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drivers: pwm_led: esp32: Clock management update
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Update clock management to better support new devices.

Signed-off-by: Raffael Rostagno <[email protected]>
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Raffael Rostagno committed Jan 9, 2025
1 parent 329f4a1 commit 1008a77
Showing 1 changed file with 63 additions and 83 deletions.
146 changes: 63 additions & 83 deletions drivers/pwm/pwm_led_esp32.c
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Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,7 @@

#include <hal/ledc_hal.h>
#include <hal/ledc_types.h>
#include <esp_clk_tree.h>

#include <soc.h>
#include <errno.h>
Expand All @@ -21,15 +22,13 @@
#include <zephyr/logging/log.h>
LOG_MODULE_REGISTER(pwm_ledc_esp32, CONFIG_PWM_LOG_LEVEL);

#if SOC_LEDC_SUPPORT_APB_CLOCK
#define CLOCK_SOURCE LEDC_APB_CLK
#elif SOC_LEDC_SUPPORT_PLL_DIV_CLOCK
#define CLOCK_SOURCE LEDC_SCLK
#if defined(CONFIG_SOC_SERIES_ESP32C2)
#define SCLK_CLK_FREQ MHZ(60)
#elif defined(CONFIG_SOC_SERIES_ESP32C6)
#define SCLK_CLK_FREQ MHZ(80)
static const int global_clks[] = LEDC_LL_GLOBAL_CLOCKS;
#if SOC_LEDC_HAS_TIMER_SPECIFIC_MUX
static const int timer_specific_clks[] = LEDC_LL_TIMER_SPECIFIC_CLOCKS;
static int lowspd_clks[ARRAY_SIZE(global_clks) + ARRAY_SIZE(timer_specific_clks)];
#endif
#if SOC_LEDC_SUPPORT_HS_MODE
static const int highspd_clks[] = {LEDC_APB_CLK, LEDC_REF_TICK};
#endif

struct pwm_ledc_esp32_data {
Expand All @@ -45,6 +44,7 @@ struct pwm_ledc_esp32_channel_config {
const ledc_mode_t speed_mode;
uint8_t resolution;
ledc_clk_src_t clock_src;
uint32_t clock_src_hz;
uint32_t duty_val;
bool inverted;
};
Expand All @@ -57,9 +57,6 @@ struct pwm_ledc_esp32_config {
const int channel_len;
};

static int pwm_led_esp32_get_cycles_per_sec(const struct device *dev, uint32_t channel_idx,
uint64_t *cycles);

static struct pwm_ledc_esp32_channel_config *get_channel_config(const struct device *dev,
int channel_id)
{
Expand Down Expand Up @@ -114,12 +111,7 @@ static int pwm_led_esp32_calculate_max_resolution(struct pwm_ledc_esp32_channel_
* Max duty resolution can be obtained with
* max_res = log2(CLK_FREQ/FREQ)
*/
#if SOC_LEDC_SUPPORT_APB_CLOCK
uint64_t clock_freq = channel->clock_src == LEDC_APB_CLK ? APB_CLK_FREQ : REF_CLK_FREQ;
#elif SOC_LEDC_SUPPORT_PLL_DIV_CLOCK
uint64_t clock_freq = SCLK_CLK_FREQ;
#endif
uint32_t max_precision_n = clock_freq/channel->freq;
uint32_t max_precision_n = channel->clock_src_hz / channel->freq;

for (uint8_t i = 0; i <= SOC_LEDC_TIMER_BIT_WIDTH; i++) {
max_precision_n /= 2;
Expand All @@ -133,49 +125,44 @@ static int pwm_led_esp32_calculate_max_resolution(struct pwm_ledc_esp32_channel_

static int pwm_led_esp32_timer_config(struct pwm_ledc_esp32_channel_config *channel)
{
/**
* Calculate max resolution based on the given frequency and the pwm clock.
*
* There are 2 clock resources for PWM:
*
* 1. APB_CLK (80MHz)
* 2. REF_TICK (1MHz)
*
* The low speed timers can be sourced from:
*
* 1. APB_CLK (80MHz)
* 2. RTC_CLK (8Mhz)
*
* The APB_CLK is mostly used
*
* First we try to find the largest resolution using the APB_CLK source.
* If the given frequency doesn't support it, we move to the next clock source.
*/
const int *clock_src;
int clock_src_num;

