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On x86, as a rule the CMOS RTC address space handler is set up by the CMOS RTC ACPI scan handler attach callback, acpi_cmos_rtc_attach(), but if the ACPI namespace does not contain a CMOS RTC device object, the CMOS RTC address space handler installation is taken care of the ACPI TAD (Timer and Alarm Device) driver. This is not particularly straightforward and can be avoided by adding the ACPI TAD device ID to the CMOS RTC ACPI scan handler which will cause it to create a platform device for ACPI TAD after installing the CMOS RTC address space handler. One related detail that needs to be taken care of, though, is that the creation of an ACPI TAD platform device should not cause cmos_rtc_platform_device_present to be set, since this may cause add_rtc_cmos() to suppress the creation of a fallback CMOS RTC platform device which may not be the right thing to do (for instance, due to the fact that the ACPI TAD driver is missing an RTC class device interface). After doing the above, the CMOS RTC address space handler installation and removal can be dropped from the ACPI TAD driver (which allows it to be simplified quite a bit), acpi_remove_cmos_rtc_space_handler() can be dropped and acpi_install_cmos_rtc_space_handler() can be made static. Update the code as per the above. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Link: https://patch.msgid.link/23028644.EfDdHjke4D@rafael.j.wysocki
107 lines
2.4 KiB
C
107 lines
2.4 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* ACPI support for CMOS RTC Address Space access
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*
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* Copyright (C) 2013, Intel Corporation
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* Authors: Lan Tianyu <tianyu.lan@intel.com>
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*/
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#define pr_fmt(fmt) "ACPI: " fmt
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#include <linux/acpi.h>
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#include <linux/device.h>
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#include <linux/err.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/mc146818rtc.h>
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#include "../internal.h"
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static const struct acpi_device_id acpi_cmos_rtc_ids[] = {
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{ "ACPI000E", 1 }, /* ACPI Time and Alarm Device (TAD) */
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ACPI_CMOS_RTC_IDS
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};
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bool cmos_rtc_platform_device_present;
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static acpi_status acpi_cmos_rtc_space_handler(u32 function,
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acpi_physical_address address,
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u32 bits, u64 *value64,
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void *handler_context,
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void *region_context)
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{
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unsigned int i, bytes = DIV_ROUND_UP(bits, 8);
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u8 *value = (u8 *)value64;
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if (address > 0xff || !value64)
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return AE_BAD_PARAMETER;
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guard(spinlock_irq)(&rtc_lock);
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if (function == ACPI_WRITE) {
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for (i = 0; i < bytes; i++, address++, value++)
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CMOS_WRITE(*value, address);
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return AE_OK;
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}
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if (function == ACPI_READ) {
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for (i = 0; i < bytes; i++, address++, value++)
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*value = CMOS_READ(address);
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return AE_OK;
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}
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return AE_BAD_PARAMETER;
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}
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static int acpi_install_cmos_rtc_space_handler(acpi_handle handle)
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{
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static bool cmos_rtc_space_handler_present __read_mostly;
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acpi_status status;
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if (cmos_rtc_space_handler_present)
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return 0;
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status = acpi_install_address_space_handler(handle,
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ACPI_ADR_SPACE_CMOS,
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acpi_cmos_rtc_space_handler,
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NULL, NULL);
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if (ACPI_FAILURE(status)) {
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pr_err("Failed to install CMOS-RTC address space handler\n");
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return -ENODEV;
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}
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cmos_rtc_space_handler_present = true;
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return 1;
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}
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static int acpi_cmos_rtc_attach(struct acpi_device *adev,
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const struct acpi_device_id *id)
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{
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int ret;
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ret = acpi_install_cmos_rtc_space_handler(adev->handle);
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if (ret < 0)
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return ret;
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if (IS_ERR_OR_NULL(acpi_create_platform_device(adev, NULL))) {
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pr_err("Failed to create a platform device for %s\n", (char *)id->id);
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return 0;
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} else if (!id->driver_data) {
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cmos_rtc_platform_device_present = true;
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}
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return 1;
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}
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static struct acpi_scan_handler cmos_rtc_handler = {
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.ids = acpi_cmos_rtc_ids,
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.attach = acpi_cmos_rtc_attach,
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};
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void __init acpi_cmos_rtc_init(void)
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{
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acpi_scan_add_handler(&cmos_rtc_handler);
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}
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