[PATCH 3/3] drivers: leds: add support for apa102c leds
From: Nicolas Belin
Date: Tue Feb 18 2020 - 04:38:24 EST
Initilial commit in order to support the apa102c RGB leds.
Signed-off-by: Nicolas Belin <nbelin@xxxxxxxxxxxx>
---
drivers/leds/Kconfig | 11 ++
drivers/leds/Makefile | 1 +
drivers/leds/leds-apa102c.c | 268 ++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 280 insertions(+)
create mode 100644 drivers/leds/leds-apa102c.c
diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
index d82f1dea3711..4fafeaaf6ee8 100644
--- a/drivers/leds/Kconfig
+++ b/drivers/leds/Kconfig
@@ -69,6 +69,17 @@ config LEDS_AN30259A
To compile this driver as a module, choose M here: the module
will be called leds-an30259a.
+config LEDS_APA102C
+ tristate "LED Support for Shiji APA102C"
+ depends on LEDS_CLASS
+ depends on SPI
+ help
+ This option enables support for the Shiji Lighthing APA102C RGB full color
+ LEDs.
+
+ To compile this driver as a module, choose M here: the module
+ will be called leds-apa102c.
+
config LEDS_APU
tristate "Front panel LED support for PC Engines APU/APU2/APU3 boards"
depends on LEDS_CLASS
diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
index d7e1107753fb..ab17f90347cb 100644
--- a/drivers/leds/Makefile
+++ b/drivers/leds/Makefile
@@ -9,6 +9,7 @@ obj-$(CONFIG_LEDS_TRIGGERS) += led-triggers.o
# LED Platform Drivers
obj-$(CONFIG_LEDS_88PM860X) += leds-88pm860x.o
obj-$(CONFIG_LEDS_AAT1290) += leds-aat1290.o
+obj-$(CONFIG_LEDS_APA102C) += leds-apa102c.o
obj-$(CONFIG_LEDS_APU) += leds-apu.o
obj-$(CONFIG_LEDS_AS3645A) += leds-as3645a.o
obj-$(CONFIG_LEDS_AN30259A) += leds-an30259a.o
diff --git a/drivers/leds/leds-apa102c.c b/drivers/leds/leds-apa102c.c
new file mode 100644
index 000000000000..e7abe3f5b7c2
--- /dev/null
+++ b/drivers/leds/leds-apa102c.c
@@ -0,0 +1,268 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Copyright (C) 2020 BayLibre, SAS
+ * Author: Nicolas Belin <nbelin@xxxxxxxxxxxx>
+ */
+
+#include <linux/leds.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/spi/spi.h>
+#include <uapi/linux/uleds.h>
+
+/*
+ * APA102C SPI protocol description:
+ * +------+----------------------------------------+------+
+ * |START | DATA FIELD: | END |
+ * |FRAME | N LED FRAMES |FRAME |
+ * +------+------+------+------+------+-----+------+------+
+ * | 0*32 | LED1 | LED2 | LED3 | LED4 | --- | LEDN | 1*32 |
+ * +------+------+------+------+------+-----+------+------+
+ *
+ * +-----------------------------------+
+ * |START FRAME 32bits |
+ * +--------+--------+--------+--------+
+ * |00000000|00000000|00000000|00000000|
+ * +--------+--------+--------+--------+
+ *
+ * +------------------------------------+
+ * |LED FRAME 32bits |
+ * +---+-----+--------+--------+--------+
+ * |111|LUMA | BLUE | GREEN | RED |
+ * +---+-----+--------+--------+--------+
+ * |3b |5bits| 8bits | 8bits | 8bits |
+ * +---+-----+--------+--------+--------+
+ * |MSB LSB|MSB LSB|MSB LSB|MSB LSB|
+ * +---+-----+--------+--------+--------+
+ *
+ * +-----------------------------------+
+ * |END FRAME 32bits |
+ * +--------+--------+--------+--------+
+ * |11111111|11111111|11111111|11111111|
+ * +--------+--------+--------+--------+
+ */
+
+/* apa102c default settings */
+#define CR_MAX_BRIGHTNESS GENMASK(7, 0)
+#define LM_MAX_BRIGHTNESS GENMASK(4, 0)
+#define CH_NUM 4
+#define START_BYTE 0
+#define END_BYTE GENMASK(7, 0)
+#define LED_FRAME_HEADER GENMASK(7, 5)
+
+enum led_channels {
+ RED,
+ GREEN,
+ BLUE,
+ LUMA,
+};
+
+struct apa102c_led {
+ char name[LED_MAX_NAME_SIZE];
+ struct apa102c *priv;
+ struct led_classdev ldev;
+ u8 brightness;
+};
+
+struct apa102c {
+ size_t led_count;
+ struct device *dev;
+ struct mutex lock;
+ struct spi_device *spi;
+ u8 *buf;
+ struct apa102c_led leds[];
+};
+
+static int apa102c_sync(struct apa102c *priv)
+{
+ int ret;
+ size_t i;
+ size_t bytes = 0;
+
+ for (i = 0; i < 4; i++)
+ priv->buf[bytes++] = START_BYTE;
+
+ for (i = 0; i < priv->led_count; i++) {
+ priv->buf[bytes++] = LED_FRAME_HEADER |
