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/syscore_ops.h>
18 #include <linux/irq.h>
19
20 #include <asm/i8259.h>
21 #include <asm/io.h>
22
23 /*
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
27 * any sense at all.
28 * this file should become arch/i386/kernel/irq.c when the old irq.c
29 * moves to arch independent land
30 */
31
32 static int i8259A_auto_eoi = -1;
33 DEFINE_RAW_SPINLOCK(i8259A_lock);
34 static void disable_8259A_irq(struct irq_data *d);
35 static void enable_8259A_irq(struct irq_data *d);
36 static void mask_and_ack_8259A(struct irq_data *d);
37 static void init_8259A(int auto_eoi);
38
39 static struct irq_chip i8259A_chip = {
40 .name = "XT-PIC",
41 .irq_mask = disable_8259A_irq,
42 .irq_disable = disable_8259A_irq,
43 .irq_unmask = enable_8259A_irq,
44 .irq_mask_ack = mask_and_ack_8259A,
45 #ifdef CONFIG_MIPS_MT_SMTC_IRQAFF
46 .irq_set_affinity = plat_set_irq_affinity,
47 #endif /* CONFIG_MIPS_MT_SMTC_IRQAFF */
48 };
49
50 /*
51 * 8259A PIC functions to handle ISA devices:
52 */
53
54 /*
55 * This contains the irq mask for both 8259A irq controllers,
56 */
57 static unsigned int cached_irq_mask = 0xffff;
58
59 #define cached_master_mask (cached_irq_mask)
60 #define cached_slave_mask (cached_irq_mask >> 8)
61
disable_8259A_irq(struct irq_data * d)62 static void disable_8259A_irq(struct irq_data *d)
63 {
64 unsigned int mask, irq = d->irq - I8259A_IRQ_BASE;
65 unsigned long flags;
66
67 mask = 1 << irq;
68 raw_spin_lock_irqsave(&i8259A_lock, flags);
69 cached_irq_mask |= mask;
70 if (irq & 8)
71 outb(cached_slave_mask, PIC_SLAVE_IMR);
72 else
73 outb(cached_master_mask, PIC_MASTER_IMR);
74 raw_spin_unlock_irqrestore(&i8259A_lock, flags);
75 }
76
enable_8259A_irq(struct irq_data * d)77 static void enable_8259A_irq(struct irq_data *d)
78 {
79 unsigned int mask, irq = d->irq - I8259A_IRQ_BASE;
80 unsigned long flags;
81
82 mask = ~(1 << irq);
83 raw_spin_lock_irqsave(&i8259A_lock, flags);
84 cached_irq_mask &= mask;
85 if (irq & 8)
86 outb(cached_slave_mask, PIC_SLAVE_IMR);
87 else
88 outb(cached_master_mask, PIC_MASTER_IMR);
89 raw_spin_unlock_irqrestore(&i8259A_lock, flags);
90 }
91
i8259A_irq_pending(unsigned int irq)92 int i8259A_irq_pending(unsigned int irq)
93 {
94 unsigned int mask;
95 unsigned long flags;
96 int ret;
97
98 irq -= I8259A_IRQ_BASE;
99 mask = 1 << irq;
100 raw_spin_lock_irqsave(&i8259A_lock, flags);
101 if (irq < 8)
102 ret = inb(PIC_MASTER_CMD) & mask;
103 else
104 ret = inb(PIC_SLAVE_CMD) & (mask >> 8);
105 raw_spin_unlock_irqrestore(&i8259A_lock, flags);
106
107 return ret;
108 }
109
make_8259A_irq(unsigned int irq)110 void make_8259A_irq(unsigned int irq)
111 {
112 disable_irq_nosync(irq);
113 irq_set_chip_and_handler(irq, &i8259A_chip, handle_level_irq);
114 enable_irq(irq);
115 }
116
117 /*
118 * This function assumes to be called rarely. Switching between
119 * 8259A registers is slow.
120 * This has to be protected by the irq controller spinlock
121 * before being called.
