arch/alpha/kernel/irq_pyxis.c

   1 /*
   2  *      linux/arch/alpha/kernel/irq_pyxis.c
   3  *
   4  * Based on code written by David A Rusling (david.rusling@reo.mts.dec.com).
   5  *
   6  * IRQ Code common to all PYXIS core logic chips.
   7  */
   8
   9 #include <linux/init.h>
  10 #include <linux/sched.h>
  11 #include <linux/irq.h>
  12
  13 #include <asm/io.h>
  14 #include <asm/core_cia.h>
  15
  16 #include "proto.h"
  17 #include "irq_impl.h"
  18
  19
  20 /* Note mask bit is true for ENABLED irqs.  */
  21 static unsigned long cached_irq_mask;
  22
  23 static inline void
  24 pyxis_update_irq_hw(unsigned long mask)
  25 {
  26         *(vulp)PYXIS_INT_MASK = mask;
  27         mb();
  28         *(vulp)PYXIS_INT_MASK;
  29 }
  30
  31 static inline void
  32 pyxis_enable_irq(unsigned int irq)
  33 {
  34         pyxis_update_irq_hw(cached_irq_mask |= 1UL << (irq - 16));
  35 }
  36
  37 static void
  38 pyxis_disable_irq(unsigned int irq)
  39 {
  40         pyxis_update_irq_hw(cached_irq_mask &= ~(1UL << (irq - 16)));
  41 }
  42
  43 static unsigned int
  44 pyxis_startup_irq(unsigned int irq)
  45 {
  46         pyxis_enable_irq(irq);
  47         return 0;
  48 }
  49
  50 static void
  51 pyxis_end_irq(unsigned int irq)
  52 {
  53         if (!(irq_desc[irq].status & (IRQ_DISABLED|IRQ_INPROGRESS)))
  54                 pyxis_enable_irq(irq);
  55 }
  56
  57 static void
  58 pyxis_mask_and_ack_irq(unsigned int irq)
  59 {
  60         unsigned long bit = 1UL << (irq - 16);
  61         unsigned long mask = cached_irq_mask &= ~bit;
  62
  63         /* Disable the interrupt.  */
  64         *(vulp)PYXIS_INT_MASK = mask;
  65         wmb();
  66         /* Ack PYXIS PCI interrupt.  */
  67         *(vulp)PYXIS_INT_REQ = bit;
  68         mb();
  69         /* Re-read to force both writes.  */
  70         *(vulp)PYXIS_INT_MASK;
  71 }
  72
  73 static struct irq_chip pyxis_irq_type = {
  74         .typename       = "PYXIS",
  75         .startup        = pyxis_startup_irq,
  76         .shutdown       = pyxis_disable_irq,
  77         .enable         = pyxis_enable_irq,
  78         .disable        = pyxis_disable_irq,
  79         .ack            = pyxis_mask_and_ack_irq,
  80         .end            = pyxis_end_irq,
  81 };
  82
  83 void
  84 pyxis_device_interrupt(unsigned long vector)
  85 {
  86         unsigned long pld;
  87         unsigned int i;
  88
  89         /* Read the interrupt summary register of PYXIS */
  90         pld = *(vulp)PYXIS_INT_REQ;
  91         pld &= cached_irq_mask;
  92
  93         /*
  94          * Now for every possible bit set, work through them and call
  95          * the appropriate interrupt handler.
  96          */
  97         while (pld) {
  98                 i = ffz(~pld);
  99                 pld &= pld - 1; /* clear least bit set */
 100                 if (i == 7)
 101                         isa_device_interrupt(vector);
 102                 else
 103                         handle_irq(16+i);
 104         }
 105 }
 106
 107 void __init
 108 init_pyxis_irqs(unsigned long ignore_mask)
 109 {
 110         long i;
 111
 112         *(vulp)PYXIS_INT_MASK = 0;              /* disable all */
 113         *(vulp)PYXIS_INT_REQ  = -1;             /* flush all */
 114         mb();
 115
 116         /* Send -INTA pulses to clear any pending interrupts ...*/
 117         *(vuip) CIA_IACK_SC;
 118
 119         for (i = 16; i < 48; ++i) {
 120                 if ((ignore_mask >> i) & 1)
 121                         continue;
 122                 irq_desc[i].status = IRQ_DISABLED | IRQ_LEVEL;
 123                 irq_desc[i].chip = &pyxis_irq_type;
 124         }
 125
 126         setup_irq(16+7, &isa_cascade_irqaction);
 127 }