linux-kernel - [PATCH v3 3/7] pwm: sun4i: Add an optional probe for bus clock

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Date:   Tue,  5 Nov 2019 14:14:52 +0100
From:   Clément Péron <peron.clem@...il.com>
To:     Thierry Reding <thierry.reding@...il.com>,
        'Uwe Kleine-König' 
        <u.kleine-koenig@...gutronix.de>, Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Maxime Ripard <mripard@...nel.org>,
        Chen-Yu Tsai <wens@...e.org>,
        Philipp Zabel <pza@...gutronix.de>
Cc:     linux-pwm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Jernej Skrabec <jernej.skrabec@...l.net>,
        Clément Péron <peron.clem@...il.com>
Subject: [PATCH v3 3/7] pwm: sun4i: Add an optional probe for bus clock

From: Jernej Skrabec <jernej.skrabec@...l.net>

H6 PWM core needs bus clock to be enabled in order to work.

Add an optional probe for it and a fallback for previous
bindings without name on module clock.

Signed-off-by: Jernej Skrabec <jernej.skrabec@...l.net>
Signed-off-by: Clément Péron <peron.clem@...il.com>
---
 drivers/pwm/pwm-sun4i.c | 45 +++++++++++++++++++++++++++++++++++++++--
 1 file changed, 43 insertions(+), 2 deletions(-)

diff --git a/drivers/pwm/pwm-sun4i.c b/drivers/pwm/pwm-sun4i.c
index 9ba83769a478..54e19fa56a4e 100644
--- a/drivers/pwm/pwm-sun4i.c
+++ b/drivers/pwm/pwm-sun4i.c
@@ -78,6 +78,7 @@ struct sun4i_pwm_data {
 
 struct sun4i_pwm_chip {
 	struct pwm_chip chip;
+	struct clk *bus_clk;
 	struct clk *clk;
 	struct reset_control *rst;
 	void __iomem *base;
@@ -363,9 +364,35 @@ static int sun4i_pwm_probe(struct platform_device *pdev)
 	if (IS_ERR(pwm->base))
 		return PTR_ERR(pwm->base);
 
-	pwm->clk = devm_clk_get(&pdev->dev, NULL);
-	if (IS_ERR(pwm->clk))
+	/* Get all clocks and reset line */
+	pwm->clk = devm_clk_get_optional(&pdev->dev, "mod");
+	if (IS_ERR(pwm->clk)) {
+		dev_err(&pdev->dev, "get clock failed %ld\n",
+			PTR_ERR(pwm->clk));
 		return PTR_ERR(pwm->clk);
+	}
+
+	/*
+	 * Fallback for old dtbs with a single clock and no name.
+	 * If a parent has a clock-name called "mod" whereas the
+	 * current node is unnamed the clock reference will be
+	 * incorrectly obtained and will not go into this fallback.
+	 */
+	if (!pwm->clk) {
+		pwm->clk = devm_clk_get(&pdev->dev, NULL);
+		if (IS_ERR(pwm->clk)) {
+			dev_err(&pdev->dev, "get clock failed %ld\n",
+				PTR_ERR(pwm->clk));
+			return PTR_ERR(pwm->clk);
+		}
+	}
+
+	pwm->bus_clk = devm_clk_get_optional(&pdev->dev, "bus");
+	if (IS_ERR(pwm->bus_clk)) {
+		dev_err(&pdev->dev, "get bus_clock failed %ld\n",
+			PTR_ERR(pwm->bus_clk));
+		return PTR_ERR(pwm->bus_clk);
+	}
 
 	pwm->rst = devm_reset_control_get_optional_shared(&pdev->dev, NULL);
 	if (IS_ERR(pwm->rst)) {
@@ -382,6 +409,17 @@ static int sun4i_pwm_probe(struct platform_device *pdev)
 		return ret;
 	}
 
+	/*
+	 * We're keeping the bus clock on for the sake of simplicity.
+	 * Actually it only needs to be on for hardware register
+	 * accesses.
+	 */
+	ret = clk_prepare_enable(pwm->bus_clk);
+	if (ret) {
+		dev_err(&pdev->dev, "Cannot prepare and enable bus_clk\n");
+		goto err_bus;
+	}
+
 	pwm->chip.dev = &pdev->dev;
 	pwm->chip.ops = &sun4i_pwm_ops;
 	pwm->chip.base = -1;
@@ -402,6 +440,8 @@ static int sun4i_pwm_probe(struct platform_device *pdev)
 	return 0;
 
 err_pwm_add:
+	clk_disable_unprepare(pwm->bus_clk);
+err_bus:
 	reset_control_assert(pwm->rst);
 
 	return ret;
@@ -416,6 +456,7 @@ static int sun4i_pwm_remove(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
+	clk_disable_unprepare(pwm->bus_clk);
 	reset_control_assert(pwm->rst);
 
 	return 0;
-- 
2.20.1