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[/] [or1k/] [trunk/] [linux/] [linux-2.4/] [arch/] [mips/] [kernel/] [i8259.c] - Rev 1275
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/* * This file is subject to the terms and conditions of the GNU General Public * License. See the file "COPYING" in the main directory of this archive * for more details. * * Code to handle x86 style IRQs plus some generic interrupt stuff. * * Copyright (C) 1992 Linus Torvalds * Copyright (C) 1994 - 2000 Ralf Baechle */ #include <linux/delay.h> #include <linux/init.h> #include <linux/ioport.h> #include <linux/interrupt.h> #include <linux/kernel.h> #include <linux/spinlock.h> #include <asm/i8259.h> #include <asm/io.h> void enable_8259A_irq(unsigned int irq); void disable_8259A_irq(unsigned int irq); /* * This is the 'legacy' 8259A Programmable Interrupt Controller, * present in the majority of PC/AT boxes. * plus some generic x86 specific things if generic specifics makes * any sense at all. * this file should become arch/i386/kernel/irq.c when the old irq.c * moves to arch independent land */ static spinlock_t i8259A_lock = SPIN_LOCK_UNLOCKED; static void end_8259A_irq (unsigned int irq) { if (!(irq_desc[irq].status & (IRQ_DISABLED|IRQ_INPROGRESS))) enable_8259A_irq(irq); } #define shutdown_8259A_irq disable_8259A_irq void mask_and_ack_8259A(unsigned int); static unsigned int startup_8259A_irq(unsigned int irq) { enable_8259A_irq(irq); return 0; /* never anything pending */ } static struct hw_interrupt_type i8259A_irq_type = { "XT-PIC", startup_8259A_irq, shutdown_8259A_irq, enable_8259A_irq, disable_8259A_irq, mask_and_ack_8259A, end_8259A_irq, NULL }; /* * 8259A PIC functions to handle ISA devices: */ /* * This contains the irq mask for both 8259A irq controllers, */ static unsigned int cached_irq_mask = 0xffff; #define cached_21 (cached_irq_mask) #define cached_A1 (cached_irq_mask >> 8) void disable_8259A_irq(unsigned int irq) { unsigned int mask = 1 << irq; unsigned long flags; spin_lock_irqsave(&i8259A_lock, flags); cached_irq_mask |= mask; if (irq & 8) outb(cached_A1,0xA1); else outb(cached_21,0x21); spin_unlock_irqrestore(&i8259A_lock, flags); } void enable_8259A_irq(unsigned int irq) { unsigned int mask = ~(1 << irq); unsigned long flags; spin_lock_irqsave(&i8259A_lock, flags); cached_irq_mask &= mask; if (irq & 8) outb(cached_A1,0xA1); else outb(cached_21,0x21); spin_unlock_irqrestore(&i8259A_lock, flags); } int i8259A_irq_pending(unsigned int irq) { unsigned int mask = 1 << irq; unsigned long flags; int ret; spin_lock_irqsave(&i8259A_lock, flags); if (irq < 8) ret = inb(0x20) & mask; else ret = inb(0xA0) & (mask >> 8); spin_unlock_irqrestore(&i8259A_lock, flags); return ret; } void make_8259A_irq(unsigned int irq) { disable_irq_nosync(irq); irq_desc[irq].handler = &i8259A_irq_type; enable_irq(irq); } /* * This function assumes to be called rarely. Switching between * 8259A registers is slow. * This has to be protected by the irq controller spinlock * before being called. */ static inline int i8259A_irq_real(unsigned int irq) { int value; int irqmask = 1 << irq; if (irq < 8) { outb(0x0B,0x20); /* ISR register */ value = inb(0x20) & irqmask; outb(0x0A,0x20); /* back to the IRR register */ return value; } outb(0x0B,0xA0); /* ISR register */ value = inb(0xA0) & (irqmask >> 8); outb(0x0A,0xA0); /* back to the IRR register */ return value; } /* * Careful! The 8259A is a fragile beast, it pretty * much _has_ to be done exactly like this (mask it * first, _then_ send the EOI, and the order of EOI * to the two 8259s is important! */ void mask_and_ack_8259A(unsigned int irq) { unsigned int irqmask = 1 << irq; unsigned long flags; spin_lock_irqsave(&i8259A_lock, flags); /* * Lightweight spurious IRQ detection. We do not want to overdo * spurious IRQ handling - it's usually a