arch/powerpc/mm/ioremap_64.c

// SPDX-License-Identifier: GPL-2.0-or-later

#include <linux/io.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>

void __iomem *__ioremap_caller(phys_addr_t addr, unsigned long size,
			       pgprot_t prot, void *caller)
{
	phys_addr_t paligned, offset;
	void __iomem *ret;
	int err;

	/* We don't support the 4K PFN hack with ioremap */
	if (pgprot_val(prot) & H_PAGE_4K_PFN)
		return NULL;

	/*
	 * Choose an address to map it to. Once the vmalloc system is running,
	 * we use it. Before that, we map using addresses going up from
	 * ioremap_bot.  vmalloc will use the addresses from IOREMAP_BASE
	 * through ioremap_bot.
	 */
	paligned = addr & PAGE_MASK;
	offset = addr & ~PAGE_MASK;
	size = PAGE_ALIGN(addr + size) - paligned;

	if (size == 0 || paligned == 0)
		return NULL;

	if (slab_is_available())
		return generic_ioremap_prot(addr, size, prot);

	pr_warn("ioremap() called early from %pS. Use early_ioremap() instead\n", caller);

	err = early_ioremap_range(ioremap_bot, paligned, size, prot);
	if (err)
		return NULL;

	ret = (void __iomem *)ioremap_bot + offset;
	ioremap_bot += size + PAGE_SIZE;

	return ret;
}

/*
 * Unmap an IO region and remove it from vmalloc'd list.
 * Access to IO memory should be serialized by driver.
 */
void iounmap(volatile void __iomem *token)
{
	if (!slab_is_available())
		return;

	generic_iounmap(token);
}
EXPORT_SYMBOL(iounmap);