// SPDX-License-Identifier: GPL-2.0-only
/* Copyright (c) 2015-2018, The Linux Foundation. All rights reserved.
 */

/*
 * Driver for interrupt combiners in the Top-level Control and Status
 * Registers (TCSR) hardware block in Qualcomm Technologies chips.
 * An interrupt combiner in this block combines a set of interrupts by
 * OR'ing the individual interrupt signals into a summary interrupt
 * signal routed to a parent interrupt controller, and provides read-
 * only, 32-bit registers to query the status of individual interrupts.
 * The status bit for IRQ n is bit (n % 32) within register (n / 32)
 * of the given combiner. Thus, each combiner can be described as a set
 * of register offsets and the number of IRQs managed.
 */

#define pr_fmt(fmt) "QCOM80B1:" fmt

#include <linux/acpi.h>
#include <linux/irqchip/chained_irq.h>
#include <linux/irqdomain.h>
#include <linux/platform_device.h>

#define REG_SIZE 32

struct combiner_reg {
        void __iomem *addr;
        unsigned long enabled;
};

struct combiner {
        struct irq_domain   *domain;
        int                 parent_irq;
        u32                 nirqs;
        u32                 nregs;
        struct combiner_reg regs[];
};

static inline int irq_nr(u32 reg, u32 bit)
{
        return reg * REG_SIZE + bit;
}

/*
 * Handler for the cascaded IRQ.
 */
static void combiner_handle_irq(struct irq_desc *desc)
{
        struct combiner *combiner = irq_desc_get_handler_data(desc);
        struct irq_chip *chip = irq_desc_get_chip(desc);
        u32 reg;

        chained_irq_enter(chip, desc);

        for (reg = 0; reg < combiner->nregs; reg++) {
                int hwirq;
                u32 bit;
                u32 status;

                bit = readl_relaxed(combiner->regs[reg].addr);
                status = bit & combiner->regs[reg].enabled;
                if (bit && !status)
                        pr_warn_ratelimited("Unexpected IRQ on CPU%d: (%08x %08lx %p)\n",
                                            smp_processor_id(), bit,
                                            combiner->regs[reg].enabled,
                                            combiner->regs[reg].addr);

                while (status) {
                        bit = __ffs(status);
                        status &= ~(1 << bit);
                        hwirq = irq_nr(reg, bit);
                        generic_handle_domain_irq(combiner->domain, hwirq);
                }
        }

        chained_irq_exit(chip, desc);
}

static void combiner_irq_chip_mask_irq(struct irq_data *data)
{
        struct combiner *combiner = irq_data_get_irq_chip_data(data);
        struct combiner_reg *reg = combiner->regs + data->hwirq / REG_SIZE;

        clear_bit(data->hwirq % REG_SIZE, &reg->enabled);
}

static void combiner_irq_chip_unmask_irq(struct irq_data *data)
{
        struct combiner *combiner = irq_data_get_irq_chip_data(data);
        struct combiner_reg *reg = combiner->regs + data->hwirq / REG_SIZE;

        set_bit(data->hwirq % REG_SIZE, &reg->enabled);
}

static struct irq_chip irq_chip = {
        .irq_mask = combiner_irq_chip_mask_irq,
        .irq_unmask = combiner_irq_chip_unmask_irq,
        .name = "qcom-irq-combiner"
};

static int combiner_irq_map(struct irq_domain *domain, unsigned int irq,
                                   irq_hw_number_t hwirq)
{
        irq_set_chip_and_handler(irq, &irq_chip, handle_level_irq);
        irq_set_chip_data(irq, domain->host_data);
        irq_set_noprobe(irq);
        return 0;
}

static void combiner_irq_unmap(struct irq_domain *domain, unsigned int irq)
{
        irq_domain_reset_irq_data(irq_get_irq_data(irq));
}

static int combiner_irq_translate(struct irq_domain *d, struct irq_fwspec *fws,
                                  unsigned long *hwirq, unsigned int *type)
{
        struct combiner *combiner = d->host_data;

        if (is_acpi_node(fws->fwnode)) {
                if (WARN_ON((fws->param_count != 2) ||
                            (fws->param[0] >= combiner->nirqs) ||
                            (fws->param[1] & IORESOURCE_IRQ_LOWEDGE) ||
                            (fws->param[1] & IORESOURCE_IRQ_HIGHEDGE)))
                        return -EINVAL;