122 */
i8259A_irq_real(unsigned int irq)123 static inline int i8259A_irq_real(unsigned int irq)
124 {
125 int value;
126 int irqmask = 1 << irq;
127
128 if (irq < 8) {
129 outb(0x0B, PIC_MASTER_CMD); /* ISR register */
130 value = inb(PIC_MASTER_CMD) & irqmask;
131 outb(0x0A, PIC_MASTER_CMD); /* back to the IRR register */
132 return value;
133 }
134 outb(0x0B, PIC_SLAVE_CMD); /* ISR register */
135 value = inb(PIC_SLAVE_CMD) & (irqmask >> 8);
136 outb(0x0A, PIC_SLAVE_CMD); /* back to the IRR register */
137 return value;
138 }
139
140 /*
141 * Careful! The 8259A is a fragile beast, it pretty
142 * much _has_ to be done exactly like this (mask it
143 * first, _then_ send the EOI, and the order of EOI
144 * to the two 8259s is important!
145 */
mask_and_ack_8259A(struct irq_data * d)146 static void mask_and_ack_8259A(struct irq_data *d)
147 {
148 unsigned int irqmask, irq = d->irq - I8259A_IRQ_BASE;
149 unsigned long flags;
150
151 irqmask = 1 << irq;
152 raw_spin_lock_irqsave(&i8259A_lock, flags);
153 /*
154 * Lightweight spurious IRQ detection. We do not want
155 * to overdo spurious IRQ handling - it's usually a sign
156 * of hardware problems, so we only do the checks we can
157 * do without slowing down good hardware unnecessarily.
158 *
159 * Note that IRQ7 and IRQ15 (the two spurious IRQs
160 * usually resulting from the 8259A-1|2 PICs) occur
161 * even if the IRQ is masked in the 8259A. Thus we
162 * can check spurious 8259A IRQs without doing the
163 * quite slow i8259A_irq_real() call for every IRQ.
164 * This does not cover 100% of spurious interrupts,
165 * but should be enough to warn the user that there
166 * is something bad going on ...
167 */
168 if (cached_irq_mask & irqmask)
169 goto spurious_8259A_irq;
170 cached_irq_mask |= irqmask;
171
172 handle_real_irq:
173 if (irq & 8) {
174 inb(PIC_SLAVE_IMR); /* DUMMY - (do we need this?) */
175 outb(cached_slave_mask, PIC_SLAVE_IMR);
176 outb(0x60+(irq&7), PIC_SLAVE_CMD);/* 'Specific EOI' to slave */
177 outb(0x60+PIC_CASCADE_IR, PIC_MASTER_CMD); /* 'Specific EOI' to master-IRQ2 */
178 } else {
179 inb(PIC_MASTER_IMR); /* DUMMY - (do we need this?) */
180 outb(cached_master_mask, PIC_MASTER_IMR);
181 outb(0x60+irq, PIC_MASTER_CMD); /* 'Specific EOI to master */
182 }
183 smtc_im_ack_irq(irq);
184 raw_spin_unlock_irqrestore(&i8259A_lock, flags);
185 return;
186
187 spurious_8259A_irq:
188 /*
189 * this is the slow path - should happen rarely.
190 */
191 if (i8259A_irq_real(irq))
192 /*
193 * oops, the IRQ _is_ in service according to the
194 * 8259A - not spurious, go handle it.
195 */
196 goto handle_real_irq;
197
198 {
199 static int spurious_irq_mask;
200 /*
201 * At this point we can be sure the IRQ is spurious,
202 * lets ACK and report it. [once per IRQ]
203 */
204 if (!(spurious_irq_mask & irqmask)) {
205 printk(KERN_DEBUG "spurious 8259A interrupt: IRQ%d.\n", irq);
206 spurious_irq_mask |= irqmask;
207 }
208 atomic_inc(&irq_err_count);
209 /*
210 * Theoretically we do not have to handle this IRQ,
211 * but in Linux this does not cause problems and is
212 * simpler for us.
213 */
214 goto handle_real_irq;
215 }
216 }
217
i8259A_resume(void)218 static void i8259A_resume(void)
219 {
220 if (i8259A_auto_eoi >= 0)
221 init_8259A(i8259A_auto_eoi);
222 }
223
i8259A_shutdown(void)224 static void i8259A_shutdown(void)
225 {
226 /* Put the i8259A into a quiescent state that
227 * the kernel initialization code can get it
228 * out of.
