arch/powerpc/kernel/irq.c

/*
 *  Derived from arch/i386/kernel/irq.c
 *    Copyright (C) 1992 Linus Torvalds
 *  Adapted from arch/i386 by Gary Thomas
 *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
 *  Updated and modified by Cort Dougan <cort@fsmlabs.com>
 *    Copyright (C) 1996-2001 Cort Dougan
 *  Adapted for Power Macintosh by Paul Mackerras
 *    Copyright (C) 1996 Paul Mackerras (paulus@cs.anu.edu.au)
 *
 * 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.
 *
 * This file contains the code used by various IRQ handling routines:
 * asking for different IRQ's should be done through these routines
 * instead of just grabbing them. Thus setups with different IRQ numbers
 * shouldn't result in any weird surprises, and installing new handlers
 * should be easier.
 *
 * The MPC8xx has an interrupt mask in the SIU.  If a bit is set, the
 * interrupt is _enabled_.  As expected, IRQ0 is bit 0 in the 32-bit
 * mask register (of which only 16 are defined), hence the weird shifting
 * and complement of the cached_irq_mask.  I want to be able to stuff
 * this right into the SIU SMASK register.
 * Many of the prep/chrp functions are conditional compiled on CONFIG_8xx
 * to reduce code space and undefined function references.
 */

#undef DEBUG

#include <linux/export.h>
#include <linux/threads.h>
#include <linux/kernel_stat.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/ptrace.h>
#include <linux/ioport.h>
#include <linux/interrupt.h>
#include <linux/timex.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include <linux/irq.h>
#include <linux/seq_file.h>
#include <linux/cpumask.h>
#include <linux/profile.h>
#include <linux/bitops.h>
#include <linux/list.h>
#include <linux/radix-tree.h>
#include <linux/mutex.h>
#include <linux/bootmem.h>
#include <linux/pci.h>
#include <linux/debugfs.h>
#include <linux/of.h>
#include <linux/of_irq.h>

#include <asm/uaccess.h>
#include <asm/system.h>
#include <asm/io.h>
#include <asm/pgtable.h>
#include <asm/irq.h>
#include <asm/cache.h>
#include <asm/prom.h>
#include <asm/ptrace.h>
#include <asm/machdep.h>
#include <asm/udbg.h>
#include <asm/smp.h>

#ifdef CONFIG_PPC64
#include <asm/paca.h>
#include <asm/firmware.h>
#include <asm/lv1call.h>
#endif
#define CREATE_TRACE_POINTS
#include <asm/trace.h>

DEFINE_PER_CPU_SHARED_ALIGNED(irq_cpustat_t, irq_stat);
EXPORT_PER_CPU_SYMBOL(irq_stat);

int __irq_offset_value;

#ifdef CONFIG_PPC32
EXPORT_SYMBOL(__irq_offset_value);
atomic_t ppc_n_lost_interrupts;

#ifdef CONFIG_TAU_INT
extern int tau_initialized;
extern int tau_interrupts(int);
#endif
#endif /* CONFIG_PPC32 */

#ifdef CONFIG_PPC64

#ifndef CONFIG_SPARSE_IRQ
EXPORT_SYMBOL(irq_desc);
#endif

int distribute_irqs = 1;

static inline notrace unsigned long get_hard_enabled(void)
{
	unsigned long enabled;

	__asm__ __volatile__("lbz %0,%1(13)"
	: "=r" (enabled) : "i" (offsetof(struct paca_struct, hard_enabled)));

	return enabled;
}

static inline notrace void set_soft_enabled(unsigned long enable)
{
	__asm__ __volatile__("stb %0,%1(13)"
	: : "r" (enable), "i" (offsetof(struct paca_struct, soft_enabled)));
}

static inline notrace void decrementer_check_overflow(void)
{
	u64 now = get_tb_or_rtc();
	u64 *next_tb;

	preempt_disable();
	next_tb = &__get_cpu_var(decrementers_next_tb);

	if (now >= *next_tb)
		set_dec(1);
	preempt_enable();
}

notrace void arch_local_irq_restore(unsigned long en)
{
	/*
	 * get_paca()->soft_enabled = en;
	 * Is it ever valid to use local_irq_restore(0) when soft_enabled is 1?
	 * That was allowed before, and in such a case we do need to take care
	 * that gcc will set soft_enabled directly via r13, not choose to use
	 * an intermediate register, lest we're preempted to a different cpu.
	 */
	set_soft_enabled(en);
	if (!en)
		return;

