136,49 @@ static ssize_t pwm_show(struct device *dev, struct device_attribute *attr,
>>> return sprintf(buf, "%u\n", ctx->pwm_value);
>>> }
>>>
>>> +static ssize_t rpm_show(struct device *dev,
>>> + struct device_attribute *attr, char *buf)
>>> +{
>>> + struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
>>> +
>>> + return sprintf(buf, "%u\n", ctx->rpm);
>>> +}
>>>
>>> static SENSOR_DEVICE_ATTR_RW(pwm1, pwm, 0);
>>> +static SENSOR_DEVICE_ATTR_RO(fan1_input, rpm, 0);
>>>
>>> static struct attribute *pwm_fan_attrs[] = {
>>> &sensor_dev_attr_pwm1.dev_attr.attr,
>>> + &sensor_dev_attr_fan1_input.dev_attr.attr,
>>> NULL,
>>> };
>>>
>>> -ATTRIBUTE_GROUPS(pwm_fan);
>>> +static umode_t pwm_fan_attrs_visible(struct kobject *kobj, struct attribute *a,
>>> + int n)
>>> +{
>>> + struct device *dev = container_of(kobj, struct device, kobj);
>>> + struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
>>> + struct device_attribute *devattr;
>>> +
>>> + /* Hide fan_input in case no interrupt is available */
>>> + devattr = container_of(a, struct device_attribute, attr);
>>> + if (devattr == &sensor_dev_attr_fan1_input.dev_attr) {
>>> + if (ctx->irq <= 0)
>>> + return 0;
>>> + }
>> Side note: This can be easier written as
>> if (n == 1 && ctx->irq <= 0)
>> return 0;
>>
>> Not that it matters much.
>>
>>> +
>>> + return a->mode;
>>> +}
>>> +
>>> +static const struct attribute_group pwm_fan_group = {
>>> + .attrs = pwm_fan_attrs,
>>> + .is_visible = pwm_fan_attrs_visible,
>>> +};
>>> +
>>> +static const struct attribute_group *pwm_fan_groups[] = {
>>> + &pwm_fan_group,
>>> + NULL,
>>> +};
>>>
>>> /* thermal cooling device callbacks */
>>> static int pwm_fan_get_max_state(struct thermal_cooling_device *cdev,
>>> @@ -261,17 +331,45 @@ static int pwm_fan_probe(struct platform_device *pdev)
>>> goto err_reg_disable;
>>> }
>>>
>>> + timer_setup(&ctx->rpm_timer, sample_timer, 0);
>>> +
>>> + if (of_property_read_u8(pdev->dev.of_node, "pulses-per-revolution",
>> This does not work: The property is not defined as u8. You have to either
>> use of_property_read_u32() or declare the property as u8.
> pulses_per_revolution is defined as u8 since this version
The variable might be, but the "pulses-per-revolution" property itself
is not being defined with the appropriate DT type ("/bits/ 8") in the
binding, and thus will be stored as a regular 32-bit cell, for which
reading it as a u8 array may or may not work correctly depending on
endianness.
TBH, unless there's a real need for a specific binary format in the FDT,
I don't think it's usually worth the bother of using irregular DT types,
especially when the practical impact amounts to possibly saving up to 3
bytes for a property which usually won't need to be specified anyway.
I'd just do something like:
u32 ppr = 2;
of_property_read_u32(np, "pulses-per-revolution", &ppr);
ctx->pulses_per_revolution = ppr;
>>
>> [ Sorry, I didn't know until recently that this is necessary ]
>>
>>> + &ctx->pulses_per_revolution)) {
>>> + ctx->pulses_per_revolution = 2;
>>> + }
>>> +
>>> + if (!ctx->pulses_per_revolution) {
>>> + dev_err(&pdev->dev, "pulses-per-revolution can't be zero.\n");
>>> + ret = -EINVAL;
>>> + goto err_pwm_disable;
>>> + }
>>> +
>>> + ctx->irq = platform_get_irq(pdev, 0);
>>> + if (ctx->irq == -EPROBE_DEFER) {
>>> + ret = ctx->irq;
>>> + goto err_pwm_disable;
>> It might be better to call platform_get_irq() and to do do this check
>> first, before enabling the regulator (in practice before calling
>> devm_regulator_get_optional). It doesn't make sense to enable the
>> regulator only to disable it because the irq is not yet available.
