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128 lines
3.2 KiB
128 lines
3.2 KiB
// SPDX-License-Identifier: GPL-2.0 |
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// Copyright (c) 2009,2018 Daniel Mack <[email protected]> |
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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/consumer.h> |
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#include <linux/slab.h> |
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#include <linux/mod_devicetable.h> |
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#include <linux/module.h> |
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#include <linux/property.h> |
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#define LED_LT3593_NAME "lt3593" |
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struct lt3593_led_data { |
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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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struct led_init_data init_data = {}; |
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const char *tmp; |
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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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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.brightness_set_blocking = lt3593_led_set; |
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led_data->cdev.brightness = state ? LED_FULL : LED_OFF; |
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init_data.fwnode = child; |
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init_data.devicename = LED_LT3593_NAME; |
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init_data.default_label = ":"; |
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ret = devm_led_classdev_register_ext(dev, &led_data->cdev, &init_data); |
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fwnode_handle_put(child); |
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if (ret < 0) |
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return ret; |
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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_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 <[email protected]>"); |
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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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