pwm: sifive: Simplify clk handling

The clk is necessary for both register access and (enabled) operation of
the PWM. Instead of

	clk_enable()
	update_hw()
	if pwm_got_enabled():
		clk_enable()
	elif pwm_got_disabled():
		clk_disable()
	clk_disable()

which is some cases only calls clk_enable() to immediately afterwards
call clk_disable again, do:

	if (!prev_state.enabled)
		clk_enable()

	# clk enabled exactly once

	update_hw()

	if (!next_state.enabled)
		clk_disable()

which is much easier.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Tested-by: Emil Renner Berthing <emil.renner.berthing@canonical.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

diff --git a/drivers/pwm/pwm-sifive.c b/drivers/pwm/pwm-sifive.c
index d833536b5e7af3d92f70ec8b89563cfd7974c636..34d23d56fa254800779c0bcb6156ea97649d588e 100644 (file)
--- a/drivers/pwm/pwm-sifive.c
+++ b/drivers/pwm/pwm-sifive.c
@@ -168,24 +168,24 @@ static int pwm_sifive_apply(struct pwm_chip *chip, struct pwm_device *pwm,
        }
        mutex_unlock(&ddata->lock);
 
-       ret = clk_enable(ddata->clk);
-       if (ret) {
-               dev_err(ddata->chip.dev, "Enable clk failed\n");
-               return ret;
+       /*
+        * If the PWM is enabled the clk is already on. So only enable it
+        * conditionally to have it on exactly once afterwards independent of
+        * the PWM state.
+        */
+       if (!enabled) {
+               ret = clk_enable(ddata->clk);
+               if (ret) {
+                       dev_err(ddata->chip.dev, "Enable clk failed\n");
+                       return ret;
+               }
        }
 
        writel(frac, ddata->regs + PWM_SIFIVE_PWMCMP(pwm->hwpwm));
 
-       if (state->enabled != enabled) {
-               if (state->enabled) {
-                       if (clk_enable(ddata->clk))
-                               dev_err(ddata->chip.dev, "Enable clk failed\n");
-               } else {
-                       clk_disable(ddata->clk);
-               }
-       }
+       if (!state->enabled)
+               clk_disable(ddata->clk);
 
-       clk_disable(ddata->clk);
        return 0;
 }