1 /*
2 * Copyright (c) 2017 Linaro Limited
3 *
4 * SPDX-License-Identifier: Apache-2.0
5 */
6
7 #include <zephyr/drivers/led_strip.h>
8
9 #include <errno.h>
10 #include <string.h>
11
12 #if DT_NODE_HAS_STATUS(DT_INST(0, greeled_lpd8806), okay)
13 #define DT_DRV_COMPAT greeled_lpd8806
14 #else
15 #define DT_DRV_COMPAT greeled_lpd8803
16 #endif
17
18 #define LOG_LEVEL CONFIG_LED_STRIP_LOG_LEVEL
19 #include <zephyr/logging/log.h>
20 LOG_MODULE_REGISTER(lpd880x);
21
22 #include <zephyr/kernel.h>
23 #include <zephyr/device.h>
24 #include <zephyr/drivers/spi.h>
25 #include <zephyr/sys/util.h>
26
27 /*
28 * LPD880X SPI master configuration:
29 *
30 * - mode 0 (the default), 8 bit, MSB first, one-line SPI
31 * - no shenanigans (no CS hold, release device lock, not an EEPROM)
32 */
33 #define LPD880X_SPI_OPERATION (SPI_OP_MODE_MASTER | \
34 SPI_TRANSFER_MSB | \
35 SPI_WORD_SET(8))
36
37 struct lpd880x_config {
38 struct spi_dt_spec bus;
39 size_t length;
40 };
41
lpd880x_update(const struct device * dev,void * data,size_t size)42 static int lpd880x_update(const struct device *dev, void *data, size_t size)
43 {
44 const struct lpd880x_config *config = dev->config;
45 /*
46 * Per the AdaFruit reverse engineering notes on the protocol,
47 * a zero byte propagates through at most 32 LED driver ICs.
48 * The LPD8803 is the worst case, at 3 output channels per IC.
49 */
50 uint8_t reset_size = DIV_ROUND_UP(DIV_ROUND_UP(size, 3), 32);
51 uint8_t reset_buf[reset_size];
52 uint8_t last = 0x00;
53 const struct spi_buf bufs[3] = {
54 {
55 /* Prepares the strip to shift in new data values. */
56 .buf = reset_buf,
57 .len = reset_size
58 },
59 {
60 /* Displays the serialized pixel data. */
61 .buf = data,
62 .len = size
63 },
64 {
65 /* Ensures the last byte of pixel data is displayed. */
66 .buf = &last,
67 .len = sizeof(last)
68 }
69
70 };
71 const struct spi_buf_set tx = {
72 .buffers = bufs,
73 .count = 3
74 };
75 size_t rc;
76
77 (void)memset(reset_buf, 0x00, reset_size);
78
79 rc = spi_write_dt(&config->bus, &tx);
80 if (rc) {
81 LOG_ERR("can't update strip: %d", rc);
82 }
83
84 return rc;
85 }
86
lpd880x_strip_update_rgb(const struct device * dev,struct led_rgb * pixels,size_t num_pixels)87 static int lpd880x_strip_update_rgb(const struct device *dev,
88 struct led_rgb *pixels,
89 size_t num_pixels)
90 {
91 uint8_t *px = (uint8_t *)pixels;
92 uint8_t r, g, b;
93 size_t i;
94
95 /*
96 * Overwrite a prefix of the pixels array with its on-wire
97 * representation, eliminating padding/scratch garbage, if any.
98 */
99 for (i = 0; i < num_pixels; i++) {
100 r = 0x80 | (pixels[i].r >> 1);
101 g = 0x80 | (pixels[i].g >> 1);
102 b = 0x80 | (pixels[i].b >> 1);
103
104 /*
105 * GRB is the ordering used by commonly available
106 * LPD880x strips.
107 */
108 *px++ = g;
109 *px++ = r;
110 *px++ = b;
111 }
112
113 return lpd880x_update(dev, pixels, 3 * num_pixels);
114 }
115
lpd880x_strip_update_channels(const struct device * dev,uint8_t * channels,size_t num_channels)116 static int lpd880x_strip_update_channels(const struct device *dev,
117 uint8_t *channels,
118 size_t num_channels)
119 {
120 size_t i;
121
122 for (i = 0; i < num_channels; i++) {
123 channels[i] = 0x80 | (channels[i] >> 1);
124 }
125
126 return lpd880x_update(dev, channels, num_channels);
127 }
128
lpd880x_strip_length(const struct device * dev)129 static size_t lpd880x_strip_length(const struct device *dev)
130 {
131 const struct lpd880x_config *config = dev->config;
132
133 return config->length;
134 }
135
lpd880x_strip_init(const struct device * dev)136 static int lpd880x_strip_init(const struct device *dev)
137 {
138 const struct lpd880x_config *config = dev->config;
139
140 if (!spi_is_ready_dt(&config->bus)) {
141 LOG_ERR("SPI device %s not ready", config->bus.bus->name);
142 return -ENODEV;
143 }
144
145 return 0;
146 }
147
148 static const struct lpd880x_config lpd880x_config = {
149 .bus = SPI_DT_SPEC_INST_GET(0, LPD880X_SPI_OPERATION, 0),
150 .length = DT_INST_PROP(0, chain_length),
151 };
152
153 static const struct led_strip_driver_api lpd880x_strip_api = {
154 .update_rgb = lpd880x_strip_update_rgb,
155 .update_channels = lpd880x_strip_update_channels,
156 .length = lpd880x_strip_length,
157 };
158
159 DEVICE_DT_INST_DEFINE(0, lpd880x_strip_init, NULL,
160 NULL, &lpd880x_config,
161 POST_KERNEL, CONFIG_LED_STRIP_INIT_PRIORITY,
162 &lpd880x_strip_api);
163
