feat(led_strip): Add composite led_strip driver

Signed-off-by: XiNGRZ <hi@xingrz.me>

app/drivers/CMakeLists.txt

@@ -5,3 +5,4 @@ add_subdirectory_ifdef(CONFIG_ZMK_DRIVERS_GPIO gpio)
 add_subdirectory(kscan)
 add_subdirectory(sensor)
 add_subdirectory(display)
+add_subdirectory(led_strip)

app/drivers/Kconfig

@@ -5,3 +5,4 @@ rsource "gpio/Kconfig"
 rsource "kscan/Kconfig"
 rsource "sensor/Kconfig"
 rsource "display/Kconfig"
+rsource "led_strip/Kconfig"

app/drivers/led_strip/CMakeLists.txt

@@ -0,0 +1,4 @@
+# Copyright (c) 2022 The ZMK Contributors
+# SPDX-License-Identifier: MIT
+
+zephyr_sources_ifdef(CONFIG_LED_STRIP_COMPOSITE led_strip_composite.c)

app/drivers/led_strip/Kconfig

@@ -0,0 +1,4 @@
+# Copyright (c) 2022 The ZMK Contributors
+# SPDX-License-Identifier: MIT
+
+rsource "Kconfig.composite"

app/drivers/led_strip/Kconfig.composite

@@ -0,0 +1,9 @@
+# Copyright (c) 2022 The ZMK Contributors
+# SPDX-License-Identifier: MIT
+
+DT_COMPAT_ZMK_LED_STRIP_COMPOSITE := zmk,led-strip-composite
+
+config LED_STRIP_COMPOSITE
+	bool
+	default $(dt_compat_enabled,$(DT_COMPAT_ZMK_LED_STRIP_COMPOSITE))
+	depends on LED_STRIP

app/drivers/led_strip/led_strip_composite.c

@@ -0,0 +1,98 @@
+/*
+ * Copyright (c) 2022 The ZMK Contributors
+ * SPDX-License-Identifier: MIT
+ */
+
+#define DT_DRV_COMPAT zmk_led_strip_composite
+
+#include <drivers/led_strip.h>
+
+#define LOG_LEVEL CONFIG_LED_STRIP_LOG_LEVEL
+#include <logging/log.h>
+LOG_MODULE_REGISTER(led_strip_composite);
+
+#include <zephyr.h>
+#include <device.h>
+
+struct led_strip_child {
+    const struct device *device;
+    uint32_t length;
+};
+
+struct led_strip_composite_config {
+    const struct led_strip_child *strips;
+    uint32_t strips_cnt;
+    uint32_t pixels_cnt;
+};
+
+static int led_strip_composite_update_rgb(const struct device *dev, struct led_rgb *pixels,
+                                          size_t num_pixels) {
+    const struct led_strip_composite_config *config = dev->config;
+
+    if (num_pixels > config->pixels_cnt) {
+        num_pixels = config->pixels_cnt;
+    }
+
+    int ret = 0;
+    uint32_t offset = 0, length = 0;
+    for (int i = 0; i < config->strips_cnt && offset < num_pixels; i++) {
+        length = config->strips[i].length;
+        if (length > num_pixels - offset) {
+            length = num_pixels - offset;
+        }
+
+        LOG_DBG("Updating led_strip %d, offset: %d, length: %d", i, offset, length);
+
+        ret = led_strip_update_rgb(config->strips[i].device, &pixels[offset], length);
+        if (ret != 0) {
+            LOG_ERR("Failed updating child led_strip device %s", config->strips[i].device->name);
+            return ret;
+        }
+
+        offset += length;
+    }
+
+    return 0;
+}
+
+static int led_strip_composite_update_channels(const struct device *dev, uint8_t *channels,
+                                               size_t num_channels) {
+    LOG_ERR("update_channels not implemented");
+    return -ENOTSUP;
+}
+
+static int led_strip_composite_init(const struct device *dev) {
+    const struct led_strip_composite_config *config = dev->config;
+
+    for (int i = 0; i < config->strips_cnt; i++) {
+        LOG_INF("Bond led_strip %d: %s, length: %d", i, config->strips[i].device->name,
+                config->strips[i].length);
+    }
+
+    return 0;
+}
+
+static const struct led_strip_driver_api led_strip_composite_api = {
+    .update_rgb = led_strip_composite_update_rgb,
+    .update_channels = led_strip_composite_update_channels,
+};
+
+#define LED_STRIP_LENGTH(inst) DT_PROP(DT_PHANDLE(inst, led_strip), chain_length)
+
+#define LED_STRIP_CHILD(inst)                                                                      \
+    {                                                                                              \
+        .device = DEVICE_DT_GET(DT_PHANDLE(inst, led_strip)),                                      \
+        .length = LED_STRIP_LENGTH(inst),                                                          \
+    },
+
+static const struct led_strip_child led_strip_children[] = {
+    DT_INST_FOREACH_CHILD(0, LED_STRIP_CHILD)};
+
+static const struct led_strip_composite_config led_strip_composite_config = {
+    .strips = led_strip_children,
+    .strips_cnt = ARRAY_SIZE(led_strip_children),
+    .pixels_cnt = DT_INST_PROP(0, chain_length),
+};
+
+DEVICE_DT_INST_DEFINE(0, &led_strip_composite_init, NULL, NULL, &led_strip_composite_config,
+                      POST_KERNEL, CONFIG_LED_STRIP_INIT_PRIORITY, &led_strip_composite_api);

app/drivers/zephyr/dts/bindings/led_strip/zmk,led-strip-composite.yaml

@@ -0,0 +1,22 @@
+# Copyright (c) 2022 The ZMK Contributors
+# SPDX-License-Identifier: MIT
+
+description: Composing multiple LED strip devices into one virtual device
+
+compatible: "zmk,led-strip-composite"
+
+properties:
+  label:
+    type: string
+    required: true
+
+  chain-length:
+    type: int
+    required: true
+
+child-binding:
+  description: "Details of an included led_strip devices"
+  properties:
+    led-strip:
+      type: phandle
+      required: true