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/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* HP PARISC soft power switch driver
*
* Copyright (c) 2001-2023 Helge Deller <deller@gmx.de>
*
* HINT:
* Support of the soft power switch button may be enabled or disabled at
* runtime through the "/proc/sys/kernel/power" procfs entry.
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/panic_notifier.h>
#include <linux/reboot.h>
#include <linux/sched/signal.h>
#include <linux/kthread.h>
#include <linux/pm.h>
#include <asm/pdc.h>
#include <asm/io.h>
#include <asm/led.h>
#define DRIVER_NAME "powersw"
#define KTHREAD_NAME "kpowerswd"
/* how often should the power button be polled ? */
#define POWERSWITCH_POLL_PER_SEC 2
/* how long does the power button needs to be down until we react ? */
#define POWERSWITCH_DOWN_SEC 2
/* assembly code to access special registers */
/* taken from PCXL ERS page 82 */
#define DIAG_CODE(code) (0x14000000 + ((code)<<5))
#define MFCPU_X(rDiagReg, t_ch, t_th, code) \
(DIAG_CODE(code) + ((rDiagReg)<<21) + ((t_ch)<<16) + ((t_th)<<0) )
#define MTCPU(dr, gr) MFCPU_X(dr, gr, 0, 0x12) /* move value of gr to dr[dr] */
#define MFCPU_C(dr, gr) MFCPU_X(dr, gr, 0, 0x30) /* for dr0 and dr8 only ! */
#define MFCPU_T(dr, gr) MFCPU_X(dr, 0, gr, 0xa0) /* all dr except dr0 and dr8 */
#define __getDIAG(dr) ( { \
register unsigned long __res asm("r28");\
__asm__ __volatile__ ( \
".word %1" : "=&r" (__res) : "i" (MFCPU_T(dr,28) ) \
); \
__res; \
} )
/* local shutdown counter */
static int shutdown_timer __read_mostly;
/* check, give feedback and start shutdown after one second */
static void process_shutdown(void)
{
if (shutdown_timer == 0)
printk(KERN_ALERT KTHREAD_NAME ": Shutdown requested...\n");
shutdown_timer++;
/* wait until the button was pressed for 1 second */
if (shutdown_timer == (POWERSWITCH_DOWN_SEC*POWERSWITCH_POLL_PER_SEC)) {
static const char msg[] = "Shutting down...";
printk(KERN_INFO KTHREAD_NAME ": %s\n", msg);
lcd_print(msg);
/* send kill signal */
if (kill_cad_pid(SIGINT, 1)) {
/* just in case killing init process failed */
machine_power_off();
}
}
}
/* main power switch task struct */
static struct task_struct *power_task;
/* filename in /proc which can be used to enable/disable the power switch */
#define SYSCTL_FILENAME "sys/kernel/power"
/* soft power switch enabled/disabled */
int pwrsw_enabled __read_mostly = 1;
/* main kernel thread worker. It polls the button state */
static int kpowerswd(void *param)
{
__set_current_state(TASK_RUNNING);
do {
int button_not_pressed;
unsigned long soft_power_reg = (unsigned long) param;
schedule_timeout_interruptible(pwrsw_enabled ? HZ : HZ/POWERSWITCH_POLL_PER_SEC);
if (unlikely(!pwrsw_enabled))
continue;
if (soft_power_reg) {
/*
* Non-Gecko-style machines:
* Check the power switch status which is read from the
* real I/O location at soft_power_reg.
* Bit 31 ("the lowest bit) is the status of the power switch.
* This bit is "1" if the button is NOT pressed.
*/
button_not_pressed = (gsc_readl(soft_power_reg) & 0x1);
} else {
/*
* On gecko style machines (e.g. 712/xx and 715/xx)
* the power switch status is stored in Bit 0 ("the highest bit")
* of CPU diagnose register 25.
* Warning: Some machines never reset the DIAG flag, even if
* the button has been released again.
