root/drivers/irqchip/irq-loongson-htvec.c
// SPDX-License-Identifier: GPL-2.0
/*
 *  Copyright (C) 2020, Jiaxun Yang <jiaxun.yang@flygoat.com>
 *  Loongson HyperTransport Interrupt Vector support
 */

#define pr_fmt(fmt) "htvec: " fmt

#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/irqchip.h>
#include <linux/irqdomain.h>
#include <linux/irqchip/chained_irq.h>
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/syscore_ops.h>

#include "irq-loongson.h"

/* Registers */
#define HTVEC_EN_OFF            0x20
#define HTVEC_MAX_PARENT_IRQ    8
#define VEC_COUNT_PER_REG       32
#define VEC_REG_IDX(irq_id)     ((irq_id) / VEC_COUNT_PER_REG)
#define VEC_REG_BIT(irq_id)     ((irq_id) % VEC_COUNT_PER_REG)

struct htvec {
        int                     num_parents;
        void __iomem            *base;
        struct irq_domain       *htvec_domain;
        raw_spinlock_t          htvec_lock;
        u32                     saved_vec_en[HTVEC_MAX_PARENT_IRQ];
};

static struct htvec *htvec_priv;

static void htvec_irq_dispatch(struct irq_desc *desc)
{
        int i;
        u32 pending;
        bool handled = false;
        struct irq_chip *chip = irq_desc_get_chip(desc);
        struct htvec *priv = irq_desc_get_handler_data(desc);

        chained_irq_enter(chip, desc);

        for (i = 0; i < priv->num_parents; i++) {
                pending = readl(priv->base + 4 * i);
                while (pending) {
                        int bit = __ffs(pending);

                        generic_handle_domain_irq(priv->htvec_domain,
                                                  bit + VEC_COUNT_PER_REG * i);
                        pending &= ~BIT(bit);
                        handled = true;
                }
        }

        if (!handled)
                spurious_interrupt();

        chained_irq_exit(chip, desc);
}

static void htvec_ack_irq(struct irq_data *d)
{
        struct htvec *priv = irq_data_get_irq_chip_data(d);

        writel(BIT(VEC_REG_BIT(d->hwirq)),
               priv->base + VEC_REG_IDX(d->hwirq) * 4);
}

static void htvec_mask_irq(struct irq_data *d)
{
        u32 reg;
        void __iomem *addr;
        struct htvec *priv = irq_data_get_irq_chip_data(d);

        raw_spin_lock(&priv->htvec_lock);
        addr = priv->base + HTVEC_EN_OFF;
        addr += VEC_REG_IDX(d->hwirq) * 4;
        reg = readl(addr);
        reg &= ~BIT(VEC_REG_BIT(d->hwirq));
        writel(reg, addr);
        raw_spin_unlock(&priv->htvec_lock);
}

static void htvec_unmask_irq(struct irq_data *d)
{
        u32 reg;
        void __iomem *addr;
        struct htvec *priv = irq_data_get_irq_chip_data(d);

        raw_spin_lock(&priv->htvec_lock);
        addr = priv->base + HTVEC_EN_OFF;
        addr += VEC_REG_IDX(d->hwirq) * 4;
        reg = readl(addr);
        reg |= BIT(VEC_REG_BIT(d->hwirq));
        writel(reg, addr);
        raw_spin_unlock(&priv->htvec_lock);
}

static struct irq_chip htvec_irq_chip = {
        .name                   = "LOONGSON_HTVEC",
        .irq_mask               = htvec_mask_irq,
        .irq_unmask             = htvec_unmask_irq,
        .irq_ack                = htvec_ack_irq,
};

static int htvec_domain_alloc(struct irq_domain *domain, unsigned int virq,
                              unsigned int nr_irqs, void *arg)
{
        int ret;
        unsigned long hwirq;
        unsigned int type, i;
        struct htvec *priv = domain->host_data;

        ret = irq_domain_translate_onecell(domain, arg, &hwirq, &type);
        if (ret)
                return ret;

        for (i = 0; i < nr_irqs; i++) {
                irq_domain_set_info(domain, virq + i, hwirq + i, &htvec_irq_chip,
                                    priv, handle_edge_irq, NULL, NULL);
        }

        return 0;
}

static void htvec_domain_free(struct irq_domain *domain, unsigned int virq,
                                  unsigned int nr_irqs)
{
        int i;

        for (i = 0; i < nr_irqs; i++) {
                struct irq_data *d = irq_domain_get_irq_data(domain, virq + i);

                irq_set_handler(virq + i, NULL);
                irq_domain_reset_irq_data(d);
        }
}

static const struct irq_domain_ops htvec_domain_ops = {
        .translate      = irq_domain_translate_onecell,
        .alloc          = htvec_domain_alloc,
        .free           = htvec_domain_free,
};

static void htvec_reset(struct htvec *priv)
{
        u32 idx;