>>
>>> + } else if (ctx->irq > 0) {
>> As written, this else is unnecessary, and static checkers will complain
>> about it.
>>
>>> + ret = devm_request_irq(&pdev->dev, ctx->irq, pulse_handler, 0,
>>> + pdev->name, ctx);
>>> + if (ret) {
>>> + dev_err(&pdev->dev, "Can't get interrupt working.\n");
>>> + goto err_pwm_disable;
We could still continue without RPM support at this point, couldn't we?
Or is this a deliberate "if that failed, then who knows how messed up
the system is..." kind of thing?
Robin.
>>> + }
>>> + ctx->sample_start = ktime_get();
>>> + mod_timer(&ctx->rpm_timer, jiffies + HZ);
>>> + }
>>> +
>>> hwmon = devm_hwmon_device_register_with_groups(&pdev->dev, "pwmfan",
>>> ctx, pwm_fan_groups);
>>> if (IS_ERR(hwmon)) {
>>> dev_err(&pdev->dev, "Failed to register hwmon device\n");
>>> ret = PTR_ERR(hwmon);
>>> - goto err_pwm_disable;
>>> + goto err_del_timer;
>>> }
>>>
>>> ret = pwm_fan_of_get_cooling_data(&pdev->dev, ctx);
>>> if (ret)
>>> - return ret;
>>> + goto err_del_timer;
>> Outch. This is buggy and should have been "goto err_pwm_disable;".
>> It needs to be fixed with a separate patch, and first, so we can
>> backport it. Can you do that ?
>
> Sure
>
> Stefan
>
On Wed, Apr 03, 2019 at 04:59:35PM +0100, Robin Murphy wrote:
> On 03/04/2019 10:55, Stefan Wahren wrote:
> >Hi Guenter,
> >
> >Am 02.04.19 um 22:55 schrieb Guenter Roeck:
> >>On Tue, Apr 02, 2019 at 04:21:50PM +0200, Stefan Wahren wrote:
> >>>This adds RPM support to the pwm-fan driver in order to use with
> >>>fancontrol/pwmconfig. This feature is intended for fans with a tachometer
> >>>output signal, which generate a defined number of pulses per revolution.
> >>>
> >>>Signed-off-by: Stefan Wahren <[email protected]>
> >>>---
> >>> drivers/hwmon/pwm-fan.c | 111 ++++++++++++++++++++++++++++++++++++++++++++++--
> >>> 1 file changed, 107 insertions(+), 4 deletions(-)
> >>>
> >>>diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
> >>>index 167221c..3245a49 100644
> >>>--- a/drivers/hwmon/pwm-fan.c
> >>>+++ b/drivers/hwmon/pwm-fan.c
> >>>@@ -18,6 +18,7 @@
> >>> #include <linux/hwmon.h>
> >>> #include <linux/hwmon-sysfs.h>
> >>>+#include <linux/interrupt.h>
> >>> #include <linux/module.h>
> >>> #include <linux/mutex.h>
> >>> #include <linux/of.h>
> >>>@@ -26,6 +27,7 @@
> >>> #include <linux/regulator/consumer.h>
> >>> #include <linux/sysfs.h>
> >>> #include <linux/thermal.h>
> >>>+#include <linux/timer.h>
> >>> #define MAX_PWM 255
> >>>@@ -33,6 +35,14 @@ struct pwm_fan_ctx {
> >>> struct mutex lock;
> >>> struct pwm_device *pwm;
> >>> struct regulator *reg_en;
> >>>+
> >>>+ int irq;
> >>>+ atomic_t pulses;
> >>>+ unsigned int rpm;
> >>>+ u8 pulses_per_revolution;
> >>>+ ktime_t sample_start;
> >>>+ struct timer_list rpm_timer;
> >>>+
> >>> unsigned int pwm_value;
> >>> unsigned int pwm_fan_state;
> >>> unsigned int pwm_fan_max_state;
> >>>@@ -40,6 +50,32 @@ struct pwm_fan_ctx {
> >>> struct thermal_cooling_device *cdev;
> >>> };
> >>>+/* This handler assumes self resetting edge triggered interrupt. */
> >>>+static irqreturn_t pulse_handler(int irq, void *dev_id)
> >>>+{
> >>>+ struct pwm_fan_ctx *ctx = dev_id;
> >>>+
> >>>+ atomic_inc(&ctx->pulses);
> >>>+
