pwm: sti: Simplify probe function using devm functions

Instead of of_clk_get_by_name() use devm_clk_get_prepared() which has
several advantages:

 - Combines getting the clock and a call to clk_prepare(). The latter
   can be dropped from sti_pwm_probe() accordingly.
 - Cares for calling clk_put() which is missing in both probe's error
   path and the remove function.
 - Cares for calling clk_unprepare() which can be dropped from the error
   paths and the remove function. (Note that not all error path got this
   right.)

With additionally using devm_pwmchip_add() instead of pwmchip_add() the
remove callback can be dropped completely. With it the last user of
platform_get_drvdata() goes away and so platform_set_drvdata() can be
dropped from the probe function, too.

Fixes: 378fe115 ("pwm: sti: Add new driver for ST's PWM IP")
Link: https://lore.kernel.org/r/81f0e1d173652f435afda6719adaed1922fe059a.1710068192.git.u.kleine-koenig@pengutronix.deSigned-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

drivers/pwm/pwm-sti.c

@@ -624,32 +624,20 @@ static int sti_pwm_probe(struct platform_device *pdev)
 		return ret;
 
 	if (cdata->pwm_num_devs) {
-		pc->pwm_clk = of_clk_get_by_name(dev->of_node, "pwm");
+		pc->pwm_clk = devm_clk_get_prepared(dev, "pwm");
 		if (IS_ERR(pc->pwm_clk)) {
 			dev_err(dev, "failed to get PWM clock\n");
 			return PTR_ERR(pc->pwm_clk);
 		}
-
-		ret = clk_prepare(pc->pwm_clk);
-		if (ret) {
-			dev_err(dev, "failed to prepare clock\n");
-			return ret;
-		}
 	}
 
 	if (cdata->cpt_num_devs) {
-		pc->cpt_clk = of_clk_get_by_name(dev->of_node, "capture");
+		pc->cpt_clk = devm_clk_get_prepared(dev, "capture");
 		if (IS_ERR(pc->cpt_clk)) {
 			dev_err(dev, "failed to get PWM capture clock\n");
 			return PTR_ERR(pc->cpt_clk);
 		}
 
-		ret = clk_prepare(pc->cpt_clk);
-		if (ret) {
-			dev_err(dev, "failed to prepare clock\n");
-			return ret;
-		}
-
 		cdata->ddata = devm_kzalloc(dev, cdata->cpt_num_devs * sizeof(*cdata->ddata), GFP_KERNEL);
 		if (!cdata->ddata)
 			return -ENOMEM;
@@ -664,27 +652,7 @@ static int sti_pwm_probe(struct platform_device *pdev)
 		mutex_init(&ddata->lock);
 	}
 
-	ret = pwmchip_add(chip);
-	if (ret < 0) {
-		clk_unprepare(pc->pwm_clk);
-		clk_unprepare(pc->cpt_clk);
-		return ret;
-	}
-
-	platform_set_drvdata(pdev, chip);
-
-	return 0;
-}
-
-static void sti_pwm_remove(struct platform_device *pdev)
-{
-	struct pwm_chip *chip = platform_get_drvdata(pdev);
-	struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
-
-	pwmchip_remove(chip);
-
-	clk_unprepare(pc->pwm_clk);
-	clk_unprepare(pc->cpt_clk);
+	return devm_pwmchip_add(dev, chip);
 }
 
 static const struct of_device_id sti_pwm_of_match[] = {
@@ -699,7 +667,6 @@ static struct platform_driver sti_pwm_driver = {
 		.of_match_table = sti_pwm_of_match,
 	},
 	.probe = sti_pwm_probe,
-	.remove_new = sti_pwm_remove,
 };
 module_platform_driver(sti_pwm_driver);