pwm: imx1: Make use of devm_pwmchip_alloc() function

This prepares the pwm-imx1 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_pwm_imx1_chip() helper macro to a static inline to
get some type safety.

Link: https://lore.kernel.org/r/c6995e0d281255a7514edf9f25a561302dcaf65f.1707900770.git.u.kleine-koenig@pengutronix.deSigned-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

drivers/pwm/pwm-imx1.c

@@ -28,10 +28,12 @@ struct pwm_imx1_chip {
 	struct clk *clk_ipg;
 	struct clk *clk_per;
 	void __iomem *mmio_base;
-	struct pwm_chip chip;
 };
 
-#define to_pwm_imx1_chip(chip)	container_of(chip, struct pwm_imx1_chip, chip)
+static inline struct pwm_imx1_chip *to_pwm_imx1_chip(struct pwm_chip *chip)
+{
+	return pwmchip_get_drvdata(chip);
+}
 
 static int pwm_imx1_clk_prepare_enable(struct pwm_chip *chip)
 {
@@ -156,11 +158,13 @@ MODULE_DEVICE_TABLE(of, pwm_imx1_dt_ids);
 
 static int pwm_imx1_probe(struct platform_device *pdev)
 {
+	struct pwm_chip *chip;
 	struct pwm_imx1_chip *imx;
 
-	imx = devm_kzalloc(&pdev->dev, sizeof(*imx), GFP_KERNEL);
-	if (!imx)
-		return -ENOMEM;
+	chip = devm_pwmchip_alloc(&pdev->dev, 1, sizeof(*imx));
+	if (IS_ERR(chip))
+		return PTR_ERR(chip);
+	imx = to_pwm_imx1_chip(chip);
 
 	imx->clk_ipg = devm_clk_get(&pdev->dev, "ipg");
 	if (IS_ERR(imx->clk_ipg))
@@ -172,15 +176,13 @@ static int pwm_imx1_probe(struct platform_device *pdev)
 		return dev_err_probe(&pdev->dev, PTR_ERR(imx->clk_per),
 				     "failed to get peripheral clock\n");
 
-	imx->chip.ops = &pwm_imx1_ops;
-	imx->chip.dev = &pdev->dev;
-	imx->chip.npwm = 1;
+	chip->ops = &pwm_imx1_ops;
 
 	imx->mmio_base = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(imx->mmio_base))
 		return PTR_ERR(imx->mmio_base);
 
-	return devm_pwmchip_add(&pdev->dev, &imx->chip);
+	return devm_pwmchip_add(&pdev->dev, chip);
 }
 
 static struct platform_driver pwm_imx1_driver = {