cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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leds-lt3593.c (3245B)

      1// SPDX-License-Identifier: GPL-2.0
      2// Copyright (c) 2009,2018 Daniel Mack <daniel@zonque.org>
      3
      4#include <linux/kernel.h>
      5#include <linux/platform_device.h>
      6#include <linux/leds.h>
      7#include <linux/delay.h>
      8#include <linux/gpio/consumer.h>
      9#include <linux/slab.h>
     10#include <linux/mod_devicetable.h>
     11#include <linux/module.h>
     12#include <linux/property.h>
     13
     14#define LED_LT3593_NAME "lt3593"
     15
     16struct lt3593_led_data {
     17	struct led_classdev cdev;
     18	struct gpio_desc *gpiod;
     19};
     20
     21static int lt3593_led_set(struct led_classdev *led_cdev,
     22			   enum led_brightness value)
     23{
     24	struct lt3593_led_data *led_dat =
     25		container_of(led_cdev, struct lt3593_led_data, cdev);
     26	int pulses;
     27
     28	/*
     29	 * The LT3593 resets its internal current level register to the maximum
     30	 * level on the first falling edge on the control pin. Each following
     31	 * falling edge decreases the current level by 625uA. Up to 32 pulses
     32	 * can be sent, so the maximum power reduction is 20mA.
     33	 * After a timeout of 128us, the value is taken from the register and
     34	 * applied is to the output driver.
     35	 */
     36
     37	if (value == 0) {
     38		gpiod_set_value_cansleep(led_dat->gpiod, 0);
     39		return 0;
     40	}
     41
     42	pulses = 32 - (value * 32) / 255;
     43
     44	if (pulses == 0) {
     45		gpiod_set_value_cansleep(led_dat->gpiod, 0);
     46		mdelay(1);
     47		gpiod_set_value_cansleep(led_dat->gpiod, 1);
     48		return 0;
     49	}
     50
     51	gpiod_set_value_cansleep(led_dat->gpiod, 1);
     52
     53	while (pulses--) {
     54		gpiod_set_value_cansleep(led_dat->gpiod, 0);
     55		udelay(1);
     56		gpiod_set_value_cansleep(led_dat->gpiod, 1);
     57		udelay(1);
     58	}
     59
     60	return 0;
     61}
     62
     63static int lt3593_led_probe(struct platform_device *pdev)
     64{
     65	struct device *dev = &pdev->dev;
     66	struct lt3593_led_data *led_data;
     67	struct fwnode_handle *child;
     68	int ret, state = LEDS_GPIO_DEFSTATE_OFF;
     69	struct led_init_data init_data = {};
     70	const char *tmp;
     71
     72	led_data = devm_kzalloc(dev, sizeof(*led_data), GFP_KERNEL);
     73	if (!led_data)
     74		return -ENOMEM;
     75
     76	if (device_get_child_node_count(dev) != 1) {
     77		dev_err(dev, "Device must have exactly one LED sub-node.");
     78		return -EINVAL;
     79	}
     80
     81	led_data->gpiod = devm_gpiod_get(dev, "lltc,ctrl", 0);
     82	if (IS_ERR(led_data->gpiod))
     83		return PTR_ERR(led_data->gpiod);
     84
     85	child = device_get_next_child_node(dev, NULL);
     86
     87	if (!fwnode_property_read_string(child, "default-state", &tmp)) {
     88		if (!strcmp(tmp, "on"))
     89			state = LEDS_GPIO_DEFSTATE_ON;
     90	}
     91
     92	led_data->cdev.brightness_set_blocking = lt3593_led_set;
     93	led_data->cdev.brightness = state ? LED_FULL : LED_OFF;
     94
     95	init_data.fwnode = child;
     96	init_data.devicename = LED_LT3593_NAME;
     97	init_data.default_label = ":";
     98
     99	ret = devm_led_classdev_register_ext(dev, &led_data->cdev, &init_data);
    100	fwnode_handle_put(child);
    101	if (ret < 0)
    102		return ret;
    103
    104	platform_set_drvdata(pdev, led_data);
    105
    106	return 0;
    107}
    108
    109static const struct of_device_id of_lt3593_leds_match[] = {
    110	{ .compatible = "lltc,lt3593", },
    111	{},
    112};
    113MODULE_DEVICE_TABLE(of, of_lt3593_leds_match);
    114
    115static struct platform_driver lt3593_led_driver = {
    116	.probe		= lt3593_led_probe,
    117	.driver		= {
    118		.name	= "leds-lt3593",
    119		.of_match_table = of_lt3593_leds_match,
    120	},
    121};
    122
    123module_platform_driver(lt3593_led_driver);
    124
    125MODULE_AUTHOR("Daniel Mack <daniel@zonque.org>");
    126MODULE_DESCRIPTION("LED driver for LT3593 controllers");
    127MODULE_LICENSE("GPL v2");
    128MODULE_ALIAS("platform:leds-lt3593");