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authorPhilip, Avinash <avinashphilip@ti.com>2012-07-24 19:35:32 +0530
committerThierry Reding <thierry.reding@avionic-design.de>2012-09-10 17:05:44 +0200
commit0aa0869c3c9b10338dd92a20fa4a9b6959f177b5 (patch)
treee88017ff289993d4142cf90ea410a2997258b24e /drivers/pwm
parent01b2d4536f0215c6d97d77e157afee04300ffc90 (diff)
downloadlinux-0aa0869c3c9b10338dd92a20fa4a9b6959f177b5.tar.bz2
pwm: Add support for configuring the PWM polarity
Some hardware supports inverting the polarity of the PWM signal. This commit adds support to the PWM framework to allow users of the PWM API to configure the polarity. Note that in order to reduce complexity, changing the polarity of a PWM signal is only allowed while the PWM is disabled. A practical example where this can prove useful is to simulate inversion of the duty cycle. While inversion of polarity and duty cycle are not exactly the same, the differences for most use-cases are negligible. Signed-off-by: Philip, Avinash <avinashphilip@ti.com> Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
Diffstat (limited to 'drivers/pwm')
-rw-r--r--drivers/pwm/core.c22
1 files changed, 22 insertions, 0 deletions
diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index c6e05078d3ad..85592e97ef2d 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -379,6 +379,28 @@ int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
EXPORT_SYMBOL_GPL(pwm_config);
/**
+ * pwm_set_polarity() - configure the polarity of a PWM signal
+ * @pwm: PWM device
+ * @polarity: new polarity of the PWM signal
+ *
+ * Note that the polarity cannot be configured while the PWM device is enabled
+ */
+int pwm_set_polarity(struct pwm_device *pwm, enum pwm_polarity polarity)
+{
+ if (!pwm || !pwm->chip->ops)
+ return -EINVAL;
+
+ if (!pwm->chip->ops->set_polarity)
+ return -ENOSYS;
+
+ if (test_bit(PWMF_ENABLED, &pwm->flags))
+ return -EBUSY;
+
+ 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
*/