> >>>+ return IRQ_HANDLED;
> >>>+}
> >>>+
> >>>+static void sample_timer(struct timer_list *t)
> >>>+{
> >>>+ struct pwm_fan_ctx *ctx = from_timer(ctx, t, rpm_timer);
> >>>+ int pulses;
> >>>+ u64 tmp;
> >>>+
> >>>+ pulses = atomic_read(&ctx->pulses);
> >>>+ atomic_sub(pulses, &ctx->pulses);
> >>>+ tmp = (u64)pulses * ktime_ms_delta(ktime_get(), ctx->sample_start) * 60;
> >>>+ do_div(tmp, ctx->pulses_per_revolution * 1000);
> >>>+ ctx->rpm = tmp;
> >>>+
> >>>+ ctx->sample_start = ktime_get();
> >>>+ mod_timer(&ctx->rpm_timer, jiffies + HZ);
> >>>+}
> >>>+
> >>> static int __set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm)
> >>> {
> >>> unsigned long period;
> >>>@@ -100,15 +136,49 @@ static ssize_t pwm_show(struct device *dev, struct device_attribute *attr,
> >>> return sprintf(buf, "%u\n", ctx->pwm_value);
> >>> }
> >>>+static ssize_t rpm_show(struct device *dev,
> >>>+ struct device_attribute *attr, char *buf)
> >>>+{
> >>>+ struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
> >>>+
> >>>+ return sprintf(buf, "%u\n", ctx->rpm);
> >>>+}
> >>> static SENSOR_DEVICE_ATTR_RW(pwm1, pwm, 0);
> >>>+static SENSOR_DEVICE_ATTR_RO(fan1_input, rpm, 0);
> >>> static struct attribute *pwm_fan_attrs[] = {
> >>> &sensor_dev_attr_pwm1.dev_attr.attr,
> >>>+ &sensor_dev_attr_fan1_input.dev_attr.attr,
> >>> NULL,
> >>> };
> >>>-ATTRIBUTE_GROUPS(pwm_fan);
> >>>+static umode_t pwm_fan_attrs_visible(struct kobject *kobj, struct attribute *a,
> >>>+ int n)
> >>>+{
> >>>+ struct device *dev = container_of(kobj, struct device, kobj);
> >>>+ struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
> >>>+ struct device_attribute *devattr;
> >>>+
> >>>+ /* Hide fan_input in case no interrupt is available */
> >>>+ devattr = container_of(a, struct device_attribute, attr);
> >>>+ if (devattr == &sensor_dev_attr_fan1_input.dev_attr) {
> >>>+ if (ctx->irq <= 0)
> >>>+ return 0;
> >>>+ }
> >>Side note: This can be easier written as
> >> if (n == 1 && ctx->irq <= 0)
> >> return 0;
> >>
> >>Not that it matters much.
> >>
> >>>+
> >>>+ return a->mode;
> >>>+}
> >>>+
> >>>+static const struct attribute_group pwm_fan_group = {
> >>>+ .attrs = pwm_fan_attrs,
> >>>+ .is_visible = pwm_fan_attrs_visible,
> >>>+};
> >>>+
> >>>+static const struct attribute_group *pwm_fan_groups[] = {
> >>>+ &pwm_fan_group,
> >>>+ NULL,
> >>>+};
> >>> /* thermal cooling device callbacks */
> >>> static int pwm_fan_get_max_state(struct thermal_cooling_device *cdev,
> >>>@@ -261,17 +331,45 @@ static int pwm_fan_probe(struct platform_device *pdev)
> >>> goto err_reg_disable;
> >>> }
> >>>+ timer_setup(&ctx->rpm_timer, sample_timer, 0);
> >>>+
> >>>+ if (of_property_read_u8(pdev->dev.of_node, "pulses-per-revolution",
> >>This does not work: The property is not defined as u8. You have to either
> >>use of_property_read_u32() or declare the property as u8.
> >pulses_per_revolution is defined as u8 since this version
>
> The variable might be, but the "pulses-per-revolution" property itself is
> not being defined with the appropriate DT type ("/bits/ 8") in the binding,
> and thus will be stored as a regular 32-bit cell, for which reading it as a
> u8 array may or may not work correctly depending on endianness.
