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>

1 files changed, 28 insertions, 1 deletions

diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index a4df2042b79c..f0feafd184a0 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -76,6 +76,7 @@ enum pwm_polarity {
 enum {
         PWMF_REQUESTED = 1 << 0,
         PWMF_ENABLED = 1 << 1,
+        PWMF_EXPORTED = 1 << 2,
 };
 
 struct pwm_device {
@@ -86,7 +87,9 @@ struct pwm_device {
         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 @@ static inline unsigned int pwm_get_period(struct pwm_device *pwm)
         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 @@ static inline void pwm_add_table(struct pwm_lookup *table, size_t num)
 }
 #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 */