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pwm: Add sysfs interface

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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>
This commit is contained in:
H Hartley Sweeten
2013-06-11 10:38:59 -07:00
committed by Thierry Reding
parent 3dd0a90947
commit 76abbdde2d
7 changed files with 524 additions and 3 deletions
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29
include/linux/pwm.h
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@@ -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 */