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![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)
253 lines
5.8 KiB
C
253 lines
5.8 KiB
C
/*
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* Interrupt management for most GSC and related devices.
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*
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* (c) Copyright 1999 Alex deVries for The Puffin Group
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* (c) Copyright 1999 Grant Grundler for Hewlett-Packard
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* (c) Copyright 1999 Matthew Wilcox
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* (c) Copyright 2000 Helge Deller
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* (c) Copyright 2001 Matthew Wilcox for Hewlett-Packard
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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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#include <linux/bitops.h>
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#include <linux/errno.h>
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#include <linux/init.h>
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#include <linux/interrupt.h>
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#include <linux/ioport.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/types.h>
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#include <asm/hardware.h>
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#include <asm/io.h>
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#include "gsc.h"
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#undef DEBUG
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#ifdef DEBUG
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#define DEBPRINTK printk
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#else
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#define DEBPRINTK(x,...)
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#endif
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int gsc_alloc_irq(struct gsc_irq *i)
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{
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int irq = txn_alloc_irq(GSC_EIM_WIDTH);
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if (irq < 0) {
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printk("cannot get irq\n");
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return irq;
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}
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i->txn_addr = txn_alloc_addr(irq);
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i->txn_data = txn_alloc_data(irq);
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i->irq = irq;
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return irq;
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}
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int gsc_claim_irq(struct gsc_irq *i, int irq)
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{
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int c = irq;
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irq += CPU_IRQ_BASE; /* virtualize the IRQ first */
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irq = txn_claim_irq(irq);
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if (irq < 0) {
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printk("cannot claim irq %d\n", c);
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return irq;
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}
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i->txn_addr = txn_alloc_addr(irq);
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i->txn_data = txn_alloc_data(irq);
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i->irq = irq;
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return irq;
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}
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EXPORT_SYMBOL(gsc_alloc_irq);
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EXPORT_SYMBOL(gsc_claim_irq);
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/* Common interrupt demultiplexer used by Asp, Lasi & Wax. */
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irqreturn_t gsc_asic_intr(int gsc_asic_irq, void *dev)
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{
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unsigned long irr;
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struct gsc_asic *gsc_asic = dev;
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irr = gsc_readl(gsc_asic->hpa + OFFSET_IRR);
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if (irr == 0)
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return IRQ_NONE;
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DEBPRINTK("%s intr, mask=0x%x\n", gsc_asic->name, irr);
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do {
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int local_irq = __ffs(irr);
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unsigned int irq = gsc_asic->global_irq[local_irq];
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__do_IRQ(irq);
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irr &= ~(1 << local_irq);
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} while (irr);
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return IRQ_HANDLED;
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}
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int gsc_find_local_irq(unsigned int irq, int *global_irqs, int limit)
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{
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int local_irq;
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for (local_irq = 0; local_irq < limit; local_irq++) {
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if (global_irqs[local_irq] == irq)
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return local_irq;
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}
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return NO_IRQ;
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}
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static void gsc_asic_disable_irq(unsigned int irq)
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{
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struct gsc_asic *irq_dev = irq_desc[irq].chip_data;
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int local_irq = gsc_find_local_irq(irq, irq_dev->global_irq, 32);
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u32 imr;
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DEBPRINTK(KERN_DEBUG "%s(%d) %s: IMR 0x%x\n", __FUNCTION__, irq,
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irq_dev->name, imr);
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/* Disable the IRQ line by clearing the bit in the IMR */
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imr = gsc_readl(irq_dev->hpa + OFFSET_IMR);
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imr &= ~(1 << local_irq);
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gsc_writel(imr, irq_dev->hpa + OFFSET_IMR);
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}
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static void gsc_asic_enable_irq(unsigned int irq)
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{
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struct gsc_asic *irq_dev = irq_desc[irq].chip_data;
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int local_irq = gsc_find_local_irq(irq, irq_dev->global_irq, 32);
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u32 imr;
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DEBPRINTK(KERN_DEBUG "%s(%d) %s: IMR 0x%x\n", __FUNCTION__, irq,
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irq_dev->name, imr);
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/* Enable the IRQ line by setting the bit in the IMR */
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imr = gsc_readl(irq_dev->hpa + OFFSET_IMR);
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imr |= 1 << local_irq;
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gsc_writel(imr, irq_dev->hpa + OFFSET_IMR);
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/*
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* FIXME: read IPR to make sure the IRQ isn't already pending.
