1 /* 2 * include/asm-mips/i8259.h 3 * 4 * i8259A interrupt definitions. 5 * 6 * Copyright (C) 2003 Maciej W. Rozycki 7 * Copyright (C) 2003 Ralf Baechle <ralf (at) linux-mips.org> 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 #ifndef _ASM_I8259_H 15 #define _ASM_I8259_H 16 17 #include <linux/compiler.h> 18 #include <linux/spinlock.h> 19 20 #include <asm/io.h> 21 #include <irq.h> 22 23 /* i8259A PIC registers */ 24 #define PIC_MASTER_CMD 0x20 25 #define PIC_MASTER_IMR 0x21 26 #define PIC_MASTER_ISR PIC_MASTER_CMD 27 #define PIC_MASTER_POLL PIC_MASTER_ISR 28 #define PIC_MASTER_OCW3 PIC_MASTER_ISR 29 #define PIC_SLAVE_CMD 0xa0 30 #define PIC_SLAVE_IMR 0xa1 31 32 /* i8259A PIC related value */ 33 #define PIC_CASCADE_IR 2 34 #define MASTER_ICW4_DEFAULT 0x01 35 #define SLAVE_ICW4_DEFAULT 0x01 36 #define PIC_ICW4_AEOI 2 37 38 extern spinlock_t i8259A_lock; 39 40 extern int i8259A_irq_pending(unsigned int irq); 41 extern void make_8259A_irq(unsigned int irq); 42 43 extern void init_i8259_irqs(void); 44 45 /* 46 * Do the traditional i8259 interrupt polling thing. This is for the few 47 * cases where no better interrupt acknowledge method is available and we 48 * absolutely must touch the i8259. 49 */ 50 static inline int i8259_irq(void) 51 { 52 int irq; 53 54 spin_lock(&i8259A_lock); 55 56 /* Perform an interrupt acknowledge cycle on controller 1. */ 57 outb(0x0C, PIC_MASTER_CMD); /* prepare for poll */ 58 irq = inb(PIC_MASTER_CMD) & 7; 59 if (irq == PIC_CASCADE_IR) { 60 /* 61 * Interrupt is cascaded so perform interrupt 62 * acknowledge on controller 2. 63 */ 64 outb(0x0C, PIC_SLAVE_CMD); /* prepare for poll */ 65 irq = (inb(PIC_SLAVE_CMD) & 7) + 8; 66 } 67 68 if (unlikely(irq == 7)) { 69 /* 70 * This may be a spurious interrupt. 71 * 72 * Read the interrupt status register (ISR). If the most 73 * significant bit is not set then there is no valid 74 * interrupt. 75 */ 76 outb(0x0B, PIC_MASTER_ISR); /* ISR register */ 77 if(~inb(PIC_MASTER_ISR) & 0x80) 78 irq = -1; 79 } 80 81 spin_unlock(&i8259A_lock); 82 83 return likely(irq >= 0) ? irq + I8259A_IRQ_BASE : irq; 84 } 85 86 #endif /* _ASM_I8259_H */ 87
