1 // SPDX-License-Identifier: GPL-2.0
2 // Copyright (c) 2019 Christian Mauderer <oss@c-mauderer.de>
5  * The driver supports controllers with a very simple SPI protocol:
6  * - one LED is controlled by a single byte on MOSI
7  * - the value of the byte gives the brightness between two values (lowest to
9  * - no return value is necessary (no MISO signal)
15  * - "ubnt,acb-spi-led": Microcontroller (SONiX 8F26E611LA) based device used
19  *   * Mode: 00 -> set brightness between 0x00 (min) and 0x3F (max)
20  *   * Mode: 01 -> pulsing pattern (min -> max -> min) with an interval. From
24  *   * Mode: 10 -> same as 01 but with only a ramp from min to max. Again a
26  *   * Mode: 11 -> blinking (off -> 25% -> off -> 25% -> ...) with a period of
36 #include <linux/spi/spi.h>
40 	/* SPI byte that will be send to switch the LED off */
42 	/* SPI byte that will be send to switch the LED to maximum brightness */
48 	struct spi_device		*spi;  member
66 	value = (u8) brightness + led->cdef->off_value;  in spi_byte_brightness_set_blocking()
68 	mutex_lock(&led->mutex);  in spi_byte_brightness_set_blocking()
69 	ret = spi_write(led->spi, &value, sizeof(value));  in spi_byte_brightness_set_blocking()
70 	mutex_unlock(&led->mutex);  in spi_byte_brightness_set_blocking()
75 static int spi_byte_probe(struct spi_device *spi)  in spi_byte_probe()  argument
78 	struct device *dev = &spi->dev;  in spi_byte_probe()
85 		dev_err(dev, "Device must have exactly one LED sub-node.");  in spi_byte_probe()
86 		return -EINVAL;  in spi_byte_probe()
91 		return -ENOMEM;  in spi_byte_probe()
93 	ret = devm_mutex_init(dev, &led->mutex);  in spi_byte_probe()
97 	led->spi = spi;  in spi_byte_probe()
98 	led->cdef = device_get_match_data(dev);  in spi_byte_probe()
99 	led->ldev.brightness = LED_OFF;  in spi_byte_probe()
100 	led->ldev.max_brightness = led->cdef->max_value - led->cdef->off_value;  in spi_byte_probe()
101 	led->ldev.brightness_set_blocking = spi_byte_brightness_set_blocking;  in spi_byte_probe()
107 		led->ldev.brightness = led->ldev.max_brightness;  in spi_byte_probe()
108 	spi_byte_brightness_set_blocking(&led->ldev,  in spi_byte_probe()
109 					 led->ldev.brightness);  in spi_byte_probe()
112 	init_data.devicename = "leds-spi-byte";  in spi_byte_probe()
115 	return devm_led_classdev_register_ext(dev, &led->ldev, &init_data);  in spi_byte_probe()
119 	{ .compatible = "ubnt,acb-spi-led", .data = &ubnt_acb_spi_led_cdef },
133 MODULE_AUTHOR("Christian Mauderer <oss@c-mauderer.de>");
134 MODULE_DESCRIPTION("single byte SPI LED driver");
136 MODULE_ALIAS("spi:leds-spi-byte");