+ priv->leds[i * CH_NUM + LUMA].brightness;
+ priv->buf[bytes++] = priv->leds[i * CH_NUM + BLUE].brightness;
+ priv->buf[bytes++] = priv->leds[i * CH_NUM + GREEN].brightness;
+ priv->buf[bytes++] = priv->leds[i * CH_NUM + RED].brightness;
+ }
+
+ for (i = 0; i < 4; i++)
+ priv->buf[bytes++] = END_BYTE;
+
+ ret = spi_write(priv->spi, priv->buf, bytes);
+
+ return ret;
+}
+
+static int apa102c_set_sync(struct led_classdev *ldev,
+ enum led_brightness brightness)
+{
+ int ret;
+ struct apa102c_led *led = container_of(ldev,
+ struct apa102c_led,
+ ldev);
+
+ dev_dbg(led->priv->dev, "Set brightness of %s to %d\n",
+ led->name, brightness);
+
+ mutex_lock(&led->priv->lock);
+ led->brightness = (u8)brightness;
+ ret = apa102c_sync(led->priv);
+ mutex_unlock(&led->priv->lock);
+
+ return ret;
+}
+
+static int apa102c_probe_dt(struct apa102c *priv)
+{
+ u32 i = 0;
+ int j = 0;
+ struct apa102c_led *led;
+ struct fwnode_handle *child;
+ struct device_node *np;
+ int ret;
+ int use_index;
+ const char *str;
+ static const char * const rgb_name[] = {"red",
+ "green",
+ "blue",
+ "luma"};
+
+ device_for_each_child_node(priv->dev, child) {
+ np = to_of_node(child);
+
+ ret = fwnode_property_read_u32(child, "reg", &i);
+ if (ret)
+ return ret;
+
+ if (i >= priv->led_count)
+ return -EINVAL;
+
+ /* use the index to create the name if the label is not set */
+ use_index = fwnode_property_read_string(child, "label", &str);
+
+ /* for each physical LED, 4 LEDs are created representing
+ * the 4 components: red, green, blue and global luma.
+ */
+ for (j = 0; j < CH_NUM; j++) {
+ led = &priv->leds[i * CH_NUM + j];
+
+ if (use_index)
+ snprintf(led->name, sizeof(led->name),
+ "apa102c:%s:%d", rgb_name[j], i);
+ else
+ snprintf(led->name, sizeof(led->name),
+ "apa102c:%s:%s", rgb_name[j], str);
+
+ fwnode_property_read_string(child,
+ "linux,default-trigger",
+ &led->ldev.default_trigger);
+
+ led->priv = priv;
+ led->ldev.name = led->name;
+ if (j == LUMA) {
+ led->ldev.brightness = led->brightness
+ = LM_MAX_BRIGHTNESS;
+ led->ldev.max_brightness = LM_MAX_BRIGHTNESS;
+ } else {
+ led->ldev.brightness = led->brightness
+ = 0;
+ led->ldev.max_brightness = CR_MAX_BRIGHTNESS;
+ }
+
+ led->ldev.brightness_set_blocking = apa102c_set_sync;
+
+ ret = devm_led_classdev_register(priv->dev, &led->ldev);
+ if (ret) {
+ dev_err(priv->dev,
+ "failed to register LED %s, err %d",
+ led->name, ret);
+ fwnode_handle_put(child);
+ return ret;
+ }
+
+ led->ldev.dev->of_node = np;
+
+ }
+ }
+
+ return 0;
+}
+
+static int apa102c_probe(struct spi_device *spi)
+{
+ struct apa102c *priv;
+ size_t led_count;
+ int ret;
+
+ led_count = device_get_child_node_count(&spi->dev);
+ if (!led_count) {
+ dev_err(&spi->dev, "No LEDs defined in device tree!");
+ return -ENODEV;
+ }
+
+ priv = devm_kzalloc(&spi->dev,
+ struct_size(priv, leds, led_count * CH_NUM),
+ GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+
+ priv->buf = devm_kzalloc(&spi->dev, led_count * CH_NUM + 8, GFP_KERNEL);
+ if (!priv->buf)
+ return -ENOMEM;
+
+ mutex_init(&priv->lock);
+ priv->led_count = led_count;
+ priv->dev = &spi->dev;
+ priv->spi = spi;
+
+ ret = apa102c_probe_dt(priv);
+ if (ret)
+ return ret;
+
+ /* Set the LEDs with default values at start */
+ apa102c_sync(priv);
+ if (ret)
+ return ret;
+
+ spi_set_drvdata(spi, priv);
+
+ return 0;
+}
+
+static int apa102c_remove(struct spi_device *spi)
+{
+ struct apa102c *priv = spi_get_drvdata(spi);
+
+ mutex_destroy(&priv->lock);
+
+ return 0;
+}
+
+static const struct of_device_id apa102c_dt_ids[] = {
+ { .compatible = "shiji,apa102c", },
+ {},
+};
+
+MODULE_DEVICE_TABLE(of, apa102c_dt_ids);
+
+static struct spi_driver apa102c_driver = {
+ .probe = apa102c_probe,
+ .remove = apa102c_remove,
+ .driver = {
+ .name = KBUILD_MODNAME,
+ .of_match_table = apa102c_dt_ids,
+ },
+};
+
+module_spi_driver(apa102c_driver);
+
+MODULE_AUTHOR("Nicolas Belin <nbelin@xxxxxxxxxxxx>");
+MODULE_DESCRIPTION("apa102c LED driver");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("spi:apa102c");
--
2.7.4