pwm: Add sysfs interface
Add a simple sysfs interface to the generic PWM framework.
/sys/class/pwm/
`-- pwmchipN/ for each PWM chip
|-- export (w/o) ask the kernel to export a PWM channel
|-- npwm (r/o) number of PWM channels in this PWM chip
|-- pwmX/ for each exported PWM channel
| |-- duty_cycle (r/w) duty cycle (in nanoseconds)
| |-- enable (r/w) enable/disable PWM
| |-- period (r/w) period (in nanoseconds)
| `-- polarity (r/w) polarity of PWM (normal/inversed)
`-- unexport (w/o) return a PWM channel to the kernel
Based on work by Lars Poeschel.
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Lars Poeschel <poeschel@lemonage.de>
Cc: Ryan Mallon <rmallon@gmail.com>
Cc: Rob Landley <rob@landley.net>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index a4df204..f0feafd 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -76,6 +76,7 @@
enum {
PWMF_REQUESTED = 1 << 0,
PWMF_ENABLED = 1 << 1,
+ PWMF_EXPORTED = 1 << 2,
};
struct pwm_device {
@@ -86,7 +87,9 @@
struct pwm_chip *chip;
void *chip_data;
- unsigned int period; /* in nanoseconds */
+ unsigned int period; /* in nanoseconds */
+ unsigned int duty_cycle; /* in nanoseconds */
+ enum pwm_polarity polarity;
};
static inline void pwm_set_period(struct pwm_device *pwm, unsigned int period)
@@ -100,6 +103,17 @@
return pwm ? pwm->period : 0;
}
+static inline void pwm_set_duty_cycle(struct pwm_device *pwm, unsigned int duty)
+{
+ if (pwm)
+ pwm->duty_cycle = duty;
+}
+
+static inline unsigned int pwm_get_duty_cycle(struct pwm_device *pwm)
+{
+ return pwm ? pwm->duty_cycle : 0;
+}
+
/*
* pwm_set_polarity - configure the polarity of a PWM signal
*/
@@ -278,4 +292,17 @@
}
#endif
+#ifdef CONFIG_PWM_SYSFS
+void pwmchip_sysfs_export(struct pwm_chip *chip);
+void pwmchip_sysfs_unexport(struct pwm_chip *chip);
+#else
+static inline void pwmchip_sysfs_export(struct pwm_chip *chip)
+{
+}
+
+static inline void pwmchip_sysfs_unexport(struct pwm_chip *chip)
+{
+}
+#endif /* CONFIG_PWM_SYSFS */
+
#endif /* __LINUX_PWM_H */