2 * This file is subject to the terms and conditions of the GNU General Public
3 * License. See the file "COPYING" in the main directory of this archive
6 * Code to handle x86 style IRQs plus some generic interrupt stuff.
8 * Copyright (C) 1992 Linus Torvalds
9 * Copyright (C) 1994 - 2000 Ralf Baechle
11 #include <linux/delay.h>
12 #include <linux/init.h>
13 #include <linux/ioport.h>
14 #include <linux/interrupt.h>
15 #include <linux/kernel.h>
16 #include <linux/spinlock.h>
17 #include <linux/sysdev.h>
18 #include <linux/irq.h>
20 #include <asm/i8259.h>
24 * This is the 'legacy' 8259A Programmable Interrupt Controller,
25 * present in the majority of PC/AT boxes.
26 * plus some generic x86 specific things if generic specifics makes
28 * this file should become arch/i386/kernel/irq.c when the old irq.c
29 * moves to arch independent land
32 static int i8259A_auto_eoi = -1;
33 DEFINE_RAW_SPINLOCK(i8259A_lock);
34 static void disable_8259A_irq(unsigned int irq);
35 static void enable_8259A_irq(unsigned int irq);
36 static void mask_and_ack_8259A(unsigned int irq);
37 static void init_8259A(int auto_eoi);
39 static struct irq_chip i8259A_chip = {
41 .mask = disable_8259A_irq,
42 .disable = disable_8259A_irq,
43 .unmask = enable_8259A_irq,
44 .mask_ack = mask_and_ack_8259A,
45 #ifdef CONFIG_MIPS_MT_SMTC_IRQAFF
46 .set_affinity = plat_set_irq_affinity,
47 #endif /* CONFIG_MIPS_MT_SMTC_IRQAFF */
51 * 8259A PIC functions to handle ISA devices:
55 * This contains the irq mask for both 8259A irq controllers,
57 static unsigned int cached_irq_mask = 0xffff;
59 #define cached_master_mask (cached_irq_mask)
60 #define cached_slave_mask (cached_irq_mask >> 8)
62 static void disable_8259A_irq(unsigned int irq)
67 irq -= I8259A_IRQ_BASE;
69 raw_spin_lock_irqsave(&i8259A_lock, flags);
70 cached_irq_mask |= mask;
72 outb(cached_slave_mask, PIC_SLAVE_IMR);
74 outb(cached_master_mask, PIC_MASTER_IMR);
75 raw_spin_unlock_irqrestore(&i8259A_lock, flags);
78 static void enable_8259A_irq(unsigned int irq)
83 irq -= I8259A_IRQ_BASE;
85 raw_spin_lock_irqsave(&i8259A_lock, flags);
86 cached_irq_mask &= mask;
88 outb(cached_slave_mask, PIC_SLAVE_IMR);
90 outb(cached_master_mask, PIC_MASTER_IMR);
91 raw_spin_unlock_irqrestore(&i8259A_lock, flags);
94 int i8259A_irq_pending(unsigned int irq)
100 irq -= I8259A_IRQ_BASE;
102 raw_spin_lock_irqsave(&i8259A_lock, flags);
104 ret = inb(PIC_MASTER_CMD) & mask;
106 ret = inb(PIC_SLAVE_CMD) & (mask >> 8);
107 raw_spin_unlock_irqrestore(&i8259A_lock, flags);
112 void make_8259A_irq(unsigned int irq)
114 disable_irq_nosync(irq);
115 set_irq_chip_and_handler(irq, &i8259A_chip, handle_level_irq);
120 * This function assumes to be called rarely. Switching between
121 * 8259A registers is slow.
122 * This has to be protected by the irq controller spinlock
123 * before being called.
