141 lines
3.5 KiB
C
141 lines
3.5 KiB
C
// SPDX-License-Identifier: GPL-2.0
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// Copyright (c) 2009,2018 Daniel Mack <daniel@zonque.org>
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#include <linux/kernel.h>
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#include <linux/platform_device.h>
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#include <linux/leds.h>
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#include <linux/delay.h>
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#include <linux/gpio.h>
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#include <linux/gpio/consumer.h>
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#include <linux/slab.h>
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#include <linux/module.h>
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#include <linux/of.h>
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#include <uapi/linux/uleds.h>
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struct lt3593_led_data {
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char name[LED_MAX_NAME_SIZE];
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struct led_classdev cdev;
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struct gpio_desc *gpiod;
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};
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static int lt3593_led_set(struct led_classdev *led_cdev,
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enum led_brightness value)
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{
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struct lt3593_led_data *led_dat =
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container_of(led_cdev, struct lt3593_led_data, cdev);
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int pulses;
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/*
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* The LT3593 resets its internal current level register to the maximum
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* level on the first falling edge on the control pin. Each following
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* falling edge decreases the current level by 625uA. Up to 32 pulses
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* can be sent, so the maximum power reduction is 20mA.
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* After a timeout of 128us, the value is taken from the register and
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* applied is to the output driver.
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*/
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if (value == 0) {
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gpiod_set_value_cansleep(led_dat->gpiod, 0);
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return 0;
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}
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pulses = 32 - (value * 32) / 255;
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if (pulses == 0) {
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gpiod_set_value_cansleep(led_dat->gpiod, 0);
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mdelay(1);
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gpiod_set_value_cansleep(led_dat->gpiod, 1);
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return 0;
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}
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gpiod_set_value_cansleep(led_dat->gpiod, 1);
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while (pulses--) {
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gpiod_set_value_cansleep(led_dat->gpiod, 0);
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udelay(1);
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gpiod_set_value_cansleep(led_dat->gpiod, 1);
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udelay(1);
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}
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return 0;
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}
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static int lt3593_led_probe(struct platform_device *pdev)
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{
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struct device *dev = &pdev->dev;
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struct lt3593_led_data *led_data;
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struct fwnode_handle *child;
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int ret, state = LEDS_GPIO_DEFSTATE_OFF;
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const char *tmp;
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if (!dev->of_node)
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return -ENODEV;
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led_data = devm_kzalloc(dev, sizeof(*led_data), GFP_KERNEL);
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if (!led_data)
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return -ENOMEM;
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if (device_get_child_node_count(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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led_data->gpiod = devm_gpiod_get(dev, "lltc,ctrl", 0);
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if (IS_ERR(led_data->gpiod))
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return PTR_ERR(led_data->gpiod);
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child = device_get_next_child_node(dev, NULL);
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ret = fwnode_property_read_string(child, "label", &tmp);
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if (ret < 0)
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snprintf(led_data->name, sizeof(led_data->name),
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"lt3593::");
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else
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snprintf(led_data->name, sizeof(led_data->name),
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"lt3593:%s", tmp);
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fwnode_property_read_string(child, "linux,default-trigger",
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&led_data->cdev.default_trigger);
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if (!fwnode_property_read_string(child, "default-state", &tmp)) {
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if (!strcmp(tmp, "on"))
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state = LEDS_GPIO_DEFSTATE_ON;
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}
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led_data->cdev.name = led_data->name;
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led_data->cdev.brightness_set_blocking = lt3593_led_set;
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led_data->cdev.brightness = state ? LED_FULL : LED_OFF;
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ret = devm_led_classdev_register(dev, &led_data->cdev);
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if (ret < 0) {
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fwnode_handle_put(child);
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return ret;
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}
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led_data->cdev.dev->of_node = dev->of_node;
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platform_set_drvdata(pdev, led_data);
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return 0;
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}
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static const struct of_device_id of_lt3593_leds_match[] = {
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{ .compatible = "lltc,lt3593", },
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{},
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};
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MODULE_DEVICE_TABLE(of, of_lt3593_leds_match);
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static struct platform_driver lt3593_led_driver = {
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.probe = lt3593_led_probe,
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.driver = {
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.name = "leds-lt3593",
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.of_match_table = of_match_ptr(of_lt3593_leds_match),
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},
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};
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module_platform_driver(lt3593_led_driver);
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MODULE_AUTHOR("Daniel Mack <daniel@zonque.org>");
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MODULE_DESCRIPTION("LED driver for LT3593 controllers");
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MODULE_LICENSE("GPL v2");
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MODULE_ALIAS("platform:leds-lt3593");
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