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