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   1 /*
   2  * arch/sh/kernel/cpu/irq/imask.c
   3  *
   4  * Copyright (C) 1999, 2000  Niibe Yutaka
   5  *
   6  * Simple interrupt handling using IMASK of SR register.
   7  *
   8  */
   9 /* NOTE: Will not work on level 15 */
  10 #include <linux/ptrace.h>
  11 #include <linux/errno.h>
  12 #include <linux/kernel_stat.h>
  13 #include <linux/signal.h>
  14 #include <linux/sched.h>
  15 #include <linux/interrupt.h>
  16 #include <linux/init.h>
  17 #include <linux/bitops.h>
  18 #include <linux/spinlock.h>
  19 #include <linux/cache.h>
  20 #include <linux/irq.h>
  21 #include <asm/system.h>
  22 #include <asm/irq.h>
  23
  24 /* Bitmap of IRQ masked */
  25 static unsigned long imask_mask = 0x7fff;
  26 static int interrupt_priority = 0;
  27
  28 static void enable_imask_irq(unsigned int irq);
  29 static void disable_imask_irq(unsigned int irq);
  30 static void shutdown_imask_irq(unsigned int irq);
  31 static void mask_and_ack_imask(unsigned int);
  32 static void end_imask_irq(unsigned int irq);
  33
  34 #define IMASK_PRIORITY  15
  35
  36 static unsigned int startup_imask_irq(unsigned int irq)
  37 {
  38         /* Nothing to do */
  39         return 0; /* never anything pending */
  40 }
  41
  42 static struct hw_interrupt_type imask_irq_type = {
  43         .typename = "SR.IMASK",
  44         .startup = startup_imask_irq,
  45         .shutdown = shutdown_imask_irq,
  46         .enable = enable_imask_irq,
  47         .disable = disable_imask_irq,
  48         .ack = mask_and_ack_imask,
  49         .end = end_imask_irq
  50 };
  51
  52 void static inline set_interrupt_registers(int ip)
  53 {
  54         unsigned long __dummy;
  55
  56         asm volatile("ldc       %2, r6_bank\n\t"
  57                      "stc       sr, %0\n\t"
  58                      "and       #0xf0, %0\n\t"
  59                      "shlr2     %0\n\t"
  60                      "cmp/eq    #0x3c, %0\n\t"
  61                      "bt/s      1f      ! CLI-ed\n\t"
  62                      " stc      sr, %0\n\t"
  63                      "and       %1, %0\n\t"
  64                      "or        %2, %0\n\t"
  65                      "ldc       %0, sr\n"
  66                      "1:"
  67                      : "=&z" (__dummy)
  68                      : "r" (~0xf0), "r" (ip << 4)
  69                      : "t");
  70 }
  71
  72 static void disable_imask_irq(unsigned int irq)
  73 {
  74         clear_bit(irq, &imask_mask);
  75         if (interrupt_priority < IMASK_PRIORITY - irq)
  76                 interrupt_priority = IMASK_PRIORITY - irq;
  77
  78         set_interrupt_registers(interrupt_priority);
  79 }
  80
  81 static void enable_imask_irq(unsigned int irq)
  82 {
  83         set_bit(irq, &imask_mask);
  84         interrupt_priority = IMASK_PRIORITY - ffz(imask_mask);
  85
  86         set_interrupt_registers(interrupt_priority);
  87 }
  88
  89 static void mask_and_ack_imask(unsigned int irq)
  90 {
  91         disable_imask_irq(irq);
  92 }
  93
  94 static void end_imask_irq(unsigned int irq)
  95 {
  96         if (!(irq_desc[irq].status & (IRQ_DISABLED|IRQ_INPROGRESS)))
  97                 enable_imask_irq(irq);
  98 }
  99
 100 static void shutdown_imask_irq(unsigned int irq)
 101 {
 102         /* Nothing to do */
 103 }
 104
 105 void make_imask_irq(unsigned int irq)
 106 {
 107         disable_irq_nosync(irq);
 108         irq_desc[irq].chip = &imask_irq_type;
 109         enable_irq(irq);
 110 }