5  * https://electronut.in/nrf52-i2s-ws2812/
7  * Note: the word "word" refers to a 32-bit integer unless otherwise stated.
11  * The I2S peripheral sends two 16-bit channel values for each clock period.
12  * A single LED color (8 data bits) will take up one 32-bit word or one LRCK
15  * SPDX-License-Identifier: Apache-2.0
28 #include <zephyr/dt-bindings/led/led.h>
49 /* Serialize an 8-bit color channel value into two 16-bit I2S values (or 1 32-bit
61 	/* Swap the two I2S values due to the (audio) channel TX order. */  in ws2812_i2s_ser()
68 	const struct ws2812_i2s_cfg *cfg = dev->config;  in ws2812_strip_update_rgb()
69 	const uint8_t sym_one = cfg->nibble_one;  in ws2812_strip_update_rgb()
70 	const uint8_t sym_zero = cfg->nibble_zero;  in ws2812_strip_update_rgb()
71 	const uint32_t reset_word = cfg->active_low ? ~0 : 0;  in ws2812_strip_update_rgb()
78 	ret = k_mem_slab_alloc(cfg->mem_slab, &mem_block, K_SECONDS(10));  in ws2812_strip_update_rgb()
80 		LOG_ERR("Unable to allocate mem slab for TX (err %d)", ret);  in ws2812_strip_update_rgb()
81 		return -ENOMEM;  in ws2812_strip_update_rgb()
85 	/* Add a pre-data reset, so the first pixel isn't skipped by the strip. */  in ws2812_strip_update_rgb()
93 	 * in color mapping on-wire format (e.g. GRB, GRBW, RGB, etc).  in ws2812_strip_update_rgb()
96 		for (uint16_t j = 0; j < cfg->num_colors; j++) {  in ws2812_strip_update_rgb()
99 			switch (cfg->color_mapping[j]) {  in ws2812_strip_update_rgb()
114 				return -EINVAL;  in ws2812_strip_update_rgb()
121 	for (uint16_t i = 0; i < cfg->reset_words; i++) {  in ws2812_strip_update_rgb()
127 	ret = i2s_write(cfg->dev, mem_block, cfg->tx_buf_bytes);  in ws2812_strip_update_rgb()
129 		k_mem_slab_free(cfg->mem_slab, mem_block);  in ws2812_strip_update_rgb()
134 	ret = i2s_trigger(cfg->dev, I2S_DIR_TX, I2S_TRIGGER_START);  in ws2812_strip_update_rgb()
140 	ret = i2s_trigger(cfg->dev, I2S_DIR_TX, I2S_TRIGGER_DRAIN);  in ws2812_strip_update_rgb()
147 	flush_time_us = cfg->lrck_period * cfg->tx_buf_bytes / sizeof(uint32_t);  in ws2812_strip_update_rgb()
148 	k_usleep(flush_time_us + cfg->extra_wait_time_us);  in ws2812_strip_update_rgb()
155 	const struct ws2812_i2s_cfg *cfg = dev->config;  in ws2812_strip_length()
157 	return cfg->length;  in ws2812_strip_length()
162 	const struct ws2812_i2s_cfg *cfg = dev->config;  in ws2812_i2s_init()
167 	lrck_hz = USEC_PER_SEC / cfg->lrck_period;  in ws2812_i2s_init()
169 		lrck_hz, cfg->lrck_period);  in ws2812_i2s_init()
171 	/* 16-bit stereo, 100kHz LCLK */  in ws2812_i2s_init()
177 	config.mem_slab = cfg->mem_slab;  in ws2812_i2s_init()
178 	config.block_size = cfg->tx_buf_bytes;  in ws2812_i2s_init()
181 	ret = i2s_configure(cfg->dev, I2S_DIR_TX, &config);  in ws2812_i2s_init()
187 	for (uint16_t i = 0; i < cfg->num_colors; i++) {  in ws2812_i2s_init()
188 		switch (cfg->color_mapping[i]) {  in ws2812_i2s_init()
196 				"Check the color-mapping DT property",  in ws2812_i2s_init()
197 				dev->name);  in ws2812_i2s_init()
198 			return -EINVAL;  in ws2812_i2s_init()