pwm: atmel-tcb: Make use of devm_pwmchip_alloc() function

This prepares the pwm-atmel-tcb 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.

Link: https://lore.kernel.org/r/c845e6c9d27c8a4037755b2ae702b0039947a3c1.1707900770.git.u.kleine-koenig@pengutronix.deSigned-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

drivers/pwm/pwm-atmel-tcb.c

@@ -47,7 +47,6 @@ struct atmel_tcb_channel {
 };
 
 struct atmel_tcb_pwm_chip {
-	struct pwm_chip chip;
 	spinlock_t lock;
 	u8 channel;
 	u8 width;
@@ -63,7 +62,7 @@ static const u8 atmel_tcb_divisors[] = { 2, 8, 32, 128, 0, };
 
 static inline struct atmel_tcb_pwm_chip *to_tcb_chip(struct pwm_chip *chip)
 {
-	return container_of(chip, struct atmel_tcb_pwm_chip, chip);
+	return pwmchip_get_drvdata(chip);
 }
 
 static int atmel_tcb_pwm_request(struct pwm_chip *chip,
@@ -397,9 +396,10 @@ static int atmel_tcb_pwm_probe(struct platform_device *pdev)
 	int err;
 	int channel;
 
-	tcbpwm = devm_kzalloc(&pdev->dev, sizeof(*tcbpwm), GFP_KERNEL);
-	if (tcbpwm == NULL)
-		return -ENOMEM;
+	chip = devm_pwmchip_alloc(&pdev->dev, NPWM, sizeof(*tcbpwm));
+	if (IS_ERR(chip))
+		return PTR_ERR(chip);
+	tcbpwm = to_tcb_chip(chip);
 
 	err = of_property_read_u32(np, "reg", &channel);
 	if (err < 0) {
@@ -437,10 +437,7 @@ static int atmel_tcb_pwm_probe(struct platform_device *pdev)
 		}
 	}
 
-	chip = &tcbpwm->chip;
-	chip->dev = &pdev->dev;
 	chip->ops = &atmel_tcb_pwm_ops;
-	chip->npwm = NPWM;
 	tcbpwm->channel = channel;
 	tcbpwm->width = config->counter_width;