1 /*
2  * J-Core SoC AIC driver
3  *
4  * Copyright (C) 2015-2016 Smart Energy Instruments, Inc.
5  *
6  * This file is subject to the terms and conditions of the GNU General Public
7  * License.  See the file "COPYING" in the main directory of this archive
8  * for more details.
9  */
10 
11 #include <linux/irq.h>
12 #include <linux/io.h>
13 #include <linux/irqchip.h>
14 #include <linux/irqdomain.h>
15 #include <linux/cpu.h>
16 #include <linux/of.h>
17 #include <linux/of_address.h>
18 #include <linux/of_irq.h>
19 
20 #define JCORE_AIC_MAX_HWIRQ	127
21 #define JCORE_AIC1_MIN_HWIRQ	16
22 #define JCORE_AIC2_MIN_HWIRQ	64
23 
24 #define JCORE_AIC1_INTPRI_REG	8
25 
26 static struct irq_chip jcore_aic;
27 
28 /*
29  * The J-Core AIC1 and AIC2 are cpu-local interrupt controllers and do
30  * not distinguish or use distinct irq number ranges for per-cpu event
31  * interrupts (timer, IPI). Since information to determine whether a
32  * particular irq number should be treated as per-cpu is not available
33  * at mapping time, we use a wrapper handler function which chooses
34  * the right handler at runtime based on whether IRQF_PERCPU was used
35  * when requesting the irq.
36  */
37 
38 static void handle_jcore_irq(struct irq_desc *desc)
39 {
40 	if (irqd_is_per_cpu(irq_desc_get_irq_data(desc)))
41 		handle_percpu_irq(desc);
42 	else
43 		handle_simple_irq(desc);
44 }
45 
46 static int jcore_aic_irqdomain_map(struct irq_domain *d, unsigned int irq,
47 				   irq_hw_number_t hwirq)
48 {
49 	struct irq_chip *aic = d->host_data;
50 
51 	irq_set_chip_and_handler(irq, aic, handle_jcore_irq);
52 
53 	return 0;
54 }
55 
56 static const struct irq_domain_ops jcore_aic_irqdomain_ops = {
57 	.map = jcore_aic_irqdomain_map,
58 	.xlate = irq_domain_xlate_onecell,
59 };
60 
61 static void noop(struct irq_data *data)
62 {
63 }
64 
65 static int __init aic_irq_of_init(struct device_node *node,
66 				  struct device_node *parent)
67 {
68 	unsigned min_irq = JCORE_AIC2_MIN_HWIRQ;
69 	unsigned dom_sz = JCORE_AIC_MAX_HWIRQ+1;
70 	struct irq_domain *domain;
71 	int ret;
72 
73 	pr_info("Initializing J-Core AIC\n");
74 
75 	/* AIC1 needs priority initialization to receive interrupts. */
76 	if (of_device_is_compatible(node, "jcore,aic1")) {
77 		unsigned cpu;
78 
79 		for_each_present_cpu(cpu) {
80 			void __iomem *base = of_iomap(node, cpu);
81 
82 			if (!base) {
83 				pr_err("Unable to map AIC for cpu %u\n", cpu);
84 				return -ENOMEM;
85 			}
86 			__raw_writel(0xffffffff, base + JCORE_AIC1_INTPRI_REG);
87 			iounmap(base);
88 		}
89 		min_irq = JCORE_AIC1_MIN_HWIRQ;
90 	}
91 
92 	/*
93 	 * The irq chip framework requires either mask/unmask or enable/disable
94 	 * function pointers to be provided, but the hardware does not have any
95 	 * such mechanism; the only interrupt masking is at the cpu level and
96 	 * it affects all interrupts. We provide dummy mask/unmask. The hardware
97 	 * handles all interrupt control and clears pending status when the cpu
98 	 * accepts the interrupt.
99 	 */
100 	jcore_aic.irq_mask = noop;
101 	jcore_aic.irq_unmask = noop;
102 	jcore_aic.name = "AIC";
103 
104 	ret = irq_alloc_descs(-1, min_irq, dom_sz - min_irq,
105 			      of_node_to_nid(node));
106 
107 	if (ret < 0)
108 		return ret;
109 
110 	domain = irq_domain_add_legacy(node, dom_sz - min_irq, min_irq, min_irq,
111 				       &jcore_aic_irqdomain_ops,
112 				       &jcore_aic);
113 	if (!domain)
114 		return -ENOMEM;
115 
116 	return 0;
117 }
118 
119 IRQCHIP_DECLARE(jcore_aic2, "jcore,aic2", aic_irq_of_init);
120 IRQCHIP_DECLARE(jcore_aic1, "jcore,aic1", aic_irq_of_init);
121