290 lines
8.7 KiB
C
290 lines
8.7 KiB
C
/*
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* Copyright (c) 2021 ITE Corporation. All Rights Reserved.
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#define DT_DRV_COMPAT ite_it8xxx2_pwm
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#include <zephyr/device.h>
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#include <zephyr/drivers/pwm.h>
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#include <zephyr/drivers/pinctrl.h>
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#include <zephyr/dt-bindings/pwm/it8xxx2_pwm.h>
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#include <errno.h>
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#include <zephyr/kernel.h>
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#include <soc.h>
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#include <soc_dt.h>
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#include <stdlib.h>
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#include <zephyr/logging/log.h>
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LOG_MODULE_REGISTER(pwm_ite_it8xxx2, CONFIG_PWM_LOG_LEVEL);
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#define PWM_CTRX_MIN 100
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#define PWM_FREQ EC_FREQ
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#define PCSSG_MASK 0x3
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struct pwm_it8xxx2_cfg {
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/* PWM channel duty cycle register */
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uintptr_t reg_dcr;
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/* PWM channel clock source selection register */
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uintptr_t reg_pcssg;
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/* PWM channel clock source gating register */
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uintptr_t reg_pcsgr;
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/* PWM channel output polarity register */
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uintptr_t reg_pwmpol;
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/* PWM channel */
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int channel;
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/* PWM prescaler control register base */
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struct pwm_it8xxx2_regs *base;
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/* Select PWM prescaler that output to PWM channel */
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int prs_sel;
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/* PWM alternate configuration */
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const struct pinctrl_dev_config *pcfg;
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};
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static void pwm_enable(const struct device *dev, int enabled)
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{
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const struct pwm_it8xxx2_cfg *config = dev->config;
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volatile uint8_t *reg_pcsgr = (uint8_t *)config->reg_pcsgr;
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int ch = config->channel;
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if (enabled) {
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/* PWM channel clock source not gating */
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*reg_pcsgr &= ~BIT(ch);
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} else {
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/* PWM channel clock source gating */
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*reg_pcsgr |= BIT(ch);
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}
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}
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static int pwm_it8xxx2_get_cycles_per_sec(const struct device *dev,
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uint32_t channel, uint64_t *cycles)
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{
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ARG_UNUSED(channel);
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/*
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* There are three ways to call pwm_it8xxx2_set_cycles() from pwm api:
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* 1) pwm_set_cycles_usec() -> pwm_set_cycles_cycles() -> pwm_it8xxx2_set_cycles()
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* target_freq = pwm_clk_src / period_cycles
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* = cycles / (period * cycles / USEC_PER_SEC)
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* = USEC_PER_SEC / period
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* 2) pwm_set_cycles_nsec() -> pwm_set_cycles_cycles() -> pwm_it8xxx2_set_cycles()
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* target_freq = pwm_clk_src / period_cycles
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* = cycles / (period * cycles / NSEC_PER_SEC)
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* = NSEC_PER_SEC / period
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* 3) pwm_set_cycles_cycles() -> pwm_it8xxx2_set_cycles()
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* target_freq = pwm_clk_src / period_cycles
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* = cycles / period
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*
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* If we need to pwm output in EC power saving mode, then we will switch
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* the prescaler clock source (cycles) from 8MHz to 32.768kHz. In order
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* to get the same target_freq in the 3) case, we always return PWM_FREQ.
