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irq.c

/*
 * linux/arch/sh/kernel/irq.c
 *
 *    Copyright (C) 1992, 1998 Linus Torvalds, Ingo Molnar
 *
 *
 * SuperH version:  Copyright (C) 1999  Niibe Yutaka
 */
#include <linux/irq.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/kernel_stat.h>
#include <linux/seq_file.h>
#include <asm/processor.h>
#include <asm/machvec.h>
#include <asm/uaccess.h>
#include <asm/thread_info.h>
#include <asm/cpu/mmu_context.h>

atomic_t irq_err_count;

/*
 * 'what should we do if we get a hw irq event on an illegal vector'.
 * each architecture has to answer this themselves, it doesn't deserve
 * a generic callback i think.
 */
void ack_bad_irq(unsigned int irq)
{
      atomic_inc(&irq_err_count);
      printk("unexpected IRQ trap at vector %02x\n", irq);
}

#if defined(CONFIG_PROC_FS)
int show_interrupts(struct seq_file *p, void *v)
{
      int i = *(loff_t *) v, j;
      struct irqaction * action;
      unsigned long flags;

      if (i == 0) {
            seq_puts(p, "           ");
            for_each_online_cpu(j)
                  seq_printf(p, "CPU%d       ",j);
            seq_putc(p, '\n');
      }

      if (i < sh_mv.mv_nr_irqs) {
            spin_lock_irqsave(&irq_desc[i].lock, flags);
            action = irq_desc[i].action;
            if (!action)
                  goto unlock;
            seq_printf(p, "%3d: ",i);
            for_each_online_cpu(j)
                  seq_printf(p, "%10u ", kstat_cpu(j).irqs[i]);
            seq_printf(p, " %14s", irq_desc[i].chip->name);
            seq_printf(p, "-%-8s", irq_desc[i].name);
            seq_printf(p, "  %s", action->name);

            for (action=action->next; action; action = action->next)
                  seq_printf(p, ", %s", action->name);
            seq_putc(p, '\n');
unlock:
            spin_unlock_irqrestore(&irq_desc[i].lock, flags);
      } else if (i == sh_mv.mv_nr_irqs)
            seq_printf(p, "Err: %10u\n", atomic_read(&irq_err_count));

      return 0;
}
#endif

#ifdef CONFIG_IRQSTACKS
/*
 * per-CPU IRQ handling contexts (thread information and stack)
 */
union irq_ctx {
      struct thread_info      tinfo;
      u32               stack[THREAD_SIZE/sizeof(u32)];
};

static union irq_ctx *hardirq_ctx[NR_CPUS] __read_mostly;
static union irq_ctx *softirq_ctx[NR_CPUS] __read_mostly;
#endif

asmlinkage int do_IRQ(unsigned int irq, struct pt_regs *regs)
{
      struct pt_regs *old_regs = set_irq_regs(regs);
#ifdef CONFIG_IRQSTACKS
      union irq_ctx *curctx, *irqctx;
#endif

      irq_enter();

#ifdef CONFIG_DEBUG_STACKOVERFLOW
      /* Debugging check for stack overflow: is there less than 1KB free? */
      {
            long sp;

            __asm__ __volatile__ ("and r15, %0" :
                              "=r" (sp) : "0" (THREAD_SIZE - 1));

            if (unlikely(sp < (sizeof(struct thread_info) + STACK_WARN))) {
                  printk("do_IRQ: stack overflow: %ld\n",
                         sp - sizeof(struct thread_info));
                  dump_stack();
            }
      }
#endif

      irq = irq_demux(evt2irq(irq));

#ifdef CONFIG_IRQSTACKS
      curctx = (union irq_ctx *)current_thread_info();
      irqctx = hardirq_ctx[smp_processor_id()];

      /*
       * this is where we switch to the IRQ stack. However, if we are
       * already using the IRQ stack (because we interrupted a hardirq
       * handler) we can't do that and just have to keep using the
       * current stack (which is the irq stack already after all)
       */
      if (curctx != irqctx) {
            u32 *isp;

            isp = (u32 *)((char *)irqctx + sizeof(*irqctx));
            irqctx->tinfo.task = curctx->tinfo.task;
            irqctx->tinfo.previous_sp = current_stack_pointer;

