leds: spi-byte: add single byte SPI LED driver (e9a804d7) · Commits · e / devices / android_kernel_fairphone_FP5

drivers/leds/Kconfig

+10 −0

Original line number	Diff line number	Diff line
		@@ -783,6 +783,16 @@ config LEDS_NIC78BX
		To compile this driver as a module, choose M here: the module
		will be called leds-nic78bx.

		config LEDS_SPI_BYTE
		tristate "LED support for SPI LED controller with a single byte"
		depends on LEDS_CLASS
		depends on SPI
		depends on OF
		help
		This option enables support for LED controller which use a single byte
		for controlling the brightness. Currently the following controller is
		supported: Ubiquiti airCube ISP microcontroller based LED controller.

		comment "LED Triggers"
		source "drivers/leds/trigger/Kconfig"

drivers/leds/Makefile

+1 −0

Original line number	Diff line number	Diff line
		@@ -77,6 +77,7 @@ obj-$(CONFIG_LEDS_PM8058) += leds-pm8058.o
		obj-$(CONFIG_LEDS_MLXCPLD) += leds-mlxcpld.o
		obj-$(CONFIG_LEDS_MLXREG) += leds-mlxreg.o
		obj-$(CONFIG_LEDS_NIC78BX) += leds-nic78bx.o
		obj-$(CONFIG_LEDS_SPI_BYTE) += leds-spi-byte.o
		obj-$(CONFIG_LEDS_MT6323) += leds-mt6323.o
		obj-$(CONFIG_LEDS_LM3692X) += leds-lm3692x.o
		obj-$(CONFIG_LEDS_SC27XX_BLTC) += leds-sc27xx-bltc.o

drivers/leds/leds-spi-byte.c

0 → 100644

+161 −0

Original line number	Diff line number	Diff line
		// SPDX-License-Identifier: GPL-2.0
		// Copyright (c) 2019 Christian Mauderer <oss@c-mauderer.de>

		/*
		* The driver supports controllers with a very simple SPI protocol:
		* - one LED is controlled by a single byte on MOSI
		* - the value of the byte gives the brightness between two values (lowest to
		* highest)
		* - no return value is necessary (no MISO signal)
		*
		* The value for minimum and maximum brightness depends on the device
		* (compatible string).
		*
		* Supported devices:
		* - "ubnt,acb-spi-led": Microcontroller (SONiX 8F26E611LA) based device used
		* for example in Ubiquiti airCube ISP. Reverse engineered protocol for this
		* controller:
		* * Higher two bits set a mode. Lower six bits are a parameter.
		* * Mode: 00 -> set brightness between 0x00 (min) and 0x3F (max)
		* * Mode: 01 -> pulsing pattern (min -> max -> min) with an interval. From
		* some tests, the period is about (50ms + 102ms * parameter). There is a
		* slightly different pattern starting from 0x10 (longer gap between the
		* pulses) but the time still follows that calculation.
		* * Mode: 10 -> same as 01 but with only a ramp from min to max. Again a
		* slight jump in the pattern at 0x10.
		* * Mode: 11 -> blinking (off -> 25% -> off -> 25% -> ...) with a period of
		* (105ms * parameter)
		* NOTE: This driver currently only supports mode 00.
		*/

		#include <linux/leds.h>
		#include <linux/module.h>
		#include <linux/of_device.h>
		#include <linux/spi/spi.h>
		#include <linux/mutex.h>
		#include <uapi/linux/uleds.h>

		struct spi_byte_chipdef {
		/* SPI byte that will be send to switch the LED off */
		u8 off_value;
		/* SPI byte that will be send to switch the LED to maximum brightness */
		u8 max_value;
		};

		struct spi_byte_led {
		struct led_classdev ldev;
		struct spi_device *spi;
		char name[LED_MAX_NAME_SIZE];
		struct mutex mutex;
		const struct spi_byte_chipdef *cdef;
		};

		static const struct spi_byte_chipdef ubnt_acb_spi_led_cdef = {
		.off_value = 0x0,
		.max_value = 0x3F,
		};

		static const struct of_device_id spi_byte_dt_ids[] = {
		{ .compatible = "ubnt,acb-spi-led", .data = &ubnt_acb_spi_led_cdef },
		{},
		};

		MODULE_DEVICE_TABLE(of, spi_byte_dt_ids);

		static int spi_byte_brightness_set_blocking(struct led_classdev *dev,
		enum led_brightness brightness)
		{
		struct spi_byte_led *led = container_of(dev, struct spi_byte_led, ldev);
		u8 value;
		int ret;

		value = (u8) brightness + led->cdef->off_value;

		mutex_lock(&led->mutex);
		ret = spi_write(led->spi, &value, sizeof(value));
		mutex_unlock(&led->mutex);

		return ret;
		}

		static int spi_byte_probe(struct spi_device *spi)
		{
		const struct of_device_id *of_dev_id;
		struct device_node *child;
		struct device *dev = &spi->dev;
		struct spi_byte_led *led;
		const char *name = "leds-spi-byte::";
		const char *state;
		int ret;

		of_dev_id = of_match_device(spi_byte_dt_ids, dev);
		if (!of_dev_id)
		return -EINVAL;

		if (of_get_child_count(dev->of_node) != 1) {
		dev_err(dev, "Device must have exactly one LED sub-node.");
		return -EINVAL;
		}
		child = of_get_next_child(dev->of_node, NULL);

		led = devm_kzalloc(dev, sizeof(*led), GFP_KERNEL);
		if (!led)
		return -ENOMEM;

		of_property_read_string(child, "label", &name);
		strlcpy(led->name, name, sizeof(led->name));
		led->spi = spi;
		mutex_init(&led->mutex);
		led->cdef = of_dev_id->data;
		led->ldev.name = led->name;
		led->ldev.brightness = LED_OFF;
		led->ldev.max_brightness = led->cdef->max_value - led->cdef->off_value;
		led->ldev.brightness_set_blocking = spi_byte_brightness_set_blocking;

		state = of_get_property(child, "default-state", NULL);
		if (state) {
		if (!strcmp(state, "on")) {
		led->ldev.brightness = led->ldev.max_brightness;
		} else if (strcmp(state, "off")) {
		/* all other cases except "off" */
		dev_err(dev, "default-state can only be 'on' or 'off'");
		return -EINVAL;
		}
		}
		spi_byte_brightness_set_blocking(&led->ldev,
		led->ldev.brightness);

		ret = devm_led_classdev_register(&spi->dev, &led->ldev);
		if (ret) {
		mutex_destroy(&led->mutex);
		return ret;
		}
		spi_set_drvdata(spi, led);

		return 0;
		}

		static int spi_byte_remove(struct spi_device *spi)
		{
		struct spi_byte_led *led = spi_get_drvdata(spi);

		mutex_destroy(&led->mutex);

		return 0;
		}

		static struct spi_driver spi_byte_driver = {
		.probe = spi_byte_probe,
		.remove = spi_byte_remove,
		.driver = {
		.name = KBUILD_MODNAME,
		.of_match_table = spi_byte_dt_ids,
		},
		};

		module_spi_driver(spi_byte_driver);

		MODULE_AUTHOR("Christian Mauderer <oss@c-mauderer.de>");
		MODULE_DESCRIPTION("single byte SPI LED driver");
		MODULE_LICENSE("GPL v2");
		MODULE_ALIAS("spi:leds-spi-byte");