xref: /openbmc/linux/arch/powerpc/sysdev/i8259.c (revision e6f6390a)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * i8259 interrupt controller driver.
4  */
5 #undef DEBUG
6 
7 #include <linux/ioport.h>
8 #include <linux/interrupt.h>
9 #include <linux/irqdomain.h>
10 #include <linux/kernel.h>
11 #include <linux/delay.h>
12 #include <asm/io.h>
13 #include <asm/i8259.h>
14 
15 static volatile void __iomem *pci_intack; /* RO, gives us the irq vector */
16 
17 static unsigned char cached_8259[2] = { 0xff, 0xff };
18 #define cached_A1 (cached_8259[0])
19 #define cached_21 (cached_8259[1])
20 
21 static DEFINE_RAW_SPINLOCK(i8259_lock);
22 
23 static struct irq_domain *i8259_host;
24 
25 /*
26  * Acknowledge the IRQ using either the PCI host bridge's interrupt
27  * acknowledge feature or poll.  How i8259_init() is called determines
28  * which is called.  It should be noted that polling is broken on some
29  * IBM and Motorola PReP boxes so we must use the int-ack feature on them.
30  */
i8259_irq(void)31 unsigned int i8259_irq(void)
32 {
33 	int irq;
34 	int lock = 0;
35 
36 	/* Either int-ack or poll for the IRQ */
37 	if (pci_intack)
38 		irq = readb(pci_intack);
39 	else {
40 		raw_spin_lock(&i8259_lock);
41 		lock = 1;
42 
43 		/* Perform an interrupt acknowledge cycle on controller 1. */
44 		outb(0x0C, 0x20);		/* prepare for poll */
45 		irq = inb(0x20) & 7;
46 		if (irq == 2 ) {
47 			/*
48 			 * Interrupt is cascaded so perform interrupt
49 			 * acknowledge on controller 2.
50 			 */
51 			outb(0x0C, 0xA0);	/* prepare for poll */
52 			irq = (inb(0xA0) & 7) + 8;
53 		}
54 	}
55 
56 	if (irq == 7) {
57 		/*
58 		 * This may be a spurious interrupt.
59 		 *
60 		 * Read the interrupt status register (ISR). If the most
61 		 * significant bit is not set then there is no valid
62 		 * interrupt.
63 		 */
64 		if (!pci_intack)
65 			outb(0x0B, 0x20);	/* ISR register */
66 		if(~inb(0x20) & 0x80)
67 			irq = 0;
68 	} else if (irq == 0xff)
69 		irq = 0;
70 
71 	if (lock)
72 		raw_spin_unlock(&i8259_lock);
73 	return irq;
74 }
75 
i8259_mask_and_ack_irq(struct irq_data * d)76 static void i8259_mask_and_ack_irq(struct irq_data *d)
77 {
78 	unsigned long flags;
79 
80 	raw_spin_lock_irqsave(&i8259_lock, flags);
81 	if (d->irq > 7) {
82 		cached_A1 |= 1 << (d->irq-8);
83 		inb(0xA1); 	/* DUMMY */
84 		outb(cached_A1, 0xA1);
85 		outb(0x20, 0xA0);	/* Non-specific EOI */
86 		outb(0x20, 0x20);	/* Non-specific EOI to cascade */
87 	} else {
88 		cached_21 |= 1 << d->irq;
89 		inb(0x21); 	/* DUMMY */
90 		outb(cached_21, 0x21);
91 		outb(0x20, 0x20);	/* Non-specific EOI */
92 	}
93 	raw_spin_unlock_irqrestore(&i8259_lock, flags);
94 }
95 
i8259_set_irq_mask(int irq_nr)96 static void i8259_set_irq_mask(int irq_nr)
97 {
98 	outb(cached_A1,0xA1);
99 	outb(cached_21,0x21);
100 }
101 
i8259_mask_irq(struct irq_data * d)102 static void i8259_mask_irq(struct irq_data *d)
103 {
104 	unsigned long flags;
105 
106 	pr_debug("i8259_mask_irq(%d)\n", d->irq);
107 
108 	raw_spin_lock_irqsave(&i8259_lock, flags);
109 	if (d->irq < 8)
110 		cached_21 |= 1 << d->irq;
111 	else
112 		cached_A1 |= 1 << (d->irq-8);
113 	i8259_set_irq_mask(d->irq);
114 	raw_spin_unlock_irqrestore(&i8259_lock, flags);
115 }
116 
i8259_unmask_irq(struct irq_data * d)117 static void i8259_unmask_irq(struct irq_data *d)
118 {
119 	unsigned long flags;
120 
121 	pr_debug("i8259_unmask_irq(%d)\n", d->irq);
122 
123 	raw_spin_lock_irqsave(&i8259_lock, flags);
124 	if (d->irq < 8)
125 		cached_21 &= ~(1 << d->irq);
126 	else
127 		cached_A1 &= ~(1 << (d->irq-8));
128 	i8259_set_irq_mask(d->irq);
129 	raw_spin_unlock_irqrestore(&i8259_lock, flags);
130 }
131 
132 static struct irq_chip i8259_pic = {
133 	.name		= "i8259",
134 	.irq_mask	= i8259_mask_irq,
135 	.irq_disable	= i8259_mask_irq,
136 	.irq_unmask	= i8259_unmask_irq,
137 	.irq_mask_ack	= i8259_mask_and_ack_irq,
138 };
139 
140 static struct resource pic1_iores = {
141 	.name = "8259 (master)",
142 	.start = 0x20,
143 	.end = 0x21,
144 	.flags = IORESOURCE_IO | IORESOURCE_BUSY,
145 };
146 
147 static struct resource pic2_iores = {
148 	.name = "8259 (slave)",
149 	.start = 0xa0,
150 	.end = 0xa1,
151 	.flags = IORESOURCE_IO | IORESOURCE_BUSY,
152 };
153 
154 static struct resource pic_edgectrl_iores = {
155 	.name = "8259 edge control",
