blob: 78cc361996489c56c866388da0d059c2b46001f0 [file] [log] [blame]
/*
* Copyright (c) 2017 Linaro Limited
*
* SPDX-License-Identifier: Apache-2.0
*/
#include <led_strip.h>
#include <errno.h>
#include <string.h>
#define SYS_LOG_LEVEL CONFIG_SYS_LOG_LED_STRIP_LEVEL
#include <logging/sys_log.h>
#include <zephyr.h>
#include <device.h>
#include <spi.h>
#include <misc/util.h>
/*
* LPD880X SPI master configuration:
*
* - mode 0 (the default), 8 bit, MSB first, one-line SPI
* - no shenanigans (no CS hold, release device lock, not an EEPROM)
*/
#define LPD880X_SPI_OPERATION (SPI_OP_MODE_MASTER | \
SPI_TRANSFER_MSB | \
SPI_WORD_SET(8) | \
SPI_LINES_SINGLE)
struct lpd880x_data {
struct spi_config config;
};
static int lpd880x_update(struct device *dev, void *data, size_t size)
{
struct lpd880x_data *drv_data = dev->driver_data;
/*
* Per the AdaFruit reverse engineering notes on the protocol,
* a zero byte propagates through at most 32 LED driver ICs.
* The LPD8803 is the worst case, at 3 output channels per IC.
*/
u8_t reset_size = ceiling_fraction(ceiling_fraction(size, 3), 32);
u8_t reset_buf[reset_size];
u8_t last = 0x00;
struct spi_buf bufs[3];
size_t rc;
/* Prepares the strip to shift in new data values. */
memset(reset_buf, 0x00, reset_size);
bufs[0].buf = reset_buf;
bufs[0].len = reset_size;
/* Displays the serialized pixel data. */
bufs[1].buf = data;
bufs[1].len = size;
/* Ensures the last byte of pixel data is displayed. */
bufs[2].buf = &last;
bufs[2].len = sizeof(last);
rc = spi_write(&drv_data->config, bufs, ARRAY_SIZE(bufs));
if (rc) {
SYS_LOG_ERR("can't update strip: %d", rc);
}
return rc;
}
static int lpd880x_strip_update_rgb(struct device *dev,
struct led_rgb *pixels,
size_t num_pixels)
{
u8_t *px = (u8_t *)pixels;
u8_t r, g, b;
size_t i;
/*
* Overwrite a prefix of the pixels array with its on-wire
* representation, eliminating padding/scratch garbage, if any.
*/
for (i = 0; i < num_pixels; i++) {
r = 0x80 | (pixels[i].r >> 1);
g = 0x80 | (pixels[i].g >> 1);
b = 0x80 | (pixels[i].b >> 1);
/*
* GRB is the ordering used by commonly available
* LPD880x strips.
*/
*px++ = g;
*px++ = r;
*px++ = b;
}
return lpd880x_update(dev, pixels, 3 * num_pixels);
}
static int lpd880x_strip_update_channels(struct device *dev, u8_t *channels,
size_t num_channels)
{
size_t i;
for (i = 0; i < num_channels; i++) {
channels[i] = 0x80 | (channels[i] >> 1);
}
return lpd880x_update(dev, channels, num_channels);
}
static int lpd880x_strip_init(struct device *dev)
{
struct lpd880x_data *data = dev->driver_data;
struct spi_config *config = &data->config;
struct device *spi;
spi = device_get_binding(CONFIG_LPD880X_STRIP_SPI_DEV_NAME);
if (!spi) {
SYS_LOG_ERR("SPI device %s not found",
CONFIG_LPD880X_STRIP_SPI_DEV_NAME);
return -ENODEV;
}
config->dev = spi;
config->frequency = CONFIG_LPD880X_STRIP_SPI_BAUD_RATE;
config->operation = LPD880X_SPI_OPERATION;
config->slave = 0; /* MOSI/CLK only; CS is not supported. */
config->cs = NULL;
return 0;
}
static struct lpd880x_data lpd880x_strip_data;
static const struct led_strip_driver_api lpd880x_strip_api = {
.update_rgb = lpd880x_strip_update_rgb,
.update_channels = lpd880x_strip_update_channels,
};
DEVICE_AND_API_INIT(lpd880x_strip, CONFIG_LPD880X_STRIP_NAME,
lpd880x_strip_init, &lpd880x_strip_data,
NULL, POST_KERNEL, CONFIG_LED_STRIP_INIT_PRIORITY,
&lpd880x_strip_api);