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linux-next/drivers/ide/legacy/macide.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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/*
* linux/drivers/ide/legacy/macide.c -- Macintosh IDE Driver
*
* Copyright (C) 1998 by Michael Schmitz
*
* This driver was written based on information obtained from the MacOS IDE
* driver binary by Mikael Forselius
*
* 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.
*/
#include <linux/types.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/blkdev.h>
#include <linux/hdreg.h>
#include <linux/delay.h>
#include <linux/ide.h>
#include <asm/machw.h>
#include <asm/macintosh.h>
#include <asm/macints.h>
#include <asm/mac_baboon.h>
#define IDE_BASE 0x50F1A000 /* Base address of IDE controller */
/*
* Generic IDE registers as offsets from the base
* These match MkLinux so they should be correct.
*/
#define IDE_DATA 0x00
#define IDE_ERROR 0x04 /* see err-bits */
#define IDE_NSECTOR 0x08 /* nr of sectors to read/write */
#define IDE_SECTOR 0x0c /* starting sector */
#define IDE_LCYL 0x10 /* starting cylinder */
#define IDE_HCYL 0x14 /* high byte of starting cyl */
#define IDE_SELECT 0x18 /* 101dhhhh , d=drive, hhhh=head */
#define IDE_STATUS 0x1c /* see status-bits */
#define IDE_CONTROL 0x38 /* control/altstatus */
/*
* Mac-specific registers
*/
/*
* this register is odd; it doesn't seem to do much and it's
* not word-aligned like virtually every other hardware register
* on the Mac...
*/
#define IDE_IFR 0x101 /* (0x101) IDE interrupt flags on Quadra:
*
* Bit 0+1: some interrupt flags
* Bit 2+3: some interrupt enable
* Bit 4: ??
* Bit 5: IDE interrupt flag (any hwif)
* Bit 6: maybe IDE interrupt enable (any hwif) ??
* Bit 7: Any interrupt condition
*/
volatile unsigned char *ide_ifr = (unsigned char *) (IDE_BASE + IDE_IFR);
static int macide_offsets[IDE_NR_PORTS] = {
IDE_DATA, IDE_ERROR, IDE_NSECTOR, IDE_SECTOR, IDE_LCYL,
IDE_HCYL, IDE_SELECT, IDE_STATUS, IDE_CONTROL
};
int macide_ack_intr(ide_hwif_t* hwif)
{
if (*ide_ifr & 0x20) {
*ide_ifr &= ~0x20;
return 1;
}
return 0;
}
#ifdef CONFIG_BLK_DEV_MAC_MEDIABAY
static void macide_mediabay_interrupt(int irq, void *dev_id)
{
int state = baboon->mb_status & 0x04;
printk(KERN_INFO "macide: media bay %s detected\n", state? "removal":"insertion");
}
#endif
/*
* Probe for a Macintosh IDE interface
*/
void macide_init(void)
{
hw_regs_t hw;
ide_hwif_t *hwif;
int index = -1;
switch (macintosh_config->ide_type) {
case MAC_IDE_QUADRA:
ide_setup_ports(&hw, IDE_BASE, macide_offsets,
0, 0, macide_ack_intr,
// quadra_ide_iops,
IRQ_NUBUS_F);
index = ide_register_hw(&hw, &hwif);
break;
case MAC_IDE_PB:
ide_setup_ports(&hw, IDE_BASE, macide_offsets,
0, 0, macide_ack_intr,
// macide_pb_iops,
IRQ_NUBUS_C);
index = ide_register_hw(&hw, &hwif);
break;
case MAC_IDE_BABOON:
ide_setup_ports(&hw, BABOON_BASE, macide_offsets,
0, 0, NULL,
// macide_baboon_iops,
IRQ_BABOON_1);
index = ide_register_hw(&hw, &hwif);
if (index == -1) break;
if (macintosh_config->ident == MAC_MODEL_PB190) {
/* Fix breakage in ide-disk.c: drive capacity */
/* is not initialized for drives without a */
/* hardware ID, and we can't get that without */
/* probing the drive which freezes a 190. */
ide_drive_t *drive = &ide_hwifs[index].drives[0];
drive->capacity64 = drive->cyl*drive->head*drive->sect;
#ifdef CONFIG_BLK_DEV_MAC_MEDIABAY
request_irq(IRQ_BABOON_2, macide_mediabay_interrupt,
IRQ_FLG_FAST, "mediabay",
macide_mediabay_interrupt);
#endif
}
break;
default:
return;
}
if (index != -1) {
hwif->mmio = 2;
if (macintosh_config->ide_type == MAC_IDE_QUADRA)
printk(KERN_INFO "ide%d: Macintosh Quadra IDE interface\n", index);
else if (macintosh_config->ide_type == MAC_IDE_PB)
printk(KERN_INFO "ide%d: Macintosh Powerbook IDE interface\n", index);
else if (macintosh_config->ide_type == MAC_IDE_BABOON)
printk(KERN_INFO "ide%d: Macintosh Powerbook Baboon IDE interface\n", index);
else
printk(KERN_INFO "ide%d: Unknown Macintosh IDE interface\n", index);
}
}
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