>
> TBH, unless there's a real need for a specific binary format in the FDT, I
> don't think it's usually worth the bother of using irregular DT types,
> especially when the practical impact amounts to possibly saving up to 3
> bytes for a property which usually won't need to be specified anyway. I'd
> just do something like:
>
> u32 ppr = 2;
>
> of_property_read_u32(np, "pulses-per-revolution", &ppr);
> ctx->pulses_per_revolution = ppr;
>
+1
Thanks,
Guenter
> >>
> >>[ Sorry, I didn't know until recently that this is necessary ]
> >>
> >>>+ &ctx->pulses_per_revolution)) {
> >>>+ ctx->pulses_per_revolution = 2;
> >>>+ }
> >>>+
> >>>+ if (!ctx->pulses_per_revolution) {
> >>>+ dev_err(&pdev->dev, "pulses-per-revolution can't be zero.\n");
> >>>+ ret = -EINVAL;
> >>>+ goto err_pwm_disable;
> >>>+ }
> >>>+
> >>>+ ctx->irq = platform_get_irq(pdev, 0);
> >>>+ if (ctx->irq == -EPROBE_DEFER) {
> >>>+ ret = ctx->irq;
> >>>+ goto err_pwm_disable;
> >>It might be better to call platform_get_irq() and to do do this check
> >>first, before enabling the regulator (in practice before calling
> >>devm_regulator_get_optional). It doesn't make sense to enable the
> >>regulator only to disable it because the irq is not yet available.
> >>
> >>>+ } else if (ctx->irq > 0) {
> >>As written, this else is unnecessary, and static checkers will complain
> >>about it.
> >>
> >>>+ ret = devm_request_irq(&pdev->dev, ctx->irq, pulse_handler, 0,
> >>>+ pdev->name, ctx);
> >>>+ if (ret) {
> >>>+ dev_err(&pdev->dev, "Can't get interrupt working.\n");
> >>>+ goto err_pwm_disable;
>
> We could still continue without RPM support at this point, couldn't we? Or
> is this a deliberate "if that failed, then who knows how messed up the
> system is..." kind of thing?
>
> Robin.
>
> >>>+ }
> >>>+ ctx->sample_start = ktime_get();
> >>>+ mod_timer(&ctx->rpm_timer, jiffies + HZ);
> >>>+ }
> >>>+
> >>> hwmon = devm_hwmon_device_register_with_groups(&pdev->dev, "pwmfan",
> >>> ctx, pwm_fan_groups);
> >>> if (IS_ERR(hwmon)) {
> >>> dev_err(&pdev->dev, "Failed to register hwmon device\n");
> >>> ret = PTR_ERR(hwmon);
> >>>- goto err_pwm_disable;
> >>>+ goto err_del_timer;
> >>> }
> >>> ret = pwm_fan_of_get_cooling_data(&pdev->dev, ctx);
> >>> if (ret)
> >>>- return ret;
> >>>+ goto err_del_timer;
> >>Outch. This is buggy and should have been "goto err_pwm_disable;".
> >>It needs to be fixed with a separate patch, and first, so we can
> >>backport it. Can you do that ?
> >
> >Sure
> >
> >Stefan
> >
Am 03.04.2019 um 17:59 schrieb Robin Murphy:
> On 03/04/2019 10:55, Stefan Wahren wrote:
>> Hi Guenter,
>>
>> Am 02.04.19 um 22:55 schrieb Guenter Roeck:
>>> On Tue, Apr 02, 2019 at 04:21:50PM +0200, Stefan Wahren wrote:
>>>> This adds RPM support to the pwm-fan driver in order to use with
>>>> fancontrol/pwmconfig. This feature is intended for fans with a
>>>> tachometer
>>>> output signal, which generate a defined number of pulses per
>>>> revolution.