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

            __asm__ __volatile__ (
                  "mov  %0, r4            \n"
                  "mov  r15, r8           \n"
                  "jsr  @%1         \n"
                  /* swith to the irq stack */
                  " mov %2, r15           \n"
                  /* restore the stack (ring zero) */
                  "mov  r8, r15           \n"
                  : /* no outputs */
                  : "r" (irq), "r" (generic_handle_irq), "r" (isp)
                  : "memory", "r0", "r1", "r2", "r3", "r4",
                    "r5", "r6", "r7", "r8", "t", "pr"
            );
      } else
#endif
            generic_handle_irq(irq);

      irq_exit();

      set_irq_regs(old_regs);
      return 1;
}

#ifdef CONFIG_IRQSTACKS
static char softirq_stack[NR_CPUS * THREAD_SIZE]
            __attribute__((__section__(".bss.page_aligned")));

static char hardirq_stack[NR_CPUS * THREAD_SIZE]
            __attribute__((__section__(".bss.page_aligned")));

/*
 * allocate per-cpu stacks for hardirq and for softirq processing
 */
void irq_ctx_init(int cpu)
{
      union irq_ctx *irqctx;

      if (hardirq_ctx[cpu])
            return;

      irqctx = (union irq_ctx *)&hardirq_stack[cpu * THREAD_SIZE];
      irqctx->tinfo.task            = NULL;
      irqctx->tinfo.exec_domain     = NULL;
      irqctx->tinfo.cpu       = cpu;
      irqctx->tinfo.preempt_count   = HARDIRQ_OFFSET;
      irqctx->tinfo.addr_limit      = MAKE_MM_SEG(0);

      hardirq_ctx[cpu] = irqctx;

      irqctx = (union irq_ctx *)&softirq_stack[cpu * THREAD_SIZE];
      irqctx->tinfo.task            = NULL;
      irqctx->tinfo.exec_domain     = NULL;
      irqctx->tinfo.cpu       = cpu;
      irqctx->tinfo.preempt_count   = 0;
      irqctx->tinfo.addr_limit      = MAKE_MM_SEG(0);

      softirq_ctx[cpu] = irqctx;

      printk("CPU %u irqstacks, hard=%p soft=%p\n",
            cpu, hardirq_ctx[cpu], softirq_ctx[cpu]);
}

void irq_ctx_exit(int cpu)
{
      hardirq_ctx[cpu] = NULL;
}

extern asmlinkage void __do_softirq(void);

asmlinkage void do_softirq(void)
{
      unsigned long flags;
      struct thread_info *curctx;
      union irq_ctx *irqctx;
      u32 *isp;

      if (in_interrupt())
            return;

      local_irq_save(flags);

      if (local_softirq_pending()) {
            curctx = current_thread_info();
            irqctx = softirq_ctx[smp_processor_id()];
            irqctx->tinfo.task = curctx->task;
            irqctx->tinfo.previous_sp = current_stack_pointer;

            /* build the stack frame on the softirq stack */
            isp = (u32 *)((char *)irqctx + sizeof(*irqctx));

            __asm__ __volatile__ (
                  "mov  r15, r9           \n"
                  "jsr  @%0         \n"
                  /* switch to the softirq stack */
                  " mov %1, r15           \n"
                  /* restore the thread stack */
                  "mov  r9, r15           \n"
                  : /* no outputs */
                  : "r" (__do_softirq), "r" (isp)
                  : "memory", "r0", "r1", "r2", "r3", "r4",
                    "r5", "r6", "r7", "r8", "r9", "r15", "t", "pr"
            );

            /*
             * Shouldnt happen, we returned above if in_interrupt():
             */
            WARN_ON_ONCE(softirq_count());
      }

      local_irq_restore(flags);
}
#endif

void __init init_IRQ(void)
{
#ifdef CONFIG_CPU_HAS_PINT_IRQ
      init_IRQ_pint();
#endif
      plat_irq_setup();

      /* Perform the machine specific initialisation */
      if (sh_mv.mv_init_irq)
            sh_mv.mv_init_irq();

      irq_ctx_init(smp_processor_id());
}

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