pwm: mxs: Make use of devm_pwmchip_alloc() function

This prepares the pwm-mxs driver to further changes of the pwm core
outlined in the commit introducing devm_pwmchip_alloc(). There is no
intended semantical change and the driver should behave as before.

Also convert the to_mxs_pwm_chip() helper macro to a static inline to
get some type safety.

Link: https://lore.kernel.org/r/39203f3bfbf4e97654db78bdc7e0c9a2b72c1368.1707900770.git.u.kleine-koenig@pengutronix.deSigned-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

drivers/pwm/pwm-mxs.c

@@ -37,12 +37,14 @@ static const u8 cdiv_shift[PERIOD_CDIV_MAX] = {
 };
 
 struct mxs_pwm_chip {
-	struct pwm_chip chip;
 	struct clk *clk;
 	void __iomem *base;
 };
 
-#define to_mxs_pwm_chip(_chip) container_of(_chip, struct mxs_pwm_chip, chip)
+static inline struct mxs_pwm_chip *to_mxs_pwm_chip(struct pwm_chip *chip)
+{
+	return pwmchip_get_drvdata(chip);
+}
 
 static int mxs_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 			 const struct pwm_state *state)
@@ -120,12 +122,21 @@ static const struct pwm_ops mxs_pwm_ops = {
 static int mxs_pwm_probe(struct platform_device *pdev)
 {
 	struct device_node *np = pdev->dev.of_node;
+	struct pwm_chip *chip;
 	struct mxs_pwm_chip *mxs;
+	u32 npwm;
 	int ret;
 
-	mxs = devm_kzalloc(&pdev->dev, sizeof(*mxs), GFP_KERNEL);
-	if (!mxs)
-		return -ENOMEM;
+	ret = of_property_read_u32(np, "fsl,pwm-number", &npwm);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "failed to get pwm number: %d\n", ret);
+		return ret;
+	}
+
+	chip = devm_pwmchip_alloc(&pdev->dev, npwm, sizeof(*mxs));
+	if (IS_ERR(chip))
+		return PTR_ERR(chip);
+	mxs = to_mxs_pwm_chip(chip);
 
 	mxs->base = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(mxs->base))
@@ -135,21 +146,14 @@ static int mxs_pwm_probe(struct platform_device *pdev)
 	if (IS_ERR(mxs->clk))
 		return PTR_ERR(mxs->clk);
 
-	mxs->chip.dev = &pdev->dev;
-	mxs->chip.ops = &mxs_pwm_ops;
-
-	ret = of_property_read_u32(np, "fsl,pwm-number", &mxs->chip.npwm);
-	if (ret < 0) {
-		dev_err(&pdev->dev, "failed to get pwm number: %d\n", ret);
-		return ret;
-	}
+	chip->ops = &mxs_pwm_ops;
 
 	/* FIXME: Only do this if the PWM isn't already running */
 	ret = stmp_reset_block(mxs->base);
 	if (ret)
 		return dev_err_probe(&pdev->dev, ret, "failed to reset PWM\n");
 
-	ret = devm_pwmchip_add(&pdev->dev, &mxs->chip);
+	ret = devm_pwmchip_add(&pdev->dev, chip);
 	if (ret < 0) {
 		dev_err(&pdev->dev, "failed to add pwm chip %d\n", ret);
 		return ret;