diff --git a/drivers/pwm/pwm-lpss.c b/drivers/pwm/pwm-lpss.c
index 75bbfe5..d77cec2 100644
--- a/drivers/pwm/pwm-lpss.c
+++ b/drivers/pwm/pwm-lpss.c
@@ -93,10 +93,12 @@
 	 * The equation is:
 	 * base_unit = round(base_unit_range * freq / c)
 	 */
-	base_unit_range = BIT(lpwm->info->base_unit_bits) - 1;
+	base_unit_range = BIT(lpwm->info->base_unit_bits);
 	freq *= base_unit_range;
 
 	base_unit = DIV_ROUND_CLOSEST_ULL(freq, c);
+	/* base_unit must not be 0 and we also want to avoid overflowing it */
+	base_unit = clamp_val(base_unit, 1, base_unit_range - 1);
 
 	on_time_div = 255ULL * duty_ns;
 	do_div(on_time_div, period_ns);
@@ -104,8 +106,7 @@
 
 	orig_ctrl = ctrl = pwm_lpss_read(pwm);
 	ctrl &= ~PWM_ON_TIME_DIV_MASK;
-	ctrl &= ~(base_unit_range << PWM_BASE_UNIT_SHIFT);
-	base_unit &= base_unit_range;
+	ctrl &= ~((base_unit_range - 1) << PWM_BASE_UNIT_SHIFT);
 	ctrl |= (u32) base_unit << PWM_BASE_UNIT_SHIFT;
 	ctrl |= on_time_div;