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
wpcm450_aic_init_hw(void)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
wpcm450_aic_handle_irq(struct pt_regs * regs)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 handle_domain_irq(aic->domain, hwirq, regs);
73 }
74
wpcm450_aic_eoi(struct irq_data * d)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
wpcm450_aic_mask(struct irq_data * d)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
wpcm450_aic_unmask(struct irq_data * d)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
wpcm450_aic_set_type(struct irq_data * d,unsigned int flow_type)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
wpcm450_aic_map(struct irq_domain * d,unsigned int irq,irq_hw_number_t hwirq)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
wpcm450_aic_of_init(struct device_node * node,struct device_node * parent)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 return -ENOMEM;
150 }
151
152 wpcm450_aic_init_hw();
153
154 set_handle_irq(wpcm450_aic_handle_irq);
155
156 aic->domain = irq_domain_add_linear(node, AIC_NUM_IRQS, &wpcm450_aic_ops, aic);
157
158 return 0;
159 }
160
161 IRQCHIP_DECLARE(wpcm450_aic, "nuvoton,wpcm450-aic", wpcm450_aic_of_init);
162