>>>>
>>>> Signed-off-by: Stefan Wahren <[email protected]>
>>>> ---
>>>> drivers/hwmon/pwm-fan.c | 111
>>>> ++++++++++++++++++++++++++++++++++++++++++++++--
>>>> 1 file changed, 107 insertions(+), 4 deletions(-)
>>>>
>>>> diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
>>>> index 167221c..3245a49 100644
>>>> --- a/drivers/hwmon/pwm-fan.c
>>>> +++ b/drivers/hwmon/pwm-fan.c
>>>> @@ -18,6 +18,7 @@
>>>> #include <linux/hwmon.h>
>>>> #include <linux/hwmon-sysfs.h>
>>>> +#include <linux/interrupt.h>
>>>> #include <linux/module.h>
>>>> #include <linux/mutex.h>
>>>> #include <linux/of.h>
>>>> @@ -26,6 +27,7 @@
>>>> #include <linux/regulator/consumer.h>
>>>> #include <linux/sysfs.h>
>>>> #include <linux/thermal.h>
>>>> +#include <linux/timer.h>
>>>> #define MAX_PWM 255
>>>> @@ -33,6 +35,14 @@ struct pwm_fan_ctx {
>>>> struct mutex lock;
>>>> struct pwm_device *pwm;
>>>> struct regulator *reg_en;
>>>> +
>>>> + int irq;
>>>> + atomic_t pulses;
>>>> + unsigned int rpm;
>>>> + u8 pulses_per_revolution;
>>>> + ktime_t sample_start;
>>>> + struct timer_list rpm_timer;
>>>> +
>>>> unsigned int pwm_value;
>>>> unsigned int pwm_fan_state;
>>>> unsigned int pwm_fan_max_state;
>>>> @@ -40,6 +50,32 @@ struct pwm_fan_ctx {
>>>> struct thermal_cooling_device *cdev;
>>>> };
>>>> +/* This handler assumes self resetting edge triggered interrupt. */
>>>> +static irqreturn_t pulse_handler(int irq, void *dev_id)
>>>> +{
>>>> + struct pwm_fan_ctx *ctx = dev_id;
>>>> +
>>>> + atomic_inc(&ctx->pulses);
>>>> +
>>>> + return IRQ_HANDLED;
>>>> +}
>>>> +
>>>> +static void sample_timer(struct timer_list *t)
>>>> +{
>>>> + struct pwm_fan_ctx *ctx = from_timer(ctx, t, rpm_timer);
>>>> + int pulses;
>>>> + u64 tmp;
>>>> +
>>>> + pulses = atomic_read(&ctx->pulses);
>>>> + atomic_sub(pulses, &ctx->pulses);
>>>> + tmp = (u64)pulses * ktime_ms_delta(ktime_get(),
>>>> ctx->sample_start) * 60;
>>>> + do_div(tmp, ctx->pulses_per_revolution * 1000);
>>>> + ctx->rpm = tmp;
>>>> +
>>>> + ctx->sample_start = ktime_get();
>>>> + mod_timer(&ctx->rpm_timer, jiffies + HZ);
>>>> +}
>>>> +
>>>> static int __set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm)
>>>> {
>>>> unsigned long period;
>>>> @@ -100,15 +136,49 @@ static ssize_t pwm_show(struct device *dev,
>>>> struct device_attribute *attr,
>>>> return sprintf(buf, "%u\n", ctx->pwm_value);
>>>> }
>>>> +static ssize_t rpm_show(struct device *dev,
>>>> + struct device_attribute *attr, char *buf)
>>>> +{
>>>> + struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
>>>> +
>>>> + return sprintf(buf, "%u\n", ctx->rpm);
>>>> +}
>>>> static SENSOR_DEVICE_ATTR_RW(pwm1, pwm, 0);
>>>> +static SENSOR_DEVICE_ATTR_RO(fan1_input, rpm, 0);
>>>> static struct attribute *pwm_fan_attrs[] = {
>>>> &sensor_dev_attr_pwm1.dev_attr.attr,
>>>> + &sensor_dev_attr_fan1_input.dev_attr.attr,
>>>> NULL,
>>>> };
>>>> -ATTRIBUTE_GROUPS(pwm_fan);
>>>> +static umode_t pwm_fan_attrs_visible(struct kobject *kobj, struct
>>>> attribute *a,
>>>> + int n)
>>>> +{
>>>> + struct device *dev = container_of(kobj, struct device, kobj);
>>>> + struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
>>>> + struct device_attribute *devattr;
>>>> +
>>>> + /* Hide fan_input in case no interrupt is available */
>>>> + devattr = container_of(a, struct device_attribute, attr);
>>>> + if (devattr == &sensor_dev_attr_fan1_input.dev_attr) {
>>>> + if (ctx->irq <= 0)
>>>> + return 0;
>>>> + }
>>> Side note: This can be easier written as
>>> if (n == 1 && ctx->irq <= 0)
>>> return 0;
>>>
>>> Not that it matters much.
