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