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ITE drivers/pwm: don't divide-by-zero

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Make sure cxcprs isn't zero, or we will have
divide-by-zero on calculating actual_freq.

Test:
1.tests/drivers/pwm/pwm_api pattern
2.GPA0(pwm0) output 79201Hz, 324Hz, 100Hz, 1Hz waveform

Signed-off-by: Ruibin Chang <Ruibin.Chang@ite.com.tw>
This commit is contained in:
Ruibin Chang 2022-05-09 13:56:52 +08:00 • committed by Carles Cufí
commit f3204b7326
1 changed files with 11 additions and 4 deletions
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15
drivers/pwm/pwm_ite_it8xxx2.c
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@ -157,11 +157,18 @@ static int pwm_it8xxx2_set_cycles(const struct device *dev,
* CTRx[7:0] value FFh results in a divisor 256 * CTRx[7:0] value FFh results in a divisor 256
*/ */
for (ctr = 0xFF; ctr >= PWM_CTRX_MIN; ctr--) { for (ctr = 0xFF; ctr >= PWM_CTRX_MIN; ctr--) {
cxcprs = (((uint32_t) pwm_clk_src) / (ctr + 1) / target_freq) - 1; cxcprs = (((uint32_t) pwm_clk_src) / (ctr + 1) / target_freq);
if (cxcprs >= 0) { /*
actual_freq = ((uint32_t) pwm_clk_src) / (ctr + 1) / (cxcprs + 1); * Make sure cxcprs isn't zero, or we will have
if (abs(actual_freq - target_freq) < deviation) * divide-by-zero on calculating actual_freq.
*/
if (cxcprs != 0) {
actual_freq = ((uint32_t) pwm_clk_src) / (ctr + 1) / cxcprs;
if (abs(actual_freq - target_freq) < deviation) {
/* CxCPRS[15:0] = cxcprs - 1 */
cxcprs--;
break; break;
}
} }
} }