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linux-kernel-test/arch/mips/sgi-ip22/ip22-reset.c
David Howells 7d12e780e0 IRQ: Maintain regs pointer globally rather than passing to IRQ handlers 
Maintain a per-CPU global "struct pt_regs *" variable which can be used instead
of passing regs around manually through all ~1800 interrupt handlers in the
Linux kernel.

The regs pointer is used in few places, but it potentially costs both stack
space and code to pass it around.  On the FRV arch, removing the regs parameter
from all the genirq function results in a 20% speed up of the IRQ exit path
(ie: from leaving timer_interrupt() to leaving do_IRQ()).

Where appropriate, an arch may override the generic storage facility and do
something different with the variable.  On FRV, for instance, the address is
maintained in GR28 at all times inside the kernel as part of general exception
handling.

Having looked over the code, it appears that the parameter may be handed down
through up to twenty or so layers of functions.  Consider a USB character
device attached to a USB hub, attached to a USB controller that posts its
interrupts through a cascaded auxiliary interrupt controller.  A character
device driver may want to pass regs to the sysrq handler through the input
layer which adds another few layers of parameter passing.

I've build this code with allyesconfig for x86_64 and i386.  I've runtested the
main part of the code on FRV and i386, though I can't test most of the drivers.
I've also done partial conversion for powerpc and MIPS - these at least compile
with minimal configurations.

This will affect all archs.  Mostly the changes should be relatively easy.
Take do_IRQ(), store the regs pointer at the beginning, saving the old one:

	struct pt_regs *old_regs = set_irq_regs(regs);

And put the old one back at the end:

	set_irq_regs(old_regs);

Don't pass regs through to generic_handle_irq() or __do_IRQ().

In timer_interrupt(), this sort of change will be necessary:

	-	update_process_times(user_mode(regs));
	-	profile_tick(CPU_PROFILING, regs);
	+	update_process_times(user_mode(get_irq_regs()));
	+	profile_tick(CPU_PROFILING);

I'd like to move update_process_times()'s use of get_irq_regs() into itself,
except that i386, alone of the archs, uses something other than user_mode().

Some notes on the interrupt handling in the drivers:

 (*) input_dev() is now gone entirely.  The regs pointer is no longer stored in
     the input_dev struct.

 (*) finish_unlinks() in drivers/usb/host/ohci-q.c needs checking.  It does
     something different depending on whether it's been supplied with a regs
     pointer or not.

 (*) Various IRQ handler function pointers have been moved to type
     irq_handler_t.

Signed-Off-By: David Howells <dhowells@redhat.com>
(cherry picked from 1b16e7ac850969f38b375e511e3fa2f474a33867 commit)
2006-10-05 15:10:12 +01:00

