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 */
mach_i8259_irq(void)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
i8259_irqdispatch(void)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
mach_irq_dispatch(unsigned int pending)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 do_perfcnt_IRQ();
79 bonito_irqdispatch();
80 } else if (pending & CAUSEF_IP3) /* CPU UART */
81 do_IRQ(LOONGSON_UART_IRQ);
82 else if (pending & CAUSEF_IP2) /* South Bridge */
83 i8259_irqdispatch();
84 else
85 spurious_interrupt();
86 }
87
ip6_action(int cpl,void * dev_id)88 static irqreturn_t ip6_action(int cpl, void *dev_id)
89 {
90 return IRQ_HANDLED;
91 }
92
mach_init_irq(void)93 void __init mach_init_irq(void)
94 {
95 /* init all controller
96 * 0-15 ------> i8259 interrupt
97 * 16-23 ------> mips cpu interrupt
98 * 32-63 ------> bonito irq
99 */
100
101 /* setup cs5536 as high level trigger */
102 LOONGSON_INTPOL = LOONGSON_INT_BIT_INT0 | LOONGSON_INT_BIT_INT1;
103 LOONGSON_INTEDGE &= ~(LOONGSON_INT_BIT_INT0 | LOONGSON_INT_BIT_INT1);
104
105 /* Sets the first-level interrupt dispatcher. */
106 mips_cpu_irq_init();
107 init_i8259_irqs();
108 bonito_irq_init();
109
110 /* setup north bridge irq (bonito) */
111 if (request_irq(LOONGSON_NORTH_BRIDGE_IRQ, ip6_action,
112 IRQF_SHARED | IRQF_NO_THREAD, "cascade", ip6_action))
113 pr_err("Failed to register north bridge cascade interrupt\n");
114 /* setup source bridge irq (i8259) */
115 if (request_irq(LOONGSON_SOUTH_BRIDGE_IRQ, no_action,
116 IRQF_NO_THREAD | IRQF_NO_SUSPEND, "cascade", NULL))
117 pr_err("Failed to register south bridge cascade interrupt\n");
118 }
119