#ifdef CONFIG_PPC_STD_MMU_64
	if (firmware_has_feature(FW_FEATURE_ISERIES)) {
		/*
		 * Do we need to disable preemption here?  Not really: in the
		 * unlikely event that we're preempted to a different cpu in
		 * between getting r13, loading its lppaca_ptr, and loading
		 * its any_int, we might call iseries_handle_interrupts without
		 * an interrupt pending on the new cpu, but that's no disaster,
		 * is it?  And the business of preempting us off the old cpu
		 * would itself involve a local_irq_restore which handles the
		 * interrupt to that cpu.
		 *
		 * But use "local_paca->lppaca_ptr" instead of "get_lppaca()"
		 * to avoid any preemption checking added into get_paca().
		 */
		if (local_paca->lppaca_ptr->int_dword.any_int)
			iseries_handle_interrupts();
	}
#endif /* CONFIG_PPC_STD_MMU_64 */

	/*
	 * if (get_paca()->hard_enabled) return;
	 * But again we need to take care that gcc gets hard_enabled directly
	 * via r13, not choose to use an intermediate register, lest we're
	 * preempted to a different cpu in between the two instructions.
	 */
	if (get_hard_enabled())
		return;

	/*
	 * Need to hard-enable interrupts here.  Since currently disabled,
	 * no need to take further asm precautions against preemption; but
	 * use local_paca instead of get_paca() to avoid preemption checking.
	 */
	local_paca->hard_enabled = en;

	/*
	 * Trigger the decrementer if we have a pending event. Some processors
	 * only trigger on edge transitions of the sign bit. We might also
	 * have disabled interrupts long enough that the decrementer wrapped
	 * to positive.
	 */
	decrementer_check_overflow();

	/*
	 * Force the delivery of pending soft-disabled interrupts on PS3.
	 * Any HV call will have this side effect.
	 */
	if (firmware_has_feature(FW_FEATURE_PS3_LV1)) {
		u64 tmp, tmp2;
		lv1_get_version_info(&tmp, &tmp2);
	}

	__hard_irq_enable();
}
EXPORT_SYMBOL(arch_local_irq_restore);
#endif /* CONFIG_PPC64 */

int arch_show_interrupts(struct seq_file *p, int prec)
{
	int j;

#if defined(CONFIG_PPC32) && defined(CONFIG_TAU_INT)
	if (tau_initialized) {
		seq_printf(p, "%*s: ", prec, "TAU");
		for_each_online_cpu(j)
			seq_printf(p, "%10u ", tau_interrupts(j));
		seq_puts(p, "  PowerPC             Thermal Assist (cpu temp)\n");
	}
#endif /* CONFIG_PPC32 && CONFIG_TAU_INT */

	seq_printf(p, "%*s: ", prec, "LOC");
	for_each_online_cpu(j)
		seq_printf(p, "%10u ", per_cpu(irq_stat, j).timer_irqs);
        seq_printf(p, "  Local timer interrupts\n");

	seq_printf(p, "%*s: ", prec, "SPU");
	for_each_online_cpu(j)
		seq_printf(p, "%10u ", per_cpu(irq_stat, j).spurious_irqs);
	seq_printf(p, "  Spurious interrupts\n");

	seq_printf(p, "%*s: ", prec, "CNT");
	for_each_online_cpu(j)
		seq_printf(p, "%10u ", per_cpu(irq_stat, j).pmu_irqs);
	seq_printf(p, "  Performance monitoring interrupts\n");

	seq_printf(p, "%*s: ", prec, "MCE");
	for_each_online_cpu(j)
		seq_printf(p, "%10u ", per_cpu(irq_stat, j).mce_exceptions);
	seq_printf(p, "  Machine check exceptions\n");

	return 0;
}

/*
 * /proc/stat helpers
 */
u64 arch_irq_stat_cpu(unsigned int cpu)
{
	u64 sum = per_cpu(irq_stat, cpu).timer_irqs;

	sum += per_cpu(irq_stat, cpu).pmu_irqs;
	sum += per_cpu(irq_stat, cpu).mce_exceptions;
	sum += per_cpu(irq_stat, cpu).spurious_irqs;

	return sum;
}

#ifdef CONFIG_HOTPLUG_CPU
void migrate_irqs(void)
{
	struct irq_desc *desc;
	unsigned int irq;
	static int warned;
	cpumask_var_t mask;
	const struct cpumask *map = cpu_online_mask;