*/
button_not_pressed = (__getDIAG(25) & 0x80000000);
}
if (likely(button_not_pressed)) {
if (unlikely(shutdown_timer && /* avoid writing if not necessary */
shutdown_timer < (POWERSWITCH_DOWN_SEC*POWERSWITCH_POLL_PER_SEC))) {
shutdown_timer = 0;
printk(KERN_INFO KTHREAD_NAME ": Shutdown request aborted.\n");
}
} else
process_shutdown();
} while (!kthread_should_stop());
return 0;
}
/*
* powerfail interruption handler (irq IRQ_FROM_REGION(CPU_IRQ_REGION)+2)
*/
#if 0
static void powerfail_interrupt(int code, void *x)
{
printk(KERN_CRIT "POWERFAIL INTERRUPTION !\n");
poweroff();
}
#endif
/*
* parisc_panic_event() is called by the panic handler.
*
* As soon as a panic occurs, our tasklets above will not
* be executed any longer. This function then re-enables
* the soft-power switch and allows the user to switch off
* the system. We rely in pdc_soft_power_button_panic()
* since this version spin_trylocks (instead of regular
* spinlock), preventing deadlocks on panic path.
*/
static int parisc_panic_event(struct notifier_block *this,
unsigned long event, void *ptr)
{
/* re-enable the soft-power switch */
pdc_soft_power_button_panic(0);
return NOTIFY_DONE;
}
static struct notifier_block parisc_panic_block = {
.notifier_call = parisc_panic_event,
.priority = INT_MAX,
};
/* qemu soft power-off function */
static int qemu_power_off(struct sys_off_data *data)
{
/* this turns the system off via SeaBIOS */
gsc_writel(0, (unsigned long) data->cb_data);
pdc_soft_power_button(1);
return NOTIFY_DONE;
}
static int __init power_init(void)
{
unsigned long ret;
unsigned long soft_power_reg;
#if 0
request_irq( IRQ_FROM_REGION(CPU_IRQ_REGION)+2, &powerfail_interrupt,
0, "powerfail", NULL);
#endif
/* enable the soft power switch if possible */
ret = pdc_soft_power_info(&soft_power_reg);
if (ret == PDC_OK)
ret = pdc_soft_power_button(1);
if (ret != PDC_OK)
soft_power_reg = -1UL;
switch (soft_power_reg) {
case 0: printk(KERN_INFO DRIVER_NAME ": Gecko-style soft power switch enabled.\n");
break;
case -1UL: printk(KERN_INFO DRIVER_NAME ": Soft power switch support not available.\n");
return -ENODEV;
default: printk(KERN_INFO DRIVER_NAME ": Soft power switch at 0x%08lx enabled.\n",
soft_power_reg);
}
power_task = NULL;
if (running_on_qemu && soft_power_reg)
register_sys_off_handler(SYS_OFF_MODE_POWER_OFF, SYS_OFF_PRIO_DEFAULT,
qemu_power_off, (void *)soft_power_reg);
else
power_task = kthread_run(kpowerswd, (void*)soft_power_reg,
KTHREAD_NAME);
if (IS_ERR(power_task)) {
printk(KERN_ERR DRIVER_NAME ": thread creation failed. Driver not loaded.\n");
pdc_soft_power_button(0);
return -EIO;
}
/* Register a call for panic conditions. */
atomic_notifier_chain_register(&panic_notifier_list,
&parisc_panic_block);
return 0;
}
static void __exit power_exit(void)
{
kthread_stop(power_task);
atomic_notifier_chain_unregister(&panic_notifier_list,
&parisc_panic_block);
pdc_soft_power_button(0);
}
arch_initcall(power_init);
module_exit(power_exit);
MODULE_AUTHOR("Helge Deller <deller@gmx.de>");
MODULE_DESCRIPTION("Soft power switch driver");
MODULE_LICENSE("Dual BSD/GPL");
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