pwm: sun4i: Prefer "mod" clock to unnamed

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@pengutronix.de>
Signed-off-by: Clément Péron <peron.clem@gmail.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

diff --git a/drivers/pwm/pwm-sun4i.c b/drivers/pwm/pwm-sun4i.c
index 487899d..8002616 100644 (file)
--- 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)) {