1 files changed, 14 insertions, 12 deletions

diff --git a/drivers/pwm/pwm-lpss.c b/drivers/pwm/pwm-lpss.c
index 295b963dbddb..72c0bce5a75c 100644
--- a/drivers/pwm/pwm-lpss.c
+++ b/drivers/pwm/pwm-lpss.c
@@ -27,7 +27,6 @@
 #define PWM_SW_UPDATE			BIT(30)
 #define PWM_BASE_UNIT_SHIFT		8
 #define PWM_ON_TIME_DIV_MASK		0x000000ff
-#define PWM_DIVISION_CORRECTION		0x2
 
 /* Size of each PWM register space if multiple */
 #define PWM_SIZE			0x400
@@ -92,8 +91,8 @@ static int pwm_lpss_config(struct pwm_chip *chip, struct pwm_device *pwm,
 			   int duty_ns, int period_ns)
 {
 	struct pwm_lpss_chip *lpwm = to_lpwm(chip);
-	u8 on_time_div;
-	unsigned long c, base_unit_range;
+	unsigned long long on_time_div;
+	unsigned long c = lpwm->info->clk_rate, base_unit_range;
 	unsigned long long base_unit, freq = NSEC_PER_SEC;
 	u32 ctrl;
 
@@ -101,21 +100,18 @@ static int pwm_lpss_config(struct pwm_chip *chip, struct pwm_device *pwm,
 
 	/*
 	 * The equation is:
-	 * base_unit = ((freq / c) * base_unit_range) + correction
+	 * base_unit = round(base_unit_range * freq / c)
 	 */
 	base_unit_range = BIT(lpwm->info->base_unit_bits);
-	base_unit = freq * base_unit_range;
+	freq *= base_unit_range;
 
-	c = lpwm->info->clk_rate;
-	if (!c)
-		return -EINVAL;
-
-	do_div(base_unit, c);
-	base_unit += PWM_DIVISION_CORRECTION;
+	base_unit = DIV_ROUND_CLOSEST_ULL(freq, c);
 
 	if (duty_ns <= 0)
 		duty_ns = 1;
-	on_time_div = 255 - (255 * duty_ns / period_ns);
+	on_time_div = 255ULL * duty_ns;
+	do_div(on_time_div, period_ns);
+	on_time_div = 255ULL - on_time_div;
 
 	pm_runtime_get_sync(chip->dev);
 
@@ -169,6 +165,7 @@ struct pwm_lpss_chip *pwm_lpss_probe(struct device *dev, struct resource *r,
 				     const struct pwm_lpss_boardinfo *info)
 {
 	struct pwm_lpss_chip *lpwm;
+	unsigned long c;
 	int ret;
 
 	lpwm = devm_kzalloc(dev, sizeof(*lpwm), GFP_KERNEL);
@@ -180,6 +177,11 @@ struct pwm_lpss_chip *pwm_lpss_probe(struct device *dev, struct resource *r,
 		return ERR_CAST(lpwm->regs);
 
 	lpwm->info = info;
+
+	c = lpwm->info->clk_rate;
+	if (!c)
+		return ERR_PTR(-EINVAL);
+
 	lpwm->chip.dev = dev;
 	lpwm->chip.ops = &pwm_lpss_ops;
 	lpwm->chip.base = -1;