pwm: sifive: Make use of devm_pwmchip_alloc() function

This prepares the pwm-sifive 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/30a4cac[e-mail]
Signed-off-by: Uwe Kleine-König <[e-mail]>

drivers/pwm/pwm-sifive.c

···
 #define PWM_SIFIVE_DEFAULT_PERIOD	10000000
 
 struct pwm_sifive_ddata {
-	struct pwm_chip	chip;
 	struct device *parent;
 	struct mutex lock; /* lock to protect user_count and approx_period */
 	struct notifier_block notifier;
···
 static inline
 struct pwm_sifive_ddata *pwm_sifive_chip_to_ddata(struct pwm_chip *chip)
 {
-	return container_of(chip, struct pwm_sifive_ddata, chip);
+	return pwmchip_get_drvdata(chip);
 }
 
 static int pwm_sifive_request(struct pwm_chip *chip, struct pwm_device *pwm)
···
 	u32 val;
 	unsigned int enabled_pwms = 0, enabled_clks = 1;
 
-	ddata = devm_kzalloc(dev, sizeof(*ddata), GFP_KERNEL);
-	if (!ddata)
-		return -ENOMEM;
+	chip = devm_pwmchip_alloc(dev, 4, sizeof(*ddata));
+	if (IS_ERR(chip))
+		return PTR_ERR(chip);
 
+	ddata = pwm_sifive_chip_to_ddata(chip);
+	ddata->parent = dev;
 	mutex_init(&ddata->lock);
-	chip = &ddata->chip;
-	chip->dev = ddata->parent = dev;
 	chip->ops = &pwm_sifive_ops;
-	chip->npwm = 4;
 
 	ddata->regs = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(ddata->regs))