arch/blackfin/kernel/irqchip.c

   1 /*
   2  * Copyright 2005-2009 Analog Devices Inc.
   3  *
   4  * Licensed under the GPL-2 or later
   5  */
   6
   7 #include <linux/kernel_stat.h>
   8 #include <linux/module.h>
   9 #include <linux/random.h>
  10 #include <linux/seq_file.h>
  11 #include <linux/kallsyms.h>
  12 #include <linux/interrupt.h>
  13 #include <linux/irq.h>
  14 #include <linux/seq_file.h>
  15 #include <asm/irq_handler.h>
  16 #include <asm/trace.h>
  17 #include <asm/pda.h>
  18
  19 static atomic_t irq_err_count;
  20 void ack_bad_irq(unsigned int irq)
  21 {
  22         atomic_inc(&irq_err_count);
  23         printk(KERN_ERR "IRQ: spurious interrupt %d\n", irq);
  24 }
  25
  26 static struct irq_desc bad_irq_desc = {
  27         .handle_irq = handle_bad_irq,
  28         .lock = __RAW_SPIN_LOCK_UNLOCKED(bad_irq_desc.lock),
  29 };
  30
  31 #ifdef CONFIG_CPUMASK_OFFSTACK
  32 /* We are not allocating a variable-sized bad_irq_desc.affinity */
  33 #error "Blackfin architecture does not support CONFIG_CPUMASK_OFFSTACK."
  34 #endif
  35
  36 #ifdef CONFIG_PROC_FS
  37 int arch_show_interrupts(struct seq_file *p, int prec)
  38 {
  39         int j;
  40
  41         seq_printf(p, "%*s: ", prec, "NMI");
  42         for_each_online_cpu(j)
  43                 seq_printf(p, "%10u ", cpu_pda[j].__nmi_count);
  44         seq_printf(p, "  CORE  Non Maskable Interrupt\n");
  45         seq_printf(p, "%*s: %10u\n", prec, "ERR", atomic_read(&irq_err_count));
  46         return 0;
  47 }
  48 #endif
  49
  50 #ifdef CONFIG_DEBUG_STACKOVERFLOW
  51 static void check_stack_overflow(int irq)
  52 {
  53         /* Debugging check for stack overflow: is there less than STACK_WARN free? */
  54         long sp = __get_SP() & (THREAD_SIZE - 1);
  55
  56         if (unlikely(sp < (sizeof(struct thread_info) + STACK_WARN))) {
  57                 dump_stack();
  58                 pr_emerg("irq%i: possible stack overflow only %ld bytes free\n",
  59                         irq, sp - sizeof(struct thread_info));
  60         }
  61 }
  62 #else
  63 static inline void check_stack_overflow(int irq) { }
  64 #endif
  65
  66 #ifndef CONFIG_IPIPE
  67 static void maybe_lower_to_irq14(void)
  68 {
  69         unsigned short pending, other_ints;
  70
  71         /*
  72          * If we're the only interrupt running (ignoring IRQ15 which
  73          * is for syscalls), lower our priority to IRQ14 so that
  74          * softirqs run at that level.  If there's another,
  75          * lower-level interrupt, irq_exit will defer softirqs to
  76          * that. If the interrupt pipeline is enabled, we are already
  77          * running at IRQ14 priority, so we don't need this code.
  78          */
  79         CSYNC();
  80         pending = bfin_read_IPEND() & ~0x8000;
  81         other_ints = pending & (pending - 1);
  82         if (other_ints == 0)
  83                 lower_to_irq14();
  84 }
  85 #else
  86 static inline void maybe_lower_to_irq14(void) { }
  87 #endif
  88
  89 /*
  90  * do_IRQ handles all hardware IRQs.  Decoded IRQs should not
  91  * come via this function.  Instead, they should provide their
  92  * own 'handler'
  93  */
  94 #ifdef CONFIG_DO_IRQ_L1
  95 __attribute__((l1_text))
  96 #endif
  97 asmlinkage void asm_do_IRQ(unsigned int irq, struct pt_regs *regs)
  98 {
  99         struct pt_regs *old_regs = set_irq_regs(regs);
 100
 101         irq_enter();
 102
 103         check_stack_overflow(irq);
 104
 105         /*
 106          * Some hardware gives randomly wrong interrupts.  Rather
 107          * than crashing, do something sensible.
 108          */
 109         if (irq >= NR_IRQS)
 110                 handle_bad_irq(&bad_irq_desc);
 111         else
 112                 generic_handle_irq(irq);
 113
 114         maybe_lower_to_irq14();
 115
 116         irq_exit();
 117
 118         set_irq_regs(old_regs);
 119 }
 120
 121 void __init init_IRQ(void)
 122 {
 123         init_arch_irq();
 124
 125 #ifdef CONFIG_DEBUG_BFIN_HWTRACE_EXPAND
 126         /* Now that evt_ivhw is set up, turn this on */
 127         trace_buff_offset = 0;
 128         bfin_write_TBUFCTL(BFIN_TRACE_ON);
 129         printk(KERN_INFO "Hardware Trace expanded to %ik\n",
 130           1 << CONFIG_DEBUG_BFIN_HWTRACE_EXPAND_LEN);
 131 #endif
 132 }