229 */
230 if (i8259A_auto_eoi >= 0) {
231 outb(0xff, PIC_MASTER_IMR); /* mask all of 8259A-1 */
232 outb(0xff, PIC_SLAVE_IMR); /* mask all of 8259A-2 */
233 }
234 }
235
236 static struct syscore_ops i8259_syscore_ops = {
237 .resume = i8259A_resume,
238 .shutdown = i8259A_shutdown,
239 };
240
i8259A_init_sysfs(void)241 static int __init i8259A_init_sysfs(void)
242 {
243 register_syscore_ops(&i8259_syscore_ops);
244 return 0;
245 }
246
247 device_initcall(i8259A_init_sysfs);
248
init_8259A(int auto_eoi)249 static void init_8259A(int auto_eoi)
250 {
251 unsigned long flags;
252
253 i8259A_auto_eoi = auto_eoi;
254
255 raw_spin_lock_irqsave(&i8259A_lock, flags);
256
257 outb(0xff, PIC_MASTER_IMR); /* mask all of 8259A-1 */
258 outb(0xff, PIC_SLAVE_IMR); /* 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, PIC_MASTER_CMD); /* ICW1: select 8259A-1 init */
264 outb_p(I8259A_IRQ_BASE + 0, PIC_MASTER_IMR); /* ICW2: 8259A-1 IR0 mapped to I8259A_IRQ_BASE + 0x00 */
265 outb_p(1U << PIC_CASCADE_IR, PIC_MASTER_IMR); /* 8259A-1 (the master) has a slave on IR2 */
266 if (auto_eoi) /* master does Auto EOI */
267 outb_p(MASTER_ICW4_DEFAULT | PIC_ICW4_AEOI, PIC_MASTER_IMR);
268 else /* master expects normal EOI */
269 outb_p(MASTER_ICW4_DEFAULT, PIC_MASTER_IMR);
270
271 outb_p(0x11, PIC_SLAVE_CMD); /* ICW1: select 8259A-2 init */
272 outb_p(I8259A_IRQ_BASE + 8, PIC_SLAVE_IMR); /* ICW2: 8259A-2 IR0 mapped to I8259A_IRQ_BASE + 0x08 */
273 outb_p(PIC_CASCADE_IR, PIC_SLAVE_IMR); /* 8259A-2 is a slave on master's IR2 */
274 outb_p(SLAVE_ICW4_DEFAULT, PIC_SLAVE_IMR); /* (slave's support for AEOI in flat mode is to be investigated) */
275 if (auto_eoi)
276 /*
277 * In AEOI mode we just have to mask the interrupt
278 * when acking.
279 */
280 i8259A_chip.irq_mask_ack = disable_8259A_irq;
281 else
282 i8259A_chip.irq_mask_ack = mask_and_ack_8259A;
283
284 udelay(100); /* wait for 8259A to initialize */
285
286 outb(cached_master_mask, PIC_MASTER_IMR); /* restore master IRQ mask */
287 outb(cached_slave_mask, PIC_SLAVE_IMR); /* restore slave IRQ mask */
288
289 raw_spin_unlock_irqrestore(&i8259A_lock, flags);
290 }
291
292 /*
293 * IRQ2 is cascade interrupt to second interrupt controller
294 */
295 static struct irqaction irq2 = {
296 .handler = no_action,
297 .name = "cascade",
298 .flags = IRQF_NO_THREAD,
299 };
300
301 static struct resource pic1_io_resource = {
302 .name = "pic1",
303 .start = PIC_MASTER_CMD,
304 .end = PIC_MASTER_IMR,
305 .flags = IORESOURCE_BUSY
306 };
307
308 static struct resource pic2_io_resource = {
309 .name = "pic2",
310 .start = PIC_SLAVE_CMD,
311 .end = PIC_SLAVE_IMR,
312 .flags = IORESOURCE_BUSY
313 };
314
315 /*
316 * On systems with i8259-style interrupt controllers we assume for
317 * driver compatibility reasons interrupts 0 - 15 to be the i8259
318 * interrupts even if the hardware uses a different interrupt numbering.
319 */
init_i8259_irqs(void)320 void __init init_i8259_irqs(void)
321 {
322 int i;
323
324 insert_resource(&ioport_resource, &pic1_io_resource);
325 insert_resource(&ioport_resource, &pic2_io_resource);
326
327 init_8259A(0);
328
329 for (i = I8259A_IRQ_BASE; i < I8259A_IRQ_BASE + 16; i++) {
330 irq_set_chip_and_handler(i, &i8259A_chip, handle_level_irq);
331 irq_set_probe(i);
332 }
333
334 setup_irq(I8259A_IRQ_BASE + PIC_CASCADE_IR, &irq2);
335 }
336