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