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*/
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*cycles = (uint64_t) PWM_FREQ;
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return 0;
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}
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static int pwm_it8xxx2_set_cycles(const struct device *dev,
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uint32_t channel, uint32_t period_cycles,
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uint32_t pulse_cycles, pwm_flags_t flags)
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{
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const struct pwm_it8xxx2_cfg *config = dev->config;
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struct pwm_it8xxx2_regs *const inst = config->base;
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volatile uint8_t *reg_dcr = (uint8_t *)config->reg_dcr;
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volatile uint8_t *reg_pwmpol = (uint8_t *)config->reg_pwmpol;
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int ch = config->channel;
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int prs_sel = config->prs_sel;
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uint32_t actual_freq = 0xffffffff, target_freq, deviation, cxcprs, ctr;
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uint64_t pwm_clk_src;
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/* Select PWM inverted polarity (ex. active-low pulse) */
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if (flags & PWM_POLARITY_INVERTED) {
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*reg_pwmpol |= BIT(ch);
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} else {
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*reg_pwmpol &= ~BIT(ch);
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}
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/* Enable PWM output open-drain */
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if (flags & PWM_IT8XXX2_OPEN_DRAIN) {
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inst->PWMODENR |= BIT(ch);
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}
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/* If pulse cycles is 0, set duty cycle 0 and enable pwm channel */
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if (pulse_cycles == 0) {
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*reg_dcr = 0;
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pwm_enable(dev, 1);
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return 0;
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}
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pwm_it8xxx2_get_cycles_per_sec(dev, channel, &pwm_clk_src);
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target_freq = ((uint32_t) pwm_clk_src) / period_cycles;
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/*
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* Support PWM output frequency:
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* 1) 8MHz clock source: 1Hz <= target_freq <= 79207Hz
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* 2) 32.768KHz clock source: 1Hz <= target_freq <= 324Hz
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* NOTE: PWM output signal maximum supported frequency comes from
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* [8MHz or 32.768KHz] / 1 / (PWM_CTRX_MIN + 1).
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* PWM output signal minimum supported frequency comes from
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* [8MHz or 32.768KHz] / 65536 / 256, the minimum integer is 1.
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*/
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if (target_freq < 1) {
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LOG_ERR("PWM output frequency is < 1 !");
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return -EINVAL;
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}
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deviation = (target_freq / 100) + 1;
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/*
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* Default clock source setting is 8MHz, when ITE chip is in power
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* saving mode, clock source 8MHz will be gated (32.768KHz won't).
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* So if we still need pwm output in mode, then we should set frequency
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* <=324Hz in board dts. Now change prescaler clock source from 8MHz to
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* 32.768KHz to support pwm output in mode.
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*/
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if (target_freq <= 324) {
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if (inst->PCFSR & BIT(prs_sel)) {
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inst->PCFSR &= ~BIT(prs_sel);
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}
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pwm_clk_src = (uint64_t) 32768;
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}
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/*
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* PWM output signal frequency is
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* pwm_clk_src / ((CxCPRS[15:0] + 1) * (CTRx[7:0] + 1))
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* NOTE: 1) define CTR minimum is 100 for more precisely when
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* calculate DCR
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* 2) CxCPRS[15:0] value 0001h results in a divisor 2
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* CxCPRS[15:0] value FFFFh results in a divisor 65536
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* CTRx[7:0] value 00h results in a divisor 1
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* CTRx[7:0] value FFh results in a divisor 256
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*/
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for (ctr = 0xFF; ctr >= PWM_CTRX_MIN; ctr--) {
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cxcprs = (((uint32_t) pwm_clk_src) / (ctr + 1) / target_freq);
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/*
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* Make sure cxcprs isn't zero, or we will have
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* divide-by-zero on calculating actual_freq.
