arch/mips/dec/kn02-irq.c

   1 /*
   2  *      linux/arch/mips/dec/kn02-irq.c
   3  *
   4  *      DECstation 5000/200 (KN02) Control and Status Register
   5  *      interrupts.
   6  *
   7  *      Copyright (c) 2002, 2003, 2005  Maciej W. Rozycki
   8  *
   9  *      This program is free software; you can redistribute it and/or
  10  *      modify it under the terms of the GNU General Public License
  11  *      as published by the Free Software Foundation; either version
  12  *      2 of the License, or (at your option) any later version.
  13  */
  14
  15 #include <linux/init.h>
  16 #include <linux/irq.h>
  17 #include <linux/spinlock.h>
  18 #include <linux/types.h>
  19
  20 #include <asm/dec/kn02.h>
  21
  22
  23 /*
  24  * Bits 7:0 of the Control Register are write-only -- the
  25  * corresponding bits of the Status Register have a different
  26  * meaning.  Hence we use a cache.  It speeds up things a bit
  27  * as well.
  28  *
  29  * There is no default value -- it has to be initialized.
  30  */
  31 u32 cached_kn02_csr;
  32 DEFINE_SPINLOCK(kn02_lock);
  33
  34
  35 static int kn02_irq_base;
  36
  37
  38 static inline void unmask_kn02_irq(unsigned int irq)
  39 {
  40         volatile u32 *csr = (volatile u32 *)CKSEG1ADDR(KN02_SLOT_BASE +
  41                                                        KN02_CSR);
  42
  43         cached_kn02_csr |= (1 << (irq - kn02_irq_base + 16));
  44         *csr = cached_kn02_csr;
  45 }
  46
  47 static inline void mask_kn02_irq(unsigned int irq)
  48 {
  49         volatile u32 *csr = (volatile u32 *)CKSEG1ADDR(KN02_SLOT_BASE +
  50                                                        KN02_CSR);
  51
  52         cached_kn02_csr &= ~(1 << (irq - kn02_irq_base + 16));
  53         *csr = cached_kn02_csr;
  54 }
  55
  56 static inline void enable_kn02_irq(unsigned int irq)
  57 {
  58         unsigned long flags;
  59
  60         spin_lock_irqsave(&kn02_lock, flags);
  61         unmask_kn02_irq(irq);
  62         spin_unlock_irqrestore(&kn02_lock, flags);
  63 }
  64
  65 static inline void disable_kn02_irq(unsigned int irq)
  66 {
  67         unsigned long flags;
  68
  69         spin_lock_irqsave(&kn02_lock, flags);
  70         mask_kn02_irq(irq);
  71         spin_unlock_irqrestore(&kn02_lock, flags);
  72 }
  73
  74
  75 static unsigned int startup_kn02_irq(unsigned int irq)
  76 {
  77         enable_kn02_irq(irq);
  78         return 0;
  79 }
  80
  81 #define shutdown_kn02_irq disable_kn02_irq
  82
  83 static void ack_kn02_irq(unsigned int irq)
  84 {
  85         spin_lock(&kn02_lock);
  86         mask_kn02_irq(irq);
  87         spin_unlock(&kn02_lock);
  88         iob();
  89 }
  90
  91 static void end_kn02_irq(unsigned int irq)
  92 {
  93         if (!(irq_desc[irq].status & (IRQ_DISABLED | IRQ_INPROGRESS)))
  94                 enable_kn02_irq(irq);
  95 }
  96
  97 static struct hw_interrupt_type kn02_irq_type = {
  98         .typename = "KN02-CSR",
  99         .startup = startup_kn02_irq,
 100         .shutdown = shutdown_kn02_irq,
 101         .enable = enable_kn02_irq,
 102         .disable = disable_kn02_irq,
 103         .ack = ack_kn02_irq,
 104         .end = end_kn02_irq,
 105 };
 106
 107
 108 void __init init_kn02_irqs(int base)
 109 {
 110         volatile u32 *csr = (volatile u32 *)CKSEG1ADDR(KN02_SLOT_BASE +
 111                                                        KN02_CSR);
 112         unsigned long flags;
 113         int i;
 114
 115         /* Mask interrupts. */
 116         spin_lock_irqsave(&kn02_lock, flags);
 117         cached_kn02_csr &= ~KN02_CSR_IOINTEN;
 118         *csr = cached_kn02_csr;
 119         iob();
 120         spin_unlock_irqrestore(&kn02_lock, flags);
 121
 122         for (i = base; i < base + KN02_IRQ_LINES; i++) {
 123                 irq_desc[i].status = IRQ_DISABLED;
 124                 irq_desc[i].action = 0;
 125                 irq_desc[i].depth = 1;
 126                 irq_desc[i].chip = &kn02_irq_type;
 127         }
 128
 129         kn02_irq_base = base;
 130 }