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 		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 
ip6_action(int cpl,void * dev_id)87 static irqreturn_t ip6_action(int cpl, void *dev_id)
88 {
89 	return IRQ_HANDLED;
90 }
91 
mach_init_irq(void)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