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
 22struct loongson_htpic {
 23	void __iomem *base;
 24	struct irq_domain *domain;
 25};
 26
 27static struct loongson_htpic *htpic;
 28
 29static 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_domain_irq(priv->domain, bit);
 52		pending &= ~BIT(bit);
 53	}
 54	chained_irq_exit(chip, desc);
 55}
 56
 57static 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
 74static void htpic_resume(void)
 75{
 76	htpic_reg_init();
 77}
 78
 79struct syscore_ops htpic_syscore_ops = {
 80	.resume		= htpic_resume,
 81};
 82
 83static 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
137out_remove_domain:
138	irq_domain_remove(htpic->domain);
139out_iounmap:
140	iounmap(htpic->base);
141out_free:
142	kfree(htpic);
143	return err;
144}
145
146IRQCHIP_DECLARE(loongson_htpic, "loongson,htpic-1.0", htpic_of_init);