sign of hardware problems, so * we only do the checks we can do without slowing down good hardware * nnecesserily. * * Note that IRQ7 and IRQ15 (the two spurious IRQs usually resulting * rom the 8259A-1|2 PICs) occur even if the IRQ is masked in the 8259A. * Thus we can check spurious 8259A IRQs without doing the quite slow * i8259A_irq_real() call for every IRQ. This does not cover 100% of * spurious interrupts, but should be enough to warn the user that * there is something bad going on ... */ if (cached_irq_mask & irqmask) goto spurious_8259A_irq; cached_irq_mask |= irqmask; handle_real_irq: if (irq & 8) { inb(0xA1); /* DUMMY - (do we need this?) */ outb(cached_A1,0xA1); outb(0x60+(irq&7),0xA0);/* 'Specific EOI' to slave */ outb(0x62,0x20); /* 'Specific EOI' to master-IRQ2 */ } else { inb(0x21); /* DUMMY - (do we need this?) */ outb(cached_21,0x21); outb(0x60+irq,0x20); /* 'Specific EOI' to master */ } spin_unlock_irqrestore(&i8259A_lock, flags); return; spurious_8259A_irq: /* * this is the slow path - should happen rarely. */ if (i8259A_irq_real(irq)) /* * oops, the IRQ _is_ in service according to the * 8259A - not spurious, go handle it. */ goto handle_real_irq; { static int spurious_irq_mask = 0; /* * At this point we can be sure the IRQ is spurious, * lets ACK and report it. [once per IRQ] */ if (!(spurious_irq_mask & irqmask)) { printk("spurious 8259A interrupt: IRQ%d.\n", irq); spurious_irq_mask |= irqmask; } atomic_inc(&irq_err_count); /* * Theoretically we do not have to handle this IRQ, * but in Linux this does not cause problems and is * simpler for us. */ goto handle_real_irq; } } void __init init_8259A(int auto_eoi) { unsigned long flags; spin_lock_irqsave(&i8259A_lock, flags); outb(0xff, 0x21); /* mask all of 8259A-1 */ outb(0xff, 0xA1); /* mask all of 8259A-2 */ /* * outb_p - this has to work on a wide range of PC hardware. */ outb_p(0x11, 0x20); /* ICW1: select 8259A-1 init */ outb_p(0x00, 0x21); /* ICW2: 8259A-1 IR0-7 mapped to 0x00-0x07 */ outb_p(0x04, 0x21); /* 8259A-1 (the master) has a slave on IR2 */ if (auto_eoi) outb_p(0x03, 0x21); /* master does Auto EOI */ else outb_p(0x01, 0x21); /* master expects normal EOI */ outb_p(0x11, 0xA0); /* ICW1: select 8259A-2 init */ outb_p(0x08, 0xA1); /* ICW2: 8259A-2 IR0-7 mapped to 0x08-0x0f */ outb_p(0x02, 0xA1); /* 8259A-2 is a slave on master's IR2 */ outb_p(0x01, 0xA1); /* (slave's support for AEOI in flat mode is to be investigated) */ if (auto_eoi) /* * in AEOI mode we just have to mask the interrupt * when acking. */ i8259A_irq_type.ack = disable_8259A_irq; else i8259A_irq_type.ack = mask_and_ack_8259A; udelay(100); /* wait for 8259A to initialize */ outb(cached_21, 0x21); /* restore master IRQ mask */ outb(cached_A1, 0xA1); /* restore slave IRQ mask */ spin_unlock_irqrestore(&i8259A_lock, flags); } asmlinkage void i8259_do_irq(int irq, struct pt_regs regs) { panic("i8259_do_irq: I want to be implemented"); } /* * IRQ2 is cascade interrupt to second interrupt controller */ static struct irqaction irq2 = { no_action, 0, 0, "cascade", NULL, NULL }; static struct resource pic1_io_resource = { "pic1", 0x20, 0x3f, IORESOURCE_BUSY }; static struct resource pic2_io_resource = { "pic2", 0xa0, 0xbf, IORESOURCE_BUSY }; /* * On systems with i8259-style interrupt controllers we assume for * driver compatibility reasons interrupts 0 - 15 to be the i8295 * interrupts even if the hardware uses a different interrupt numbering. */ void __init init_i8259_irqs (void) { int i; request_resource(&ioport_resource, &pic1_io_resource); request_resource(&ioport_resource, &pic2_io_resource); init_8259A(0); for (i = 0; i < 16; i++) { irq_desc[i].status = IRQ_DISABLED; irq_desc[i].action = 0; irq_desc[i].depth = 1; irq_desc[i].handler = &i8259A_irq_type; } setup_irq(2, &irq2); }
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