// SPDX-License-Identifier: GPL-2.0-only
/*
 * ACPI support for CMOS RTC Address Space access
 *
 * Copyright (C) 2013, Intel Corporation
 * Authors: Lan Tianyu <tianyu.lan@intel.com>
 */

#define pr_fmt(fmt) "ACPI: " fmt

#include <linux/acpi.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mc146818rtc.h>

#include "../internal.h"

static const struct acpi_device_id acpi_cmos_rtc_ids[] = {
        { "ACPI000E", 1 }, /* ACPI Time and Alarm Device (TAD) */
        ACPI_CMOS_RTC_IDS
};

bool cmos_rtc_platform_device_present;

static acpi_status acpi_cmos_rtc_space_handler(u32 function,
                                               acpi_physical_address address,
                                               u32 bits, u64 *value64,
                                               void *handler_context,
                                               void *region_context)
{
        unsigned int i, bytes = DIV_ROUND_UP(bits, 8);
        u8 *value = (u8 *)value64;

        if (address > 0xff || !value64)
                return AE_BAD_PARAMETER;

        guard(spinlock_irq)(&rtc_lock);

        if (function == ACPI_WRITE) {
                for (i = 0; i < bytes; i++, address++, value++)
                        CMOS_WRITE(*value, address);

                return AE_OK;
        }

        if (function == ACPI_READ) {
                for (i = 0; i < bytes; i++, address++, value++)
                        *value = CMOS_READ(address);

                return AE_OK;
        }

        return AE_BAD_PARAMETER;
}

static int acpi_install_cmos_rtc_space_handler(acpi_handle handle)
{
        static bool cmos_rtc_space_handler_present __read_mostly;
        acpi_status status;

        if (cmos_rtc_space_handler_present)
                return 0;

        status = acpi_install_address_space_handler(handle,
                                                    ACPI_ADR_SPACE_CMOS,
                                                    acpi_cmos_rtc_space_handler,
                                                    NULL, NULL);
        if (ACPI_FAILURE(status)) {
                pr_err("Failed to install CMOS-RTC address space handler\n");
                return -ENODEV;
        }

        cmos_rtc_space_handler_present = true;

        return 1;
}

static int acpi_cmos_rtc_attach(struct acpi_device *adev,
                                const struct acpi_device_id *id)
{
        int ret;

        ret = acpi_install_cmos_rtc_space_handler(adev->handle);
        if (ret < 0)
                return ret;

        if (IS_ERR_OR_NULL(acpi_create_platform_device(adev, NULL))) {
                pr_err("Failed to create a platform device for %s\n", (char *)id->id);
                return 0;
        } else if (!id->driver_data) {
                cmos_rtc_platform_device_present = true;
        }
        return 1;
}

static struct acpi_scan_handler cmos_rtc_handler = {
        .ids = acpi_cmos_rtc_ids,
        .attach = acpi_cmos_rtc_attach,
};

void __init acpi_cmos_rtc_init(void)
{
        acpi_scan_add_handler(&cmos_rtc_handler);
}