1 files changed, 11 insertions, 13 deletions

diff --git a/drivers/pwm/pwm-atmel.c b/drivers/pwm/pwm-atmel.c
index 6e700a541ca3..d3c22de9ee47 100644
--- a/drivers/pwm/pwm-atmel.c
+++ b/drivers/pwm/pwm-atmel.c
@@ -102,7 +102,7 @@ static int atmel_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
                             int duty_ns, int period_ns)
 {
         struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
-        unsigned long clk_rate, prd, dty;
+        unsigned long prd, dty;
         unsigned long long div;
         unsigned int pres = 0;
         u32 val;
@@ -113,20 +113,18 @@ static int atmel_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
                 return -EBUSY;
         }
 
-        clk_rate = clk_get_rate(atmel_pwm->clk);
-        div = clk_rate;
+        /* Calculate the period cycles and prescale value */
+        div = (unsigned long long)clk_get_rate(atmel_pwm->clk) * period_ns;
+        do_div(div, NSEC_PER_SEC);
 
-        /* Calculate the period cycles */
         while (div > PWM_MAX_PRD) {
-                div = clk_rate / (1 << pres);
-                div = div * period_ns;
-                /* 1/Hz = 100000000 ns */
-                do_div(div, 1000000000);
-
-                if (pres++ > PRD_MAX_PRES) {
-                        dev_err(chip->dev, "pres exceeds the maximum value\n");
-                        return -EINVAL;
-                }
+                div >>= 1;
+                pres++;
+        }
+
+        if (pres > PRD_MAX_PRES) {
+                dev_err(chip->dev, "pres exceeds the maximum value\n");
+                return -EINVAL;
         }
 
         /* Calculate the duty cycles */