drivers/parisc/power.c

   1 /* SPDX-License-Identifier: GPL-2.0-or-later */
   2 /*
   3  * HP PARISC soft power switch driver
   4  *
   5  * Copyright (c) 2001-2023 Helge Deller <deller@gmx.de>
   6  *
   7  *  HINT:
   8  *  Support of the soft power switch button may be enabled or disabled at
   9  *  runtime through the "/proc/sys/kernel/power" procfs entry.
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/init.h>
  14 #include <linux/kernel.h>
  15 #include <linux/panic_notifier.h>
  16 #include <linux/reboot.h>
  17 #include <linux/sched/signal.h>
  18 #include <linux/kthread.h>
  19 #include <linux/pm.h>
  20
  21 #include <asm/pdc.h>
  22 #include <asm/io.h>
  23 #include <asm/led.h>
  24
  25 #define DRIVER_NAME  "powersw"
  26 #define KTHREAD_NAME "kpowerswd"
  27
  28 /* how often should the power button be polled ? */
  29 #define POWERSWITCH_POLL_PER_SEC 2
  30
  31 /* how long does the power button needs to be down until we react ? */
  32 #define POWERSWITCH_DOWN_SEC 2
  33
  34 /* assembly code to access special registers */
  35 /* taken from PCXL ERS page 82 */
  36 #define DIAG_CODE(code)         (0x14000000 + ((code)<<5))
  37
  38 #define MFCPU_X(rDiagReg, t_ch, t_th, code) \
  39         (DIAG_CODE(code) + ((rDiagReg)<<21) + ((t_ch)<<16) + ((t_th)<<0) )
  40
  41 #define MTCPU(dr, gr)           MFCPU_X(dr, gr,  0, 0x12)       /* move value of gr to dr[dr] */
  42 #define MFCPU_C(dr, gr)         MFCPU_X(dr, gr,  0, 0x30)       /* for dr0 and dr8 only ! */
  43 #define MFCPU_T(dr, gr)         MFCPU_X(dr,  0, gr, 0xa0)       /* all dr except dr0 and dr8 */
  44
  45 #define __getDIAG(dr) ( {                       \
  46         register unsigned long __res asm("r28");\
  47          __asm__ __volatile__ (                 \
  48                 ".word %1" : "=&r" (__res) : "i" (MFCPU_T(dr,28) ) \
  49         );                                      \
  50         __res;                                  \
  51 } )
  52
  53 /* local shutdown counter */
  54 static int shutdown_timer __read_mostly;
  55
  56 /* check, give feedback and start shutdown after one second */
  57 static void process_shutdown(void)
  58 {
  59         if (shutdown_timer == 0)
  60                 printk(KERN_ALERT KTHREAD_NAME ": Shutdown requested...\n");
  61
  62         shutdown_timer++;
  63
  64         /* wait until the button was pressed for 1 second */
  65         if (shutdown_timer == (POWERSWITCH_DOWN_SEC*POWERSWITCH_POLL_PER_SEC)) {
  66                 static const char msg[] = "Shutting down...";
  67                 printk(KERN_INFO KTHREAD_NAME ": %s\n", msg);
  68                 lcd_print(msg);
  69
  70                 /* send kill signal */
  71                 if (kill_cad_pid(SIGINT, 1)) {
  72                         /* just in case killing init process failed */
  73                         machine_power_off();
  74                 }
  75         }
  76 }
  77
  78
  79 /* main power switch task struct */
  80 static struct task_struct *power_task;
  81
  82 /* filename in /proc which can be used to enable/disable the power switch */
  83 #define SYSCTL_FILENAME "sys/kernel/power"
  84
  85 /* soft power switch enabled/disabled */
  86 int pwrsw_enabled __read_mostly = 1;
  87
  88 /* main kernel thread worker. It polls the button state */
  89 static int kpowerswd(void *param)
  90 {
  91         __set_current_state(TASK_RUNNING);
  92
  93         do {
  94                 int button_not_pressed;
  95                 unsigned long soft_power_reg = (unsigned long) param;
  96
  97                 schedule_timeout_interruptible(pwrsw_enabled ? HZ : HZ/POWERSWITCH_POLL_PER_SEC);
  98
  99                 if (unlikely(!pwrsw_enabled))
 100                         continue;
 101
 102                 if (soft_power_reg) {
 103                         /*
 104                          * Non-Gecko-style machines:
 105                          * Check the power switch status which is read from the
 106                          * real I/O location at soft_power_reg.
 107                          * Bit 31 ("the lowest bit) is the status of the power switch.
 108                          * This bit is "1" if the button is NOT pressed.
 109                          */
 110                         button_not_pressed = (gsc_readl(soft_power_reg) & 0x1);
 111                 } else {
 112                         /*
 113                          * On gecko style machines (e.g. 712/xx and 715/xx)
 114                          * the power switch status is stored in Bit 0 ("the highest bit")
 115                          * of CPU diagnose register 25.
 116                          * Warning: Some machines never reset the DIAG flag, even if
 117                          * the button has been released again.
