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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 <asm/irq.h>
  15 #include <asm/processor.h>
  16 #include <asm/uaccess.h>
  17 #include <asm/thread_info.h>
  18 #include <asm/cpu/mmu_context.h>
  19
  20 /*
  21  * 'what should we do if we get a hw irq event on an illegal vector'.
  22  * each architecture has to answer this themselves, it doesn't deserve
  23  * a generic callback i think.
  24  */
  25 void ack_bad_irq(unsigned int irq)
  26 {
  27         printk("unexpected IRQ trap at vector %02x\n", irq);
  28 }
  29
  30 #if defined(CONFIG_PROC_FS)
  31 int show_interrupts(struct seq_file *p, void *v)
  32 {
  33         int i = *(loff_t *) v, j;
  34         struct irqaction * action;
  35         unsigned long flags;
  36
  37         if (i == 0) {
  38                 seq_puts(p, "           ");
  39                 for_each_online_cpu(j)
  40                         seq_printf(p, "CPU%d       ",j);
  41                 seq_putc(p, '\n');
  42         }
  43
  44         if (i < NR_IRQS) {
  45                 spin_lock_irqsave(&irq_desc[i].lock, flags);
  46                 action = irq_desc[i].action;
  47                 if (!action)
  48                         goto unlock;
  49                 seq_printf(p, "%3d: ",i);
  50                 seq_printf(p, "%10u ", kstat_irqs(i));
  51                 seq_printf(p, " %14s", irq_desc[i].chip->typename);
  52                 seq_printf(p, "  %s", action->name);
  53
  54                 for (action=action->next; action; action = action->next)
  55                         seq_printf(p, ", %s", action->name);
  56                 seq_putc(p, '\n');
  57 unlock:
  58                 spin_unlock_irqrestore(&irq_desc[i].lock, flags);
  59         }
  60         return 0;
  61 }
  62 #endif
  63
  64 #ifdef CONFIG_4KSTACKS
  65 /*
  66  * per-CPU IRQ handling contexts (thread information and stack)
  67  */
  68 union irq_ctx {
  69         struct thread_info      tinfo;
  70         u32                     stack[THREAD_SIZE/sizeof(u32)];
  71 };
  72
  73 static union irq_ctx *hardirq_ctx[NR_CPUS];
  74 static union irq_ctx *softirq_ctx[NR_CPUS];
  75 #endif
  76
  77 asmlinkage int do_IRQ(unsigned long r4, unsigned long r5,
  78                       unsigned long r6, unsigned long r7,
  79                       struct pt_regs regs)
  80 {
  81         int irq = r4;
  82 #ifdef CONFIG_4KSTACKS
  83         union irq_ctx *curctx, *irqctx;
  84 #endif
  85
  86         irq_enter();
  87
  88 #ifdef CONFIG_DEBUG_STACKOVERFLOW
  89         /* Debugging check for stack overflow: is there less than 1KB free? */
  90         {
  91                 long sp;
  92
  93                 __asm__ __volatile__ ("and r15, %0" :
  94                                         "=r" (sp) : "0" (THREAD_SIZE - 1));
  95
  96                 if (unlikely(sp < (sizeof(struct thread_info) + STACK_WARN))) {
  97                         printk("do_IRQ: stack overflow: %ld\n",
  98                                sp - sizeof(struct thread_info));
  99                         dump_stack();
 100                 }
 101         }
 102 #endif
 103
 104 #ifdef CONFIG_CPU_HAS_INTEVT
 105         __asm__ __volatile__ (
 106 #ifdef CONFIG_CPU_HAS_SR_RB
 107                 "stc    r2_bank, %0\n\t"
 108 #else
 109                 "mov.l  @%1, %0\n\t"
 110 #endif
 111                 "shlr2  %0\n\t"
 112                 "shlr2  %0\n\t"
 113                 "shlr   %0\n\t"
 114                 "add    #-16, %0\n\t"
 115                 : "=z" (irq), "=r" (r4)
 116                 : "1" (INTEVT)
 117                 : "memory"
 118         );
 119 #endif
 120
 121         irq = irq_demux(irq);
 122
 123 #ifdef CONFIG_4KSTACKS
 124         curctx = (union irq_ctx *)current_thread_info();
 125         irqctx = hardirq_ctx[smp_processor_id()];
 126
 127         /*
 128          * this is where we switch to the IRQ stack. However, if we are
 129          * already using the IRQ stack (because we interrupted a hardirq
 130          * handler) we can't do that and just have to keep using the
 131          * current stack (which is the irq stack already after all)
 132          */
 133         if (curctx != irqctx) {
 134                 u32 *isp;
 135
 136                 isp = (u32 *)((char *)irqctx + sizeof(*irqctx));
 137                 irqctx->tinfo.task = curctx->tinfo.task;
 138                 irqctx->tinfo.previous_sp = current_stack_pointer;
 139
 140                 __asm__ __volatile__ (
 141                         "mov    %0, r4          \n"
 142                         "mov    %1, r5          \n"
 143                         "mov    r15, r9         \n"
 144                         "jsr    @%2             \n"
 145                         /* swith to the irq stack */
 146                         " mov   %3, r15         \n"
 147                         /* restore the stack (ring zero) */
 148                         "mov    r9, r15         \n"
 149                         : /* no outputs */
 150                         : "r" (irq), "r" (&regs), "r" (__do_IRQ), "r" (isp)
 151                         /* XXX: A somewhat excessive clobber list? -PFM */
 152                         : "memory", "r0", "r1", "r2", "r3", "r4",
 153                           "r5", "r6", "r7", "r8", "t", "pr"
 154                 );
 155         } else
 156 #endif
 157                 __do_IRQ(irq, &regs);
 158
 159         irq_exit();
 160
 161         return 1;
 162 }
 163
 164 #ifdef CONFIG_4KSTACKS
 165 /*
 166  * These should really be __section__(".bss.page_aligned") as well, but
 167  * gcc's 3.0 and earlier don't handle that correctly.
