linux/drivers/acpi/osi.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  osi.c - _OSI implementation
 *
 *  Copyright (C) 2016 Intel Corporation
 *    Author: Lv Zheng <[email protected]>
 */

/* Uncomment next line to get verbose printout */
/* #define DEBUG */
#define pr_fmt(fmt) …

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/acpi.h>
#include <linux/dmi.h>
#include <linux/platform_data/x86/apple.h>

#include "internal.h"


#define OSI_STRING_LENGTH_MAX …
#define OSI_STRING_ENTRIES_MAX …

struct acpi_osi_entry { … };

static struct acpi_osi_config { … } osi_config;

static struct acpi_osi_config osi_config;
static struct acpi_osi_entry
osi_setup_entries[OSI_STRING_ENTRIES_MAX] __initdata = …;

static u32 acpi_osi_handler(acpi_string interface, u32 supported)
{ … }

void __init acpi_osi_setup(char *str)
{ … }

static void __init __acpi_osi_setup_darwin(bool enable)
{ … }

static void __init acpi_osi_setup_darwin(bool enable)
{ … }

/*
 * The story of _OSI(Linux)
 *
 * From pre-history through Linux-2.6.22, Linux responded TRUE upon a BIOS
 * OSI(Linux) query.
 *
 * Unfortunately, reference BIOS writers got wind of this and put
 * OSI(Linux) in their example code, quickly exposing this string as
 * ill-conceived and opening the door to an un-bounded number of BIOS
 * incompatibilities.
 *
 * For example, OSI(Linux) was used on resume to re-POST a video card on
 * one system, because Linux at that time could not do a speedy restore in
 * its native driver. But then upon gaining quick native restore
 * capability, Linux has no way to tell the BIOS to skip the time-consuming
 * POST -- putting Linux at a permanent performance disadvantage. On
 * another system, the BIOS writer used OSI(Linux) to infer native OS
 * support for IPMI!  On other systems, OSI(Linux) simply got in the way of
 * Linux claiming to be compatible with other operating systems, exposing
 * BIOS issues such as skipped device initialization.
 *
 * So "Linux" turned out to be a really poor chose of OSI string, and from
 * Linux-2.6.23 onward we respond FALSE.
 *
 * BIOS writers should NOT query _OSI(Linux) on future systems. Linux will
 * complain on the console when it sees it, and return FALSE. To get Linux
 * to return TRUE for your system  will require a kernel source update to
 * add a DMI entry, or boot with "acpi_osi=Linux"
 */
static void __init __acpi_osi_setup_linux(bool enable)
{ … }

static void __init acpi_osi_setup_linux(bool enable)
{ … }

/*
 * Modify the list of "OS Interfaces" reported to BIOS via _OSI
 *
 * empty string disables _OSI
 * string starting with '!' disables that string
 * otherwise string is added to list, augmenting built-in strings
 */
static void __init acpi_osi_setup_late(void)
{ … }

static int __init osi_setup(char *str)
{ … }
__setup(…);

bool acpi_osi_is_win8(void)
{ … }
EXPORT_SYMBOL(…);

static void __init acpi_osi_dmi_darwin(void)
{ … }

static void __init acpi_osi_dmi_linux(bool enable,
				      const struct dmi_system_id *d)
{ … }

static int __init dmi_enable_osi_linux(const struct dmi_system_id *d)
{ … }

static int __init dmi_disable_osi_vista(const struct dmi_system_id *d)
{ … }

static int __init dmi_disable_osi_win7(const struct dmi_system_id *d)
{ … }

static int __init dmi_disable_osi_win8(const struct dmi_system_id *d)
{ … }

/*
 * Linux default _OSI response behavior is determined by this DMI table.
 *
 * Note that _OSI("Linux")/_OSI("Darwin") determined here can be overridden
 * by acpi_osi=!Linux/acpi_osi=!Darwin command line options.
 */
static const struct dmi_system_id acpi_osi_dmi_table[] __initconst = …;

static __init void acpi_osi_dmi_blacklisted(void)
{ … }

int __init early_acpi_osi_init(void)
{ … }

int __init acpi_osi_init(void)
{ … }