1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (C) 2020 Birger Koblitz <mail@birger-koblitz.de>
4  * Copyright (C) 2020 Bert Vermeulen <bert@biot.com>
5  * Copyright (C) 2020 John Crispin <john@phrozen.org>
6  */
7 
8 #include <linux/of_irq.h>
9 #include <linux/irqchip.h>
10 #include <linux/spinlock.h>
11 #include <linux/of_address.h>
12 #include <linux/irqchip/chained_irq.h>
13 
14 /* Global Interrupt Mask Register */
15 #define RTL_ICTL_GIMR		0x00
16 /* Global Interrupt Status Register */
17 #define RTL_ICTL_GISR		0x04
18 /* Interrupt Routing Registers */
19 #define RTL_ICTL_IRR0		0x08
20 #define RTL_ICTL_IRR1		0x0c
21 #define RTL_ICTL_IRR2		0x10
22 #define RTL_ICTL_IRR3		0x14
23 
24 #define RTL_ICTL_NUM_INPUTS	32
25 
26 #define REG(x)		(realtek_ictl_base + x)
27 
28 static DEFINE_RAW_SPINLOCK(irq_lock);
29 static void __iomem *realtek_ictl_base;
30 
31 /*
32  * IRR0-IRR3 store 4 bits per interrupt, but Realtek uses inverted numbering,
33  * placing IRQ 31 in the first four bits. A routing value of '0' means the
34  * interrupt is left disconnected. Routing values {1..15} connect to output
35  * lines {0..14}.
36  */
37 #define IRR_OFFSET(idx)		(4 * (3 - (idx * 4) / 32))
38 #define IRR_SHIFT(idx)		((idx * 4) % 32)
39 
40 static void write_irr(void __iomem *irr0, int idx, u32 value)
41 {
42 	unsigned int offset = IRR_OFFSET(idx);
43 	unsigned int shift = IRR_SHIFT(idx);
44 	u32 irr;
45 
46 	irr = readl(irr0 + offset) & ~(0xf << shift);
47 	irr |= (value & 0xf) << shift;
48 	writel(irr, irr0 + offset);
49 }
50 
51 static void realtek_ictl_unmask_irq(struct irq_data *i)
52 {
53 	unsigned long flags;
54 	u32 value;
55 
56 	raw_spin_lock_irqsave(&irq_lock, flags);
57 
58 	value = readl(REG(RTL_ICTL_GIMR));
59 	value |= BIT(i->hwirq);
60 	writel(value, REG(RTL_ICTL_GIMR));
61 
62 	raw_spin_unlock_irqrestore(&irq_lock, flags);
63 }
64 
65 static void realtek_ictl_mask_irq(struct irq_data *i)
66 {
67 	unsigned long flags;
68 	u32 value;
69 
70 	raw_spin_lock_irqsave(&irq_lock, flags);
71 
72 	value = readl(REG(RTL_ICTL_GIMR));
73 	value &= ~BIT(i->hwirq);
74 	writel(value, REG(RTL_ICTL_GIMR));
75 
76 	raw_spin_unlock_irqrestore(&irq_lock, flags);
77 }
78 
79 static struct irq_chip realtek_ictl_irq = {
80 	.name = "realtek-rtl-intc",
81 	.irq_mask = realtek_ictl_mask_irq,
82 	.irq_unmask = realtek_ictl_unmask_irq,
83 };
84 
85 static int intc_map(struct irq_domain *d, unsigned int irq, irq_hw_number_t hw)
86 {
87 	unsigned long flags;
88 
89 	irq_set_chip_and_handler(irq, &realtek_ictl_irq, handle_level_irq);
90 
91 	raw_spin_lock_irqsave(&irq_lock, flags);
92 	write_irr(REG(RTL_ICTL_IRR0), hw, 1);
93 	raw_spin_unlock_irqrestore(&irq_lock, flags);
94 
95 	return 0;
96 }
97 
98 static const struct irq_domain_ops irq_domain_ops = {
99 	.map = intc_map,
100 	.xlate = irq_domain_xlate_onecell,
101 };
102 
103 static void realtek_irq_dispatch(struct irq_desc *desc)
104 {
105 	struct irq_chip *chip = irq_desc_get_chip(desc);
106 	struct irq_domain *domain;
107 	unsigned long pending;
108 	unsigned int soc_int;
109 
110 	chained_irq_enter(chip, desc);
111 	pending = readl(REG(RTL_ICTL_GIMR)) & readl(REG(RTL_ICTL_GISR));
112 
113 	if (unlikely(!pending)) {
114 		spurious_interrupt();
115 		goto out;
116 	}
117 
118 	domain = irq_desc_get_handler_data(desc);
119 	for_each_set_bit(soc_int, &pending, 32)
120 		generic_handle_domain_irq(domain, soc_int);
121 
122 out:
123 	chained_irq_exit(chip, desc);
124 }
125 
126 static int __init realtek_rtl_of_init(struct device_node *node, struct device_node *parent)
127 {
128 	struct of_phandle_args oirq;
129 	struct irq_domain *domain;
130 	unsigned int soc_irq;
131 	int parent_irq;
132 
133 	realtek_ictl_base = of_iomap(node, 0);
134 	if (!realtek_ictl_base)
135 		return -ENXIO;
136 
137 	/* Disable all cascaded interrupts and clear routing */
138 	writel(0, REG(RTL_ICTL_GIMR));
139 	for (soc_irq = 0; soc_irq < RTL_ICTL_NUM_INPUTS; soc_irq++)
140 		write_irr(REG(RTL_ICTL_IRR0), soc_irq, 0);
141 
142 	if (WARN_ON(!of_irq_count(node))) {
143 		/*
144 		 * If DT contains no parent interrupts, assume MIPS CPU IRQ 2
145 		 * (HW0) is connected to the first output. This is the case for
146 		 * all known hardware anyway. "interrupt-map" is deprecated, so
147 		 * don't bother trying to parse that.
148 		 */
149 		oirq.np = of_find_compatible_node(NULL, NULL, "mti,cpu-interrupt-controller");
150 		oirq.args_count = 1;
151 		oirq.args[0] = 2;
152 
153 		parent_irq = irq_create_of_mapping(&oirq);
154 
155 		of_node_put(oirq.np);
156 	} else {
157 		parent_irq = of_irq_get(node, 0);
158 	}
159 
160 	if (parent_irq < 0)
161 		return parent_irq;
162 	else if (!parent_irq)
163 		return -ENODEV;
164 
165 	domain = irq_domain_add_linear(node, RTL_ICTL_NUM_INPUTS, &irq_domain_ops, NULL);
166 	if (!domain)
167 		return -ENOMEM;
168 
169 	irq_set_chained_handler_and_data(parent_irq, realtek_irq_dispatch, domain);
170 
171 	return 0;
172 }
173 
174 IRQCHIP_DECLARE(realtek_rtl_intc, "realtek,rtl-intc", realtek_rtl_of_init);
175