#if SOC_LEDC_SUPPORT_APB_CLOCK
channel->clock_src = LEDC_APB_CLK;
if (channel->speed_mode == LEDC_LOW_SPEED_MODE) {
#ifdef SOC_LEDC_HAS_TIMER_SPECIFIC_MUX
clock_src = lowspd_clks;
clock_src_num = ARRAY_SIZE(lowspd_clks);
#else
clock_src = global_clks;
clock_src_num = ARRAY_SIZE(global_clks);
#endif
if (!pwm_led_esp32_calculate_max_resolution(channel)) {
return 0;
}

#if SOC_LEDC_SUPPORT_REF_TICK
channel->clock_src = LEDC_REF_TICK;
if (!pwm_led_esp32_calculate_max_resolution(channel)) {
return 0;
#ifdef SOC_LEDC_SUPPORT_HS_MODE
else {
clock_src = highspd_clks;
clock_src_num = ARRAY_SIZE(highspd_clks);
}
#endif

/**
* ESP32 - S2,S3 and C3 variants have only 14 bits counter.
* where as the plain ESP32 variant has 20 bits counter.
* application failed to set low frequency(1Hz) in S2, S3 and C3 variants.
* to get very low frequencies on these variants,
* frequency needs to be tuned with 18 bits clock divider.
* so select the slow clock source (1MHz) with highest counter resolution.
* this can be handled on the func 'pwm_led_esp32_timer_set' with 'prescaler'.
* Calculate max resolution based on the given frequency and the pwm clock.
* Try each clock source available depending on the device and channel type.
*/
for (int i = 0; i < clock_src_num; i++) {
channel->clock_src = clock_src[i];
esp_clk_tree_src_get_freq_hz(channel->clock_src, ESP_CLK_TREE_SRC_FREQ_PRECISION_CACHED, &channel->clock_src_hz);
if (!pwm_led_esp32_calculate_max_resolution(channel)) {
return 0;
}
}

/* Frequency is too low for this device, so even though best precision can't
* be achieved we can set max resolution and consider that the previous
* loop selects clock from fastest to slowest, so this is the best
* configuration achievable.
*/
channel->resolution = SOC_LEDC_TIMER_BIT_WIDTH;

return 0;
}

Expand All @@ -188,30 +175,7 @@ static int pwm_led_esp32_timer_set(const struct device *dev,

__ASSERT_NO_MSG(channel->freq > 0);

switch (channel->clock_src) {
#if SOC_LEDC_SUPPORT_APB_CLOCK
case LEDC_APB_CLK:
/** This expression comes from ESP32 Espressif's Technical Reference
* Manual chapter 13.2.2 Timers.
* div_num is a fixed point value (Q10.8).
*/
prescaler = ((uint64_t) APB_CLK_FREQ << 8) / channel->freq / precision;
break;
#endif
#if SOC_LEDC_SUPPORT_PLL_DIV_CLOCK
case LEDC_SCLK:
prescaler = ((uint64_t) SCLK_CLK_FREQ << 8) / channel->freq / precision;
break;
#endif
#if SOC_LEDC_SUPPORT_REF_TICK
case LEDC_REF_TICK:
prescaler = ((uint64_t) REF_CLK_FREQ << 8) / channel->freq / precision;
break;
#endif
default:
LOG_ERR("Invalid clock source (%d)", channel->clock_src);
return -EINVAL;
}
prescaler = ((uint64_t)channel->clock_src_hz << 8) / channel->freq / precision;

if (prescaler < 0x100 || prescaler > 0x3FFFF) {
LOG_ERR("Prescaler out of range: %#X", prescaler);
Expand Down Expand Up @@ -248,11 +212,7 @@ static int pwm_led_esp32_get_cycles_per_sec(const struct device *dev, uint32_t c
return -EINVAL;
}