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* If so, we need to read IRR and manually call do_irq().
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*/
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}
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static unsigned int gsc_asic_startup_irq(unsigned int irq)
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{
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gsc_asic_enable_irq(irq);
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return 0;
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}
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static struct hw_interrupt_type gsc_asic_interrupt_type = {
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.typename = "GSC-ASIC",
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.startup = gsc_asic_startup_irq,
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.shutdown = gsc_asic_disable_irq,
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.enable = gsc_asic_enable_irq,
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.disable = gsc_asic_disable_irq,
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.ack = no_ack_irq,
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.end = no_end_irq,
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};
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int gsc_assign_irq(struct hw_interrupt_type *type, void *data)
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{
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static int irq = GSC_IRQ_BASE;
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if (irq > GSC_IRQ_MAX)
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return NO_IRQ;
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irq_desc[irq].chip = type;
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irq_desc[irq].chip_data = data;
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return irq++;
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}
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void gsc_asic_assign_irq(struct gsc_asic *asic, int local_irq, int *irqp)
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{
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int irq = asic->global_irq[local_irq];
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if (irq <= 0) {
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irq = gsc_assign_irq(&gsc_asic_interrupt_type, asic);
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if (irq == NO_IRQ)
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return;
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asic->global_irq[local_irq] = irq;
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}
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*irqp = irq;
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}
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static struct device *next_device(struct klist_iter *i)
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{
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struct klist_node * n = klist_next(i);
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return n ? container_of(n, struct device, knode_parent) : NULL;
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}
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void gsc_fixup_irqs(struct parisc_device *parent, void *ctrl,
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void (*choose_irq)(struct parisc_device *, void *))
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{
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struct device *dev;
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struct klist_iter i;
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klist_iter_init(&parent->dev.klist_children, &i);
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while ((dev = next_device(&i))) {
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struct parisc_device *padev = to_parisc_device(dev);
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/* work-around for 715/64 and others which have parent
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at path [5] and children at path [5/0/x] */
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if (padev->id.hw_type == HPHW_FAULTY)
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return gsc_fixup_irqs(padev, ctrl, choose_irq);
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choose_irq(padev, ctrl);
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}
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klist_iter_exit(&i);
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}
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int gsc_common_setup(struct parisc_device *parent, struct gsc_asic *gsc_asic)
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{
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struct resource *res;
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int i;
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gsc_asic->gsc = parent;
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/* Initialise local irq -> global irq mapping */
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for (i = 0; i < 32; i++) {
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gsc_asic->global_irq[i] = NO_IRQ;
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}
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/* allocate resource region */
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res = request_mem_region(gsc_asic->hpa, 0x100000, gsc_asic->name);
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if (res) {
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res->flags = IORESOURCE_MEM; /* do not mark it busy ! */
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}
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#if 0
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printk(KERN_WARNING "%s IRQ %d EIM 0x%x", gsc_asic->name,
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parent->irq, gsc_asic->eim);
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if (gsc_readl(gsc_asic->hpa + OFFSET_IMR))
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printk(" IMR is non-zero! (0x%x)",
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gsc_readl(gsc_asic->hpa + OFFSET_IMR));
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printk("\n");
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#endif
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return 0;
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}
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extern struct parisc_driver lasi_driver;
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extern struct parisc_driver asp_driver;
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extern struct parisc_driver wax_driver;
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void __init gsc_init(void)
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{
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#ifdef CONFIG_GSC_LASI
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register_parisc_driver(&lasi_driver);
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register_parisc_driver(&asp_driver);
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#endif
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#ifdef CONFIG_GSC_WAX
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register_parisc_driver(&wax_driver);
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#endif
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}
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