linux-kernel - [PATCH 5/7] pwm: jz4740: Allow selection of PWM channels 0 and 1

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Message-Id: <20190809123031.24219-6-paul@crapouillou.net>
Date:   Fri,  9 Aug 2019 14:30:29 +0200
From:   Paul Cercueil <paul@...pouillou.net>
To:     Thierry Reding <thierry.reding@...il.com>
Cc:     Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>, od@...c.me,
        linux-pwm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Paul Cercueil <paul@...pouillou.net>,
        Mathieu Malaterre <malat@...ian.org>,
        Artur Rojek <contact@...ur-rojek.eu>
Subject: [PATCH 5/7] pwm: jz4740: Allow selection of PWM channels 0 and 1

The TCU channels 0 and 1 were previously reserved for system tasks, and
thus unavailable for PWM.

Signed-off-by: Paul Cercueil <paul@...pouillou.net>
Tested-by: Mathieu Malaterre <malat@...ian.org>
Tested-by: Artur Rojek <contact@...ur-rojek.eu>
---
 drivers/pwm/pwm-jz4740.c | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/drivers/pwm/pwm-jz4740.c b/drivers/pwm/pwm-jz4740.c
index f20dc2e19240..85e2110aae4f 100644
--- a/drivers/pwm/pwm-jz4740.c
+++ b/drivers/pwm/pwm-jz4740.c
@@ -28,6 +28,19 @@ static inline struct jz4740_pwm_chip *to_jz4740(struct pwm_chip *chip)
 	return container_of(chip, struct jz4740_pwm_chip, chip);
 }
 
+static bool jz4740_pwm_can_use_chn(struct jz4740_pwm_chip *jz,
+				   unsigned int channel)
+{
+	/* Enable all TCU channels for PWM use by default except channels 0/1 */
+	u32 pwm_channels_mask = GENMASK(NUM_PWM - 1, 2);
+
+	device_property_read_u32(jz->chip.dev->parent,
+				 "ingenic,pwm-channels-mask",
+				 &pwm_channels_mask);
+
+	return !!(pwm_channels_mask & BIT(channel));
+}
+
 static int jz4740_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
 {
 	struct jz4740_pwm_chip *jz = to_jz4740(chip);
@@ -35,11 +48,7 @@ static int jz4740_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
 	char clk_name[16];
 	int ret;
 
-	/*
-	 * Timers 0 and 1 are used for system tasks, so they are unavailable
-	 * for use as PWMs.
-	 */
-	if (pwm->hwpwm < 2)
+	if (!jz4740_pwm_can_use_chn(jz, pwm->hwpwm))
 		return -EBUSY;
 
 	snprintf(clk_name, sizeof(clk_name), "timer%u", pwm->hwpwm);
-- 
2.21.0.593.g511ec345e18