linux/drivers/parisc/power.c
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   1/*
   2 * linux/drivers/parisc/power.c
   3 * HP PARISC soft power switch support driver
   4 *
   5 * Copyright (c) 2001-2007 Helge Deller <deller@gmx.de>
   6 * All rights reserved.
   7 *
   8 *
   9 * Redistribution and use in source and binary forms, with or without
  10 * modification, are permitted provided that the following conditions
  11 * are met:
  12 * 1. Redistributions of source code must retain the above copyright
  13 *    notice, this list of conditions, and the following disclaimer,
  14 *    without modification.
  15 * 2. The name of the author may not be used to endorse or promote products
  16 *    derived from this software without specific prior written permission.
  17 *
  18 * Alternatively, this software may be distributed under the terms of the
  19 * GNU General Public License ("GPL").
  20 *
  21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
  25 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30 *
  31 *
  32 *  HINT:
  33 *  Support of the soft power switch button may be enabled or disabled at
  34 *  runtime through the "/proc/sys/kernel/power" procfs entry.
  35 */ 
  36
  37#include <linux/module.h>
  38#include <linux/init.h>
  39#include <linux/kernel.h>
  40#include <linux/notifier.h>
  41#include <linux/reboot.h>
  42#include <linux/sched.h>
  43#include <linux/kthread.h>
  44#include <linux/pm.h>
  45
  46#include <asm/pdc.h>
  47#include <asm/io.h>
  48#include <asm/led.h>
  49
  50#define DRIVER_NAME  "powersw"
  51#define KTHREAD_NAME "kpowerswd"
  52
  53/* how often should the power button be polled ? */
  54#define POWERSWITCH_POLL_PER_SEC 2
  55
  56/* how long does the power button needs to be down until we react ? */
  57#define POWERSWITCH_DOWN_SEC 2
  58
  59/* assembly code to access special registers */
  60/* taken from PCXL ERS page 82 */
  61#define DIAG_CODE(code)         (0x14000000 + ((code)<<5))
  62
  63#define MFCPU_X(rDiagReg, t_ch, t_th, code) \
  64        (DIAG_CODE(code) + ((rDiagReg)<<21) + ((t_ch)<<16) + ((t_th)<<0) )
  65        
  66#define MTCPU(dr, gr)           MFCPU_X(dr, gr,  0, 0x12)       /* move value of gr to dr[dr] */
  67#define MFCPU_C(dr, gr)         MFCPU_X(dr, gr,  0, 0x30)       /* for dr0 and dr8 only ! */
  68#define MFCPU_T(dr, gr)         MFCPU_X(dr,  0, gr, 0xa0)       /* all dr except dr0 and dr8 */
  69        
  70#define __getDIAG(dr) ( {                       \
  71        register unsigned long __res asm("r28");\
  72         __asm__ __volatile__ (                 \
  73                ".word %1" : "=&r" (__res) : "i" (MFCPU_T(dr,28) ) \
  74        );                                      \
  75        __res;                                  \
  76} )
  77
  78/* local shutdown counter */
  79static int shutdown_timer __read_mostly;
  80
  81/* check, give feedback and start shutdown after one second */
  82static void process_shutdown(void)
  83{
  84        if (shutdown_timer == 0)
  85                printk(KERN_ALERT KTHREAD_NAME ": Shutdown requested...\n");
  86
  87        shutdown_timer++;
  88        
  89        /* wait until the button was pressed for 1 second */
  90        if (shutdown_timer == (POWERSWITCH_DOWN_SEC*POWERSWITCH_POLL_PER_SEC)) {
  91                static const char msg[] = "Shutting down...";
  92                printk(KERN_INFO KTHREAD_NAME ": %s\n", msg);
  93                lcd_print(msg);
  94
  95                /* send kill signal */
  96                if (kill_cad_pid(SIGINT, 1)) {
  97                        /* just in case killing init process failed */
  98                        if (pm_power_off)
  99                                pm_power_off();
 100                }
 101        }
 102}
 103
 104
 105/* main power switch task struct */
 106static struct task_struct *power_task;
 107
 108/* filename in /proc which can be used to enable/disable the power switch */
 109#define SYSCTL_FILENAME "sys/kernel/power"
 110
 111/* soft power switch enabled/disabled */
 112int pwrsw_enabled __read_mostly = 1;
 113
 114/* main kernel thread worker. It polls the button state */
 115static int kpowerswd(void *param)
 116{
 117        __set_current_state(TASK_RUNNING);
 118
 119        do {
 120                int button_not_pressed;
 121                unsigned long soft_power_reg = (unsigned long) param;
 122
 123                schedule_timeout_interruptible(pwrsw_enabled ? HZ : HZ/POWERSWITCH_POLL_PER_SEC);
 124                __set_current_state(TASK_RUNNING);
 125
 126                if (unlikely(!pwrsw_enabled))
 127                        continue;
 128
 129                if (soft_power_reg) {
 130                        /*
 131                         * Non-Gecko-style machines:
 132                         * Check the power switch status which is read from the
 133                         * real I/O location at soft_power_reg.
