pwm: sifive: Simplify offset calculation for PWMCMP registers

Instead of explicitly using PWM_SIFIVE_PWMCMP0 + pwm->hwpwm *
PWM_SIFIVE_SIZE_PWMCMP for each access to one of the PWMCMP registers,
introduce a macro that takes the hwpwm id as parameter.

For the register definition using a plain 4 instead of the cpp constant
PWM_SIFIVE_SIZE_PWMCMP is easier to read, so define the offset macro
without the constant. The latter can then be dropped as there are no
users left.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Tested-by: Emil Renner Berthing <emil.renner.berthing@canonical.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

drivers/pwm/pwm-sifive.c

@@ -23,7 +23,7 @@
 #define PWM_SIFIVE_PWMCFG		0x0
 #define PWM_SIFIVE_PWMCOUNT		0x8
 #define PWM_SIFIVE_PWMS			0x10
-#define PWM_SIFIVE_PWMCMP0		0x20
+#define PWM_SIFIVE_PWMCMP(i)		(0x20 + 4 * (i))
 
 /* PWMCFG fields */
 #define PWM_SIFIVE_PWMCFG_SCALE		GENMASK(3, 0)
@@ -36,8 +36,6 @@
 #define PWM_SIFIVE_PWMCFG_GANG		BIT(24)
 #define PWM_SIFIVE_PWMCFG_IP		BIT(28)
 
-/* PWM_SIFIVE_SIZE_PWMCMP is used to calculate offset for pwmcmpX registers */
-#define PWM_SIFIVE_SIZE_PWMCMP		4
 #define PWM_SIFIVE_CMPWIDTH		16
 #define PWM_SIFIVE_DEFAULT_PERIOD	10000000
 
@@ -112,8 +110,7 @@ static void pwm_sifive_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 	struct pwm_sifive_ddata *ddata = pwm_sifive_chip_to_ddata(chip);
 	u32 duty, val;
 
-	duty = readl(ddata->regs + PWM_SIFIVE_PWMCMP0 +
-		     pwm->hwpwm * PWM_SIFIVE_SIZE_PWMCMP);
+	duty = readl(ddata->regs + PWM_SIFIVE_PWMCMP(pwm->hwpwm));
 
 	state->enabled = duty > 0;
 
@@ -193,8 +190,7 @@ static int pwm_sifive_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 		pwm_sifive_update_clock(ddata, clk_get_rate(ddata->clk));
 	}
 
-	writel(frac, ddata->regs + PWM_SIFIVE_PWMCMP0 +
-	       pwm->hwpwm * PWM_SIFIVE_SIZE_PWMCMP);
+	writel(frac, ddata->regs + PWM_SIFIVE_PWMCMP(pwm->hwpwm));
 
 	if (state->enabled != enabled)
 		pwm_sifive_enable(chip, state->enabled);