1 /*
2 * i8259 interrupt controller driver.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version
7 * 2 of the License, or (at your option) any later version.
8 */
9 #undef DEBUG
10
11 #include <linux/init.h>
12 #include <linux/ioport.h>
13 #include <linux/interrupt.h>
14 #include <linux/kernel.h>
15 #include <linux/delay.h>
16 #include <asm/io.h>
17 #include <asm/i8259.h>
18 #include <asm/prom.h>
19
20 static volatile void __iomem *pci_intack; /* RO, gives us the irq vector */
21
22 static unsigned char cached_8259[2] = { 0xff, 0xff };
23 #define cached_A1 (cached_8259[0])
24 #define cached_21 (cached_8259[1])
25
26 static DEFINE_SPINLOCK(i8259_lock);
27
28 static struct irq_host *i8259_host;
29
30 /*
31 * Acknowledge the IRQ using either the PCI host bridge's interrupt
32 * acknowledge feature or poll. How i8259_init() is called determines
33 * which is called. It should be noted that polling is broken on some
34 * IBM and Motorola PReP boxes so we must use the int-ack feature on them.
35 */
i8259_irq(void)36 unsigned int i8259_irq(void)
37 {
38 int irq;
39 int lock = 0;
40
41 /* Either int-ack or poll for the IRQ */
42 if (pci_intack)
43 irq = readb(pci_intack);
44 else {
45 spin_lock(&i8259_lock);
46 lock = 1;
47
48 /* Perform an interrupt acknowledge cycle on controller 1. */
49 outb(0x0C, 0x20); /* prepare for poll */
50 irq = inb(0x20) & 7;
51 if (irq == 2 ) {
52 /*
53 * Interrupt is cascaded so perform interrupt
54 * acknowledge on controller 2.
55 */
56 outb(0x0C, 0xA0); /* prepare for poll */
57 irq = (inb(0xA0) & 7) + 8;
58 }
59 }
60
61 if (irq == 7) {
62 /*
63 * This may be a spurious interrupt.
64 *
65 * Read the interrupt status register (ISR). If the most
66 * significant bit is not set then there is no valid
67 * interrupt.
68 */
69 if (!pci_intack)
70 outb(0x0B, 0x20); /* ISR register */
71 if(~inb(0x20) & 0x80)
72 irq = NO_IRQ;
73 } else if (irq == 0xff)
74 irq = NO_IRQ;
75
76 if (lock)
77 spin_unlock(&i8259_lock);
78 return irq;
79 }
80
i8259_mask_and_ack_irq(unsigned int irq_nr)81 static void i8259_mask_and_ack_irq(unsigned int irq_nr)
82 {
83 unsigned long flags;
84
85 spin_lock_irqsave(&i8259_lock, flags);
86 if (irq_nr > 7) {
87 cached_A1 |= 1 << (irq_nr-8);
88 inb(0xA1); /* DUMMY */
89 outb(cached_A1, 0xA1);
90 outb(0x20, 0xA0); /* Non-specific EOI */
91 outb(0x20, 0x20); /* Non-specific EOI to cascade */
92 } else {
93 cached_21 |= 1 << irq_nr;
94 inb(0x21); /* DUMMY */
95 outb(cached_21, 0x21);
96 outb(0x20, 0x20); /* Non-specific EOI */
97 }
98 spin_unlock_irqrestore(&i8259_lock, flags);
99 }
100
i8259_set_irq_mask(int irq_nr)101 static void i8259_set_irq_mask(int irq_nr)
102 {
103 outb(cached_A1,0xA1);
104 outb(cached_21,0x21);
105 }
106
i8259_mask_irq(unsigned int irq_nr)107 static void i8259_mask_irq(unsigned int irq_nr)
108 {
109 unsigned long flags;
110
111 pr_debug("i8259_mask_irq(%d)\n", irq_nr);
112
113 spin_lock_irqsave(&i8259_lock, flags);
114 if (irq_nr < 8)
115 cached_21 |= 1 << irq_nr;
116 else
117 cached_A1 |= 1 << (irq_nr-8);
118 i8259_set_irq_mask(irq_nr);
119 spin_unlock_irqrestore(&i8259_lock, flags);
120 }
121
i8259_unmask_irq(unsigned int irq_nr)122 static void i8259_unmask_irq(unsigned int irq_nr)
123 {
124 unsigned long flags;
125
126 pr_debug("i8259_unmask_irq(%d)\n", irq_nr);
127
128 spin_lock_irqsave(&i8259_lock, flags);
129 if (irq_nr < 8)
130 cached_21 &= ~(1 << irq_nr);
131 else
132 cached_A1 &= ~(1 << (irq_nr-8));
133 i8259_set_irq_mask(irq_nr);
134 spin_unlock_irqrestore(&i8259_lock, flags);
135 }
136
137 static struct irq_chip i8259_pic = {
138 .typename = " i8259 ",
139 .mask = i8259_mask_irq,
140 .disable = i8259_mask_irq,
141 .unmask = i8259_unmask_irq,
142 .mask_ack = i8259_mask_and_ack_irq,
143 };
144
145 static struct resource pic1_iores = {
146 .name = "8259 (master)",
147 .start = 0x20,
148 .end = 0x21,
149 .flags = IORESOURCE_BUSY,
150 };
151
152 static struct resource pic2_iores = {
153 .name = "8259 (slave)",
154 .start = 0xa0,
155 .end = 0xa1,
156 .flags = IORESOURCE_BUSY,
157 };
158
159 static struct resource pic_edgectrl_iores = {
160 .name = "8259 edge control",
161 .start = 0x4d0,
162 .end = 0x4d1,
163 .flags = IORESOURCE_BUSY,
164 };
165
i8259_host_match(struct irq_host * h,struct device_node * node)166 static int i8259_host_match(struct irq_host *h, struct device_node *node)
