linux-kernel - [PATCH v5 24/46] pwm: sti: add support for initial state retrieval

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Message-Id: <1459368249-13241-25-git-send-email-boris.brezillon@free-electrons.com>
Date:	Wed, 30 Mar 2016 22:03:47 +0200
From:	Boris Brezillon <boris.brezillon@...e-electrons.com>
To:	Thierry Reding <thierry.reding@...il.com>,
	linux-pwm@...r.kernel.org
Cc:	Mike Turquette <mturquette@...libre.com>,
	Stephen Boyd <sboyd@...eaurora.org>, linux-clk@...r.kernel.org,
	Mark Brown <broonie@...nel.org>,
	Liam Girdwood <lgirdwood@...il.com>,
	Kamil Debski <k.debski@...sung.com>, lm-sensors@...sensors.org,
	Jean Delvare <jdelvare@...e.com>,
	Guenter Roeck <linux@...ck-us.net>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	linux-input@...r.kernel.org, Bryan Wu <cooloney@...il.com>,
	Richard Purdie <rpurdie@...ys.net>,
	Jacek Anaszewski <j.anaszewski@...sung.com>,
	linux-leds@...r.kernel.org,
	Maxime Ripard <maxime.ripard@...e-electrons.com>,
	Chen-Yu Tsai <wens@...e.org>, linux-sunxi@...glegroups.com,
	Joachim Eastwood <manabian@...il.com>,
	Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
	Heiko Stuebner <heiko@...ech.de>,
	linux-rockchip@...ts.infradead.org,
	Jingoo Han <jingoohan1@...il.com>,
	Lee Jones <lee.jones@...aro.org>, linux-fbdev@...r.kernel.org,
	Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
	Tomi Valkeinen <tomi.valkeinen@...com>,
	Robert Jarzmik <robert.jarzmik@...e.fr>,
	Alexandre Belloni <alexandre.belloni@...e-electrons.com>,
	Kukjin Kim <kgene@...nel.org>,
	Krzysztof Kozlowski <k.kozlowski@...sung.com>,
	linux-samsung-soc@...r.kernel.org, intel-gfx@...ts.freedesktop.org,
	Daniel Vetter <daniel.vetter@...el.com>,
	Jani Nikula <jani.nikula@...ux.intel.com>,
	Jonathan Corbet <corbet@....net>, linux-doc@...r.kernel.org,
	David Airlie <airlied@...ux.ie>,
	Daniel Vetter <daniel@...ll.ch>,
	dri-devel@...ts.freedesktop.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Hartley Sweeten <hsweeten@...ionengravers.com>,
	Ryan Mallon <rmallon@...il.com>,
	Alexander Shiyan <shc_work@...l.ru>,
	Milo Kim <milo.kim@...com>,
	Boris Brezillon <boris.brezillon@...e-electrons.com>
Subject: [PATCH v5 24/46] pwm: sti: add support for initial state retrieval

Implement ->get_state() to provide support for initial state retrieval.

Signed-off-by: Boris Brezillon <boris.brezillon@...e-electrons.com>
---
 drivers/pwm/pwm-sti.c | 41 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/drivers/pwm/pwm-sti.c b/drivers/pwm/pwm-sti.c
index 92abbd5..0fbca94 100644
--- a/drivers/pwm/pwm-sti.c
+++ b/drivers/pwm/pwm-sti.c
@@ -238,6 +238,46 @@ static void sti_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 	mutex_unlock(&pc->sti_pwm_lock);
 }
 
+static void sti_pwm_get_state(struct pwm_chip *chip,
+			      struct pwm_device *pwm,
+			      struct pwm_state *pstate)
+{
+	struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
+	unsigned int regval, prescaler;
+	u64 timens;
+	int ret;
+
+	/* The clock has to be enabled to access PWM registers */
+	ret = clk_enable(pc->clk);
+	if (ret) {
+		dev_err(chip->dev, "Failed to enable PWM clk");
+		return;
+	}
+
+	regmap_field_read(pc->prescale_high, &regval);
+	prescaler = regval << 4;
+	regmap_field_read(pc->prescale_low, &regval);
+	prescaler |= regval;
+
+	timens = (u64)(prescaler + 1) * NSEC_PER_SEC *
+		 (pc->cdata->max_pwm_cnt + 1);
+	do_div(timens, pc->clk_rate);
+
+	pstate->period = timens;
+
+	regmap_read(pc->regmap, STI_DS_REG(pwm->hwpwm), &regval);
+	timens = (u64)(regval + 1) * pstate->period;
+	do_div(timens, pc->cdata->max_pwm_cnt + 1);
+	pstate->duty_cycle = timens;
+
+	regmap_field_read(pc->pwm_en, &regval);
+	pstate->enabled = regval;
+
+	pstate->polarity = PWM_POLARITY_NORMAL;
+
+	clk_disable(pc->clk);
+}
+
 static void sti_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
 {
 	struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
@@ -249,6 +289,7 @@ static const struct pwm_ops sti_pwm_ops = {
 	.config = sti_pwm_config,
 	.enable = sti_pwm_enable,
 	.disable = sti_pwm_disable,
+	.get_state = sti_pwm_get_state,
 	.free = sti_pwm_free,
 	.owner = THIS_MODULE,
 };
-- 
2.5.0