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Diffstat (limited to 'arch/mips/include/asm/i8259.h')
| -rw-r--r-- | arch/mips/include/asm/i8259.h | 96 |
1 files changed, 96 insertions, 0 deletions
diff --git a/arch/mips/include/asm/i8259.h b/arch/mips/include/asm/i8259.h new file mode 100644 index 000000000..47543d564 --- /dev/null +++ b/arch/mips/include/asm/i8259.h @@ -0,0 +1,96 @@ +/* + * include/asm-mips/i8259.h + * + * i8259A interrupt definitions. + * + * Copyright (C) 2003 Maciej W. Rozycki + * Copyright (C) 2003 Ralf Baechle <ralf@linux-mips.org> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + */ +#ifndef _ASM_I8259_H +#define _ASM_I8259_H + +#include <linux/compiler.h> +#include <linux/spinlock.h> + +#include <asm/io.h> +#include <irq.h> + +/* i8259A PIC registers */ +#define PIC_MASTER_CMD 0x20 +#define PIC_MASTER_IMR 0x21 +#define PIC_MASTER_ISR PIC_MASTER_CMD +#define PIC_MASTER_POLL PIC_MASTER_ISR +#define PIC_MASTER_OCW3 PIC_MASTER_ISR +#define PIC_SLAVE_CMD 0xa0 +#define PIC_SLAVE_IMR 0xa1 + +/* i8259A PIC related value */ +#define PIC_CASCADE_IR 2 +#define MASTER_ICW4_DEFAULT 0x01 +#define SLAVE_ICW4_DEFAULT 0x01 +#define PIC_ICW4_AEOI 2 + +extern raw_spinlock_t i8259A_lock; + +extern void make_8259A_irq(unsigned int irq); + +extern void init_i8259_irqs(void); + +/** + * i8159_set_poll() - Override the i8259 polling function + * @poll: pointer to platform-specific polling function + * + * Call this to override the generic i8259 polling function, which directly + * accesses i8259 registers, with a platform specific one which may be faster + * in cases where hardware provides a more optimal means of polling for an + * interrupt. + */ +extern void i8259_set_poll(int (*poll)(void)); + +/* + * Do the traditional i8259 interrupt polling thing. This is for the few + * cases where no better interrupt acknowledge method is available and we + * absolutely must touch the i8259. + */ +static inline int i8259_irq(void) +{ + int irq; + + raw_spin_lock(&i8259A_lock); + + /* Perform an interrupt acknowledge cycle on controller 1. */ + outb(0x0C, PIC_MASTER_CMD); /* prepare for poll */ + irq = inb(PIC_MASTER_CMD) & 7; + if (irq == PIC_CASCADE_IR) { + /* + * Interrupt is cascaded so perform interrupt + * acknowledge on controller 2. + */ + outb(0x0C, PIC_SLAVE_CMD); /* prepare for poll */ + irq = (inb(PIC_SLAVE_CMD) & 7) + 8; + } + + if (unlikely(irq == 7)) { + /* + * This may be a spurious interrupt. + * + * Read the interrupt status register (ISR). If the most + * significant bit is not set then there is no valid + * interrupt. + */ + outb(0x0B, PIC_MASTER_ISR); /* ISR register */ + if(~inb(PIC_MASTER_ISR) & 0x80) + irq = -1; + } + + raw_spin_unlock(&i8259A_lock); + + return likely(irq >= 0) ? irq + I8259A_IRQ_BASE : irq; +} + +#endif /* _ASM_I8259_H */ |