        /* Clear IRQ cause registers, mask all interrupts */
        for (idx = 0; idx < priv->num_parents; idx++) {
                writel_relaxed(0x0, priv->base + HTVEC_EN_OFF + 4 * idx);
                writel_relaxed(0xFFFFFFFF, priv->base + 4 * idx);
        }
}

static int htvec_suspend(void *data)
{
        int i;

        for (i = 0; i < htvec_priv->num_parents; i++)
                htvec_priv->saved_vec_en[i] = readl(htvec_priv->base + HTVEC_EN_OFF + 4 * i);

        return 0;
}

static void htvec_resume(void *data)
{
        int i;

        for (i = 0; i < htvec_priv->num_parents; i++)
                writel(htvec_priv->saved_vec_en[i], htvec_priv->base + HTVEC_EN_OFF + 4 * i);
}

static const struct syscore_ops htvec_syscore_ops = {
        .suspend = htvec_suspend,
        .resume = htvec_resume,
};

static struct syscore htvec_syscore = {
        .ops = &htvec_syscore_ops,
};

static int htvec_init(phys_addr_t addr, unsigned long size,
                int num_parents, int parent_irq[], struct fwnode_handle *domain_handle)
{
        int i;
        struct htvec *priv;

        priv = kzalloc_obj(*priv);
        if (!priv)
                return -ENOMEM;

        priv->num_parents = num_parents;
        priv->base = ioremap(addr, size);
        raw_spin_lock_init(&priv->htvec_lock);

        /* Setup IRQ domain */
        priv->htvec_domain = irq_domain_create_linear(domain_handle,
                                        (VEC_COUNT_PER_REG * priv->num_parents),
                                        &htvec_domain_ops, priv);
        if (!priv->htvec_domain) {
                pr_err("loongson-htvec: cannot add IRQ domain\n");
                goto iounmap_base;
        }

        htvec_reset(priv);

        for (i = 0; i < priv->num_parents; i++) {
                irq_set_chained_handler_and_data(parent_irq[i],
                                                 htvec_irq_dispatch, priv);
        }

        htvec_priv = priv;

        register_syscore(&htvec_syscore);

        return 0;

iounmap_base:
        iounmap(priv->base);
        kfree(priv);

        return -EINVAL;
}

#ifdef CONFIG_OF

static int htvec_of_init(struct device_node *node,
                                struct device_node *parent)
{
        int i, err;
        int parent_irq[8];
        int num_parents = 0;
        struct resource res;

        if (of_address_to_resource(node, 0, &res))
                return -EINVAL;

        /* Interrupt may come from any of the 8 interrupt lines */
        for (i = 0; i < HTVEC_MAX_PARENT_IRQ; i++) {
                parent_irq[i] = irq_of_parse_and_map(node, i);
                if (parent_irq[i] <= 0)
                        break;

                num_parents++;
        }

        err = htvec_init(res.start, resource_size(&res),
                        num_parents, parent_irq, of_fwnode_handle(node));
        if (err < 0)
                return err;

        return 0;
}

IRQCHIP_DECLARE(htvec, "loongson,htvec-1.0", htvec_of_init);

#endif

#ifdef CONFIG_ACPI
static int __init pch_pic_parse_madt(union acpi_subtable_headers *header,
                                        const unsigned long end)
{
        struct acpi_madt_bio_pic *pchpic_entry = (struct acpi_madt_bio_pic *)header;

        return pch_pic_acpi_init(htvec_priv->htvec_domain, pchpic_entry);
}

static int __init pch_msi_parse_madt(union acpi_subtable_headers *header,
                                        const unsigned long end)
{
        struct acpi_madt_msi_pic *pchmsi_entry = (struct acpi_madt_msi_pic *)header;

        return pch_msi_acpi_init(htvec_priv->htvec_domain, pchmsi_entry);
}

static int __init acpi_cascade_irqdomain_init(void)
{
        int r;

        r = acpi_table_parse_madt(ACPI_MADT_TYPE_BIO_PIC, pch_pic_parse_madt, 0);
        if (r < 0)
                return r;

        r = acpi_table_parse_madt(ACPI_MADT_TYPE_MSI_PIC, pch_msi_parse_madt, 0);
        if (r < 0)
                return r;

        return 0;
}

int __init htvec_acpi_init(struct irq_domain *parent, struct acpi_madt_ht_pic *acpi_htvec)
{
        int i, ret, num_parents, parent_irq[8];
        struct fwnode_handle *domain_handle;
        phys_addr_t addr;

        if (!acpi_htvec)
                return -EINVAL;

        num_parents = HTVEC_MAX_PARENT_IRQ;
        addr = (phys_addr_t)acpi_htvec->address;

        domain_handle = irq_domain_alloc_fwnode(&addr);
        if (!domain_handle) {
                pr_err("Unable to allocate domain handle\n");
                return -ENOMEM;
        }

        /* Interrupt may come from any of the 8 interrupt lines */
        for (i = 0; i < HTVEC_MAX_PARENT_IRQ; i++)
                parent_irq[i] = irq_create_mapping(parent, acpi_htvec->cascade[i]);

        ret = htvec_init(addr, acpi_htvec->size, num_parents, parent_irq, domain_handle);
        if (ret == 0)
                ret = acpi_cascade_irqdomain_init();
        else
                irq_domain_free_fwnode(domain_handle);

        return ret;
}

#endif