[PATCH v9 2/6] pwm: sun4i: Prefer "mod" clock to unnamed

Clément Péron
2019-11-24T17:29:04Z

New device tree bindings called the source clock of the module
"mod" when several clocks are defined.

Try to get a clock called "mod" if nothing is found try to get
an unnamed clock.

Reviewed-by: Uwe Kleine-König <u.kleine-koenig-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
Signed-off-by: Clément Péron <peron.clem-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
drivers/pwm/pwm-sun4i.c | 29 +++++++++++++++++++++++++++--
1 file changed, 27 insertions(+), 2 deletions(-)

diff --git a/drivers/pwm/pwm-sun4i.c b/drivers/pwm/pwm-sun4i.c
index 487899d4cc3f..80026167044b 100644
--- a/drivers/pwm/pwm-sun4i.c
+++ b/drivers/pwm/pwm-sun4i.c
@@ -362,9 +362,34 @@ 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))
+ /*
+ * All hardware variants need a source clock that is divided and
+ * then feeds the counter that defines the output wave form. In the
+ * device tree this clock is either unnamed or called "mod".
+ * Some variants (e.g. H6) need another clock to access the
+ * hardware registers; this is called "bus".
+ * So we request "mod" first (and ignore the corner case that a
+ * parent provides a "mod" clock while the right one would be the
+ * unnamed one of the PWM device) and if this is not found we fall
+ * back to the first clock of the PWM.
+ */
+ pwm->clk = devm_clk_get_optional(&pdev->dev, "mod");
+ if (IS_ERR(pwm->clk)) {
+ if (PTR_ERR(pwm->rst) != -EPROBE_DEFER)
+ dev_err(&pdev->dev, "get mod clock failed %pe\n",
+ pwm->clk);
return PTR_ERR(pwm->clk);
+ }
+
+ if (!pwm->clk) {
+ pwm->clk = devm_clk_get(&pdev->dev, NULL);
+ if (IS_ERR(pwm->clk)) {
+ if (PTR_ERR(pwm->rst) != -EPROBE_DEFER)
+ dev_err(&pdev->dev, "get unnamed clock failed %pe\n",
+ pwm->clk);
+ return PTR_ERR(pwm->clk);
+ }
+ }

pwm->rst = devm_reset_control_get_optional_shared(&pdev->dev, NULL);
if (IS_ERR(pwm->rst)) {
--
2.20.1

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