>>>
>>>> +
>>>> + return a->mode;
>>>> +}
>>>> +
>>>> +static const struct attribute_group pwm_fan_group = {
>>>> + .attrs = pwm_fan_attrs,
>>>> + .is_visible = pwm_fan_attrs_visible,
>>>> +};
>>>> +
>>>> +static const struct attribute_group *pwm_fan_groups[] = {
>>>> + &pwm_fan_group,
>>>> + NULL,
>>>> +};
>>>> /* thermal cooling device callbacks */
>>>> static int pwm_fan_get_max_state(struct thermal_cooling_device
>>>> *cdev,
>>>> @@ -261,17 +331,45 @@ static int pwm_fan_probe(struct
>>>> platform_device *pdev)
>>>> goto err_reg_disable;
>>>> }
>>>> + timer_setup(&ctx->rpm_timer, sample_timer, 0);
>>>> +
>>>> + if (of_property_read_u8(pdev->dev.of_node,
>>>> "pulses-per-revolution",
>>> This does not work: The property is not defined as u8. You have to
>>> either
>>> use of_property_read_u32() or declare the property as u8.
>> pulses_per_revolution is defined as u8 since this version
>
> The variable might be, but the "pulses-per-revolution" property itself
> is not being defined with the appropriate DT type ("/bits/ 8") in the
> binding, and thus will be stored as a regular 32-bit cell, for which
> reading it as a u8 array may or may not work correctly depending on
> endianness.
>
> TBH, unless there's a real need for a specific binary format in the
> FDT, I don't think it's usually worth the bother of using irregular DT
> types, especially when the practical impact amounts to possibly saving
> up to 3 bytes for a property which usually won't need to be specified
> anyway. I'd just do something like:
>
> u32 ppr = 2;
>
> of_property_read_u32(np, "pulses-per-revolution", &ppr);
> ctx->pulses_per_revolution = ppr;
My intention was to avoid another overflow in case the device tree
provides unrealistic values ( my expected range 1 - 10 ). Saving space
would be a benefit, but i'm okay with this suggestion.
>
>>>
>>> [ Sorry, I didn't know until recently that this is necessary ]
>>>
>>>> + &ctx->pulses_per_revolution)) {
>>>> + ctx->pulses_per_revolution = 2;
>>>> + }
>>>> +
>>>> + if (!ctx->pulses_per_revolution) {
>>>> + dev_err(&pdev->dev, "pulses-per-revolution can't be
>>>> zero.\n");
>>>> + ret = -EINVAL;
>>>> + goto err_pwm_disable;
>>>> + }
>>>> +
>>>> + ctx->irq = platform_get_irq(pdev, 0);
>>>> + if (ctx->irq == -EPROBE_DEFER) {
>>>> + ret = ctx->irq;
>>>> + goto err_pwm_disable;
>>> It might be better to call platform_get_irq() and to do do this check
>>> first, before enabling the regulator (in practice before calling
>>> devm_regulator_get_optional). It doesn't make sense to enable the
>>> regulator only to disable it because the irq is not yet available.
>>>
>>>> + } else if (ctx->irq > 0) {
>>> As written, this else is unnecessary, and static checkers will complain
>>> about it.
>>>
>>>> + ret = devm_request_irq(&pdev->dev, ctx->irq,
>>>> pulse_handler, 0,
>>>> + pdev->name, ctx);
>>>> + if (ret) {
>>>> + dev_err(&pdev->dev, "Can't get interrupt working.\n");
>>>> + goto err_pwm_disable;
>
> We could still continue without RPM support at this point, couldn't
> we? Or is this a deliberate "if that failed, then who knows how messed
> up the system is..." kind of thing?
In case someone specified an interrupt, the user expect it to work. This
helps to identify broken DT faster.
The gpio-fan also have optional irq support and also bail out if
devm_request_irq fails.
Btw i will add the return code into the error message.
Stefan