linux/drivers/irqchip/irq-loongson-htpic.c
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   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_irq(irq_linear_revmap(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);
 147