                *hwirq = fws->param[0];
                *type = fws->param[1];
                return 0;
        }

        return -EINVAL;
}

static const struct irq_domain_ops domain_ops = {
        .map = combiner_irq_map,
        .unmap = combiner_irq_unmap,
        .translate = combiner_irq_translate
};

static acpi_status count_registers_cb(struct acpi_resource *ares, void *context)
{
        int *count = context;

        if (ares->type == ACPI_RESOURCE_TYPE_GENERIC_REGISTER)
                ++(*count);
        return AE_OK;
}

static int count_registers(struct platform_device *pdev)
{
        acpi_handle ahandle = ACPI_HANDLE(&pdev->dev);
        acpi_status status;
        int count = 0;

        if (!acpi_has_method(ahandle, METHOD_NAME__CRS))
                return -EINVAL;

        status = acpi_walk_resources(ahandle, METHOD_NAME__CRS,
                                     count_registers_cb, &count);
        if (ACPI_FAILURE(status))
                return -EINVAL;
        return count;
}

struct get_registers_context {
        struct device *dev;
        struct combiner *combiner;
        int err;
};

static acpi_status get_registers_cb(struct acpi_resource *ares, void *context)
{
        struct get_registers_context *ctx = context;
        struct acpi_resource_generic_register *reg;
        phys_addr_t paddr;
        void __iomem *vaddr;

        if (ares->type != ACPI_RESOURCE_TYPE_GENERIC_REGISTER)
                return AE_OK;

        reg = &ares->data.generic_reg;
        paddr = reg->address;
        if ((reg->space_id != ACPI_SPACE_MEM) ||
            (reg->bit_offset != 0) ||
            (reg->bit_width > REG_SIZE)) {
                dev_err(ctx->dev, "Bad register resource @%pa\n", &paddr);
                ctx->err = -EINVAL;
                return AE_ERROR;
        }

        vaddr = devm_ioremap(ctx->dev, reg->address, REG_SIZE);
        if (!vaddr) {
                dev_err(ctx->dev, "Can't map register @%pa\n", &paddr);
                ctx->err = -ENOMEM;
                return AE_ERROR;
        }

        ctx->combiner->regs[ctx->combiner->nregs].addr = vaddr;
        ctx->combiner->nirqs += reg->bit_width;
        ctx->combiner->nregs++;
        return AE_OK;
}

static int get_registers(struct platform_device *pdev, struct combiner *comb)
{
        acpi_handle ahandle = ACPI_HANDLE(&pdev->dev);
        acpi_status status;
        struct get_registers_context ctx;

        if (!acpi_has_method(ahandle, METHOD_NAME__CRS))
                return -EINVAL;

        ctx.dev = &pdev->dev;
        ctx.combiner = comb;
        ctx.err = 0;

        status = acpi_walk_resources(ahandle, METHOD_NAME__CRS,
                                     get_registers_cb, &ctx);
        if (ACPI_FAILURE(status))
                return ctx.err;
        return 0;
}

static int combiner_probe(struct platform_device *pdev)
{
        struct combiner *combiner;
        int nregs;
        int err;

        nregs = count_registers(pdev);
        if (nregs <= 0) {
                dev_err(&pdev->dev, "Error reading register resources\n");
                return -EINVAL;
        }

        combiner = devm_kzalloc(&pdev->dev, struct_size(combiner, regs, nregs),
                                GFP_KERNEL);
        if (!combiner)
                return -ENOMEM;

        err = get_registers(pdev, combiner);
        if (err < 0)
                return err;

        combiner->parent_irq = platform_get_irq(pdev, 0);
        if (combiner->parent_irq <= 0)
                return -EPROBE_DEFER;

        combiner->domain = irq_domain_create_linear(pdev->dev.fwnode, combiner->nirqs,
                                                    &domain_ops, combiner);
        if (!combiner->domain)
                /* Errors printed by irq_domain_create_linear */
                return -ENODEV;

        irq_set_chained_handler_and_data(combiner->parent_irq,
                                         combiner_handle_irq, combiner);

        dev_info(&pdev->dev, "Initialized with [p=%d,n=%d,r=%p]\n",
                 combiner->parent_irq, combiner->nirqs, combiner->regs[0].addr);
        return 0;
}

static const struct acpi_device_id qcom_irq_combiner_ids[] = {
        { "QCOM80B1", },
        { }
};

static struct platform_driver qcom_irq_combiner_driver = {
        .driver = {
                .name = "qcom-irq-combiner",
                .acpi_match_table = ACPI_PTR(qcom_irq_combiner_ids),
        },
        .probe = combiner_probe,
};
builtin_platform_driver(qcom_irq_combiner_driver);