pwm: imx27: Fix rounding behavior

To not trigger the warnings provided by CONFIG_PWM_DEBUG

 - use up-rounding in .get_state()
 - don't divide by the result of a division
 - don't use the rounded counter value for the period length to calculate
   the counter value for the duty cycle

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

diff --git a/drivers/pwm/pwm-imx27.c b/drivers/pwm/pwm-imx27.c
index a6e40d4..732a6f3 100644 (file)
--- a/drivers/pwm/pwm-imx27.c
+++ b/drivers/pwm/pwm-imx27.c
@@ -150,13 +150,12 @@ static void pwm_imx27_get_state(struct pwm_chip *chip,
 
        prescaler = MX3_PWMCR_PRESCALER_GET(val);
        pwm_clk = clk_get_rate(imx->clk_per);
-       pwm_clk = DIV_ROUND_CLOSEST_ULL(pwm_clk, prescaler);
        val = readl(imx->mmio_base + MX3_PWMPR);
        period = val >= MX3_PWMPR_MAX ? MX3_PWMPR_MAX : val;
 
        /* PWMOUT (Hz) = PWMCLK / (PWMPR + 2) */
-       tmp = NSEC_PER_SEC * (u64)(period + 2);
-       state->period = DIV_ROUND_CLOSEST_ULL(tmp, pwm_clk);
+       tmp = NSEC_PER_SEC * (u64)(period + 2) * prescaler;
+       state->period = DIV_ROUND_UP_ULL(tmp, pwm_clk);
 
        /*
         * PWMSAR can be read only if PWM is enabled. If the PWM is disabled,
@@ -167,8 +166,8 @@ static void pwm_imx27_get_state(struct pwm_chip *chip,
        else
                val = imx->duty_cycle;
 
-       tmp = NSEC_PER_SEC * (u64)(val);
-       state->duty_cycle = DIV_ROUND_CLOSEST_ULL(tmp, pwm_clk);
+       tmp = NSEC_PER_SEC * (u64)(val) * prescaler;
+       state->duty_cycle = DIV_ROUND_UP_ULL(tmp, pwm_clk);
 
        pwm_imx27_clk_disable_unprepare(imx);
 }
@@ -220,22 +219,23 @@ static int pwm_imx27_apply(struct pwm_chip *chip, struct pwm_device *pwm,
        struct pwm_imx27_chip *imx = to_pwm_imx27_chip(chip);
        struct pwm_state cstate;
        unsigned long long c;
+       unsigned long long clkrate;
        int ret;
        u32 cr;
 
        pwm_get_state(pwm, &cstate);
 
-       c = clk_get_rate(imx->clk_per);
-       c *= state->period;
+       clkrate = clk_get_rate(imx->clk_per);
+       c = clkrate * state->period;
 
-       do_div(c, 1000000000);
+       do_div(c, NSEC_PER_SEC);
        period_cycles = c;
 
        prescale = period_cycles / 0x10000 + 1;
 
        period_cycles /= prescale;
-       c = (unsigned long long)period_cycles * state->duty_cycle;
-       do_div(c, state->period);
+       c = clkrate * state->duty_cycle;
+       do_div(c, NSEC_PER_SEC * prescale);
        duty_cycles = c;
 
        /*