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*/
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if (cxcprs != 0) {
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actual_freq = ((uint32_t) pwm_clk_src) / (ctr + 1) / cxcprs;
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if (abs(actual_freq - target_freq) < deviation) {
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/* CxCPRS[15:0] = cxcprs - 1 */
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cxcprs--;
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break;
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}
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}
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}
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if (cxcprs > UINT16_MAX) {
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LOG_ERR("PWM prescaler CxCPRS only support 2 bytes !");
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return -EINVAL;
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}
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/* Set PWM prescaler clock divide and cycle time register */
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if (prs_sel == PWM_PRESCALER_C4) {
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inst->C4CPRS = cxcprs & 0xFF;
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inst->C4MCPRS = (cxcprs >> 8) & 0xFF;
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inst->CTR1 = ctr;
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} else if (prs_sel == PWM_PRESCALER_C6) {
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inst->C6CPRS = cxcprs & 0xFF;
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inst->C6MCPRS = (cxcprs >> 8) & 0xFF;
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inst->CTR2 = ctr;
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} else if (prs_sel == PWM_PRESCALER_C7) {
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inst->C7CPRS = cxcprs & 0xFF;
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inst->C7MCPRS = (cxcprs >> 8) & 0xFF;
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inst->CTR3 = ctr;
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}
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/* Set PWM channel duty cycle register */
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*reg_dcr = (ctr * pulse_cycles) / period_cycles;
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/* PWM channel clock source not gating */
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pwm_enable(dev, 1);
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LOG_DBG("clock source freq %d, target freq %d",
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(uint32_t) pwm_clk_src, target_freq);
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return 0;
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}
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static int pwm_it8xxx2_init(const struct device *dev)
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{
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const struct pwm_it8xxx2_cfg *config = dev->config;
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struct pwm_it8xxx2_regs *const inst = config->base;
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volatile uint8_t *reg_pcssg = (uint8_t *)config->reg_pcssg;
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int ch = config->channel;
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int prs_sel = config->prs_sel;
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int pcssg_shift;
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int pcssg_mask;
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int status;
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/* PWM channel clock source gating before configuring */
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pwm_enable(dev, 0);
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/* Select clock source 8MHz for prescaler */
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inst->PCFSR |= BIT(prs_sel);
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/* Bit shift and mask of prescaler clock source select group register */
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pcssg_shift = (ch % 4) * 2;
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pcssg_mask = (prs_sel & PCSSG_MASK) << pcssg_shift;
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/* Select which prescaler output to PWM channel */
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*reg_pcssg &= ~(PCSSG_MASK << pcssg_shift);
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*reg_pcssg |= pcssg_mask;
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/*
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* The cycle timer1 of it8320 later series was enhanced from
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* 8bits to 10bits resolution, and others are still 8bit resolution.
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* Because the cycle timer1 high byte default value is not zero,
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* we clear cycle timer1 high byte at init and use it as 8-bit
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* resolution like others.
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*/
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inst->CTR1M = 0;
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/* Enable PWMs clock counter */
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inst->ZTIER |= IT8XXX2_PWM_PCCE;
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/* Set alternate mode of PWM pin */
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status = pinctrl_apply_state(config->pcfg, PINCTRL_STATE_DEFAULT);
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if (status < 0) {
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LOG_ERR("Failed to configure PWM pins");
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return status;
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}
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return 0;
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}
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static const struct pwm_driver_api pwm_it8xxx2_api = {
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.set_cycles = pwm_it8xxx2_set_cycles,
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.get_cycles_per_sec = pwm_it8xxx2_get_cycles_per_sec,
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};
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/* Device Instance */
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#define PWM_IT8XXX2_INIT(inst) \
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PINCTRL_DT_INST_DEFINE(inst); \
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\
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static const struct pwm_it8xxx2_cfg pwm_it8xxx2_cfg_##inst = { \
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.reg_dcr = DT_INST_REG_ADDR_BY_IDX(inst, 0), \
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.reg_pcssg = DT_INST_REG_ADDR_BY_IDX(inst, 1), \
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.reg_pcsgr = DT_INST_REG_ADDR_BY_IDX(inst, 2), \
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.reg_pwmpol = DT_INST_REG_ADDR_BY_IDX(inst, 3), \
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.channel = DT_PROP(DT_INST(inst, ite_it8xxx2_pwm), channel), \
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.base = (struct pwm_it8xxx2_regs *) DT_REG_ADDR(DT_NODELABEL(prs)), \
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.prs_sel = DT_PROP(DT_INST(inst, ite_it8xxx2_pwm), prescaler_cx), \
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.pcfg = PINCTRL_DT_INST_DEV_CONFIG_GET(inst), \
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}; \
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\
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DEVICE_DT_INST_DEFINE(inst, \
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&pwm_it8xxx2_init, \
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NULL, \
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NULL, \
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&pwm_it8xxx2_cfg_##inst, \
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PRE_KERNEL_1, \
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CONFIG_PWM_INIT_PRIORITY, \
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&pwm_it8xxx2_api);
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DT_INST_FOREACH_STATUS_OKAY(PWM_IT8XXX2_INIT)
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