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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 <[email protected]>
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 */
79 static int shutdown_timer __read_mostly;
80 
81 /* check, give feedback and start shutdown after one second */
82 static 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 */
106 static 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 */
112 int pwrsw_enabled __read_mostly = 1;
113 
114 /* main kernel thread worker. It polls the button state */
115 static int kpowerswd(void *param)
116 {
118 
119  do {
120  int button_not_pressed;
121  unsigned long soft_power_reg = (unsigned long) param;
122 
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
169 static 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  */
184 static int parisc_panic_event(struct notifier_block *this,
185  unsigned long event, void *ptr)
186 {
187  /* re-enable the soft-power switch */
189  return NOTIFY_DONE;
190 }
191 
192 static struct notifier_block parisc_panic_block = {
193  .notifier_call = parisc_panic_event,
194  .priority = INT_MAX,
195 };
196 
197 
198 static 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");
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 
240 static 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 
248 }
249 
250 arch_initcall(power_init);
251 module_exit(power_exit);
252 
253 
254 MODULE_AUTHOR("Helge Deller <[email protected]>");
255 MODULE_DESCRIPTION("Soft power switch driver");
256 MODULE_LICENSE("Dual BSD/GPL");