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1/*
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
4 * for more details.
5 *
6 * Code to handle x86 style IRQs plus some generic interrupt stuff.
7 *
8 * Copyright (C) 1992 Linus Torvalds
9 * Copyright (C) 1994 - 2000 Ralf Baechle
10 */
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
19#include <asm/i8259.h>
20#include <asm/io.h>
21
22void enable_8259A_irq(unsigned int irq);
23void disable_8259A_irq(unsigned int irq);
24
25/*
26 * This is the 'legacy' 8259A Programmable Interrupt Controller,
27 * present in the majority of PC/AT boxes.
28 * plus some generic x86 specific things if generic specifics makes
29 * any sense at all.
30 * this file should become arch/i386/kernel/irq.c when the old irq.c
31 * moves to arch independent land
32 */
33
34spinlock_t i8259A_lock = SPIN_LOCK_UNLOCKED;
35
36static void end_8259A_irq (unsigned int irq)
37{
38 if (!(irq_desc[irq].status & (IRQ_DISABLED|IRQ_INPROGRESS)) &&
39 irq_desc[irq].action)
40 enable_8259A_irq(irq);
41}
42
43#define shutdown_8259A_irq disable_8259A_irq
44
45void mask_and_ack_8259A(unsigned int);
46
47static unsigned int startup_8259A_irq(unsigned int irq)
48{
49 enable_8259A_irq(irq);
50
51 return 0; /* never anything pending */
52}
53
54static struct hw_interrupt_type i8259A_irq_type = {
55 "XT-PIC",
56 startup_8259A_irq,
57 shutdown_8259A_irq,
58 enable_8259A_irq,
59 disable_8259A_irq,
60 mask_and_ack_8259A,
61 end_8259A_irq,
62 NULL
63};
64
65/*
66 * 8259A PIC functions to handle ISA devices:
67 */
68
69/*
70 * This contains the irq mask for both 8259A irq controllers,
71 */
72static unsigned int cached_irq_mask = 0xffff;
73
74#define cached_21 (cached_irq_mask)
75#define cached_A1 (cached_irq_mask >> 8)
76
77void disable_8259A_irq(unsigned int irq)
78{
79 unsigned int mask = 1 << irq;
80 unsigned long flags;
81
82 spin_lock_irqsave(&i8259A_lock, flags);
83 cached_irq_mask |= mask;
84 if (irq & 8)
85 outb(cached_A1,0xA1);
86 else
87 outb(cached_21,0x21);
88 spin_unlock_irqrestore(&i8259A_lock, flags);
89}
90
91void enable_8259A_irq(unsigned int irq)
92{
93 unsigned int mask = ~(1 << irq);
94 unsigned long flags;
95
96 spin_lock_irqsave(&i8259A_lock, flags);
97 cached_irq_mask &= mask;
98 if (irq & 8)
99 outb(cached_A1,0xA1);
100 else
101 outb(cached_21,0x21);
102 spin_unlock_irqrestore(&i8259A_lock, flags);
103}
104
105int i8259A_irq_pending(unsigned int irq)
106{
107 unsigned int mask = 1 << irq;
108 unsigned long flags;
109 int ret;
110
111 spin_lock_irqsave(&i8259A_lock, flags);
112 if (irq < 8)
113 ret = inb(0x20) & mask;
114 else
115 ret = inb(0xA0) & (mask >> 8);
116 spin_unlock_irqrestore(&i8259A_lock, flags);
117
118 return ret;
119}
120
121void make_8259A_irq(unsigned int irq)
122{
123 disable_irq_nosync(irq);
124 irq_desc[irq].handler = &i8259A_irq_type;
125 enable_irq(irq);
126}
127
128/*
129 * This function assumes to be called rarely. Switching between
130 * 8259A registers is slow.
131 * This has to be protected by the irq controller spinlock
132 * before being called.
133 */
134static inline int i8259A_irq_real(unsigned int irq)
135{
136 int value;
137 int irqmask = 1 << irq;
138
139 if (irq < 8) {
140 outb(0x0B,0x20); /* ISR register */
141 value = inb(0x20) & irqmask;
142 outb(0x0A,0x20); /* back to the IRR register */
143 return value;
144 }
145 outb(0x0B,0xA0); /* ISR register */
146 value = inb(0xA0) & (irqmask >> 8);
147 outb(0x0A,0xA0); /* back to the IRR register */
148 return value;
149}
150
151/*
152 * Careful! The 8259A is a fragile beast, it pretty
153 * much _has_ to be done exactly like this (mask it
154 * first, _then_ send the EOI, and the order of EOI
155 * to the two 8259s is important!
156 */
157void mask_and_ack_8259A(unsigned int irq)
158{
159 unsigned int irqmask = 1 << irq;
160 unsigned long flags;
161
162 spin_lock_irqsave(&i8259A_lock, flags);
163 /*
164 * Lightweight spurious IRQ detection. We do not want to overdo
165 * spurious IRQ handling - it's usually a sign of hardware problems, so
166 * we only do the checks we can do without slowing down good hardware
167 * nnecesserily.
168 *
169 * Note that IRQ7 and IRQ15 (the two spurious IRQs usually resulting
170 * rom the 8259A-1|2 PICs) occur even if the IRQ is masked in the 8259A.
171 * Thus we can check spurious 8259A IRQs without doing the quite slow
172 * i8259A_irq_real() call for every IRQ. This does not cover 100% of
173 * spurious interrupts, but should be enough to warn the user that
174 * there is something bad going on ...