167 {
168 return h->of_node == NULL || h->of_node == node;
169 }
170
i8259_host_map(struct irq_host * h,unsigned int virq,irq_hw_number_t hw)171 static int i8259_host_map(struct irq_host *h, unsigned int virq,
172 irq_hw_number_t hw)
173 {
174 pr_debug("i8259_host_map(%d, 0x%lx)\n", virq, hw);
175
176 /* We block the internal cascade */
177 if (hw == 2)
178 get_irq_desc(virq)->status |= IRQ_NOREQUEST;
179
180 /* We use the level handler only for now, we might want to
181 * be more cautious here but that works for now
182 */
183 get_irq_desc(virq)->status |= IRQ_LEVEL;
184 set_irq_chip_and_handler(virq, &i8259_pic, handle_level_irq);
185 return 0;
186 }
187
i8259_host_unmap(struct irq_host * h,unsigned int virq)188 static void i8259_host_unmap(struct irq_host *h, unsigned int virq)
189 {
190 /* Make sure irq is masked in hardware */
191 i8259_mask_irq(virq);
192
193 /* remove chip and handler */
194 set_irq_chip_and_handler(virq, NULL, NULL);
195
196 /* Make sure it's completed */
197 synchronize_irq(virq);
198 }
199
i8259_host_xlate(struct irq_host * h,struct device_node * ct,u32 * intspec,unsigned int intsize,irq_hw_number_t * out_hwirq,unsigned int * out_flags)200 static int i8259_host_xlate(struct irq_host *h, struct device_node *ct,
201 u32 *intspec, unsigned int intsize,
202 irq_hw_number_t *out_hwirq, unsigned int *out_flags)
203 {
204 static unsigned char map_isa_senses[4] = {
205 IRQ_TYPE_LEVEL_LOW,
206 IRQ_TYPE_LEVEL_HIGH,
207 IRQ_TYPE_EDGE_FALLING,
208 IRQ_TYPE_EDGE_RISING,
209 };
210
211 *out_hwirq = intspec[0];
212 if (intsize > 1 && intspec[1] < 4)
213 *out_flags = map_isa_senses[intspec[1]];
214 else
215 *out_flags = IRQ_TYPE_NONE;
216
217 return 0;
218 }
219
220 static struct irq_host_ops i8259_host_ops = {
221 .match = i8259_host_match,
222 .map = i8259_host_map,
223 .unmap = i8259_host_unmap,
224 .xlate = i8259_host_xlate,
225 };
226
i8259_get_host(void)227 struct irq_host *i8259_get_host(void)
228 {
229 return i8259_host;
230 }
231
232 /**
233 * i8259_init - Initialize the legacy controller
234 * @node: device node of the legacy PIC (can be NULL, but then, it will match
235 * all interrupts, so beware)
236 * @intack_addr: PCI interrupt acknowledge (real) address which will return
237 * the active irq from the 8259
238 */
i8259_init(struct device_node * node,unsigned long intack_addr)239 void i8259_init(struct device_node *node, unsigned long intack_addr)
240 {
241 unsigned long flags;
242
243 /* initialize the controller */
244 spin_lock_irqsave(&i8259_lock, flags);
245
246 /* Mask all first */
247 outb(0xff, 0xA1);
248 outb(0xff, 0x21);
249
250 /* init master interrupt controller */
251 outb(0x11, 0x20); /* Start init sequence */
252 outb(0x00, 0x21); /* Vector base */
253 outb(0x04, 0x21); /* edge tiggered, Cascade (slave) on IRQ2 */
254 outb(0x01, 0x21); /* Select 8086 mode */
255
256 /* init slave interrupt controller */
257 outb(0x11, 0xA0); /* Start init sequence */
258 outb(0x08, 0xA1); /* Vector base */
259 outb(0x02, 0xA1); /* edge triggered, Cascade (slave) on IRQ2 */
260 outb(0x01, 0xA1); /* Select 8086 mode */
261
262 /* That thing is slow */
263 udelay(100);
264
265 /* always read ISR */
266 outb(0x0B, 0x20);
267 outb(0x0B, 0xA0);
268
269 /* Unmask the internal cascade */
270 cached_21 &= ~(1 << 2);
271
272 /* Set interrupt masks */
273 outb(cached_A1, 0xA1);
274 outb(cached_21, 0x21);
275
276 spin_unlock_irqrestore(&i8259_lock, flags);
277
278 /* create a legacy host */
279 i8259_host = irq_alloc_host(node, IRQ_HOST_MAP_LEGACY,
280 0, &i8259_host_ops, 0);
281 if (i8259_host == NULL) {
282 printk(KERN_ERR "i8259: failed to allocate irq host !\n");
283 return;
284 }
285
286 /* reserve our resources */
287 /* XXX should we continue doing that ? it seems to cause problems
288 * with further requesting of PCI IO resources for that range...
289 * need to look into it.
290 */
291 request_resource(&ioport_resource, &pic1_iores);
292 request_resource(&ioport_resource, &pic2_iores);
293 request_resource(&ioport_resource, &pic_edgectrl_iores);
294
295 if (intack_addr != 0)
296 pci_intack = ioremap(intack_addr, 1);
297
298 printk(KERN_INFO "i8259 legacy interrupt controller initialized\n");
299 }
300