// 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[] = {
        { "PNP0B00" },
        { "PNP0B01" },
        { "PNP0B02" },
        {}
};

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

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

        if (function != ACPI_WRITE && function != ACPI_READ)
                return AE_BAD_PARAMETER;

        spin_lock_irq(&rtc_lock);

        for (i = 0; i < DIV_ROUND_UP(bits, 8); ++i, ++address, ++value)
                if (function == ACPI_READ)
                        *value = CMOS_READ(address);
                else
                        CMOS_WRITE(*value, address);

        spin_unlock_irq(&rtc_lock);

        return AE_OK;
}

int acpi_install_cmos_rtc_space_handler(acpi_handle handle)
{
        acpi_status status;

        status = acpi_install_address_space_handler(handle,
                        ACPI_ADR_SPACE_CMOS,
                        &acpi_cmos_rtc_space_handler,
                        NULL, NULL);
        if (ACPI_FAILURE(status)) {
                pr_err("Error installing CMOS-RTC region handler\n");
                return -ENODEV;
        }

        return 1;
}
EXPORT_SYMBOL_GPL(acpi_install_cmos_rtc_space_handler);

void acpi_remove_cmos_rtc_space_handler(acpi_handle handle)
{
        if (ACPI_FAILURE(acpi_remove_address_space_handler(handle,
                        ACPI_ADR_SPACE_CMOS, &acpi_cmos_rtc_space_handler)))
                pr_err("Error removing CMOS-RTC region handler\n");
}
EXPORT_SYMBOL_GPL(acpi_remove_cmos_rtc_space_handler);

static int acpi_cmos_rtc_attach_handler(struct acpi_device *adev, const struct acpi_device_id *id)
{
        return acpi_install_cmos_rtc_space_handler(adev->handle);
}

static void acpi_cmos_rtc_detach_handler(struct acpi_device *adev)
{
        acpi_remove_cmos_rtc_space_handler(adev->handle);
}

static struct acpi_scan_handler cmos_rtc_handler = {
        .ids = acpi_cmos_rtc_ids,
        .attach = acpi_cmos_rtc_attach_handler,
        .detach = acpi_cmos_rtc_detach_handler,
};

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