u-boot/arch/x86/cpu/intel_common/car2_uninit.S

/* SPDX-License-Identifier: GPL-2.0 */
/*
 * Copyright 2017 Intel Corp.
 * Copyright 2019 Google LLC
 * Taken from coreboot file exit_car.S
 */

#include <config.h>
#include <asm/msr-index.h>
#include <asm/mtrr.h>

.text
.global car_uninit
car_uninit:

	/*
	 * Retrieve return address from stack as it will get trashed below if
	 * execution is utilizing the cache-as-ram stack.
	 */
	pop	%ebx

	/* Disable MTRRs */
	mov	$(MTRR_DEF_TYPE_MSR), %ecx
	rdmsr
	and	$(~(MTRR_DEF_TYPE_EN | MTRR_DEF_TYPE_FIX_EN)), %eax
	wrmsr

#ifdef CONFIG_INTEL_CAR_NEM
.global car_nem_teardown
car_nem_teardown:

	/* invalidate cache contents */
	invd

	/* Knock down bit 1 then bit 0 of NEM control not combining steps */
	mov	$(MSR_EVICT_CTL), %ecx
	rdmsr
	and	$(~(1 << 1)), %eax
	wrmsr
	and	$(~(1 << 0)), %eax
	wrmsr

#elif IS_ENABLED(CONFIG_INTEL_CAR_CQOS)
.global car_cqos_teardown
car_cqos_teardown:

	/* Go back to all-evicting mode, set both masks to all-1s */
	mov	$MSR_L2_QOS_MASK(0), %ecx
	rdmsr
	mov	$~0, %al
	wrmsr

	mov	$MSR_L2_QOS_MASK(1), %ecx
	rdmsr
	mov	$~0, %al
	wrmsr

	/* Reset CLOS selector to 0 */
	mov	$MSR_IA32_PQR_ASSOC, %ecx
	rdmsr
	and	$~MSR_IA32_PQR_ASSOC_MASK, %edx
	wrmsr

#elif IS_ENABLED(CONFIG_INTEL_CAR_NEM_ENHANCED)
.global car_nem_enhanced_teardown
car_nem_enhanced_teardown:

	/* invalidate cache contents */
	invd

	/* Knock down bit 1 then bit 0 of NEM control not combining steps */
	mov	$(MSR_EVICT_CTL), %ecx
	rdmsr
	and	$(~(1 << 1)), %eax
	wrmsr
	and	$(~(1 << 0)), %eax
	wrmsr

	/* Reset CLOS selector to 0 */
	mov	$IA32_PQR_ASSOC, %ecx
	rdmsr
	and	$~IA32_PQR_ASSOC_MASK, %edx
	wrmsr
#endif

	/* Return to caller */
	jmp	*%ebx