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 else 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"); 249