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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 <[email protected]>
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 */
54static int shutdown_timer __read_mostly;
55
56/* check, give feedback and start shutdown after one second */
57static 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 */
80static 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 */
86static int pwrsw_enabled __read_mostly = 1;
87
88static const struct ctl_table power_sysctl_table[] = {
89 {
90 .procname = "soft-power",
91 .data = &pwrsw_enabled,
92 .maxlen = sizeof(int),
93 .mode = 0644,
94 .proc_handler = proc_dointvec,
95 },
96};
97
98static int __init init_power_sysctl(void)
99{
100 register_sysctl_init("kernel", power_sysctl_table);
101 return 0;
102}
103
104arch_initcall(init_power_sysctl);
105
106/* main kernel thread worker. It polls the button state */
107static int kpowerswd(void *param)
108{
109 __set_current_state(TASK_RUNNING);
110
111 do {
112 int button_not_pressed;
113 unsigned long soft_power_reg = (unsigned long) param;
114
115 schedule_timeout_interruptible(pwrsw_enabled ? HZ : HZ/POWERSWITCH_POLL_PER_SEC);
116
117 if (unlikely(!pwrsw_enabled))
118 continue;
119
120 if (soft_power_reg) {
121 /*
122 * Non-Gecko-style machines:
123 * Check the power switch status which is read from the
124 * real I/O location at soft_power_reg.
125 * Bit 31 ("the lowest bit) is the status of the power switch.
126 * This bit is "1" if the button is NOT pressed.
127 */
128 button_not_pressed = (gsc_readl(soft_power_reg) & 0x1);
129 } else {
130 /*
131 * On gecko style machines (e.g. 712/xx and 715/xx)
132 * the power switch status is stored in Bit 0 ("the highest bit")
133 * of CPU diagnose register 25.
134 * Warning: Some machines never reset the DIAG flag, even if
135 * the button has been released again.
136 */
137 button_not_pressed = (__getDIAG(25) & 0x80000000);
138 }
139
140 if (likely(button_not_pressed)) {
141 if (unlikely(shutdown_timer && /* avoid writing if not necessary */
142 shutdown_timer < (POWERSWITCH_DOWN_SEC*POWERSWITCH_POLL_PER_SEC))) {
143 shutdown_timer = 0;
144 printk(KERN_INFO KTHREAD_NAME ": Shutdown request aborted.\n");
145 }
146 } else
147 process_shutdown();
148
149
150 } while (!kthread_should_stop());
151
152 return 0;
153}
154
155
156/*
157 * powerfail interruption handler (irq IRQ_FROM_REGION(CPU_IRQ_REGION)+2)
158 */
159#if 0
160static void powerfail_interrupt(int code, void *x)
161{
162 printk(KERN_CRIT "POWERFAIL INTERRUPTION !\n");
163 poweroff();
164}
165#endif
166
167
168
169
170/*
171 * parisc_panic_event() is called by the panic handler.
172 *
173 * As soon as a panic occurs, our tasklets above will not
174 * be executed any longer. This function then re-enables
175 * the soft-power switch and allows the user to switch off
176 * the system. We rely in pdc_soft_power_button_panic()
177 * since this version spin_trylocks (instead of regular
178 * spinlock), preventing deadlocks on panic path.
179 */
180static int parisc_panic_event(struct notifier_block *this,
181 unsigned long event, void *ptr)
182{
183 /* re-enable the soft-power switch */
184 pdc_soft_power_button_panic(0);
185 return NOTIFY_DONE;
186}
187
188static struct notifier_block parisc_panic_block = {
189 .notifier_call = parisc_panic_event,
190 .priority = INT_MAX,
191};
192
193/* qemu soft power-off function */
194static int qemu_power_off(struct sys_off_data *data)
195{
196 /* this turns the system off via SeaBIOS */
197 gsc_writel(0, (unsigned long) data->cb_data);
198 pdc_soft_power_button(1);
199 return NOTIFY_DONE;
200}
201
202static int __init power_init(void)
203{
204 unsigned long ret;
205 unsigned long soft_power_reg;
206
207#if 0
208 request_irq( IRQ_FROM_REGION(CPU_IRQ_REGION)+2, &powerfail_interrupt,
209 0, "powerfail", NULL);
210#endif
211
212 /* enable the soft power switch if possible */
213 ret = pdc_soft_power_info(&soft_power_reg);
214 if (ret == PDC_OK)
215 ret = pdc_soft_power_button(1);
216 if (ret != PDC_OK)
217 soft_power_reg = -1UL;
218
219 switch (soft_power_reg) {
220 case 0: printk(KERN_INFO DRIVER_NAME ": Gecko-style soft power switch enabled.\n");
221 break;
222
223 case -1UL: printk(KERN_INFO DRIVER_NAME ": Soft power switch support not available.\n");
224 return -ENODEV;
225
226 default: printk(KERN_INFO DRIVER_NAME ": Soft power switch at 0x%08lx enabled.\n",
227 soft_power_reg);
228 }
229
230 power_task = NULL;
231 if (running_on_qemu && soft_power_reg)
232 register_sys_off_handler(SYS_OFF_MODE_POWER_OFF, SYS_OFF_PRIO_DEFAULT,
233 qemu_power_off, (void *)soft_power_reg);
234 if (!running_on_qemu || soft_power_reg)
235 power_task = kthread_run(kpowerswd, (void*)soft_power_reg,
236 KTHREAD_NAME);
237 if (IS_ERR(power_task)) {
238 printk(KERN_ERR DRIVER_NAME ": thread creation failed. Driver not loaded.\n");
239 pdc_soft_power_button(0);
240 return -EIO;
241 }
242
243 /* Register a call for panic conditions. */
244 atomic_notifier_chain_register(&panic_notifier_list,
245 &parisc_panic_block);
246
247 return 0;
248}
249
250static void __exit power_exit(void)
251{
252 kthread_stop(power_task);
253
254 atomic_notifier_chain_unregister(&panic_notifier_list,
255 &parisc_panic_block);
256
257 pdc_soft_power_button(0);
258}
259
260arch_initcall(power_init);
261module_exit(power_exit);
262
263
264MODULE_AUTHOR("Helge Deller <[email protected]>");
265MODULE_DESCRIPTION("Soft power switch driver");
266MODULE_LICENSE("Dual BSD/GPL");