1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *  Copyright (C) 2020, Jiaxun Yang <jiaxun.yang@flygoat.com>
4  *  Loongson HTPIC IRQ support
5  */
6 
7 #include <linux/init.h>
8 #include <linux/of_address.h>
9 #include <linux/of_irq.h>
10 #include <linux/irqchip.h>
11 #include <linux/irqchip/chained_irq.h>
12 #include <linux/irq.h>
13 #include <linux/io.h>
14 #include <linux/syscore_ops.h>
15 
16 #include <asm/i8259.h>
17 
18 #define HTPIC_MAX_PARENT_IRQ	4
19 #define HTINT_NUM_VECTORS	8
20 #define HTINT_EN_OFF		0x20
21 
22 struct loongson_htpic {
23 	void __iomem *base;
24 	struct irq_domain *domain;
25 };
26 
27 static struct loongson_htpic *htpic;
28 
29 static void htpic_irq_dispatch(struct irq_desc *desc)
30 {
31 	struct loongson_htpic *priv = irq_desc_get_handler_data(desc);
32 	struct irq_chip *chip = irq_desc_get_chip(desc);
33 	uint32_t pending;
34 
35 	chained_irq_enter(chip, desc);
36 	pending = readl(priv->base);
37 	/* Ack all IRQs at once, otherwise IRQ flood might happen */
38 	writel(pending, priv->base);
39 
40 	if (!pending)
41 		spurious_interrupt();
42 
43 	while (pending) {
44 		int bit = __ffs(pending);
45 
46 		if (unlikely(bit > 15)) {
47 			spurious_interrupt();
48 			break;
49 		}
50 
51 		generic_handle_irq(irq_linear_revmap(priv->domain, bit));
52 		pending &= ~BIT(bit);
53 	}
54 	chained_irq_exit(chip, desc);
55 }
56 
57 static void htpic_reg_init(void)
58 {
59 	int i;
60 
61 	for (i = 0; i < HTINT_NUM_VECTORS; i++) {
62 		/* Disable all HT Vectors */
63 		writel(0x0, htpic->base + HTINT_EN_OFF + i * 0x4);
64 		/* Read back to force write */
65 		(void) readl(htpic->base + i * 0x4);
66 		/* Ack all possible pending IRQs */
67 		writel(GENMASK(31, 0), htpic->base + i * 0x4);
68 	}
69 
70 	/* Enable 16 vectors for PIC */
71 	writel(0xffff, htpic->base + HTINT_EN_OFF);
72 }
73 
74 static void htpic_resume(void)
75 {
76 	htpic_reg_init();
77 }
78 
79 struct syscore_ops htpic_syscore_ops = {
80 	.resume		= htpic_resume,
81 };
82 
83 static int __init htpic_of_init(struct device_node *node, struct device_node *parent)
84 {
85 	unsigned int parent_irq[4];
86 	int i, err;
87 	int num_parents = 0;
88 
89 	if (htpic) {
90 		pr_err("loongson-htpic: Only one HTPIC is allowed in the system\n");
91 		return -ENODEV;
92 	}
93 
94 	htpic = kzalloc(sizeof(*htpic), GFP_KERNEL);
95 	if (!htpic)
96 		return -ENOMEM;
97 
98 	htpic->base = of_iomap(node, 0);
99 	if (!htpic->base) {
100 		err = -ENODEV;
101 		goto out_free;
102 	}
103 
104 	htpic->domain = __init_i8259_irqs(node);
105 	if (!htpic->domain) {
106 		pr_err("loongson-htpic: Failed to initialize i8259 IRQs\n");
107 		err = -ENOMEM;
108 		goto out_iounmap;
109 	}
110 
111 	/* Interrupt may come from any of the 4 interrupt line */
112 	for (i = 0; i < HTPIC_MAX_PARENT_IRQ; i++) {
113 		parent_irq[i] = irq_of_parse_and_map(node, i);
114 		if (parent_irq[i] <= 0)
115 			break;
116 
117 		num_parents++;
118 	}
119 
120 	if (!num_parents) {
121 		pr_err("loongson-htpic: Failed to get parent irqs\n");
122 		err = -ENODEV;
123 		goto out_remove_domain;
124 	}
125 
126 	htpic_reg_init();
127 
128 	for (i = 0; i < num_parents; i++) {
129 		irq_set_chained_handler_and_data(parent_irq[i],
130 						htpic_irq_dispatch, htpic);
131 	}
132 
133 	register_syscore_ops(&htpic_syscore_ops);
134 
135 	return 0;
136 
137 out_remove_domain:
138 	irq_domain_remove(htpic->domain);
139 out_iounmap:
140 	iounmap(htpic->base);
141 out_free:
142 	kfree(htpic);
143 	return err;
144 }
145 
146 IRQCHIP_DECLARE(loongson_htpic, "loongson,htpic-1.0", htpic_of_init);
147