	alloc_cpumask_var(&mask, GFP_KERNEL);

	for_each_irq(irq) {
		struct irq_data *data;
		struct irq_chip *chip;

		desc = irq_to_desc(irq);
		if (!desc)
			continue;

		data = irq_desc_get_irq_data(desc);
		if (irqd_is_per_cpu(data))
			continue;

		chip = irq_data_get_irq_chip(data);

		cpumask_and(mask, data->affinity, map);
		if (cpumask_any(mask) >= nr_cpu_ids) {
			printk("Breaking affinity for irq %i\n", irq);
			cpumask_copy(mask, map);
		}
		if (chip->irq_set_affinity)
			chip->irq_set_affinity(data, mask, true);
		else if (desc->action && !(warned++))
			printk("Cannot set affinity for irq %i\n", irq);
	}

	free_cpumask_var(mask);

	local_irq_enable();
	mdelay(1);
	local_irq_disable();
}
#endif

static inline void handle_one_irq(unsigned int irq)
{
	struct thread_info *curtp, *irqtp;
	unsigned long saved_sp_limit;
	struct irq_desc *desc;

	desc = irq_to_desc(irq);
	if (!desc)
		return;

	/* Switch to the irq stack to handle this */
	curtp = current_thread_info();
	irqtp = hardirq_ctx[smp_processor_id()];

	if (curtp == irqtp) {
		/* We're already on the irq stack, just handle it */
		desc->handle_irq(irq, desc);
		return;
	}

	saved_sp_limit = current->thread.ksp_limit;

	irqtp->task = curtp->task;
	irqtp->flags = 0;

	/* Copy the softirq bits in preempt_count so that the
	 * softirq checks work in the hardirq context. */
	irqtp->preempt_count = (irqtp->preempt_count & ~SOFTIRQ_MASK) |
			       (curtp->preempt_count & SOFTIRQ_MASK);

	current->thread.ksp_limit = (unsigned long)irqtp +
		_ALIGN_UP(sizeof(struct thread_info), 16);

	call_handle_irq(irq, desc, irqtp, desc->handle_irq);
	current->thread.ksp_limit = saved_sp_limit;
	irqtp->task = NULL;

	/* Set any flag that may have been set on the
	 * alternate stack
	 */
	if (irqtp->flags)
		set_bits(irqtp->flags, &curtp->flags);
}

static inline void check_stack_overflow(void)
{
#ifdef CONFIG_DEBUG_STACKOVERFLOW
	long sp;

	sp = __get_SP() & (THREAD_SIZE-1);

	/* check for stack overflow: is there less than 2KB free? */
	if (unlikely(sp < (sizeof(struct thread_info) + 2048))) {
		printk("do_IRQ: stack overflow: %ld\n",
			sp - sizeof(struct thread_info));
		dump_stack();
	}
#endif
}

void do_IRQ(struct pt_regs *regs)
{
	struct pt_regs *old_regs = set_irq_regs(regs);
	unsigned int irq;

	trace_irq_entry(regs);

	irq_enter();

	check_stack_overflow();

	irq = ppc_md.get_irq();

	if (irq != NO_IRQ && irq != NO_IRQ_IGNORE)
		handle_one_irq(irq);
	else if (irq != NO_IRQ_IGNORE)
		__get_cpu_var(irq_stat).spurious_irqs++;

	irq_exit();
	set_irq_regs(old_regs);

#ifdef CONFIG_PPC_ISERIES
	if (firmware_has_feature(FW_FEATURE_ISERIES) &&
			get_lppaca()->int_dword.fields.decr_int) {
		get_lppaca()->int_dword.fields.decr_int = 0;
		/* Signal a fake decrementer interrupt */
		timer_interrupt(regs);
	}
#endif

	trace_irq_exit(regs);
}

void __init init_IRQ(void)
{
	if (ppc_md.init_IRQ)
		ppc_md.init_IRQ();

	exc_lvl_ctx_init();

	irq_ctx_init();
}

#if defined(CONFIG_BOOKE) || defined(CONFIG_40x)
struct thread_info   *critirq_ctx[NR_CPUS] __read_mostly;
struct thread_info    *dbgirq_ctx[NR_CPUS] __read_mostly;
struct thread_info *mcheckirq_ctx[NR_CPUS] __read_mostly;

void exc_lvl_ctx_init(void)
{
	struct thread_info *tp;
	int i, cpu_nr;

	for_each_possible_cpu(i) {
#ifdef CONFIG_PPC64
		cpu_nr = i;
#else
		cpu_nr = get_hard_smp_processor_id(i);
#endif
		memset((void *)critirq_ctx[cpu_nr], 0, THREAD_SIZE);
		tp = critirq_ctx[cpu_nr];
		tp->cpu = cpu_nr;
		tp->preempt_count = 0;