156 	.start = 0x4d0,
157 	.end = 0x4d1,
158 	.flags = IORESOURCE_IO | IORESOURCE_BUSY,
159 };
160 
i8259_host_match(struct irq_domain * h,struct device_node * node,enum irq_domain_bus_token bus_token)161 static int i8259_host_match(struct irq_domain *h, struct device_node *node,
162 			    enum irq_domain_bus_token bus_token)
163 {
164 	struct device_node *of_node = irq_domain_get_of_node(h);
165 	return of_node == NULL || of_node == node;
166 }
167 
i8259_host_map(struct irq_domain * h,unsigned int virq,irq_hw_number_t hw)168 static int i8259_host_map(struct irq_domain *h, unsigned int virq,
169 			  irq_hw_number_t hw)
170 {
171 	pr_debug("i8259_host_map(%d, 0x%lx)\n", virq, hw);
172 
173 	/* We block the internal cascade */
174 	if (hw == 2)
175 		irq_set_status_flags(virq, IRQ_NOREQUEST);
176 
177 	/* We use the level handler only for now, we might want to
178 	 * be more cautious here but that works for now
179 	 */
180 	irq_set_status_flags(virq, IRQ_LEVEL);
181 	irq_set_chip_and_handler(virq, &i8259_pic, handle_level_irq);
182 	return 0;
183 }
184 
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)185 static int i8259_host_xlate(struct irq_domain *h, struct device_node *ct,
186 			    const u32 *intspec, unsigned int intsize,
187 			    irq_hw_number_t *out_hwirq, unsigned int *out_flags)
188 {
189 	static unsigned char map_isa_senses[4] = {
190 		IRQ_TYPE_LEVEL_LOW,
191 		IRQ_TYPE_LEVEL_HIGH,
192 		IRQ_TYPE_EDGE_FALLING,
193 		IRQ_TYPE_EDGE_RISING,
194 	};
195 
196 	*out_hwirq = intspec[0];
197 	if (intsize > 1 && intspec[1] < 4)
198 		*out_flags = map_isa_senses[intspec[1]];
199 	else
200 		*out_flags = IRQ_TYPE_NONE;
201 
202 	return 0;
203 }
204 
205 static const struct irq_domain_ops i8259_host_ops = {
206 	.match = i8259_host_match,
207 	.map = i8259_host_map,
208 	.xlate = i8259_host_xlate,
209 };
210 
i8259_get_host(void)211 struct irq_domain *__init i8259_get_host(void)
212 {
213 	return i8259_host;
214 }
215 
216 /**
217  * i8259_init - Initialize the legacy controller
218  * @node: device node of the legacy PIC (can be NULL, but then, it will match
219  *        all interrupts, so beware)
220  * @intack_addr: PCI interrupt acknowledge (real) address which will return
221  *             	 the active irq from the 8259
222  */
i8259_init(struct device_node * node,unsigned long intack_addr)223 void i8259_init(struct device_node *node, unsigned long intack_addr)
224 {
225 	unsigned long flags;
226 
227 	/* initialize the controller */
228 	raw_spin_lock_irqsave(&i8259_lock, flags);
229 
230 	/* Mask all first */
231 	outb(0xff, 0xA1);
232 	outb(0xff, 0x21);
233 
234 	/* init master interrupt controller */
235 	outb(0x11, 0x20); /* Start init sequence */
236 	outb(0x00, 0x21); /* Vector base */
237 	outb(0x04, 0x21); /* edge triggered, Cascade (slave) on IRQ2 */
238 	outb(0x01, 0x21); /* Select 8086 mode */
239 
240 	/* init slave interrupt controller */
241 	outb(0x11, 0xA0); /* Start init sequence */
242 	outb(0x08, 0xA1); /* Vector base */
243 	outb(0x02, 0xA1); /* edge triggered, Cascade (slave) on IRQ2 */
244 	outb(0x01, 0xA1); /* Select 8086 mode */
245 
246 	/* That thing is slow */
247 	udelay(100);
248 
249 	/* always read ISR */
250 	outb(0x0B, 0x20);
251 	outb(0x0B, 0xA0);
252 
253 	/* Unmask the internal cascade */
254 	cached_21 &= ~(1 << 2);
255 
256 	/* Set interrupt masks */
257 	outb(cached_A1, 0xA1);
258 	outb(cached_21, 0x21);
259 
260 	raw_spin_unlock_irqrestore(&i8259_lock, flags);
261 
262 	/* create a legacy host */
263 	i8259_host = irq_domain_add_legacy(node, NR_IRQS_LEGACY, 0, 0,
264 					   &i8259_host_ops, NULL);
265 	if (i8259_host == NULL) {
266 		printk(KERN_ERR "i8259: failed to allocate irq host !\n");
267 		return;
268 	}
269 
270 	/* reserve our resources */
271 	/* XXX should we continue doing that ? it seems to cause problems
272 	 * with further requesting of PCI IO resources for that range...
273 	 * need to look into it.
274 	 */
275 	request_resource(&ioport_resource, &pic1_iores);
276 	request_resource(&ioport_resource, &pic2_iores);
277 	request_resource(&ioport_resource, &pic_edgectrl_iores);
278 
279 	if (intack_addr != 0)
280 		pci_intack = ioremap(intack_addr, 1);
281 
282 	printk(KERN_INFO "i8259 legacy interrupt controller initialized\n");
283 }
284