125 static inline int i8259A_irq_real(unsigned int irq)
128 int irqmask = 1 << irq;
131 outb(0x0B, PIC_MASTER_CMD); /* ISR register */
132 value = inb(PIC_MASTER_CMD) & irqmask;
133 outb(0x0A, PIC_MASTER_CMD); /* back to the IRR register */
136 outb(0x0B, PIC_SLAVE_CMD); /* ISR register */
137 value = inb(PIC_SLAVE_CMD) & (irqmask >> 8);
138 outb(0x0A, PIC_SLAVE_CMD); /* back to the IRR register */
143 * Careful! The 8259A is a fragile beast, it pretty
144 * much _has_ to be done exactly like this (mask it
145 * first, _then_ send the EOI, and the order of EOI
146 * to the two 8259s is important!
148 static void mask_and_ack_8259A(unsigned int irq)
150 unsigned int irqmask;
153 irq -= I8259A_IRQ_BASE;
155 raw_spin_lock_irqsave(&i8259A_lock, flags);
157 * Lightweight spurious IRQ detection. We do not want
158 * to overdo spurious IRQ handling - it's usually a sign
159 * of hardware problems, so we only do the checks we can
160 * do without slowing down good hardware unnecessarily.
162 * Note that IRQ7 and IRQ15 (the two spurious IRQs
163 * usually resulting from the 8259A-1|2 PICs) occur
164 * even if the IRQ is masked in the 8259A. Thus we
165 * can check spurious 8259A IRQs without doing the
166 * quite slow i8259A_irq_real() call for every IRQ.
167 * This does not cover 100% of spurious interrupts,
168 * but should be enough to warn the user that there
169 * is something bad going on ...
171 if (cached_irq_mask & irqmask)
172 goto spurious_8259A_irq;
173 cached_irq_mask |= irqmask;
177 inb(PIC_SLAVE_IMR); /* DUMMY - (do we need this?) */
178 outb(cached_slave_mask, PIC_SLAVE_IMR);
179 outb(0x60+(irq&7), PIC_SLAVE_CMD);/* 'Specific EOI' to slave */
180 outb(0x60+PIC_CASCADE_IR, PIC_MASTER_CMD); /* 'Specific EOI' to master-IRQ2 */
182 inb(PIC_MASTER_IMR); /* DUMMY - (do we need this?) */
183 outb(cached_master_mask, PIC_MASTER_IMR);
184 outb(0x60+irq, PIC_MASTER_CMD); /* 'Specific EOI to master */
186 smtc_im_ack_irq(irq);
187 raw_spin_unlock_irqrestore(&i8259A_lock, flags);
192 * this is the slow path - should happen rarely.
194 if (i8259A_irq_real(irq))
196 * oops, the IRQ _is_ in service according to the
197 * 8259A - not spurious, go handle it.
199 goto handle_real_irq;
202 static int spurious_irq_mask;
204 * At this point we can be sure the IRQ is spurious,
205 * lets ACK and report it. [once per IRQ]
207 if (!(spurious_irq_mask & irqmask)) {
208 printk(KERN_DEBUG "spurious 8259A interrupt: IRQ%d.\n", irq);
209 spurious_irq_mask |= irqmask;
211 atomic_inc(&irq_err_count);
213 * Theoretically we do not have to handle this IRQ,
214 * but in Linux this does not cause problems and is
217 goto handle_real_irq;
221 static int i8259A_resume(struct sys_device *dev)
223 if (i8259A_auto_eoi >= 0)
224 init_8259A(i8259A_auto_eoi);
228 static int i8259A_shutdown(struct sys_device *dev)
230 /* Put the i8259A into a quiescent state that
231 * the kernel initialization code can get it
234 if (i8259A_auto_eoi >= 0) {
235 outb(0xff, PIC_MASTER_IMR); /* mask all of 8259A-1 */
236 outb(0xff, PIC_SLAVE_IMR); /* mask all of 8259A-1 */
241 static struct sysdev_class i8259_sysdev_class = {
243 .resume = i8259A_resume,
244 .shutdown = i8259A_shutdown,
247 static struct sys_device device_i8259A = {
249 .cls = &i8259_sysdev_class,
252 static int __init i8259A_init_sysfs(void)
254 int error = sysdev_class_register(&i8259_sysdev_class);
256 error = sysdev_register(&device_i8259A);
260 device_initcall(i8259A_init_sysfs);
262 static void init_8259A(int auto_eoi)
266 i8259A_auto_eoi = auto_eoi;
268 raw_spin_lock_irqsave(&i8259A_lock, flags);
270 outb(0xff, PIC_MASTER_IMR); /* mask all of 8259A-1 */
271 outb(0xff, PIC_SLAVE_IMR); /* mask all of 8259A-2 */
274 * outb_p - this has to work on a wide range of PC hardware.
