linux-kernel - [PATCH v9 5/8] pwm: core: Support new PWM_USAGE

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Date:   Thu, 15 Apr 2021 14:14:52 +0200
From:   Clemens Gruber <clemens.gruber@...ruber.com>
To:     linux-pwm@...r.kernel.org
Cc:     Thierry Reding <thierry.reding@...il.com>,
        Sven Van Asbroeck <TheSven73@...il.com>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Clemens Gruber <clemens.gruber@...ruber.com>
Subject: [PATCH v9 5/8] pwm: core: Support new PWM_USAGE_POWER flag

If the flag PWM_USAGE_POWER is set on a channel, the PWM driver may
optimize the signal as long as the power output is not changed.

Depending on the specific driver, the optimization could for example
improve EMI (if supported) by phase-shifting the individual channels.

Signed-off-by: Clemens Gruber <clemens.gruber@...ruber.com>
---
 drivers/pwm/core.c  | 9 +++++++--
 include/linux/pwm.h | 1 +
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index a8eff4b3ee36..56a9c739e1b2 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -153,9 +153,14 @@ of_pwm_xlate_with_flags(struct pwm_chip *pc, const struct of_phandle_args *args)
 
 	pwm->args.period = args->args[1];
 	pwm->args.polarity = PWM_POLARITY_NORMAL;
+	pwm->args.usage_power = false;
 
-	if (args->args_count > 2 && args->args[2] & PWM_POLARITY_INVERTED)
-		pwm->args.polarity = PWM_POLARITY_INVERSED;
+	if (args->args_count > 2) {
+		if (args->args[2] & PWM_POLARITY_INVERTED)
+			pwm->args.polarity = PWM_POLARITY_INVERSED;
+		if (args->args[2] & PWM_USAGE_POWER)
+			pwm->args.usage_power = true;
+	}
 
 	return pwm;
 }
diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index e4d84d4db293..555e050e8bec 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -41,6 +41,7 @@ enum pwm_polarity {
 struct pwm_args {
 	u64 period;
 	enum pwm_polarity polarity;
+	bool usage_power;
 };
 
 enum {
-- 
2.31.1