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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 
 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                 .owner = THIS_MODULE,
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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