| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * ip22-irq.S: Interrupt exception dispatch code for FullHouse and |
| 3 | * Guiness. |
| 4 | * |
| 5 | * Copyright (C) 1996 David S. Miller (dm@engr.sgi.com) |
| 6 | */ |
| 7 | |
| 8 | #include <asm/asm.h> |
| 9 | #include <asm/mipsregs.h> |
| 10 | #include <asm/regdef.h> |
| 11 | #include <asm/stackframe.h> |
| 12 | |
| 13 | /* A lot of complication here is taken away because: |
| 14 | * |
| 15 | * 1) We handle one interrupt and return, sitting in a loop and moving across |
| 16 | * all the pending IRQ bits in the cause register is _NOT_ the answer, the |
| 17 | * common case is one pending IRQ so optimize in that direction. |
| 18 | * |
| 19 | * 2) We need not check against bits in the status register IRQ mask, that |
| 20 | * would make this routine slow as hell. |
| 21 | * |
| 22 | * 3) Linux only thinks in terms of all IRQs on or all IRQs off, nothing in |
| 23 | * between like BSD spl() brain-damage. |
| 24 | * |
| 25 | * Furthermore, the IRQs on the INDY look basically (barring software IRQs |
| 26 | * which we don't use at all) like: |
| 27 | * |
| 28 | * MIPS IRQ Source |
| 29 | * -------- ------ |
| 30 | * 0 Software (ignored) |
| 31 | * 1 Software (ignored) |
| 32 | * 2 Local IRQ level zero |
| 33 | * 3 Local IRQ level one |
| 34 | * 4 8254 Timer zero |
| 35 | * 5 8254 Timer one |
| 36 | * 6 Bus Error |
| 37 | * 7 R4k timer (what we use) |
| 38 | * |
| 39 | * We handle the IRQ according to _our_ priority which is: |
| 40 | * |
| 41 | * Highest ---- R4k Timer |
| 42 | * Local IRQ zero |
| 43 | * Local IRQ one |
| 44 | * Bus Error |
| 45 | * 8254 Timer zero |
| 46 | * Lowest ---- 8254 Timer one |
| 47 | * |
| 48 | * then we just return, if multiple IRQs are pending then we will just take |
| 49 | * another exception, big deal. |
| 50 | */ |
| 51 | |
| 52 | .text |
| 53 | .set noreorder |
| 54 | .set noat |
| 55 | .align 5 |
| 56 | NESTED(indyIRQ, PT_SIZE, sp) |
| 57 | SAVE_ALL |
| 58 | CLI |
| 59 | .set at |
| 60 | mfc0 s0, CP0_CAUSE # get irq mask |
| 61 | |
| 62 | /* First we check for r4k counter/timer IRQ. */ |
| 63 | andi a0, s0, CAUSEF_IP7 |
| 64 | beq a0, zero, 1f |
| 65 | andi a0, s0, CAUSEF_IP2 # delay slot, check local level zero |
| 66 | |
| 67 | /* Wheee, a timer interrupt. */ |
| 68 | jal indy_r4k_timer_interrupt |
| 69 | move a0, sp # delay slot |
| 70 | j ret_from_irq |
| 71 | nop # delay slot |
| 72 | |
| 73 | 1: |
| 74 | beq a0, zero, 1f |
| 75 | andi a0, s0, CAUSEF_IP3 # delay slot, check local level one |
| 76 | |
| 77 | /* Wheee, local level zero interrupt. */ |
| 78 | jal indy_local0_irqdispatch |
| 79 | move a0, sp # delay slot |
| 80 | |
| 81 | j ret_from_irq |
| 82 | nop # delay slot |
| 83 | |
| 84 | 1: |
| 85 | beq a0, zero, 1f |
| 86 | andi a0, s0, CAUSEF_IP6 # delay slot, check bus error |
| 87 | |
| 88 | /* Wheee, local level one interrupt. */ |
| 89 | jal indy_local1_irqdispatch |
| 90 | move a0, sp # delay slot |
| 91 | j ret_from_irq |
| 92 | nop # delay slot |
| 93 | |
| 94 | 1: |
| 95 | beq a0, zero, 1f |
| 96 | andi a0, s0, (CAUSEF_IP4 | CAUSEF_IP5) # delay slot |
| 97 | |
| 98 | /* Wheee, an asynchronous bus error... */ |
| 99 | jal indy_buserror_irq |
| 100 | move a0, sp # delay slot |
| 101 | j ret_from_irq |
| 102 | nop # delay slot |
| 103 | |
| 104 | 1: |
| 105 | /* Here by mistake? It is possible, that by the time we take |
| 106 | * the exception the IRQ pin goes low, so just leave if this |
| 107 | * is the case. |
| 108 | */ |
| 109 | beq a0, zero, 1f |
| 110 | nop # delay slot |
| 111 | |
| 112 | /* Must be one of the 8254 timers... */ |
| 113 | jal indy_8254timer_irq |
| 114 | move a0, sp # delay slot |
| 115 | 1: |
| 116 | j ret_from_irq |
| 117 | nop # delay slot |
| 118 | END(indyIRQ) |