linux-kernel - [PATCH 1/4] pwm: mxs: implement ->apply

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Message-Id: <20190923081348.6843-2-linux@rasmusvillemoes.dk>
Date:   Mon, 23 Sep 2019 10:13:45 +0200
From:   Rasmus Villemoes <linux@...musvillemoes.dk>
To:     Thierry Reding <thierry.reding@...il.com>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>
Cc:     devicetree@...r.kernel.org, Rob Herring <robh+dt@...nel.org>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        linux-pwm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 1/4] pwm: mxs: implement ->apply

In preparation for supporting setting the polarity, switch the driver
to support the ->apply method.

Signed-off-by: Rasmus Villemoes <linux@...musvillemoes.dk>
---
 drivers/pwm/pwm-mxs.c | 62 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)

diff --git a/drivers/pwm/pwm-mxs.c b/drivers/pwm/pwm-mxs.c
index 04c0f6b95c1a..c70c26a9ff68 100644
--- a/drivers/pwm/pwm-mxs.c
+++ b/drivers/pwm/pwm-mxs.c
@@ -26,6 +26,7 @@
 #define  PERIOD_PERIOD_MAX	0x10000
 #define  PERIOD_ACTIVE_HIGH	(3 << 16)
 #define  PERIOD_INACTIVE_LOW	(2 << 18)
+#define  PERIOD_POLARITY_NORMAL	(PERIOD_ACTIVE_HIGH | PERIOD_INACTIVE_LOW)
 #define  PERIOD_CDIV(div)	(((div) & 0x7) << 20)
 #define  PERIOD_CDIV_MAX	8
 
@@ -41,6 +42,66 @@ struct mxs_pwm_chip {
 
 #define to_mxs_pwm_chip(_chip) container_of(_chip, struct mxs_pwm_chip, chip)
 
+static int mxs_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
+			 struct pwm_state *state)
+{
+	struct mxs_pwm_chip *mxs = to_mxs_pwm_chip(chip);
+	int ret, div = 0;
+	unsigned int period_cycles, duty_cycles;
+	unsigned long rate;
+	unsigned long long c;
+
+	if (state->polarity != PWM_POLARITY_NORMAL)
+		return -ENOTSUPP;
+
+	rate = clk_get_rate(mxs->clk);
+	while (1) {
+		c = rate / cdiv[div];
+		c = c * state->period;
+		do_div(c, 1000000000);
+		if (c < PERIOD_PERIOD_MAX)
+			break;
+		div++;
+		if (div >= PERIOD_CDIV_MAX)
+			return -EINVAL;
+	}
+
+	period_cycles = c;
+	c *= state->duty_cycle;
+	do_div(c, state->period);
+	duty_cycles = c;
+
+	/*
+	 * If the PWM channel is disabled, make sure to turn on the clock
+	 * before writing the register. Otherwise, keep it enabled.
+	 */
+	if (!pwm_is_enabled(pwm)) {
+		ret = clk_prepare_enable(mxs->clk);
+		if (ret)
+			return ret;
+	}
+
+	writel(duty_cycles << 16,
+	       mxs->base + PWM_ACTIVE0 + pwm->hwpwm * 0x20);
+	writel(PERIOD_PERIOD(period_cycles) | PERIOD_POLARITY_NORMAL | PERIOD_CDIV(div),
+	       mxs->base + PWM_PERIOD0 + pwm->hwpwm * 0x20);
+
+	if (state->enabled) {
+		if (!pwm_is_enabled(pwm)) {
+			/*
+			 * The clock was enabled above. Just enable
+			 * the channel in the control register.
+			 */
+			writel(1 << pwm->hwpwm, mxs->base + PWM_CTRL + SET);
+		}
+	} else {
+		if (pwm_is_enabled(pwm))
+			writel(1 << pwm->hwpwm, mxs->base + PWM_CTRL + CLR);
+		clk_disable_unprepare(mxs->clk);
+	}
+	return 0;
+}
+
 static int mxs_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 			  int duty_ns, int period_ns)
 {
@@ -116,6 +177,7 @@ static void mxs_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 }
 
 static const struct pwm_ops mxs_pwm_ops = {
+	.apply = mxs_pwm_apply,
 	.config = mxs_pwm_config,
 	.enable = mxs_pwm_enable,
 	.disable = mxs_pwm_disable,
-- 
2.20.1