#if SOC_LEDC_SUPPORT_APB_CLOCK
*cycles = channel->clock_src == LEDC_APB_CLK ? APB_CLK_FREQ : REF_CLK_FREQ;
#elif SOC_LEDC_SUPPORT_PLL_DIV_CLOCK
*cycles = SCLK_CLK_FREQ;
#endif
*cycles = (uint64_t)channel->clock_src_hz;

return 0;
}
Expand Down Expand Up @@ -301,7 +261,12 @@ static int pwm_led_esp32_channel_update_frequency(const struct device *dev,
}
}

pwm_led_esp32_timer_config(channel);
ret = pwm_led_esp32_timer_config(channel);

if (ret < 0) {
LOG_ERR("Error finding timer config for channel %d for requested frequency", channel->idx);
return ret;
}

ret = pwm_led_esp32_timer_set(dev, channel);

Expand Down Expand Up @@ -335,6 +300,8 @@ static int pwm_led_esp32_set_cycles(const struct device *dev, uint32_t channel_i
channel->inverted = false;
}

ledc_hal_init(&data->hal, channel->speed_mode);

if ((pulse_cycles == period_cycles) || (pulse_cycles == 0)) {
/* For duty 0% and 100% stop PWM, set output level and return */
pwm_led_esp32_stop(data, channel, (pulse_cycles == period_cycles));
Expand Down Expand Up @@ -379,16 +346,30 @@ int pwm_led_esp32_init(const struct device *dev)
/* Enable peripheral */
clock_control_on(config->clock_dev, config->clock_subsys);

ledc_hal_init(&data->hal, config->channel_config[0].speed_mode);
#if SOC_LEDC_HAS_TIMER_SPECIFIC_MUX
/* Combine clock sources to include timer specific sources */
memcpy(lowspd_clks, global_clks, sizeof(global_clks));
memcpy(&lowspd_clks[ARRAY_SIZE(global_clks)], timer_specific_clks, sizeof(timer_specific_clks));
#endif

for (int i = 0; i < config->channel_len; ++i) {
channel = &config->channel_config[i];

ledc_hal_init(&data->hal, channel->speed_mode);

if (channel->speed_mode == LEDC_LOW_SPEED_MODE) {
channel->clock_src = global_clks[0];
ledc_hal_set_slow_clk_sel(&data->hal, channel->clock_src);
}
#ifdef SOC_LEDC_SUPPORT_HS_MODE
else {
channel->clock_src = highspd_clks[0];
}
#endif
ledc_hal_set_clock_source(&data->hal, channel->timer_num, channel->clock_src);

esp_clk_tree_src_get_freq_hz(channel->clock_src, ESP_CLK_TREE_SRC_FREQ_PRECISION_CACHED, &channel->clock_src_hz);

ledc_hal_bind_channel_timer(&data->hal, channel->channel_num, channel->timer_num);
pwm_led_esp32_stop(data, channel, channel->inverted);
ledc_hal_timer_rst(&data->hal, channel->timer_num);
Expand Down Expand Up @@ -418,7 +399,6 @@ PINCTRL_DT_INST_DEFINE(0);
.timer_num = DT_PROP(node_id, timer), \
.speed_mode = DT_REG_ADDR(node_id) < SOC_LEDC_CHANNEL_NUM ? LEDC_LOW_SPEED_MODE \
: !LEDC_LOW_SPEED_MODE, \
.clock_src = CLOCK_SOURCE, \
.inverted = DT_PWMS_FLAGS(node_id), \
},

Expand Down

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