175 */
176 if (cached_irq_mask & irqmask)
177 goto spurious_8259A_irq;
178 cached_irq_mask |= irqmask;
179
180handle_real_irq:
181 if (irq & 8) {
182 inb(0xA1); /* DUMMY - (do we need this?) */
183 outb(cached_A1,0xA1);
184 outb(0x60+(irq&7),0xA0);/* 'Specific EOI' to slave */
185 outb(0x62,0x20); /* 'Specific EOI' to master-IRQ2 */
186 } else {
187 inb(0x21); /* DUMMY - (do we need this?) */
188 outb(cached_21,0x21);
189 outb(0x60+irq,0x20); /* 'Specific EOI' to master */
190 }
191 spin_unlock_irqrestore(&i8259A_lock, flags);
192 return;
193
194spurious_8259A_irq:
195 /*
196 * this is the slow path - should happen rarely.
197 */
198 if (i8259A_irq_real(irq))
199 /*
200 * oops, the IRQ _is_ in service according to the
201 * 8259A - not spurious, go handle it.
202 */
203 goto handle_real_irq;
204
205 {
206 static int spurious_irq_mask = 0;
207 /*
208 * At this point we can be sure the IRQ is spurious,
209 * lets ACK and report it. [once per IRQ]
210 */
211 if (!(spurious_irq_mask & irqmask)) {
212 printk(KERN_DEBUG "spurious 8259A interrupt: IRQ%d.\n", irq);
213 spurious_irq_mask |= irqmask;
214 }
215 atomic_inc(&irq_err_count);
216 /*
217 * Theoretically we do not have to handle this IRQ,
218 * but in Linux this does not cause problems and is
219 * simpler for us.
220 */
221 goto handle_real_irq;
222 }
223}
224
225static int i8259A_resume(struct sys_device *dev)
226{
227 init_8259A(0);
228 return 0;
229}
230
231static struct sysdev_class i8259_sysdev_class = {
232 set_kset_name("i8259"),
233 .resume = i8259A_resume,
234};
235
236static struct sys_device device_i8259A = {
237 .id = 0,
238 .cls = &i8259_sysdev_class,
239};
240
241static int __init i8259A_init_sysfs(void)
242{
243 int error = sysdev_class_register(&i8259_sysdev_class);
244 if (!error)
245 error = sysdev_register(&device_i8259A);
246 return error;
247}
248
249device_initcall(i8259A_init_sysfs);
250
251void __init init_8259A(int auto_eoi)
252{
253 unsigned long flags;
254
255 spin_lock_irqsave(&i8259A_lock, flags);
256
257 outb(0xff, 0x21); /* mask all of 8259A-1 */
258 outb(0xff, 0xA1); /* mask all of 8259A-2 */
259
260 /*
261 * outb_p - this has to work on a wide range of PC hardware.
262 */
263 outb_p(0x11, 0x20); /* ICW1: select 8259A-1 init */
264 outb_p(0x00, 0x21); /* ICW2: 8259A-1 IR0-7 mapped to 0x00-0x07 */
265 outb_p(0x04, 0x21); /* 8259A-1 (the master) has a slave on IR2 */
266 if (auto_eoi)
267 outb_p(0x03, 0x21); /* master does Auto EOI */
268 else
269 outb_p(0x01, 0x21); /* master expects normal EOI */
270
271 outb_p(0x11, 0xA0); /* ICW1: select 8259A-2 init */
272 outb_p(0x08, 0xA1); /* ICW2: 8259A-2 IR0-7 mapped to 0x08-0x0f */
273 outb_p(0x02, 0xA1); /* 8259A-2 is a slave on master's IR2 */
274 outb_p(0x01, 0xA1); /* (slave's support for AEOI in flat mode
275 is to be investigated) */
276
277 if (auto_eoi)
278 /*
279 * in AEOI mode we just have to mask the interrupt
280 * when acking.
281 */
282 i8259A_irq_type.ack = disable_8259A_irq;
283 else
284 i8259A_irq_type.ack = mask_and_ack_8259A;
285
286 udelay(100); /* wait for 8259A to initialize */
287
288 outb(cached_21, 0x21); /* restore master IRQ mask */
289 outb(cached_A1, 0xA1); /* restore slave IRQ mask */
290
291 spin_unlock_irqrestore(&i8259A_lock, flags);
292}
293
294/*
295 * IRQ2 is cascade interrupt to second interrupt controller
296 */
297static struct irqaction irq2 = {
298 no_action, 0, CPU_MASK_NONE, "cascade", NULL, NULL
299};
300
301static struct resource pic1_io_resource = {
302 "pic1", 0x20, 0x3f, IORESOURCE_BUSY
303};
304
305static struct resource pic2_io_resource = {
306 "pic2", 0xa0, 0xbf, IORESOURCE_BUSY
307};
308
309/*
310 * On systems with i8259-style interrupt controllers we assume for
311 * driver compatibility reasons interrupts 0 - 15 to be the i8295
312 * interrupts even if the hardware uses a different interrupt numbering.
313 */
314void __init init_i8259_irqs (void)
315{
316 int i;
317
318 request_resource(&ioport_resource, &pic1_io_resource);
319 request_resource(&ioport_resource, &pic2_io_resource);
320
321 init_8259A(0);
322
323 for (i = 0; i < 16; i++) {
324 irq_desc[i].status = IRQ_DISABLED;
325 irq_desc[i].action = 0;
326 irq_desc[i].depth = 1;
327 irq_desc[i].handler = &i8259A_irq_type;
328 }
329
330 setup_irq(2, &irq2);
331}