144 lines
3.4 KiB
C
144 lines
3.4 KiB
C
/*
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* Copyright (c) 2017 Linaro Limited
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#include <led_strip.h>
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#include <errno.h>
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#include <string.h>
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#define SYS_LOG_LEVEL CONFIG_SYS_LOG_LED_STRIP_LEVEL
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#include <logging/sys_log.h>
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#include <zephyr.h>
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#include <device.h>
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#include <spi.h>
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#include <misc/util.h>
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/*
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* LPD880X SPI master configuration:
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*
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* - mode 0 (the default), 8 bit, MSB first, one-line SPI
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* - no shenanigans (no CS hold, release device lock, not an EEPROM)
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*/
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#define LPD880X_SPI_OPERATION (SPI_OP_MODE_MASTER | \
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SPI_TRANSFER_MSB | \
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SPI_WORD_SET(8) | \
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SPI_LINES_SINGLE)
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struct lpd880x_data {
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struct spi_config config;
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};
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static int lpd880x_update(struct device *dev, void *data, size_t size)
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{
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struct lpd880x_data *drv_data = dev->driver_data;
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/*
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* Per the AdaFruit reverse engineering notes on the protocol,
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* a zero byte propagates through at most 32 LED driver ICs.
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* The LPD8803 is the worst case, at 3 output channels per IC.
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*/
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u8_t reset_size = ceiling_fraction(ceiling_fraction(size, 3), 32);
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u8_t reset_buf[reset_size];
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u8_t last = 0x00;
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struct spi_buf bufs[3];
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size_t rc;
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/* Prepares the strip to shift in new data values. */
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memset(reset_buf, 0x00, reset_size);
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bufs[0].buf = reset_buf;
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bufs[0].len = reset_size;
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/* Displays the serialized pixel data. */
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bufs[1].buf = data;
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bufs[1].len = size;
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/* Ensures the last byte of pixel data is displayed. */
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bufs[2].buf = &last;
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bufs[2].len = sizeof(last);
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rc = spi_write(&drv_data->config, bufs, ARRAY_SIZE(bufs));
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if (rc) {
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SYS_LOG_ERR("can't update strip: %d", rc);
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}
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return rc;
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}
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static int lpd880x_strip_update_rgb(struct device *dev,
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struct led_rgb *pixels,
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size_t num_pixels)
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{
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u8_t *px = (u8_t *)pixels;
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u8_t r, g, b;
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size_t i;
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/*
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* Overwrite a prefix of the pixels array with its on-wire
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* representation, eliminating padding/scratch garbage, if any.
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*/
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for (i = 0; i < num_pixels; i++) {
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r = 0x80 | (pixels[i].r >> 1);
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g = 0x80 | (pixels[i].g >> 1);
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b = 0x80 | (pixels[i].b >> 1);
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/*
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* GRB is the ordering used by commonly available
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* LPD880x strips.
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*/
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*px++ = g;
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*px++ = r;
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*px++ = b;
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}
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return lpd880x_update(dev, pixels, 3 * num_pixels);
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}
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static int lpd880x_strip_update_channels(struct device *dev, u8_t *channels,
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size_t num_channels)
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{
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size_t i;
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for (i = 0; i < num_channels; i++) {
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channels[i] = 0x80 | (channels[i] >> 1);
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}
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return lpd880x_update(dev, channels, num_channels);
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}
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static int lpd880x_strip_init(struct device *dev)
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{
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struct lpd880x_data *data = dev->driver_data;
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struct spi_config *config = &data->config;
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struct device *spi;
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spi = device_get_binding(CONFIG_LPD880X_STRIP_SPI_DEV_NAME);
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if (!spi) {
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SYS_LOG_ERR("SPI device %s not found",
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CONFIG_LPD880X_STRIP_SPI_DEV_NAME);
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return -ENODEV;
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}
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config->dev = spi;
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config->frequency = CONFIG_LPD880X_STRIP_SPI_BAUD_RATE;
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config->operation = LPD880X_SPI_OPERATION;
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config->slave = 0; /* MOSI/CLK only; CS is not supported. */
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config->cs = NULL;
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return 0;
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}
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static struct lpd880x_data lpd880x_strip_data;
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static const struct led_strip_driver_api lpd880x_strip_api = {
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.update_rgb = lpd880x_strip_update_rgb,
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.update_channels = lpd880x_strip_update_channels,
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};
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DEVICE_AND_API_INIT(lpd880x_strip, CONFIG_LPD880X_STRIP_NAME,
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lpd880x_strip_init, &lpd880x_strip_data,
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NULL, POST_KERNEL, CONFIG_LED_STRIP_INIT_PRIORITY,
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&lpd880x_strip_api);
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