mm/early_ioremap.c

/*
 * Provide common bits of early_ioremap() support for architectures needing
 * temporary mappings during boot before ioremap() is available.
 *
 * This is mostly a direct copy of the x86 early_ioremap implementation.
 *
 * (C) Copyright 1995 1996, 2014 Linus Torvalds
 *
 */
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/vmalloc.h>
#include <asm/fixmap.h>

#ifdef CONFIG_MMU
static int early_ioremap_debug __initdata;

static int __init early_ioremap_debug_setup(char *str)
{
	early_ioremap_debug = 1;

	return 0;
}
early_param("early_ioremap_debug", early_ioremap_debug_setup);

static int after_paging_init __initdata;

void __init __weak early_ioremap_shutdown(void)
{
}

void __init early_ioremap_reset(void)
{
	early_ioremap_shutdown();
	after_paging_init = 1;
}

/*
 * Generally, ioremap() is available after paging_init() has been called.
 * Architectures wanting to allow early_ioremap after paging_init() can
 * define __late_set_fixmap and __late_clear_fixmap to do the right thing.
 */
#ifndef __late_set_fixmap
static inline void __init __late_set_fixmap(enum fixed_addresses idx,
					    phys_addr_t phys, pgprot_t prot)
{
	BUG();
}
#endif

#ifndef __late_clear_fixmap
static inline void __init __late_clear_fixmap(enum fixed_addresses idx)
{
	BUG();
}
#endif

static void __iomem *prev_map[FIX_BTMAPS_SLOTS] __initdata;
static unsigned long prev_size[FIX_BTMAPS_SLOTS] __initdata;
static unsigned long slot_virt[FIX_BTMAPS_SLOTS] __initdata;

void __init early_ioremap_setup(void)
{
	int i;

	for (i = 0; i < FIX_BTMAPS_SLOTS; i++)
		if (WARN_ON(prev_map[i]))
			break;

	for (i = 0; i < FIX_BTMAPS_SLOTS; i++)
		slot_virt[i] = __fix_to_virt(FIX_BTMAP_BEGIN - NR_FIX_BTMAPS*i);
}

static int __init check_early_ioremap_leak(void)
{
	int count = 0;
	int i;

	for (i = 0; i < FIX_BTMAPS_SLOTS; i++)
		if (prev_map[i])
			count++;

	if (WARN(count, KERN_WARNING
		 "Debug warning: early ioremap leak of %d areas detected.\n"
		 "please boot with early_ioremap_debug and report the dmesg.\n",
		 count))
		return 1;
	return 0;
}
late_initcall(check_early_ioremap_leak);

static void __init __iomem *
__early_ioremap(resource_size_t phys_addr, unsigned long size, pgprot_t prot)
{
	unsigned long offset;
	resource_size_t last_addr;
	unsigned int nrpages;
	enum fixed_addresses idx;
	int i, slot;

	WARN_ON(system_state != SYSTEM_BOOTING);

	slot = -1;
	for (i = 0; i < FIX_BTMAPS_SLOTS; i++) {
		if (!prev_map[i]) {
			slot = i;
			break;
		}
	}

	if (WARN(slot < 0, "%s(%08llx, %08lx) not found slot\n",
		 __func__, (u64)phys_addr, size))
		return NULL;

	/* Don't allow wraparound or zero size */
	last_addr = phys_addr + size - 1;
	if (WARN_ON(!size || last_addr < phys_addr))
		return NULL;

	prev_size[slot] = size;
	/*
	 * Mappings have to be page-aligned
	 */
	offset = phys_addr & ~PAGE_MASK;
	phys_addr &= PAGE_MASK;
	size = PAGE_ALIGN(last_addr + 1) - phys_addr;

	/*
	 * Mappings have to fit in the FIX_BTMAP area.
	 */
	nrpages = size >> PAGE_SHIFT;
	if (WARN_ON(nrpages > NR_FIX_BTMAPS))
		return NULL;

	/*
	 * Ok, go for it..
	 */
	idx = FIX_BTMAP_BEGIN - NR_FIX_BTMAPS*slot;
	while (nrpages > 0) {
		if (after_paging_init)
			__late_set_fixmap(idx, phys_addr, prot);
		else
			__early_set_fixmap(idx, phys_addr, prot);
		phys_addr += PAGE_SIZE;
		--idx;
		--nrpages;
	}
	WARN(early_ioremap_debug, "%s(%08llx, %08lx) [%d] => %08lx + %08lx\n",
	     __func__, (u64)phys_addr, size, slot, offset, slot_virt[slot]);

	prev_map[slot] = (void __iomem *)(offset + slot_virt[slot]);
	return prev_map[slot];
}

void __init early_iounmap(void __iomem *addr, unsigned long size)
{
	unsigned long virt_addr;
	unsigned long offset;
	unsigned int nrpages;
	enum fixed_addresses idx;
	int i, slot;

	slot = -1;
	for (i = 0; i < FIX_BTMAPS_SLOTS; i++) {
		if (prev_map[i] == addr) {
			slot = i;
			break;
		}
	}

	if (WARN(slot < 0, "early_iounmap(%p, %08lx) not found slot\n",
		 addr, size))
		return;

	if (WARN(prev_size[slot] != size,
		 "early_iounmap(%p, %08lx) [%d] size not consistent %08lx\n",
		 addr, size, slot, prev_size[slot]))
		return;

	WARN(early_ioremap_debug, "early_iounmap(%p, %08lx) [%d]\n",
	     addr, size, slot);

	virt_addr = (unsigned long)addr;
	if (WARN_ON(virt_addr < fix_to_virt(FIX_BTMAP_BEGIN)))
		return;

	offset = virt_addr & ~PAGE_MASK;
	nrpages = PAGE_ALIGN(offset + size) >> PAGE_SHIFT;

	idx = FIX_BTMAP_BEGIN - NR_FIX_BTMAPS*slot;
	while (nrpages > 0) {
		if (after_paging_init)
			__late_clear_fixmap(idx);
		else
			__early_set_fixmap(idx, 0, FIXMAP_PAGE_CLEAR);
		--idx;
		--nrpages;
	}
	prev_map[slot] = NULL;
}

/* Remap an IO device */
void __init __iomem *
early_ioremap(resource_size_t phys_addr, unsigned long size)
{
	return __early_ioremap(phys_addr, size, FIXMAP_PAGE_IO);
}

/* Remap memory */
void __init *
early_memremap(resource_size_t phys_addr, unsigned long size)
{
	return (__force void *)__early_ioremap(phys_addr, size,
					       FIXMAP_PAGE_NORMAL);
}
#else /* CONFIG_MMU */

void __init __iomem *
early_ioremap(resource_size_t phys_addr, unsigned long size)
{
	return (__force void __iomem *)phys_addr;
}

/* Remap memory */
void __init *
early_memremap(resource_size_t phys_addr, unsigned long size)
{
	return (void *)phys_addr;
}

void __init early_iounmap(void __iomem *addr, unsigned long size)
{
}

#endif /* CONFIG_MMU */


void __init early_memunmap(void *addr, unsigned long size)
{
	early_iounmap((__force void __iomem *)addr, size);
}