drivers/input/misc/rb532_button.c

   1 /*
   2  * Support for the S1 button on Routerboard 532
   3  *
   4  * Copyright (C) 2009  Phil Sutter <n0-1@freewrt.org>
   5  */
   6
   7 #include <linux/input-polldev.h>
   8 #include <linux/module.h>
   9 #include <linux/platform_device.h>
  10 #include <linux/gpio.h>
  11
  12 #include <asm/mach-rc32434/gpio.h>
  13 #include <asm/mach-rc32434/rb.h>
  14
  15 #define DRV_NAME "rb532-button"
  16
  17 #define RB532_BTN_RATE 100 /* msec */
  18 #define RB532_BTN_KSYM BTN_0
  19
  20 /* The S1 button state is provided by GPIO pin 1. But as this
  21  * pin is also used for uart input as alternate function, the
  22  * operational modes must be switched first:
  23  * 1) disable uart using set_latch_u5()
  24  * 2) turn off alternate function implicitly through
  25  *    gpio_direction_input()
  26  * 3) read the GPIO's current value
  27  * 4) undo step 2 by enabling alternate function (in this
  28  *    mode the GPIO direction is fixed, so no change needed)
  29  * 5) turn on uart again
  30  * The GPIO value occurs to be inverted, so pin high means
  31  * button is not pressed.
  32  */
  33 static bool rb532_button_pressed(void)
  34 {
  35         int val;
  36
  37         set_latch_u5(0, LO_FOFF);
  38         gpio_direction_input(GPIO_BTN_S1);
  39
  40         val = gpio_get_value(GPIO_BTN_S1);
  41
  42         rb532_gpio_set_func(GPIO_BTN_S1);
  43         set_latch_u5(LO_FOFF, 0);
  44
  45         return !val;
  46 }
  47
  48 static void rb532_button_poll(struct input_polled_dev *poll_dev)
  49 {
  50         input_report_key(poll_dev->input, RB532_BTN_KSYM,
  51                          rb532_button_pressed());
  52         input_sync(poll_dev->input);
  53 }
  54
  55 static int rb532_button_probe(struct platform_device *pdev)
  56 {
  57         struct input_polled_dev *poll_dev;
  58         int error;
  59
  60         poll_dev = input_allocate_polled_device();
  61         if (!poll_dev)
  62                 return -ENOMEM;
  63
  64         poll_dev->poll = rb532_button_poll;
  65         poll_dev->poll_interval = RB532_BTN_RATE;
  66
  67         poll_dev->input->name = "rb532 button";
  68         poll_dev->input->phys = "rb532/button0";
  69         poll_dev->input->id.bustype = BUS_HOST;
  70         poll_dev->input->dev.parent = &pdev->dev;
  71
  72         dev_set_drvdata(&pdev->dev, poll_dev);
  73
  74         input_set_capability(poll_dev->input, EV_KEY, RB532_BTN_KSYM);
  75
  76         error = input_register_polled_device(poll_dev);
  77         if (error) {
  78                 input_free_polled_device(poll_dev);
  79                 return error;
  80         }
  81
  82         return 0;
  83 }
  84
  85 static int rb532_button_remove(struct platform_device *pdev)
  86 {
  87         struct input_polled_dev *poll_dev = dev_get_drvdata(&pdev->dev);
  88
  89         input_unregister_polled_device(poll_dev);
  90         input_free_polled_device(poll_dev);
  91
  92         return 0;
  93 }
  94
  95 static struct platform_driver rb532_button_driver = {
  96         .probe = rb532_button_probe,
  97         .remove = rb532_button_remove,
  98         .driver = {
  99                 .name = DRV_NAME,
 100         },
 101 };
 102 module_platform_driver(rb532_button_driver);
 103
 104 MODULE_AUTHOR("Phil Sutter <n0-1@freewrt.org>");
 105 MODULE_LICENSE("GPL");
 106 MODULE_DESCRIPTION("Support for S1 button on Routerboard 532");
 107 MODULE_ALIAS("platform:" DRV_NAME);