Duty cycle inversion of PWM wave should achieved through PWM polarity inversion. Also polarity of PWM wave should configurable from slave drivers,
Configure polarity 1. PWM_POLARITY_NORMAL -> duty ns defines ON period of PWM wave 2. PWM_POLARITY_INVERSE -> duty ns defines OFF period of PWM wave. This patch adds support for configuring PWM polarity in PWM frame work. Signed-off-by: Philip, Avinash <avinashphi...@ti.com> --- Configuring polarity to be done with PWM device disabled, if not failure reported. If PWM device is enabled while configuring polarity, disabling and re_enabling make it complex. Whoever uses this API has to taken care of the basic rules. Discussions related to this can found at http://www.spinics.net/lists/kernel/msg1372110.html :100644 100644 ecb7690... 24d5495... M drivers/pwm/core.c :100644 100644 21d076c... 2e4e960... M include/linux/pwm.h drivers/pwm/core.c | 32 ++++++++++++++++++++++++++++++++ include/linux/pwm.h | 15 +++++++++++++++ 2 files changed, 47 insertions(+), 0 deletions(-) diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c index ecb7690..24d5495 100644 --- a/drivers/pwm/core.c +++ b/drivers/pwm/core.c @@ -379,6 +379,38 @@ int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns) EXPORT_SYMBOL_GPL(pwm_config); /** + * pwm_set_polarity() - change PWM device Polarity + * @pwm: PWM device + * @polarity: Configure polarity of PWM + * + * Polarity to be configured with PWM device disabled. + */ +int pwm_set_polarity(struct pwm_device *pwm, int polarity) +{ + int pwm_flags = PWM_POLARITY_NORMAL; + + if (!pwm || !pwm->chip->ops->set_polarity) + return -EINVAL; + + if (test_bit(PWMF_ENABLED, &pwm->flags)) { + dev_err(pwm->chip->dev, + "Polarity configuration Failed!, PWM device enabled\n"); + return -EBUSY; + } + + if (polarity == PWM_POLARITY_INVERSE) + pwm_flags = PWM_POLARITY_INVERSE; + + if (!pwm_flags) + clear_bit(PWMF_POLARITY_INVERSE, &pwm->flags); + else + set_bit(PWMF_POLARITY_INVERSE, &pwm->flags); + + return pwm->chip->ops->set_polarity(pwm->chip, pwm, polarity); +} +EXPORT_SYMBOL_GPL(pwm_set_polarity); + +/** * pwm_enable() - start a PWM output toggling * @pwm: PWM device */ diff --git a/include/linux/pwm.h b/include/linux/pwm.h index 21d076c..2e4e960 100644 --- a/include/linux/pwm.h +++ b/include/linux/pwm.h @@ -21,6 +21,16 @@ void pwm_free(struct pwm_device *pwm); */ int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns); +enum { + PWM_POLARITY_NORMAL, /* ON period depends on duty_ns */ + PWM_POLARITY_INVERSE, /* OFF period depends on duty_ns */ +}; + +/* + * pwm_set_polarity - set polarity of PWM device + */ +int pwm_set_polarity(struct pwm_device *pwm, int polarity); + /* * pwm_enable - start a PWM output toggling */ @@ -37,6 +47,7 @@ struct pwm_chip; enum { PWMF_REQUESTED = 1 << 0, PWMF_ENABLED = 1 << 1, + PWMF_POLARITY_INVERSE = 1 << 2, }; struct pwm_device { @@ -66,6 +77,7 @@ static inline unsigned int pwm_get_period(struct pwm_device *pwm) * @request: optional hook for requesting a PWM * @free: optional hook for freeing a PWM * @config: configure duty cycles and period length for this PWM + * @set_polarity: configure polarity of PWM * @enable: enable PWM output toggling * @disable: disable PWM output toggling * @dbg_show: optional routine to show contents in debugfs @@ -79,6 +91,9 @@ struct pwm_ops { int (*config)(struct pwm_chip *chip, struct pwm_device *pwm, int duty_ns, int period_ns); + int (*set_polarity)(struct pwm_chip *chip, + struct pwm_device *pwm, + int polarity); int (*enable)(struct pwm_chip *chip, struct pwm_device *pwm); void (*disable)(struct pwm_chip *chip, -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
