Use the DTS property #pwm-cells to determine if the PWM controller needs
to enable the WDT reload feature, which changes the duty cycle to a
preprogrammed value after a WDT/EXTRST#. When #pwm-cells = <4>, the
feature will be enabled, and the PWM consumer can use the 4th argument to
set the reload duty cycle [0-255].
Signed-off-by: Billy Tsai <billy_tsai@xxxxxxxxxxxxxx>
Change-Id: Ided520f73220581e3b37819a106ec81ebf9bb5a6
---
drivers/hwmon/aspeed-g6-pwm-tach.c | 49 ++++++++++++++++++++++++++++++
drivers/pwm/core.c | 6 ++--
include/linux/pwm.h | 10 ++++++
3 files changed, 62 insertions(+), 3 deletions(-)
diff --git a/drivers/hwmon/aspeed-g6-pwm-tach.c b/drivers/hwmon/aspeed-g6-pwm-tach.c
index 75eadda738ab..df47f9aa8ee6 100644
--- a/drivers/hwmon/aspeed-g6-pwm-tach.c
+++ b/drivers/hwmon/aspeed-g6-pwm-tach.c
@@ -56,6 +56,7 @@
#include <linux/of_platform.h>
#include <linux/platform_device.h>
#include <linux/pwm.h>
+#include <dt-bindings/pwm/pwm.h>
#include <linux/reset.h>
#include <linux/sysfs.h>
@@ -452,6 +453,51 @@ static void aspeed_pwm_tach_reset_assert(void *data)
reset_control_assert(rst);
}
+static void aspeed_pwm_set_wdt_reload(struct pwm_chip *chip,
+ struct pwm_device *pwm,
+ u64 reload_duty_cycle)
+{
+ struct aspeed_pwm_tach_data *priv = aspeed_pwm_chip_to_data(chip);
+ u32 hwpwm = pwm->hwpwm, val;
+
+ val = readl(priv->base + PWM_ASPEED_DUTY_CYCLE(hwpwm));
+ val &= ~PWM_ASPEED_DUTY_CYCLE_POINT_AS_WDT;
+ val |= FIELD_PREP(PWM_ASPEED_DUTY_CYCLE_POINT_AS_WDT,
+ reload_duty_cycle);
+ writel(val, priv->base + PWM_ASPEED_DUTY_CYCLE(hwpwm));
+
+ val = readl(priv->base + PWM_ASPEED_CTRL(hwpwm));
+ val |= PWM_ASPEED_CTRL_DUTY_LOAD_AS_WDT_ENABLE;
+ writel(val, priv->base + PWM_ASPEED_CTRL(hwpwm));
+}
+
+static struct pwm_device *
+aspeed_pwm_xlate(struct pwm_chip *chip, const struct of_phandle_args *args)
+{
+ struct pwm_device *pwm;
+
+ /* flags in the fourth cell are optional */
+ if (args->args_count < 3)
+ return ERR_PTR(-EINVAL);
+
+ if (args->args[0] >= chip->npwm)
+ return ERR_PTR(-EINVAL);
+
+ pwm = pwm_request_from_chip(chip, args->args[0], NULL);
+ if (IS_ERR(pwm))
+ return pwm;
+
+ pwm->args.period = args->args[1];
+ pwm->args.polarity = PWM_POLARITY_NORMAL;
+ if (args->args[2] & PWM_POLARITY_INVERTED)
+ pwm->args.polarity = PWM_POLARITY_INVERSED;
+
+ if (args->args_count > 3 && args->args[3] < U8_MAX)
+ aspeed_pwm_set_wdt_reload(chip, pwm, args->args[3]);
+
+ return pwm;
+}
+
static int aspeed_pwm_tach_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev, *hwmon;
@@ -493,6 +539,9 @@ static int aspeed_pwm_tach_probe(struct platform_device *pdev)
pwmchip_set_drvdata(chip, priv);
chip->ops = &aspeed_pwm_ops;
+ if (IS_ENABLED(CONFIG_OF))
+ chip->of_xlate = aspeed_pwm_xlate;
+
ret = devm_pwmchip_add(dev, chip);
if (ret)
return dev_err_probe(dev, ret, "Failed to add PWM chip\n");
diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index 6e752e148b98..8251f7b361ab 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -422,9 +422,8 @@ static int pwm_device_request(struct pwm_device *pwm, const char *label)
* chip. A negative error code is returned if the index is not valid for the
* specified PWM chip or if the PWM device cannot be requested.
*/
-static struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
- unsigned int index,
- const char *label)
+struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
+ unsigned int index, const char *label)
{
struct pwm_device *pwm;
int err;
@@ -442,6 +441,7 @@ static struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
return pwm;
}
+EXPORT_SYMBOL_GPL(pwm_request_from_chip);
struct pwm_device *
of_pwm_xlate_with_flags(struct pwm_chip *chip, const struct of_phandle_args *args)
diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index 8acd60b53f58..95ae885f65c3 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -405,6 +405,8 @@ void pwmchip_remove(struct pwm_chip *chip);
int __devm_pwmchip_add(struct device *dev, struct pwm_chip *chip, struct module *owner);
#define devm_pwmchip_add(dev, chip) __devm_pwmchip_add(dev, chip, THIS_MODULE)
+struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
+ unsigned int index, const char *label);
struct pwm_device *of_pwm_xlate_with_flags(struct pwm_chip *chip,
const struct of_phandle_args *args);
struct pwm_device *of_pwm_single_xlate(struct pwm_chip *chip,
@@ -504,6 +506,14 @@ static inline void pwm_put(struct pwm_device *pwm)
might_sleep();
}
+static inline struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
+ unsigned int index,
+ const char *label)
+{
+ might_sleep();
+ return ERR_PTR(-ENODEV);
+}
+
static inline struct pwm_device *devm_pwm_get(struct device *dev,
const char *consumer)
{
--
2.25.1