 134                         * Bit 31 ("the lowest bit) is the status of the power switch.
 135                         * This bit is "1" if the button is NOT pressed.
 136                         */
 137                        button_not_pressed = (gsc_readl(soft_power_reg) & 0x1);
 138                } else {
 139                        /*
 140                         * On gecko style machines (e.g. 712/xx and 715/xx) 
 141                         * the power switch status is stored in Bit 0 ("the highest bit")
 142                         * of CPU diagnose register 25.
 143                         * Warning: Some machines never reset the DIAG flag, even if
 144                         * the button has been released again.
 145                         */
 146                        button_not_pressed = (__getDIAG(25) & 0x80000000);
 147                }
 148
 149                if (likely(button_not_pressed)) {
 150                        if (unlikely(shutdown_timer && /* avoid writing if not necessary */
 151                                shutdown_timer < (POWERSWITCH_DOWN_SEC*POWERSWITCH_POLL_PER_SEC))) {
 152                                shutdown_timer = 0;
 153                                printk(KERN_INFO KTHREAD_NAME ": Shutdown request aborted.\n");
 154                        }
 155                } else
 156                        process_shutdown();
 157
 158
 159        } while (!kthread_should_stop());
 160
 161        return 0;
 162}
 163
 164
 165/*
 166 * powerfail interruption handler (irq IRQ_FROM_REGION(CPU_IRQ_REGION)+2) 
 167 */
 168#if 0
 169static void powerfail_interrupt(int code, void *x)
 170{
 171        printk(KERN_CRIT "POWERFAIL INTERRUPTION !\n");
 172        poweroff();
 173}
 174#endif
 175
 176
 177
 178
 179/* parisc_panic_event() is called by the panic handler.
 180 * As soon as a panic occurs, our tasklets above will not be
 181 * executed any longer. This function then re-enables the 
 182 * soft-power switch and allows the user to switch off the system
 183 */
 184static int parisc_panic_event(struct notifier_block *this,
 185                unsigned long event, void *ptr)
 186{
 187        /* re-enable the soft-power switch */
 188        pdc_soft_power_button(0);
 189        return NOTIFY_DONE;
 190}
 191
 192static struct notifier_block parisc_panic_block = {
 193        .notifier_call  = parisc_panic_event,
 194        .priority       = INT_MAX,
 195};
 196
 197
 198static int __init power_init(void)
 199{
 200        unsigned long ret;
 201        unsigned long soft_power_reg;
 202
 203#if 0
 204        request_irq( IRQ_FROM_REGION(CPU_IRQ_REGION)+2, &powerfail_interrupt,
 205                0, "powerfail", NULL);
 206#endif
 207
 208        /* enable the soft power switch if possible */
 209        ret = pdc_soft_power_info(&soft_power_reg);
 210        if (ret == PDC_OK)
 211                ret = pdc_soft_power_button(1);
 212        if (ret != PDC_OK)
 213                soft_power_reg = -1UL;
 214        
 215        switch (soft_power_reg) {
 216        case 0:         printk(KERN_INFO DRIVER_NAME ": Gecko-style soft power switch enabled.\n");
 217                        break;
 218                        
 219        case -1UL:      printk(KERN_INFO DRIVER_NAME ": Soft power switch support not available.\n");
 220                        return -ENODEV;
 221        
 222        default:        printk(KERN_INFO DRIVER_NAME ": Soft power switch at 0x%08lx enabled.\n",
 223                                soft_power_reg);
 224        }
 225
 226        power_task = kthread_run(kpowerswd, (void*)soft_power_reg, KTHREAD_NAME);
 227        if (IS_ERR(power_task)) {
 228                printk(KERN_ERR DRIVER_NAME ": thread creation failed.  Driver not loaded.\n");
 229                pdc_soft_power_button(0);
 230                return -EIO;
 231        }
 232
 233        /* Register a call for panic conditions. */
 234        atomic_notifier_chain_register(&panic_notifier_list,
 235                        &parisc_panic_block);
 236
 237        return 0;
 238}
 239
 240static void __exit power_exit(void)
 241{
 242        kthread_stop(power_task);
 243
 244        atomic_notifier_chain_unregister(&panic_notifier_list,
 245                        &parisc_panic_block);
 246
 247        pdc_soft_power_button(0);
 248}
 249
 250arch_initcall(power_init);
 251module_exit(power_exit);
 252
 253
 254MODULE_AUTHOR("Helge Deller <deller@gmx.de>");
 255MODULE_DESCRIPTION("Soft power switch driver");
 256MODULE_LICENSE("Dual BSD/GPL");
 257
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