123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154 |
- // SPDX-License-Identifier: GPL-2.0
- // Copyright (c) 2019 Christian Mauderer <[email protected]>
- /*
- * 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)
- {
- 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;
- if (of_get_available_child_count(dev_of_node(dev)) != 1) {
- dev_err(dev, "Device must have exactly one LED sub-node.");
- return -EINVAL;
- }
- child = of_get_next_available_child(dev_of_node(dev), 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 = device_get_match_data(dev);
- 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 void spi_byte_remove(struct spi_device *spi)
- {
- struct spi_byte_led *led = spi_get_drvdata(spi);
- mutex_destroy(&led->mutex);
- }
- 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 <[email protected]>");
- MODULE_DESCRIPTION("single byte SPI LED driver");
- MODULE_LICENSE("GPL v2");
- MODULE_ALIAS("spi:leds-spi-byte");
|