linux_kernel/drivers/acpi/x86/utils.c

/*
 * X86 ACPI Utility Functions
 *
 * Copyright (C) 2017 Hans de Goede <hdegoede@redhat.com>
 *
 * Based on various non upstream patches to support the CHT Whiskey Cove PMIC:
 * Copyright (C) 2013-2015 Intel Corporation. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/acpi.h>
#include <asm/cpu_device_id.h>
#include <asm/intel-family.h>
#include "../internal.h"

/*
 * Some ACPI devices are hidden (status == 0x0) in recent BIOS-es because
 * some recent Windows drivers bind to one device but poke at multiple
 * devices at the same time, so the others get hidden.
 * We work around this by always reporting ACPI_STA_DEFAULT for these
 * devices. Note this MUST only be done for devices where this is safe.
 *
 * This forcing of devices to be present is limited to specific CPU (SoC)
 * models both to avoid potentially causing trouble on other models and
 * because some HIDs are re-used on different SoCs for completely
 * different devices.
 */
struct always_present_id {
	struct acpi_device_id hid[2];
	struct x86_cpu_id cpu_ids[2];
	const char *uid;
};

#define ICPU(model)	{ X86_VENDOR_INTEL, 6, model, X86_FEATURE_ANY, }

#define ENTRY(hid, uid, cpu_models) {					\
	{ { hid, }, {} },						\
	{ cpu_models, {} },						\
	uid,								\
}

static const struct always_present_id always_present_ids[] = {
	/*
	 * Bay / Cherry Trail PWM directly poked by GPU driver in win10,
	 * but Linux uses a separate PWM driver, harmless if not used.
	 */
	ENTRY("80860F09", "1", ICPU(INTEL_FAM6_ATOM_SILVERMONT1)),
	ENTRY("80862288", "1", ICPU(INTEL_FAM6_ATOM_AIRMONT)),
	/*
	 * The INT0002 device is necessary to clear wakeup interrupt sources
	 * on Cherry Trail devices, without it we get nobody cared IRQ msgs.
	 */
	ENTRY("INT0002", "1", ICPU(INTEL_FAM6_ATOM_AIRMONT)),
};

bool acpi_device_always_present(struct acpi_device *adev)
{
	u32 *status = (u32 *)&adev->status;
	u32 old_status = *status;
	bool ret = false;
	unsigned int i;

	/* acpi_match_device_ids checks status, so set it to default */
	*status = ACPI_STA_DEFAULT;
	for (i = 0; i < ARRAY_SIZE(always_present_ids); i++) {
		if (acpi_match_device_ids(adev, always_present_ids[i].hid))
			continue;

		if (!adev->pnp.unique_id ||
		    strcmp(adev->pnp.unique_id, always_present_ids[i].uid))
			continue;

		if (!x86_match_cpu(always_present_ids[i].cpu_ids))
			continue;

		if (old_status != ACPI_STA_DEFAULT) /* Log only once */
			dev_info(&adev->dev,
				 "Device [%s] is in always present list\n",
				 adev->pnp.bus_id);

		ret = true;
		break;
	}
	*status = old_status;

	return ret;
}