linux-kernel - [PATCH v2 06/13] pwm: sti: Add support for hardware readout

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Message-Id: <1465403688-17098-7-git-send-email-boris.brezillon@free-electrons.com>
Date:	Wed,  8 Jun 2016 18:34:41 +0200
From:	Boris Brezillon <boris.brezillon@...e-electrons.com>
To:	Thierry Reding <thierry.reding@...il.com>,
	linux-pwm@...r.kernel.org, Mark Brown <broonie@...nel.org>,
	Liam Girdwood <lgirdwood@...il.com>
Cc:	Heiko Stuebner <heiko@...ech.de>,
	linux-rockchip@...ts.infradead.org,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>, devicetree@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Milo Kim <milo.kim@...com>,
	Doug Anderson <dianders@...gle.com>,
	Caesar Wang <wxt@...k-chips.com>,
	Stephen Barber <smbarber@...omium.org>,
	Brian Norris <briannorris@...omium.org>,
	Ajit Pal Singh <ajitpal.singh@...com>,
	Srinivas Kandagatla <srinivas.kandagatla@...il.com>,
	Maxime Coquelin <maxime.coquelin@...com>,
	Patrice Chotard <patrice.chotard@...com>, kernel@...inux.com,
	Laxman Dewangan <ldewangan@...dia.com>,
	Boris Brezillon <boris.brezillon@...e-electrons.com>
Subject: [PATCH v2 06/13] pwm: sti: Add support for hardware readout

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 | 38 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/drivers/pwm/pwm-sti.c b/drivers/pwm/pwm-sti.c
index 92abbd5..6300d3e 100644
--- a/drivers/pwm/pwm-sti.c
+++ b/drivers/pwm/pwm-sti.c
@@ -238,6 +238,43 @@ 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 *state)
+{
+	struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
+	unsigned int regval, prescaler;
+	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;
+	state->period = DIV_ROUND_CLOSEST_ULL((u64)(prescaler + 1) *
+					      NSEC_PER_SEC *
+					      (pc->cdata->max_pwm_cnt + 1),
+					      pc->clk_rate);
+
+	regmap_read(pc->regmap, STI_DS_REG(pwm->hwpwm), &regval);
+	state->duty_cycle = DIV_ROUND_CLOSEST_ULL((u64)(regval + 1) *
+						  state->period,
+						  pc->cdata->max_pwm_cnt + 1);
+
+	regmap_field_read(pc->pwm_en, &regval);
+	state->enabled = regval;
+
+	state->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 +286,7 @@ 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,
 };
-- 
2.7.4