1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright (C) 2007 Lemote Inc.
4 * Author: Fuxin Zhang, zhangfx@lemote.com
5 */
6
7 #include <linux/export.h>
8 #include <linux/init.h>
9 #include <linux/interrupt.h>
10
11 #include <asm/irq_cpu.h>
12 #include <asm/i8259.h>
13 #include <asm/mipsregs.h>
14
15 #include <loongson.h>
16 #include <machine.h>
17
18 #define LOONGSON_TIMER_IRQ (MIPS_CPU_IRQ_BASE + 7) /* cpu timer */
19 #define LOONGSON_NORTH_BRIDGE_IRQ (MIPS_CPU_IRQ_BASE + 6) /* bonito */
20 #define LOONGSON_UART_IRQ (MIPS_CPU_IRQ_BASE + 3) /* cpu serial port */
21 #define LOONGSON_SOUTH_BRIDGE_IRQ (MIPS_CPU_IRQ_BASE + 2) /* i8259 */
22
23 #define LOONGSON_INT_BIT_INT0 (1 << 11)
24 #define LOONGSON_INT_BIT_INT1 (1 << 12)
25
26 /*
27 * The generic i8259_irq() make the kernel hang on booting. Since we cannot
28 * get the irq via the IRR directly, we access the ISR instead.
29 */
30 int mach_i8259_irq(void)
31 {
32 int irq, isr;
33
34 irq = -1;
35
36 if ((LOONGSON_INTISR & LOONGSON_INTEN) & LOONGSON_INT_BIT_INT0) {
37 raw_spin_lock(&i8259A_lock);
38 isr = inb(PIC_MASTER_CMD) &
39 ~inb(PIC_MASTER_IMR) & ~(1 << PIC_CASCADE_IR);
40 if (!isr)
41 isr = (inb(PIC_SLAVE_CMD) & ~inb(PIC_SLAVE_IMR)) << 8;
42 irq = ffs(isr) - 1;
43 if (unlikely(irq == 7)) {
44 /*
45 * This may be a spurious interrupt.
46 *
47 * Read the interrupt status register (ISR). If the most
48 * significant bit is not set then there is no valid
49 * interrupt.
50 */
51 outb(0x0B, PIC_MASTER_ISR); /* ISR register */
52 if (~inb(PIC_MASTER_ISR) & 0x80)
53 irq = -1;
54 }
55 raw_spin_unlock(&i8259A_lock);
56 }
57
58 return irq;
59 }
60 EXPORT_SYMBOL(mach_i8259_irq);
61
62 static void i8259_irqdispatch(void)
63 {
64 int irq;
65
66 irq = mach_i8259_irq();
67 if (irq >= 0)
68 do_IRQ(irq);
69 else
70 spurious_interrupt();
71 }
72
73 void mach_irq_dispatch(unsigned int pending)
74 {
75 if (pending & CAUSEF_IP7)
76 do_IRQ(LOONGSON_TIMER_IRQ);
77 else if (pending & CAUSEF_IP6) { /* North Bridge, Perf counter */
78 bonito_irqdispatch();
79 } else if (pending & CAUSEF_IP3) /* CPU UART */
80 do_IRQ(LOONGSON_UART_IRQ);
81 else if (pending & CAUSEF_IP2) /* South Bridge */
82 i8259_irqdispatch();
83 else
84 spurious_interrupt();
85 }
86
87 static irqreturn_t ip6_action(int cpl, void *dev_id)
88 {
89 return IRQ_HANDLED;
90 }
91
92 void __init mach_init_irq(void)
93 {
94 /* init all controller
95 * 0-15 ------> i8259 interrupt
96 * 16-23 ------> mips cpu interrupt
97 * 32-63 ------> bonito irq
98 */
99
100 /* setup cs5536 as high level trigger */
101 LOONGSON_INTPOL = LOONGSON_INT_BIT_INT0 | LOONGSON_INT_BIT_INT1;
102 LOONGSON_INTEDGE &= ~(LOONGSON_INT_BIT_INT0 | LOONGSON_INT_BIT_INT1);
103
104 /* Sets the first-level interrupt dispatcher. */
105 mips_cpu_irq_init();
106 init_i8259_irqs();
107 bonito_irq_init();
108
109 /* setup north bridge irq (bonito) */
110 if (request_irq(LOONGSON_NORTH_BRIDGE_IRQ, ip6_action,
111 IRQF_SHARED | IRQF_NO_THREAD, "cascade", ip6_action))
112 pr_err("Failed to register north bridge cascade interrupt\n");
113 /* setup source bridge irq (i8259) */
114 if (request_irq(LOONGSON_SOUTH_BRIDGE_IRQ, no_action,
115 IRQF_NO_THREAD | IRQF_NO_SUSPEND, "cascade", NULL))
116 pr_err("Failed to register south bridge cascade interrupt\n");
117 }
118
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