Commit 4a3cba5e authored by Myron Stowe's avatar Myron Stowe Committed by Len Brown
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ACPI: Page based coalescing of I/O remappings optimization 



This patch optimizes ACPI MMIO remappings by keeping track of the
remappings on a PAGE_SIZE granularity.

When an ioremap() occurs, the underlying infrastructure works on a 'page'
based granularity.  As such, an ioremap() request for 1 byte for example,
will end up mapping in an entire (PAGE_SIZE) page.  Huang Ying took
advantage of this in commit 15651291 by
checking if subsequent ioremap() requests reside within any of the list's
existing remappings still in place, and if so, incrementing a reference
count on the existing mapping as opposed to performing another ioremap().

Signed-off-by: default avatarMyron Stowe <myron.stowe@hp.com>
Signed-off-by: default avatarLen Brown <len.brown@intel.com>
parent 78cdb3ed

drivers/acpi/osl.c

+51 −11
Original line number Diff line number Diff line
@@ -104,6 +104,7 @@ struct acpi_ioremap { 
	void __iomem *virt;

	acpi_physical_address phys;

	acpi_size size;

	struct kref ref;

};



static LIST_HEAD(acpi_ioremaps);
@@ -245,14 +246,27 @@ acpi_physical_address __init acpi_os_get_root_pointer(void) 
}



/* Must be called with 'acpi_ioremap_lock' or RCU read lock held. */

static void __iomem *

acpi_map_vaddr_lookup(acpi_physical_address phys, acpi_size size)

static struct acpi_ioremap *

acpi_map_lookup(acpi_physical_address phys, acpi_size size)

{

	struct acpi_ioremap *map;



	list_for_each_entry_rcu(map, &acpi_ioremaps, list)

		if (map->phys <= phys &&

		    phys + size <= map->phys + map->size)

			return map;



	return NULL;

}



/* Must be called with 'acpi_ioremap_lock' or RCU read lock held. */

static void __iomem *

acpi_map_vaddr_lookup(acpi_physical_address phys, unsigned int size)

{

	struct acpi_ioremap *map;



	map = acpi_map_lookup(phys, size);

	if (map)

		return map->virt + (phys - map->phys);



	return NULL;
@@ -265,7 +279,8 @@ acpi_map_lookup_virt(void __iomem *virt, acpi_size size) 
	struct acpi_ioremap *map;



	list_for_each_entry_rcu(map, &acpi_ioremaps, list)

		if (map->virt == virt && map->size == size)

		if (map->virt <= virt &&

		    virt + size <= map->virt + map->size)

			return map;



	return NULL;
@@ -274,9 +289,10 @@ acpi_map_lookup_virt(void __iomem *virt, acpi_size size) 
void __iomem *__init_refok

acpi_os_map_memory(acpi_physical_address phys, acpi_size size)

{

	struct acpi_ioremap *map;

	unsigned long flags;

	struct acpi_ioremap *map, *tmp_map;

	unsigned long flags, pg_sz;

	void __iomem *virt;

	phys_addr_t pg_off;



	if (phys > ULONG_MAX) {

		printk(KERN_ERR PREFIX "Cannot map memory that high\n");
@@ -290,7 +306,9 @@ acpi_os_map_memory(acpi_physical_address phys, acpi_size size) 
	if (!map)

		return NULL;



	virt = ioremap(phys, size);

	pg_off = round_down(phys, PAGE_SIZE);

	pg_sz = round_up(phys + size, PAGE_SIZE) - pg_off;

	virt = ioremap(pg_off, pg_sz);

	if (!virt) {

		kfree(map);

		return NULL;
@@ -298,21 +316,40 @@ acpi_os_map_memory(acpi_physical_address phys, acpi_size size) 


	INIT_LIST_HEAD(&map->list);

	map->virt = virt;

	map->phys = phys;

	map->size = size;

	map->phys = pg_off;

	map->size = pg_sz;

	kref_init(&map->ref);



	spin_lock_irqsave(&acpi_ioremap_lock, flags);

	/* Check if page has already been mapped. */

	tmp_map = acpi_map_lookup(phys, size);

	if (tmp_map) {

		kref_get(&tmp_map->ref);

		spin_unlock_irqrestore(&acpi_ioremap_lock, flags);

		iounmap(map->virt);

		kfree(map);

		return tmp_map->virt + (phys - tmp_map->phys);

	}

	list_add_tail_rcu(&map->list, &acpi_ioremaps);

	spin_unlock_irqrestore(&acpi_ioremap_lock, flags);



	return virt;

	return map->virt + (phys - map->phys);

}

EXPORT_SYMBOL_GPL(acpi_os_map_memory);



static void acpi_kref_del_iomap(struct kref *ref)

{

	struct acpi_ioremap *map;



	map = container_of(ref, struct acpi_ioremap, ref);

	list_del_rcu(&map->list);

}



void __ref acpi_os_unmap_memory(void __iomem *virt, acpi_size size)

{

	struct acpi_ioremap *map;

	unsigned long flags;

	int del;



	if (!acpi_gbl_permanent_mmap) {

		__acpi_unmap_table(virt, size);
@@ -328,9 +365,12 @@ void __ref acpi_os_unmap_memory(void __iomem *virt, acpi_size size) 
		return;

	}



	list_del_rcu(&map->list);

	del = kref_put(&map->ref, acpi_kref_del_iomap);

	spin_unlock_irqrestore(&acpi_ioremap_lock, flags);



	if (!del)

		return;



	synchronize_rcu();

	iounmap(map->virt);

	kfree(map);

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