drivers/irqchip/irq-loongson-htpic.c

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