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/*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 1997, 1998, 2001, 03, 05, 06 by Ralf Baechle
*/
#include <linux/linkage.h>
#include <linux/init.h>
#include <linux/ds1286.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/notifier.h>
#include <linux/pm.h>
#include <linux/timer.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/system.h>
#include <asm/reboot.h>
#include <asm/sgialib.h>
#include <asm/sgi/ioc.h>
#include <asm/sgi/hpc3.h>
#include <asm/sgi/mc.h>
#include <asm/sgi/ip22.h>
/*
* Just powerdown if init hasn't done after POWERDOWN_TIMEOUT seconds.
* I'm not sure if this feature is a good idea, for now it's here just to
* make the power button make behave just like under IRIX.
*/
#define POWERDOWN_TIMEOUT 120
/*
* Blink frequency during reboot grace period and when panicked.
*/
#define POWERDOWN_FREQ (HZ / 4)
#define PANIC_FREQ (HZ / 8)
static struct timer_list power_timer, blink_timer, debounce_timer, volume_timer;
#define MACHINE_PANICED 1
#define MACHINE_SHUTTING_DOWN 2
static int machine_state;
static void ATTRIB_NORET sgi_machine_power_off(void)
{
unsigned int tmp;
local_irq_disable();
/* Disable watchdog */
tmp = hpc3c0->rtcregs[RTC_CMD] & 0xff;
hpc3c0->rtcregs[RTC_CMD] = tmp | RTC_WAM;
hpc3c0->rtcregs[RTC_WSEC] = 0;
hpc3c0->rtcregs[RTC_WHSEC] = 0;
while (1) {
sgioc->panel = ~SGIOC_PANEL_POWERON;
/* Good bye cruel world ... */
/* If we're still running, we probably got sent an alarm
interrupt. Read the flag to clear it. */
tmp = hpc3c0->rtcregs[RTC_HOURS_ALARM];
}
}
static void ATTRIB_NORET sgi_machine_restart(char *command)
{
if (machine_state & MACHINE_SHUTTING_DOWN)
sgi_machine_power_off();
sgimc->cpuctrl0 |= SGIMC_CCTRL0_SYSINIT;
while (1);
}
static void ATTRIB_NORET sgi_machine_halt(void)
{
if (machine_state & MACHINE_SHUTTING_DOWN)
sgi_machine_power_off();
ArcEnterInteractiveMode();
}
static void power_timeout(unsigned long data)
{
sgi_machine_power_off();
}
static void blink_timeout(unsigned long data)
{
/* XXX fix this for fullhouse */
sgi_ioc_reset ^= (SGIOC_RESET_LC0OFF|SGIOC_RESET_LC1OFF);
sgioc->reset = sgi_ioc_reset;
mod_timer(&blink_timer, jiffies + data);
}
static void debounce(unsigned long data)
{
del_timer(&debounce_timer);
if (sgint->istat1 & SGINT_ISTAT1_PWR) {
/* Interrupt still being sent. */
debounce_timer.expires = jiffies + (HZ / 20); /* 0.05s */
add_timer(&debounce_timer);
sgioc->panel = SGIOC_PANEL_POWERON | SGIOC_PANEL_POWERINTR |
SGIOC_PANEL_VOLDNINTR | SGIOC_PANEL_VOLDNHOLD |
SGIOC_PANEL_VOLUPINTR | SGIOC_PANEL_VOLUPHOLD;
return;
}
if (machine_state & MACHINE_PANICED)
sgimc->cpuctrl0 |= SGIMC_CCTRL0_SYSINIT;
enable_irq(SGI_PANEL_IRQ);
}
static inline void power_button(void)
{
if (machine_state & MACHINE_PANICED)
return;
if ((machine_state & MACHINE_SHUTTING_DOWN) ||
kill_cad_pid(SIGINT, 1)) {
/* No init process or button pressed twice. */
sgi_machine_power_off();
}
machine_state |= MACHINE_SHUTTING_DOWN;
blink_timer.data = POWERDOWN_FREQ;
blink_timeout(POWERDOWN_FREQ);
init_timer(&power_timer);
power_timer.function = power_timeout;
power_timer.expires = jiffies + POWERDOWN_TIMEOUT * HZ;
add_timer(&power_timer);
}
void (*indy_volume_button)(int) = NULL;
EXPORT_SYMBOL(indy_volume_button);
static inline void volume_up_button(unsigned long data)
{
del_timer(&volume_timer);
if (indy_volume_button)
indy_volume_button(1);
if (sgint->istat1 & SGINT_ISTAT1_PWR) {
volume_timer.expires = jiffies + (HZ / 100);
add_timer(&volume_timer);
}
}
static inline void volume_down_button(unsigned long data)
{
del_timer(&volume_timer);
if (indy_volume_button)
indy_volume_button(-1);
if (sgint->istat1 & SGINT_ISTAT1_PWR) {
volume_timer.expires = jiffies + (HZ / 100);
add_timer(&volume_timer);
}
}
static irqreturn_t panel_int(int irq, void *dev_id)
{
unsigned int buttons;
buttons = sgioc->panel;
sgioc->panel = SGIOC_PANEL_POWERON | SGIOC_PANEL_POWERINTR;
if (sgint->istat1 & SGINT_ISTAT1_PWR) {
/* Wait until interrupt goes away */
disable_irq(SGI_PANEL_IRQ);
init_timer(&debounce_timer);
debounce_timer.function = debounce;
debounce_timer.expires = jiffies + 5;
add_timer(&debounce_timer);
}
/* Power button was pressed
* ioc.ps page 22: "The Panel Register is called Power Control by Full
* House. Only lowest 2 bits are used. Guiness uses upper four bits
* for volume control". This is not true, all bits are pulled high
* on fullhouse */
if (ip22_is_fullhouse() || !(buttons & SGIOC_PANEL_POWERINTR)) {
power_button();
return IRQ_HANDLED;
}
/* TODO: mute/unmute */
/* Volume up button was pressed */
if (!(buttons & SGIOC_PANEL_VOLUPINTR)) {
init_timer(&volume_timer);
volume_timer.function = volume_up_button;
volume_timer.expires = jiffies + (HZ / 100);
add_timer(&volume_timer);
}
/* Volume down button was pressed */
if (!(buttons & SGIOC_PANEL_VOLDNINTR)) {
init_timer(&volume_timer);
volume_timer.function = volume_down_button;
volume_timer.expires = jiffies + (HZ / 100);
add_timer(&volume_timer);
}
return IRQ_HANDLED;
}
static int panic_event(struct notifier_block *this, unsigned long event,
void *ptr)
{
if (machine_state & MACHINE_PANICED)
return NOTIFY_DONE;
machine_state |= MACHINE_PANICED;
blink_timer.data = PANIC_FREQ;
blink_timeout(PANIC_FREQ);
return NOTIFY_DONE;
}
static struct notifier_block panic_block = {
.notifier_call = panic_event,
};
static int __init reboot_setup(void)
{
_machine_restart = sgi_machine_restart;
_machine_halt = sgi_machine_halt;
pm_power_off = sgi_machine_power_off;
request_irq(SGI_PANEL_IRQ, panel_int, 0, "Front Panel", NULL);
init_timer(&blink_timer);
blink_timer.function = blink_timeout;
atomic_notifier_chain_register(&panic_notifier_list, &panic_block);
return 0;
}
subsys_initcall(reboot_setup);
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