 168  */
 169 static char softirq_stack[NR_CPUS * THREAD_SIZE]
 170                 __attribute__((__aligned__(THREAD_SIZE)));
 171
 172 static char hardirq_stack[NR_CPUS * THREAD_SIZE]
 173                 __attribute__((__aligned__(THREAD_SIZE)));
 174
 175 /*
 176  * allocate per-cpu stacks for hardirq and for softirq processing
 177  */
 178 void irq_ctx_init(int cpu)
 179 {
 180         union irq_ctx *irqctx;
 181
 182         if (hardirq_ctx[cpu])
 183                 return;
 184
 185         irqctx = (union irq_ctx *)&hardirq_stack[cpu * THREAD_SIZE];
 186         irqctx->tinfo.task              = NULL;
 187         irqctx->tinfo.exec_domain       = NULL;
 188         irqctx->tinfo.cpu               = cpu;
 189         irqctx->tinfo.preempt_count     = HARDIRQ_OFFSET;
 190         irqctx->tinfo.addr_limit        = MAKE_MM_SEG(0);
 191
 192         hardirq_ctx[cpu] = irqctx;
 193
 194         irqctx = (union irq_ctx *)&softirq_stack[cpu * THREAD_SIZE];
 195         irqctx->tinfo.task              = NULL;
 196         irqctx->tinfo.exec_domain       = NULL;
 197         irqctx->tinfo.cpu               = cpu;
 198         irqctx->tinfo.preempt_count     = SOFTIRQ_OFFSET;
 199         irqctx->tinfo.addr_limit        = MAKE_MM_SEG(0);
 200
 201         softirq_ctx[cpu] = irqctx;
 202
 203         printk("CPU %u irqstacks, hard=%p soft=%p\n",
 204                 cpu, hardirq_ctx[cpu], softirq_ctx[cpu]);
 205 }
 206
 207 void irq_ctx_exit(int cpu)
 208 {
 209         hardirq_ctx[cpu] = NULL;
 210 }
 211
 212 extern asmlinkage void __do_softirq(void);
 213
 214 asmlinkage void do_softirq(void)
 215 {
 216         unsigned long flags;
 217         struct thread_info *curctx;
 218         union irq_ctx *irqctx;
 219         u32 *isp;
 220
 221         if (in_interrupt())
 222                 return;
 223
 224         local_irq_save(flags);
 225
 226         if (local_softirq_pending()) {
 227                 curctx = current_thread_info();
 228                 irqctx = softirq_ctx[smp_processor_id()];
 229                 irqctx->tinfo.task = curctx->task;
 230                 irqctx->tinfo.previous_sp = current_stack_pointer;
 231
 232                 /* build the stack frame on the softirq stack */
 233                 isp = (u32 *)((char *)irqctx + sizeof(*irqctx));
 234
 235                 __asm__ __volatile__ (
 236                         "mov    r15, r9         \n"
 237                         "jsr    @%0             \n"
 238                         /* switch to the softirq stack */
 239                         " mov   %1, r15         \n"
 240                         /* restore the thread stack */
 241                         "mov    r9, r15         \n"
 242                         : /* no outputs */
 243                         : "r" (__do_softirq), "r" (isp)
 244                         /* XXX: A somewhat excessive clobber list? -PFM */
 245                         : "memory", "r0", "r1", "r2", "r3", "r4",
 246                           "r5", "r6", "r7", "r8", "r9", "r15", "t", "pr"
 247                 );
 248         }
 249
 250         local_irq_restore(flags);
 251 }
 252 EXPORT_SYMBOL(do_softirq);
 253 #endif