pwm: sun4i: Add an optional probe for bus clock

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

Add an optional probe for it.

Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
Signed-off-by: Clément Péron <peron.clem@gmail.com>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

diff --git a/drivers/pwm/pwm-sun4i.c b/drivers/pwm/pwm-sun4i.c
index 8002616..a6727dd 100644 (file)
--- 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;
@@ -391,6 +392,14 @@ static int sun4i_pwm_probe(struct platform_device *pdev)
                }
        }
 
+       pwm->bus_clk = devm_clk_get_optional(&pdev->dev, "bus");
+       if (IS_ERR(pwm->bus_clk)) {
+               if (PTR_ERR(pwm->rst) != -EPROBE_DEFER)
+                       dev_err(&pdev->dev, "get bus clock failed %pe\n",
+                               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)) {
                if (PTR_ERR(pwm->rst) != -EPROBE_DEFER)
@@ -407,6 +416,17 @@ 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 %pe\n",
+                       ERR_PTR(ret));
+               goto err_bus;
+       }
+
        pwm->chip.dev = &pdev->dev;
        pwm->chip.ops = &sun4i_pwm_ops;
        pwm->chip.base = -1;
@@ -427,6 +447,8 @@ 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;
@@ -441,6 +463,7 @@ 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;