LXR linux/drivers/input/misc/rb532

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Support for the S1 button on Routerboard 532
   4 *
   5 * Copyright (C) 2009  Phil Sutter <n0-1@freewrt.org>
   6 */
   7
   8#include <linux/input.h>
   9#include <linux/module.h>
  10#include <linux/platform_device.h>
  11#include <linux/gpio.h>
  12
  13#include <asm/mach-rc32434/gpio.h>
  14#include <asm/mach-rc32434/rb.h>
  15
  16#define DRV_NAME "rb532-button"
  17
  18#define RB532_BTN_RATE 100 /* msec */
  19#define RB532_BTN_KSYM BTN_0
  20
  21/* The S1 button state is provided by GPIO pin 1. But as this
  22 * pin is also used for uart input as alternate function, the
  23 * operational modes must be switched first:
  24 * 1) disable uart using set_latch_u5()
  25 * 2) turn off alternate function implicitly through
  26 *    gpio_direction_input()
  27 * 3) read the GPIO's current value
  28 * 4) undo step 2 by enabling alternate function (in this
  29 *    mode the GPIO direction is fixed, so no change needed)
  30 * 5) turn on uart again
  31 * The GPIO value occurs to be inverted, so pin high means
  32 * button is not pressed.
  33 */
  34static bool rb532_button_pressed(void)
  35{
  36        int val;
  37
  38        set_latch_u5(0, LO_FOFF);
  39        gpio_direction_input(GPIO_BTN_S1);
  40
  41        val = gpio_get_value(GPIO_BTN_S1);
  42
  43        rb532_gpio_set_func(GPIO_BTN_S1);
  44        set_latch_u5(LO_FOFF, 0);
  45
  46        return !val;
  47}
  48
  49static void rb532_button_poll(struct input_dev *input)
  50{
  51        input_report_key(input, RB532_BTN_KSYM, rb532_button_pressed());
  52        input_sync(input);
  53}
  54
  55static int rb532_button_probe(struct platform_device *pdev)
  56{
  57        struct input_dev *input;
  58        int error;
  59
  60        input = devm_input_allocate_device(&pdev->dev);
  61        if (!input)
  62                return -ENOMEM;
  63
  64        input->name = "rb532 button";
  65        input->phys = "rb532/button0";
  66        input->id.bustype = BUS_HOST;
  67
  68        input_set_capability(input, EV_KEY, RB532_BTN_KSYM);
  69
  70        error = input_setup_polling(input, rb532_button_poll);
  71        if (error)
  72                return error;
  73
  74        input_set_poll_interval(input, RB532_BTN_RATE);
  75
  76        error = input_register_device(input);
  77        if (error)
  78                return error;
  79
  80        return 0;
  81}
  82
  83static struct platform_driver rb532_button_driver = {
  84        .probe = rb532_button_probe,
  85        .driver = {
  86                .name = DRV_NAME,
  87        },
  88};
  89module_platform_driver(rb532_button_driver);
  90
  91MODULE_AUTHOR("Phil Sutter <n0-1@freewrt.org>");
  92MODULE_LICENSE("GPL");
  93MODULE_DESCRIPTION("Support for S1 button on Routerboard 532");
  94MODULE_ALIAS("platform:" DRV_NAME);
  95