summaryrefslogtreecommitdiff
path: root/arch/alpha/kernel/irq_i8259.c
blob: 50bfec9b588ffbc8ba4d08a47c532bf5f0de7299 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
/*
 *      linux/arch/alpha/kernel/irq_i8259.c
 *
 * This is the 'legacy' 8259A Programmable Interrupt Controller,
 * present in the majority of PC/AT boxes.
 *
 * Started hacking from linux-2.3.30pre6/arch/i386/kernel/i8259.c.
 */

#include <linux/init.h>
#include <linux/cache.h>
#include <linux/sched.h>
#include <linux/irq.h>
#include <linux/interrupt.h>

#include <asm/io.h>

#include "proto.h"
#include "irq_impl.h"


/* Note mask bit is true for DISABLED irqs.  */
static unsigned int cached_irq_mask = 0xffff;
static DEFINE_SPINLOCK(i8259_irq_lock);

static inline void
i8259_update_irq_hw(unsigned int irq, unsigned long mask)
{
	int port = 0x21;
	if (irq & 8) mask >>= 8;
	if (irq & 8) port = 0xA1;
	outb(mask, port);
}

inline void
i8259a_enable_irq(unsigned int irq)
{
	spin_lock(&i8259_irq_lock);
	i8259_update_irq_hw(irq, cached_irq_mask &= ~(1 << irq));
	spin_unlock(&i8259_irq_lock);
}

static inline void
__i8259a_disable_irq(unsigned int irq)
{
	i8259_update_irq_hw(irq, cached_irq_mask |= 1 << irq);
}

void
i8259a_disable_irq(unsigned int irq)
{
	spin_lock(&i8259_irq_lock);
	__i8259a_disable_irq(irq);
	spin_unlock(&i8259_irq_lock);
}

void
i8259a_mask_and_ack_irq(unsigned int irq)
{
	spin_lock(&i8259_irq_lock);
	__i8259a_disable_irq(irq);

	/* Ack the interrupt making it the lowest priority.  */
	if (irq >= 8) {
		outb(0xE0 | (irq - 8), 0xa0);   /* ack the slave */
		irq = 2;
	}
	outb(0xE0 | irq, 0x20);			/* ack the master */
	spin_unlock(&i8259_irq_lock);
}

unsigned int
i8259a_startup_irq(unsigned int irq)
{
	i8259a_enable_irq(irq);
	return 0; /* never anything pending */
}

void
i8259a_end_irq(unsigned int irq)
{
	if (!(irq_desc[irq].status & (IRQ_DISABLED|IRQ_INPROGRESS)))
		i8259a_enable_irq(irq);
}

struct irq_chip i8259a_irq_type = {
	.typename	= "XT-PIC",
	.startup	= i8259a_startup_irq,
	.shutdown	= i8259a_disable_irq,
	.enable		= i8259a_enable_irq,
	.disable	= i8259a_disable_irq,
	.ack		= i8259a_mask_and_ack_irq,
	.end		= i8259a_end_irq,
};

void __init
init_i8259a_irqs(void)
{
	static struct irqaction cascade = {
		.handler	= no_action,
		.name		= "cascade",
	};

	long i;

	outb(0xff, 0x21);	/* mask all of 8259A-1 */
	outb(0xff, 0xA1);	/* mask all of 8259A-2 */

	for (i = 0; i < 16; i++) {
		irq_desc[i].status = IRQ_DISABLED;
		irq_desc[i].chip = &i8259a_irq_type;
	}

	setup_irq(2, &cascade);
}


#if defined(CONFIG_ALPHA_GENERIC)
# define IACK_SC	alpha_mv.iack_sc
#elif defined(CONFIG_ALPHA_APECS)
# define IACK_SC	APECS_IACK_SC
#elif defined(CONFIG_ALPHA_LCA)
# define IACK_SC	LCA_IACK_SC
#elif defined(CONFIG_ALPHA_CIA)
# define IACK_SC	CIA_IACK_SC
#elif defined(CONFIG_ALPHA_PYXIS)
# define IACK_SC	PYXIS_IACK_SC
#elif defined(CONFIG_ALPHA_TITAN)
# define IACK_SC	TITAN_IACK_SC
#elif defined(CONFIG_ALPHA_TSUNAMI)
# define IACK_SC	TSUNAMI_IACK_SC
#elif defined(CONFIG_ALPHA_IRONGATE)
# define IACK_SC        IRONGATE_IACK_SC
#endif
/* Note that CONFIG_ALPHA_POLARIS is intentionally left out here, since
   sys_rx164 wants to use isa_no_iack_sc_device_interrupt for some reason.  */

#if defined(IACK_SC)
void
isa_device_interrupt(unsigned long vector)
{
	/*
	 * Generate a PCI interrupt acknowledge cycle.  The PIC will
	 * respond with the interrupt vector of the highest priority
	 * interrupt that is pending.  The PALcode sets up the
	 * interrupts vectors such that irq level L generates vector L.
	 */
	int j = *(vuip) IACK_SC;
	j &= 0xff;
	handle_irq(j);
}
#endif

#if defined(CONFIG_ALPHA_GENERIC) || !defined(IACK_SC)
void
isa_no_iack_sc_device_interrupt(unsigned long vector)
{
	unsigned long pic;

	/*
	 * It seems to me that the probability of two or more *device*
	 * interrupts occurring at almost exactly the same time is
	 * pretty low.  So why pay the price of checking for
	 * additional interrupts here if the common case can be
	 * handled so much easier?
	 */
	/* 
	 *  The first read of gives you *all* interrupting lines.
	 *  Therefore, read the mask register and and out those lines
	 *  not enabled.  Note that some documentation has 21 and a1 
	 *  write only.  This is not true.
	 */
	pic = inb(0x20) | (inb(0xA0) << 8);	/* read isr */
	pic &= 0xFFFB;				/* mask out cascade & hibits */

	while (pic) {
		int j = ffz(~pic);
		pic &= pic - 1;
		handle_irq(j);
	}
}
#endif