276 outb_p(0x11, PIC_MASTER_CMD); /* ICW1: select 8259A-1 init */
277 outb_p(I8259A_IRQ_BASE + 0, PIC_MASTER_IMR); /* ICW2: 8259A-1 IR0 mapped to I8259A_IRQ_BASE + 0x00 */
278 outb_p(1U << PIC_CASCADE_IR, PIC_MASTER_IMR); /* 8259A-1 (the master) has a slave on IR2 */
279 if (auto_eoi) /* master does Auto EOI */
280 outb_p(MASTER_ICW4_DEFAULT | PIC_ICW4_AEOI, PIC_MASTER_IMR);
281 else /* master expects normal EOI */
282 outb_p(MASTER_ICW4_DEFAULT, PIC_MASTER_IMR);
284 outb_p(0x11, PIC_SLAVE_CMD); /* ICW1: select 8259A-2 init */
285 outb_p(I8259A_IRQ_BASE + 8, PIC_SLAVE_IMR); /* ICW2: 8259A-2 IR0 mapped to I8259A_IRQ_BASE + 0x08 */
286 outb_p(PIC_CASCADE_IR, PIC_SLAVE_IMR); /* 8259A-2 is a slave on master's IR2 */
287 outb_p(SLAVE_ICW4_DEFAULT, PIC_SLAVE_IMR); /* (slave's support for AEOI in flat mode is to be investigated) */
290 * In AEOI mode we just have to mask the interrupt
293 i8259A_chip.mask_ack = disable_8259A_irq;
295 i8259A_chip.mask_ack = mask_and_ack_8259A;
297 udelay(100); /* wait for 8259A to initialize */
299 outb(cached_master_mask, PIC_MASTER_IMR); /* restore master IRQ mask */
300 outb(cached_slave_mask, PIC_SLAVE_IMR); /* restore slave IRQ mask */
302 raw_spin_unlock_irqrestore(&i8259A_lock, flags);
306 * IRQ2 is cascade interrupt to second interrupt controller
308 static struct irqaction irq2 = {
309 .handler = no_action,
313 static struct resource pic1_io_resource = {
315 .start = PIC_MASTER_CMD,
316 .end = PIC_MASTER_IMR,
317 .flags = IORESOURCE_BUSY
320 static struct resource pic2_io_resource = {
322 .start = PIC_SLAVE_CMD,
323 .end = PIC_SLAVE_IMR,
324 .flags = IORESOURCE_BUSY
328 * On systems with i8259-style interrupt controllers we assume for
329 * driver compatibility reasons interrupts 0 - 15 to be the i8259
330 * interrupts even if the hardware uses a different interrupt numbering.
332 void __init init_i8259_irqs(void)
336 insert_resource(&ioport_resource, &pic1_io_resource);
337 insert_resource(&ioport_resource, &pic2_io_resource);
341 for (i = I8259A_IRQ_BASE; i < I8259A_IRQ_BASE + 16; i++) {
342 set_irq_chip_and_handler(i, &i8259A_chip, handle_level_irq);
346 setup_irq(I8259A_IRQ_BASE + PIC_CASCADE_IR, &irq2);