 118                          */
 119                         button_not_pressed = (__getDIAG(25) & 0x80000000);
 120                 }
 121
 122                 if (likely(button_not_pressed)) {
 123                         if (unlikely(shutdown_timer && /* avoid writing if not necessary */
 124                                 shutdown_timer < (POWERSWITCH_DOWN_SEC*POWERSWITCH_POLL_PER_SEC))) {
 125                                 shutdown_timer = 0;
 126                                 printk(KERN_INFO KTHREAD_NAME ": Shutdown request aborted.\n");
 127                         }
 128                 } else
 129                         process_shutdown();
 130
 131
 132         } while (!kthread_should_stop());
 133
 134         return 0;
 135 }
 136
 137
 138 /*
 139  * powerfail interruption handler (irq IRQ_FROM_REGION(CPU_IRQ_REGION)+2)
 140  */
 141 #if 0
 142 static void powerfail_interrupt(int code, void *x)
 143 {
 144         printk(KERN_CRIT "POWERFAIL INTERRUPTION !\n");
 145         poweroff();
 146 }
 147 #endif
 148
 149
 150
 151
 152 /*
 153  * parisc_panic_event() is called by the panic handler.
 154  *
 155  * As soon as a panic occurs, our tasklets above will not
 156  * be executed any longer. This function then re-enables
 157  * the soft-power switch and allows the user to switch off
 158  * the system. We rely in pdc_soft_power_button_panic()
 159  * since this version spin_trylocks (instead of regular
 160  * spinlock), preventing deadlocks on panic path.
 161  */
 162 static int parisc_panic_event(struct notifier_block *this,
 163                 unsigned long event, void *ptr)
 164 {
 165         /* re-enable the soft-power switch */
 166         pdc_soft_power_button_panic(0);
 167         return NOTIFY_DONE;
 168 }
 169
 170 static struct notifier_block parisc_panic_block = {
 171         .notifier_call  = parisc_panic_event,
 172         .priority       = INT_MAX,
 173 };
 174
 175 /* qemu soft power-off function */
 176 static int qemu_power_off(struct sys_off_data *data)
 177 {
 178         /* this turns the system off via SeaBIOS */
 179         gsc_writel(0, (unsigned long) data->cb_data);
 180         pdc_soft_power_button(1);
 181         return NOTIFY_DONE;
 182 }
 183
 184 static int __init power_init(void)
 185 {
 186         unsigned long ret;
 187         unsigned long soft_power_reg;
 188
 189 #if 0
 190         request_irq( IRQ_FROM_REGION(CPU_IRQ_REGION)+2, &powerfail_interrupt,
 191                 0, "powerfail", NULL);
 192 #endif
 193
 194         /* enable the soft power switch if possible */
 195         ret = pdc_soft_power_info(&soft_power_reg);
 196         if (ret == PDC_OK)
 197                 ret = pdc_soft_power_button(1);
 198         if (ret != PDC_OK)
 199                 soft_power_reg = -1UL;
 200
 201         switch (soft_power_reg) {
 202         case 0:         printk(KERN_INFO DRIVER_NAME ": Gecko-style soft power switch enabled.\n");
 203                         break;
 204
 205         case -1UL:      printk(KERN_INFO DRIVER_NAME ": Soft power switch support not available.\n");
 206                         return -ENODEV;
 207
 208         default:        printk(KERN_INFO DRIVER_NAME ": Soft power switch at 0x%08lx enabled.\n",
 209                                 soft_power_reg);
 210         }
 211
 212         power_task = NULL;
 213         if (running_on_qemu && soft_power_reg)
 214                 register_sys_off_handler(SYS_OFF_MODE_POWER_OFF, SYS_OFF_PRIO_DEFAULT,
 215                                         qemu_power_off, (void *)soft_power_reg);
 216         if (!running_on_qemu || soft_power_reg)
 217                 power_task = kthread_run(kpowerswd, (void*)soft_power_reg,
 218                                         KTHREAD_NAME);
 219         if (IS_ERR(power_task)) {
 220                 printk(KERN_ERR DRIVER_NAME ": thread creation failed.  Driver not loaded.\n");
 221                 pdc_soft_power_button(0);
 222                 return -EIO;
 223         }
 224
 225         /* Register a call for panic conditions. */
 226         atomic_notifier_chain_register(&panic_notifier_list,
 227                         &parisc_panic_block);
 228
 229         return 0;
 230 }
 231
 232 static void __exit power_exit(void)
 233 {
 234         kthread_stop(power_task);
 235
 236         atomic_notifier_chain_unregister(&panic_notifier_list,
 237                         &parisc_panic_block);
 238
 239         pdc_soft_power_button(0);
 240 }
 241
 242 arch_initcall(power_init);
 243 module_exit(power_exit);
 244
 245
 246 MODULE_AUTHOR("Helge Deller <deller@gmx.de>");
 247 MODULE_DESCRIPTION("Soft power switch driver");
 248 MODULE_LICENSE("Dual BSD/GPL");