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   1 /*
   2  * linux/arch/sh/kernel/irq.c
   3  *
   4  *      Copyright (C) 1992, 1998 Linus Torvalds, Ingo Molnar
   5  *
   6  *
   7  * SuperH version:  Copyright (C) 1999  Niibe Yutaka
   8  */
   9 #include <linux/irq.h>
  10 #include <linux/interrupt.h>
  11 #include <linux/module.h>
  12 #include <linux/kernel_stat.h>
  13 #include <linux/seq_file.h>
  14 #include <linux/io.h>
  15 #include <asm/irq.h>
  16 #include <asm/processor.h>
  17 #include <asm/uaccess.h>
  18 #include <asm/thread_info.h>
  19 #include <asm/cpu/mmu_context.h>
  20
  21 atomic_t irq_err_count;
  22
  23 /*
  24  * 'what should we do if we get a hw irq event on an illegal vector'.
  25  * each architecture has to answer this themselves, it doesn't deserve
  26  * a generic callback i think.
  27  */
  28 void ack_bad_irq(unsigned int irq)
  29 {
  30         atomic_inc(&irq_err_count);
  31         printk("unexpected IRQ trap at vector %02x\n", irq);
  32 }
  33
  34 #if defined(CONFIG_PROC_FS)
  35 int show_interrupts(struct seq_file *p, void *v)
  36 {
  37         int i = *(loff_t *) v, j;
  38         struct irqaction * action;
  39         unsigned long flags;
  40
  41         if (i == 0) {
  42                 seq_puts(p, "           ");
  43                 for_each_online_cpu(j)
  44                         seq_printf(p, "CPU%d       ",j);
  45                 seq_putc(p, '\n');
  46         }
  47
  48         if (i < NR_IRQS) {
  49                 spin_lock_irqsave(&irq_desc[i].lock, flags);
  50                 action = irq_desc[i].action;
  51                 if (!action)
  52                         goto unlock;
  53                 seq_printf(p, "%3d: ",i);
  54                 for_each_online_cpu(j)
  55                         seq_printf(p, "%10u ", kstat_cpu(j).irqs[i]);
  56                 seq_printf(p, " %14s", irq_desc[i].chip->name);
  57                 seq_printf(p, "-%s", handle_irq_name(irq_desc[i].handle_irq));
  58                 seq_printf(p, "  %s", action->name);
  59
  60                 for (action=action->next; action; action = action->next)
  61                         seq_printf(p, ", %s", action->name);
  62                 seq_putc(p, '\n');
  63 unlock:
  64                 spin_unlock_irqrestore(&irq_desc[i].lock, flags);
  65         } else if (i == NR_IRQS)
  66                 seq_printf(p, "Err: %10u\n", atomic_read(&irq_err_count));
  67
  68         return 0;
  69 }
  70 #endif
  71
  72 #ifdef CONFIG_4KSTACKS
  73 /*
  74  * per-CPU IRQ handling contexts (thread information and stack)
  75  */
  76 union irq_ctx {
  77         struct thread_info      tinfo;
  78         u32                     stack[THREAD_SIZE/sizeof(u32)];
  79 };
  80
  81 static union irq_ctx *hardirq_ctx[NR_CPUS];
  82 static union irq_ctx *softirq_ctx[NR_CPUS];
  83 #endif
  84
  85 asmlinkage int do_IRQ(unsigned long r4, unsigned long r5,
  86                       unsigned long r6, unsigned long r7,
  87                       struct pt_regs regs)
  88 {
  89         struct pt_regs *old_regs = set_irq_regs(&regs);
  90         int irq;
  91 #ifdef CONFIG_4KSTACKS
  92         union irq_ctx *curctx, *irqctx;
  93 #endif
  94
  95         irq_enter();
  96
  97 #ifdef CONFIG_DEBUG_STACKOVERFLOW
  98         /* Debugging check for stack overflow: is there less than 1KB free? */
  99         {
 100                 long sp;
 101
 102                 __asm__ __volatile__ ("and r15, %0" :
 103                                         "=r" (sp) : "0" (THREAD_SIZE - 1));
 104
 105                 if (unlikely(sp < (sizeof(struct thread_info) + STACK_WARN))) {
 106                         printk("do_IRQ: stack overflow: %ld\n",
 107                                sp - sizeof(struct thread_info));
 108                         dump_stack();
 109                 }
 110         }
 111 #endif
 112
 113 #ifdef CONFIG_CPU_HAS_INTEVT
 114         irq = (ctrl_inl(INTEVT) >> 5) - 16;
 115 #else
 116         irq = r4;
 117 #endif
 118
 119         irq = irq_demux(irq);
 120
 121 #ifdef CONFIG_4KSTACKS
 122         curctx = (union irq_ctx *)current_thread_info();
 123         irqctx = hardirq_ctx[smp_processor_id()];
 124
 125         /*
 126          * this is where we switch to the IRQ stack. However, if we are
 127          * already using the IRQ stack (because we interrupted a hardirq
 128          * handler) we can't do that and just have to keep using the
 129          * current stack (which is the irq stack already after all)
 130          */
 131         if (curctx != irqctx) {
 132                 u32 *isp;
 133
 134                 isp = (u32 *)((char *)irqctx + sizeof(*irqctx));
 135                 irqctx->tinfo.task = curctx->tinfo.task;
 136                 irqctx->tinfo.previous_sp = current_stack_pointer;
 137
 138                 __asm__ __volatile__ (
 139                         "mov    %0, r4          \n"
 140                         "mov    r15, r9         \n"
 141                         "jsr    @%1             \n"
 142                         /* swith to the irq stack */
 143                         " mov   %2, r15         \n"
 144                         /* restore the stack (ring zero) */
 145                         "mov    r9, r15         \n"
 146                         : /* no outputs */
 147                         : "r" (irq), "r" (generic_handle_irq), "r" (isp)
 148                         /* XXX: A somewhat excessive clobber list? -PFM */
 149                         : "memory", "r0", "r1", "r2", "r3", "r4",
 150                           "r5", "r6", "r7", "r8", "t", "pr"
 151                 );
 152         } else
 153 #endif
 154                 generic_handle_irq(irq);
 155
 156         irq_exit();
 157
 158         set_irq_regs(old_regs);
 159         return 1;
 160 }
 161
 162 #ifdef CONFIG_4KSTACKS
 163 /*
 164  * These should really be __section__(".bss.page_aligned") as well, but
 165  * gcc's 3.0 and earlier don't handle that correctly.
