![David Howells](/assets/img/avatar_default.png)
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)
175 lines
4.5 KiB
C
175 lines
4.5 KiB
C
/*
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* $Id: amijoy.c,v 1.13 2002/01/22 20:26:32 vojtech Exp $
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*
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* Copyright (c) 1998-2001 Vojtech Pavlik
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*/
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/*
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* Driver for Amiga joysticks for Linux/m68k
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*/
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/*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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* Should you need to contact me, the author, you can do so either by
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* e-mail - mail your message to <vojtech@ucw.cz>, or by paper mail:
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* Vojtech Pavlik, Simunkova 1594, Prague 8, 182 00 Czech Republic
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*/
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#include <linux/types.h>
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#include <linux/errno.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/init.h>
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#include <linux/input.h>
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#include <linux/interrupt.h>
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#include <linux/mutex.h>
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#include <asm/system.h>
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#include <asm/amigahw.h>
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#include <asm/amigaints.h>
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MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
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MODULE_DESCRIPTION("Driver for Amiga joysticks");
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MODULE_LICENSE("GPL");
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static int amijoy[2] = { 0, 1 };
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module_param_array_named(map, amijoy, uint, NULL, 0);
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MODULE_PARM_DESC(map, "Map of attached joysticks in form of <a>,<b> (default is 0,1)");
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__obsolete_setup("amijoy=");
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static int amijoy_used;
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static DEFINE_MUTEX(amijoy_mutex);
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static struct input_dev *amijoy_dev[2];
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static char *amijoy_phys[2] = { "amijoy/input0", "amijoy/input1" };
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static irqreturn_t amijoy_interrupt(int irq, void *dummy)
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{
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int i, data = 0, button = 0;
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for (i = 0; i < 2; i++)
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if (amijoy[i]) {
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switch (i) {
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case 0: data = ~amiga_custom.joy0dat; button = (~ciaa.pra >> 6) & 1; break;
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case 1: data = ~amiga_custom.joy1dat; button = (~ciaa.pra >> 7) & 1; break;
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}
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input_report_key(amijoy_dev[i], BTN_TRIGGER, button);
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input_report_abs(amijoy_dev[i], ABS_X, ((data >> 1) & 1) - ((data >> 9) & 1));
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data = ~(data ^ (data << 1));
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input_report_abs(amijoy_dev[i], ABS_Y, ((data >> 1) & 1) - ((data >> 9) & 1));
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input_sync(amijoy_dev[i]);
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}
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return IRQ_HANDLED;
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}
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static int amijoy_open(struct input_dev *dev)
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{
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int err;
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err = mutex_lock_interruptible(&amijoy_mutex);
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if (err)
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return err;
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if (!amijoy_used && request_irq(IRQ_AMIGA_VERTB, amijoy_interrupt, 0, "amijoy", amijoy_interrupt)) {
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printk(KERN_ERR "amijoy.c: Can't allocate irq %d\n", IRQ_AMIGA_VERTB);
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err = -EBUSY;
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goto out;
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}
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amijoy_used++;
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out:
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mutex_unlock(&amijoy_mutex);
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return err;
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}
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static void amijoy_close(struct input_dev *dev)
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{
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mutex_lock(&amijoy_mutex);
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if (!--amijoy_used)
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free_irq(IRQ_AMIGA_VERTB, amijoy_interrupt);
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mutex_unlock(&amijoy_mutex);
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}
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static int __init amijoy_init(void)
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{
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int i, j;
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int err;
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for (i = 0; i < 2; i++) {
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if (!amijoy[i])
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continue;
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amijoy_dev[i] = input_allocate_device();
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if (!amijoy_dev[i]) {
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err = -ENOMEM;
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goto fail;
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}
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if (!request_mem_region(CUSTOM_PHYSADDR + 10 + i * 2, 2, "amijoy [Denise]")) {
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input_free_device(amijoy_dev[i]);
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err = -EBUSY;
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goto fail;
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}
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amijoy_dev[i]->name = "Amiga joystick";
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amijoy_dev[i]->phys = amijoy_phys[i];
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amijoy_dev[i]->id.bustype = BUS_AMIGA;
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amijoy_dev[i]->id.vendor = 0x0001;
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amijoy_dev[i]->id.product = 0x0003;
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amijoy_dev[i]->id.version = 0x0100;
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amijoy_dev[i]->open = amijoy_open;
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amijoy_dev[i]->close = amijoy_close;
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amijoy_dev[i]->evbit[0] = BIT(EV_KEY) | BIT(EV_ABS);
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amijoy_dev[i]->absbit[0] = BIT(ABS_X) | BIT(ABS_Y);
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amijoy_dev[i]->keybit[LONG(BTN_LEFT)] = BIT(BTN_LEFT) | BIT(BTN_MIDDLE) | BIT(BTN_RIGHT);
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for (j = 0; j < 2; j++) {
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amijoy_dev[i]->absmin[ABS_X + j] = -1;
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amijoy_dev[i]->absmax[ABS_X + j] = 1;
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}
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input_register_device(amijoy_dev[i]);
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}
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return 0;
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fail: while (--i >= 0)
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if (amijoy[i]) {
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input_unregister_device(amijoy_dev[i]);
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release_mem_region(CUSTOM_PHYSADDR + 10 + i * 2, 2);
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}
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return err;
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}
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static void __exit amijoy_exit(void)
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{
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int i;
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for (i = 0; i < 2; i++)
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if (amijoy[i]) {
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input_unregister_device(amijoy_dev[i]);
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release_mem_region(CUSTOM_PHYSADDR + 10 + i * 2, 2);
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}
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}
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module_init(amijoy_init);
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module_exit(amijoy_exit);
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