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Linux/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);
108 

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