1 // SPDX-License-Identifier: GPL-2.0-only
2 // Copyright 2021 Jonathan Neuschäfer
3 
4 #include <linux/irqchip.h>
5 #include <linux/of_address.h>
6 #include <linux/of_irq.h>
7 #include <linux/printk.h>
8 
9 #include <asm/exception.h>
10 
11 #define AIC_SCR(x)	((x)*4)	/* Source control registers */
12 #define AIC_GEN		0x84	/* Interrupt group enable control register */
13 #define AIC_GRSR	0x88	/* Interrupt group raw status register */
14 #define AIC_IRSR	0x100	/* Interrupt raw status register */
15 #define AIC_IASR	0x104	/* Interrupt active status register */
16 #define AIC_ISR		0x108	/* Interrupt status register */
17 #define AIC_IPER	0x10c	/* Interrupt priority encoding register */
18 #define AIC_ISNR	0x110	/* Interrupt source number register */
19 #define AIC_IMR		0x114	/* Interrupt mask register */
20 #define AIC_OISR	0x118	/* Output interrupt status register */
21 #define AIC_MECR	0x120	/* Mask enable command register */
22 #define AIC_MDCR	0x124	/* Mask disable command register */
23 #define AIC_SSCR	0x128	/* Source set command register */
24 #define AIC_SCCR	0x12c	/* Source clear command register */
25 #define AIC_EOSCR	0x130	/* End of service command register */
26 
27 #define AIC_SCR_SRCTYPE_LOW_LEVEL	(0 << 6)
28 #define AIC_SCR_SRCTYPE_HIGH_LEVEL	(1 << 6)
29 #define AIC_SCR_SRCTYPE_NEG_EDGE	(2 << 6)
30 #define AIC_SCR_SRCTYPE_POS_EDGE	(3 << 6)
31 #define AIC_SCR_PRIORITY(x)		(x)
32 #define AIC_SCR_PRIORITY_MASK		0x7
33 
34 #define AIC_NUM_IRQS		32
35 
36 struct wpcm450_aic {
37 	void __iomem *regs;
38 	struct irq_domain *domain;
39 };
40 
41 static struct wpcm450_aic *aic;
42 
43 static void wpcm450_aic_init_hw(void)
44 {
45 	int i;
46 
47 	/* Disable (mask) all interrupts */
48 	writel(0xffffffff, aic->regs + AIC_MDCR);
49 
50 	/*
51 	 * Make sure the interrupt controller is ready to serve new interrupts.
52 	 * Reading from IPER indicates that the nIRQ signal may be deasserted,
53 	 * and writing to EOSCR indicates that interrupt handling has finished.
54 	 */
55 	readl(aic->regs + AIC_IPER);
56 	writel(0, aic->regs + AIC_EOSCR);
57 
58 	/* Initialize trigger mode and priority of each interrupt source */
59 	for (i = 0; i < AIC_NUM_IRQS; i++)
60 		writel(AIC_SCR_SRCTYPE_HIGH_LEVEL | AIC_SCR_PRIORITY(7),
61 		       aic->regs + AIC_SCR(i));
62 }
63 
64 static void __exception_irq_entry wpcm450_aic_handle_irq(struct pt_regs *regs)
65 {
66 	int hwirq;
67 
68 	/* Determine the interrupt source */
69 	/* Read IPER to signal that nIRQ can be de-asserted */
70 	hwirq = readl(aic->regs + AIC_IPER) / 4;
71 
72 	generic_handle_domain_irq(aic->domain, hwirq);
73 }
74 
75 static void wpcm450_aic_eoi(struct irq_data *d)
76 {
77 	/* Signal end-of-service */
78 	writel(0, aic->regs + AIC_EOSCR);
79 }
80 
81 static void wpcm450_aic_mask(struct irq_data *d)
82 {
83 	unsigned int mask = BIT(d->hwirq);
84 
85 	/* Disable (mask) the interrupt */
86 	writel(mask, aic->regs + AIC_MDCR);
87 }
88 
89 static void wpcm450_aic_unmask(struct irq_data *d)
90 {
91 	unsigned int mask = BIT(d->hwirq);
92 
93 	/* Enable (unmask) the interrupt */
94 	writel(mask, aic->regs + AIC_MECR);
95 }
96 
97 static int wpcm450_aic_set_type(struct irq_data *d, unsigned int flow_type)
98 {
99 	/*
100 	 * The hardware supports high/low level, as well as rising/falling edge
101 	 * modes, and the DT binding accommodates for that, but as long as
102 	 * other modes than high level mode are not used and can't be tested,
103 	 * they are rejected in this driver.
104 	 */
105 	if ((flow_type & IRQ_TYPE_SENSE_MASK) != IRQ_TYPE_LEVEL_HIGH)
106 		return -EINVAL;
107 
108 	return 0;
109 }
110 
111 static struct irq_chip wpcm450_aic_chip = {
112 	.name = "wpcm450-aic",
113 	.irq_eoi = wpcm450_aic_eoi,
114 	.irq_mask = wpcm450_aic_mask,
115 	.irq_unmask = wpcm450_aic_unmask,
116 	.irq_set_type = wpcm450_aic_set_type,
117 };
118 
119 static int wpcm450_aic_map(struct irq_domain *d, unsigned int irq, irq_hw_number_t hwirq)
120 {
121 	if (hwirq >= AIC_NUM_IRQS)
122 		return -EPERM;
123 
124 	irq_set_chip_and_handler(irq, &wpcm450_aic_chip, handle_fasteoi_irq);
125 	irq_set_chip_data(irq, aic);
126 	irq_set_probe(irq);
127 
128 	return 0;
129 }
130 
131 static const struct irq_domain_ops wpcm450_aic_ops = {
132 	.map = wpcm450_aic_map,
133 	.xlate = irq_domain_xlate_twocell,
134 };
135 
136 static int __init wpcm450_aic_of_init(struct device_node *node,
137 				      struct device_node *parent)
138 {
139 	if (parent)
140 		return -EINVAL;
141 
142 	aic = kzalloc(sizeof(*aic), GFP_KERNEL);
143 	if (!aic)
144 		return -ENOMEM;
145 
146 	aic->regs = of_iomap(node, 0);
147 	if (!aic->regs) {
148 		pr_err("Failed to map WPCM450 AIC registers\n");
149 		kfree(aic);
150 		return -ENOMEM;
151 	}
152 
153 	wpcm450_aic_init_hw();
154 
155 	set_handle_irq(wpcm450_aic_handle_irq);
156 
157 	aic->domain = irq_domain_add_linear(node, AIC_NUM_IRQS, &wpcm450_aic_ops, aic);
158 
159 	return 0;
160 }
161 
162 IRQCHIP_DECLARE(wpcm450_aic, "nuvoton,wpcm450-aic", wpcm450_aic_of_init);
163