linux/arch/powerpc/kernel/dma-swiotlb.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Contains routines needed to support swiotlb for ppc.
 *
 * Copyright (C) 2009-2010 Freescale Semiconductor, Inc.
 * Author: Becky Bruce
 */
#include <linux/memblock.h>
#include <asm/machdep.h>
#include <asm/swiotlb.h>

unsigned int ppc_swiotlb_enable;
unsigned int ppc_swiotlb_flags;

void __init swiotlb_detect_4g(void)
{
	if ((memblock_end_of_DRAM() - 1) > 0xffffffff)
		ppc_swiotlb_enable = 1;
}

static int __init check_swiotlb_enabled(void)
{
	if (ppc_swiotlb_enable)
		swiotlb_print_info();
	else
		swiotlb_exit();

	return 0;
}
subsys_initcall(check_swiotlb_enabled);