#ifdef CONFIG_BOOKE
		memset((void *)dbgirq_ctx[cpu_nr], 0, THREAD_SIZE);
		tp = dbgirq_ctx[cpu_nr];
		tp->cpu = cpu_nr;
		tp->preempt_count = 0;

		memset((void *)mcheckirq_ctx[cpu_nr], 0, THREAD_SIZE);
		tp = mcheckirq_ctx[cpu_nr];
		tp->cpu = cpu_nr;
		tp->preempt_count = HARDIRQ_OFFSET;
#endif
	}
}
#endif

struct thread_info *softirq_ctx[NR_CPUS] __read_mostly;
struct thread_info *hardirq_ctx[NR_CPUS] __read_mostly;

void irq_ctx_init(void)
{
	struct thread_info *tp;
	int i;

	for_each_possible_cpu(i) {
		memset((void *)softirq_ctx[i], 0, THREAD_SIZE);
		tp = softirq_ctx[i];
		tp->cpu = i;
		tp->preempt_count = 0;

		memset((void *)hardirq_ctx[i], 0, THREAD_SIZE);
		tp = hardirq_ctx[i];
		tp->cpu = i;
		tp->preempt_count = HARDIRQ_OFFSET;
	}
}

static inline void do_softirq_onstack(void)
{
	struct thread_info *curtp, *irqtp;
	unsigned long saved_sp_limit = current->thread.ksp_limit;

	curtp = current_thread_info();
	irqtp = softirq_ctx[smp_processor_id()];
	irqtp->task = curtp->task;
	irqtp->flags = 0;
	current->thread.ksp_limit = (unsigned long)irqtp +
				    _ALIGN_UP(sizeof(struct thread_info), 16);
	call_do_softirq(irqtp);
	current->thread.ksp_limit = saved_sp_limit;
	irqtp->task = NULL;

	/* Set any flag that may have been set on the
	 * alternate stack
	 */
	if (irqtp->flags)
		set_bits(irqtp->flags, &curtp->flags);
}

void do_softirq(void)
{
	unsigned long flags;

	if (in_interrupt())
		return;

	local_irq_save(flags);

	if (local_softirq_pending())
		do_softirq_onstack();

	local_irq_restore(flags);
}

irq_hw_number_t irqd_to_hwirq(struct irq_data *d)
{
	return d->hwirq;
}
EXPORT_SYMBOL_GPL(irqd_to_hwirq);

irq_hw_number_t virq_to_hw(unsigned int virq)
{
	struct irq_data *irq_data = irq_get_irq_data(virq);
	return WARN_ON(!irq_data) ? 0 : irq_data->hwirq;
}
EXPORT_SYMBOL_GPL(virq_to_hw);

#ifdef CONFIG_SMP
int irq_choose_cpu(const struct cpumask *mask)
{
	int cpuid;

	if (cpumask_equal(mask, cpu_all_mask)) {
		static int irq_rover;
		static DEFINE_RAW_SPINLOCK(irq_rover_lock);
		unsigned long flags;

		/* Round-robin distribution... */
do_round_robin:
		raw_spin_lock_irqsave(&irq_rover_lock, flags);

		irq_rover = cpumask_next(irq_rover, cpu_online_mask);
		if (irq_rover >= nr_cpu_ids)
			irq_rover = cpumask_first(cpu_online_mask);

		cpuid = irq_rover;

		raw_spin_unlock_irqrestore(&irq_rover_lock, flags);
	} else {
		cpuid = cpumask_first_and(mask, cpu_online_mask);
		if (cpuid >= nr_cpu_ids)
			goto do_round_robin;
	}

	return get_hard_smp_processor_id(cpuid);
}
#else
int irq_choose_cpu(const struct cpumask *mask)
{
	return hard_smp_processor_id();
}
#endif

int arch_early_irq_init(void)
{
	return 0;
}

#ifdef CONFIG_PPC64
static int __init setup_noirqdistrib(char *str)
{
	distribute_irqs = 0;
	return 1;
}

__setup("noirqdistrib", setup_noirqdistrib);
#endif /* CONFIG_PPC64 */