 166  */
 167 static char softirq_stack[NR_CPUS * THREAD_SIZE]
 168                 __attribute__((__aligned__(THREAD_SIZE)));
 169
 170 static char hardirq_stack[NR_CPUS * THREAD_SIZE]
 171                 __attribute__((__aligned__(THREAD_SIZE)));
 172
 173 /*
 174  * allocate per-cpu stacks for hardirq and for softirq processing
 175  */
 176 void irq_ctx_init(int cpu)
 177 {
 178         union irq_ctx *irqctx;
 179
 180         if (hardirq_ctx[cpu])
 181                 return;
 182
 183         irqctx = (union irq_ctx *)&hardirq_stack[cpu * THREAD_SIZE];
 184         irqctx->tinfo.task              = NULL;
 185         irqctx->tinfo.exec_domain       = NULL;
 186         irqctx->tinfo.cpu               = cpu;
 187         irqctx->tinfo.preempt_count     = HARDIRQ_OFFSET;
 188         irqctx->tinfo.addr_limit        = MAKE_MM_SEG(0);
 189
 190         hardirq_ctx[cpu] = irqctx;
 191
 192         irqctx = (union irq_ctx *)&softirq_stack[cpu * THREAD_SIZE];
 193         irqctx->tinfo.task              = NULL;
 194         irqctx->tinfo.exec_domain       = NULL;
 195         irqctx->tinfo.cpu               = cpu;
 196         irqctx->tinfo.preempt_count     = SOFTIRQ_OFFSET;
 197         irqctx->tinfo.addr_limit        = MAKE_MM_SEG(0);
 198
 199         softirq_ctx[cpu] = irqctx;
 200
 201         printk("CPU %u irqstacks, hard=%p soft=%p\n",
 202                 cpu, hardirq_ctx[cpu], softirq_ctx[cpu]);
 203 }
 204
 205 void irq_ctx_exit(int cpu)
 206 {
 207         hardirq_ctx[cpu] = NULL;
 208 }
 209
 210 extern asmlinkage void __do_softirq(void);
 211
 212 asmlinkage void do_softirq(void)
 213 {
 214         unsigned long flags;
 215         struct thread_info *curctx;
 216         union irq_ctx *irqctx;
 217         u32 *isp;
 218
 219         if (in_interrupt())
 220                 return;
 221
 222         local_irq_save(flags);
 223
 224         if (local_softirq_pending()) {
 225                 curctx = current_thread_info();
 226                 irqctx = softirq_ctx[smp_processor_id()];
 227                 irqctx->tinfo.task = curctx->task;
 228                 irqctx->tinfo.previous_sp = current_stack_pointer;
 229
 230                 /* build the stack frame on the softirq stack */
 231                 isp = (u32 *)((char *)irqctx + sizeof(*irqctx));
 232
 233                 __asm__ __volatile__ (
 234                         "mov    r15, r9         \n"
 235                         "jsr    @%0             \n"
 236                         /* switch to the softirq stack */
 237                         " mov   %1, r15         \n"
 238                         /* restore the thread stack */
 239                         "mov    r9, r15         \n"
 240                         : /* no outputs */
 241                         : "r" (__do_softirq), "r" (isp)
 242                         /* XXX: A somewhat excessive clobber list? -PFM */
 243                         : "memory", "r0", "r1", "r2", "r3", "r4",
 244                           "r5", "r6", "r7", "r8", "r9", "r15", "t", "pr"
 245                 );
 246         }
 247
 248         local_irq_restore(flags);
 249 }
 250 EXPORT_SYMBOL(do_softirq);
 251 #endif