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156 lines
4.4 KiB
156 lines
4.4 KiB
// SPDX-License-Identifier: GPL-2.0 |
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// Copyright (c) 2019 Christian Mauderer <[email protected]> |
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/* |
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* The driver supports controllers with a very simple SPI protocol: |
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* - one LED is controlled by a single byte on MOSI |
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* - the value of the byte gives the brightness between two values (lowest to |
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* highest) |
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* - no return value is necessary (no MISO signal) |
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* |
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* The value for minimum and maximum brightness depends on the device |
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* (compatible string). |
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* |
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* Supported devices: |
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* - "ubnt,acb-spi-led": Microcontroller (SONiX 8F26E611LA) based device used |
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* for example in Ubiquiti airCube ISP. Reverse engineered protocol for this |
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* controller: |
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* * Higher two bits set a mode. Lower six bits are a parameter. |
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* * Mode: 00 -> set brightness between 0x00 (min) and 0x3F (max) |
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* * Mode: 01 -> pulsing pattern (min -> max -> min) with an interval. From |
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* some tests, the period is about (50ms + 102ms * parameter). There is a |
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* slightly different pattern starting from 0x10 (longer gap between the |
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* pulses) but the time still follows that calculation. |
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* * Mode: 10 -> same as 01 but with only a ramp from min to max. Again a |
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* slight jump in the pattern at 0x10. |
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* * Mode: 11 -> blinking (off -> 25% -> off -> 25% -> ...) with a period of |
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* (105ms * parameter) |
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* NOTE: This driver currently only supports mode 00. |
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*/ |
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#include <linux/leds.h> |
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#include <linux/module.h> |
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#include <linux/of_device.h> |
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#include <linux/spi/spi.h> |
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#include <linux/mutex.h> |
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#include <uapi/linux/uleds.h> |
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struct spi_byte_chipdef { |
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/* SPI byte that will be send to switch the LED off */ |
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u8 off_value; |
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/* SPI byte that will be send to switch the LED to maximum brightness */ |
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u8 max_value; |
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}; |
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struct spi_byte_led { |
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struct led_classdev ldev; |
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struct spi_device *spi; |
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char name[LED_MAX_NAME_SIZE]; |
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struct mutex mutex; |
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const struct spi_byte_chipdef *cdef; |
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}; |
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static const struct spi_byte_chipdef ubnt_acb_spi_led_cdef = { |
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.off_value = 0x0, |
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.max_value = 0x3F, |
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}; |
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static const struct of_device_id spi_byte_dt_ids[] = { |
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{ .compatible = "ubnt,acb-spi-led", .data = &ubnt_acb_spi_led_cdef }, |
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{}, |
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}; |
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MODULE_DEVICE_TABLE(of, spi_byte_dt_ids); |
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static int spi_byte_brightness_set_blocking(struct led_classdev *dev, |
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enum led_brightness brightness) |
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{ |
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struct spi_byte_led *led = container_of(dev, struct spi_byte_led, ldev); |
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u8 value; |
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int ret; |
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value = (u8) brightness + led->cdef->off_value; |
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mutex_lock(&led->mutex); |
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ret = spi_write(led->spi, &value, sizeof(value)); |
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mutex_unlock(&led->mutex); |
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return ret; |
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} |
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static int spi_byte_probe(struct spi_device *spi) |
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{ |
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struct device_node *child; |
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struct device *dev = &spi->dev; |
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struct spi_byte_led *led; |
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const char *name = "leds-spi-byte::"; |
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const char *state; |
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int ret; |
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if (of_get_available_child_count(dev_of_node(dev)) != 1) { |
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dev_err(dev, "Device must have exactly one LED sub-node."); |
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return -EINVAL; |
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} |
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child = of_get_next_available_child(dev_of_node(dev), NULL); |
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led = devm_kzalloc(dev, sizeof(*led), GFP_KERNEL); |
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if (!led) |
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return -ENOMEM; |
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of_property_read_string(child, "label", &name); |
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strlcpy(led->name, name, sizeof(led->name)); |
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led->spi = spi; |
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mutex_init(&led->mutex); |
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led->cdef = device_get_match_data(dev); |
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led->ldev.name = led->name; |
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led->ldev.brightness = LED_OFF; |
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led->ldev.max_brightness = led->cdef->max_value - led->cdef->off_value; |
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led->ldev.brightness_set_blocking = spi_byte_brightness_set_blocking; |
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state = of_get_property(child, "default-state", NULL); |
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if (state) { |
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if (!strcmp(state, "on")) { |
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led->ldev.brightness = led->ldev.max_brightness; |
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} else if (strcmp(state, "off")) { |
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/* all other cases except "off" */ |
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dev_err(dev, "default-state can only be 'on' or 'off'"); |
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return -EINVAL; |
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} |
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} |
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spi_byte_brightness_set_blocking(&led->ldev, |
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led->ldev.brightness); |
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ret = devm_led_classdev_register(&spi->dev, &led->ldev); |
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if (ret) { |
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mutex_destroy(&led->mutex); |
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return ret; |
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} |
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spi_set_drvdata(spi, led); |
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return 0; |
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} |
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static int spi_byte_remove(struct spi_device *spi) |
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{ |
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struct spi_byte_led *led = spi_get_drvdata(spi); |
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mutex_destroy(&led->mutex); |
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return 0; |
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} |
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static struct spi_driver spi_byte_driver = { |
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.probe = spi_byte_probe, |
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.remove = spi_byte_remove, |
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.driver = { |
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.name = KBUILD_MODNAME, |
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.of_match_table = spi_byte_dt_ids, |
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}, |
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}; |
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module_spi_driver(spi_byte_driver); |
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MODULE_AUTHOR("Christian Mauderer <[email protected]>"); |
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MODULE_DESCRIPTION("single byte SPI LED driver"); |
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MODULE_LICENSE("GPL v2"); |
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MODULE_ALIAS("spi:leds-spi-byte");
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