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linux/arch/frv/kernel/irq-mb93493.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

150 lines
3.6 KiB
C
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/* irq-mb93493.c: MB93493 companion chip interrupt handler
*
* Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/ptrace.h>
#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/ioport.h>
#include <linux/interrupt.h>
#include <linux/init.h>
#include <linux/irq.h>
#include <asm/io.h>
#include <asm/system.h>
#include <asm/bitops.h>
#include <asm/delay.h>
#include <asm/irq.h>
#include <asm/irc-regs.h>
#include <asm/mb93493-irqs.h>
#include <asm/mb93493-regs.h>
#define IRQ_ROUTE_ONE(X) (X##_ROUTE << (X - IRQ_BASE_MB93493))
#define IRQ_ROUTING \
(IRQ_ROUTE_ONE(IRQ_MB93493_VDC) | \
IRQ_ROUTE_ONE(IRQ_MB93493_VCC) | \
IRQ_ROUTE_ONE(IRQ_MB93493_AUDIO_OUT) | \
IRQ_ROUTE_ONE(IRQ_MB93493_I2C_0) | \
IRQ_ROUTE_ONE(IRQ_MB93493_I2C_1) | \
IRQ_ROUTE_ONE(IRQ_MB93493_USB) | \
IRQ_ROUTE_ONE(IRQ_MB93493_LOCAL_BUS) | \
IRQ_ROUTE_ONE(IRQ_MB93493_PCMCIA) | \
IRQ_ROUTE_ONE(IRQ_MB93493_GPIO) | \
IRQ_ROUTE_ONE(IRQ_MB93493_AUDIO_IN))
/*
* daughter board PIC operations
* - there is no way to ACK interrupts in the MB93493 chip
*/
static void frv_mb93493_mask(unsigned int irq)
{
uint32_t iqsr;
volatile void *piqsr;
if (IRQ_ROUTING & (1 << (irq - IRQ_BASE_MB93493)))
piqsr = __addr_MB93493_IQSR(1);
else
piqsr = __addr_MB93493_IQSR(0);
iqsr = readl(piqsr);
iqsr &= ~(1 << (irq - IRQ_BASE_MB93493 + 16));
writel(iqsr, piqsr);
}
static void frv_mb93493_ack(unsigned int irq)
{
}
static void frv_mb93493_unmask(unsigned int irq)
{
uint32_t iqsr;
volatile void *piqsr;
if (IRQ_ROUTING & (1 << (irq - IRQ_BASE_MB93493)))
piqsr = __addr_MB93493_IQSR(1);
else
piqsr = __addr_MB93493_IQSR(0);
iqsr = readl(piqsr);
iqsr |= 1 << (irq - IRQ_BASE_MB93493 + 16);
writel(iqsr, piqsr);
}
static struct irq_chip frv_mb93493_pic = {
.name = "mb93093",
.ack = frv_mb93493_ack,
.mask = frv_mb93493_mask,
.mask_ack = frv_mb93493_mask,
.unmask = frv_mb93493_unmask,
};
/*
* MB93493 PIC interrupt handler
*/
static irqreturn_t mb93493_interrupt(int irq, void *_piqsr)
{
volatile void *piqsr = _piqsr;
uint32_t iqsr;
iqsr = readl(piqsr);
iqsr = iqsr & (iqsr >> 16) & 0xffff;
/* poll all the triggered IRQs */
while (iqsr) {
int irq;
asm("scan %1,gr0,%0" : "=r"(irq) : "r"(iqsr));
irq = 31 - irq;
iqsr &= ~(1 << irq);
generic_handle_irq(IRQ_BASE_MB93493 + irq);
}
return IRQ_HANDLED;
}
/*
* define an interrupt action for each MB93493 PIC output
* - use dev_id to indicate the MB93493 PIC input to output mappings
*/
static struct irqaction mb93493_irq[2] = {
[0] = {
.handler = mb93493_interrupt,
.flags = IRQF_DISABLED | IRQF_SHARED,
.mask = CPU_MASK_NONE,
.name = "mb93493.0",
.dev_id = (void *) __addr_MB93493_IQSR(0),
},
[1] = {
.handler = mb93493_interrupt,
.flags = IRQF_DISABLED | IRQF_SHARED,
.mask = CPU_MASK_NONE,
.name = "mb93493.1",
.dev_id = (void *) __addr_MB93493_IQSR(1),
}
};
/*
* initialise the motherboard MB93493's PIC
*/
void __init mb93493_init(void)
{
int irq;
for (irq = IRQ_BASE_MB93493 + 0; irq <= IRQ_BASE_MB93493 + 10; irq++)
set_irq_chip_and_handler(irq, &frv_mb93493_pic, handle_edge_irq);
/* the MB93493 drives external IRQ inputs on the CPU PIC */
setup_irq(IRQ_CPU_MB93493_0, &mb93493_irq[0]);
setup_irq(IRQ_CPU_MB93493_1, &mb93493_irq[1]);
}
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