arch/arm/mach-ixp4xx/dsmg600-power.c

   1 /*
   2  * arch/arm/mach-ixp4xx/dsmg600-power.c
   3  *
   4  * DSM-G600 Power/Reset driver
   5  * Author: Michael Westerhof <mwester@dls.net>
   6  *
   7  * Based on nslu2-power.c
   8  *  Copyright (C) 2005 Tower Technologies
   9  *  Author: Alessandro Zummo <a.zummo@towertech.it>
  10  *
  11  * which was based on nslu2-io.c
  12  *  Copyright (C) 2004 Karen Spearel
  13  *
  14  * Maintainers: http://www.nslu2-linux.org/
  15  *
  16  * This program is free software; you can redistribute it and/or modify
  17  * it under the terms of the GNU General Public License version 2 as
  18  * published by the Free Software Foundation.
  19  *
  20  */
  21
  22 #include <linux/module.h>
  23 #include <linux/reboot.h>
  24 #include <linux/interrupt.h>
  25 #include <linux/irq.h>
  26 #include <linux/jiffies.h>
  27 #include <linux/timer.h>
  28
  29 #include <asm/mach-types.h>
  30
  31 extern void ctrl_alt_del(void);
  32
  33 /* This is used to make sure the power-button pusher is serious.  The button
  34  * must be held until the value of this counter reaches zero.
  35  */
  36 static volatile int power_button_countdown;
  37
  38 /* Must hold the button down for at least this many counts to be processed */
  39 #define PBUTTON_HOLDDOWN_COUNT 4 /* 2 secs */
  40
  41 static void dsmg600_power_handler(unsigned long data);
  42 static DEFINE_TIMER(dsmg600_power_timer, dsmg600_power_handler, 0, 0);
  43
  44 static void dsmg600_power_handler(unsigned long data)
  45 {
  46         /* This routine is called twice per second to check the
  47          * state of the power button.
  48          */
  49
  50         if (*IXP4XX_GPIO_GPINR & DSMG600_PB_BM) {
  51
  52                 /* IO Pin is 1 (button pushed) */
  53                 if (power_button_countdown == 0) {
  54                         /* Signal init to do the ctrlaltdel action, this will bypass
  55                          * init if it hasn't started and do a kernel_restart.
  56                          */
  57                         ctrl_alt_del();
  58
  59                         /* Change the state of the power LED to "blink" */
  60                         gpio_line_set(DSMG600_LED_PWR_GPIO, IXP4XX_GPIO_LOW);
  61                 }
  62                 power_button_countdown--;
  63
  64         } else {
  65                 power_button_countdown = PBUTTON_HOLDDOWN_COUNT;
  66         }
  67
  68         mod_timer(&dsmg600_power_timer, jiffies + msecs_to_jiffies(500));
  69 }
  70
  71 static irqreturn_t dsmg600_reset_handler(int irq, void *dev_id)
  72 {
  73         /* This is the paper-clip reset, it shuts the machine down directly. */
  74         machine_power_off();
  75
  76         return IRQ_HANDLED;
  77 }
  78
  79 static int __init dsmg600_power_init(void)
  80 {
  81         if (!(machine_is_dsmg600()))
  82                 return 0;
  83
  84         if (request_irq(DSMG600_RB_IRQ, &dsmg600_reset_handler,
  85                 IRQF_DISABLED | IRQF_TRIGGER_LOW, "DSM-G600 reset button",
  86                 NULL) < 0) {
  87
  88                 printk(KERN_DEBUG "Reset Button IRQ %d not available\n",
  89                         DSMG600_RB_IRQ);
  90
  91                 return -EIO;
  92         }
  93
  94         /* The power button on the D-Link DSM-G600 is on GPIO 15, but
  95          * it cannot handle interrupts on that GPIO line.  So we'll
  96          * have to poll it with a kernel timer.
  97          */
  98
  99         /* Make sure that the power button GPIO is set up as an input */
 100         gpio_line_config(DSMG600_PB_GPIO, IXP4XX_GPIO_IN);
 101
 102         /* Set the initial value for the power button IRQ handler */
 103         power_button_countdown = PBUTTON_HOLDDOWN_COUNT;
 104
 105         mod_timer(&dsmg600_power_timer, jiffies + msecs_to_jiffies(500));
 106
 107         return 0;
 108 }
 109
 110 static void __exit dsmg600_power_exit(void)
 111 {
 112         if (!(machine_is_dsmg600()))
 113                 return;
 114
 115         del_timer_sync(&dsmg600_power_timer);
 116
 117         free_irq(DSMG600_RB_IRQ, NULL);
 118 }
 119
 120 module_init(dsmg600_power_init);
 121 module_exit(dsmg600_power_exit);
 122
 123 MODULE_AUTHOR("Michael Westerhof <mwester@dls.net>");
 124 MODULE_DESCRIPTION("DSM-G600 Power/Reset driver");
 125 MODULE_LICENSE("GPL");