[PATCH v6 4/8] pwm: sun4i: Add an optional probe for bus clock

From: ClÃment PÃron
Date: Mon Nov 18 2019 - 06:01:15 EST


From: Jernej Skrabec <jernej.skrabec@xxxxxxxx>

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@xxxxxxxx>
Signed-off-by: ClÃment PÃron <peron.clem@xxxxxxxxx>
---
drivers/pwm/pwm-sun4i.c | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)

diff --git a/drivers/pwm/pwm-sun4i.c b/drivers/pwm/pwm-sun4i.c
index 6d97fef4ed43..ce83d479ba0e 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;
@@ -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)
@@ -406,6 +415,16 @@ 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;
@@ -426,6 +445,8 @@ 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;
@@ -440,6 +461,7 @@ 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