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Commit 620242ae authored by Myron Stowe's avatar Myron Stowe Committed by Len Brown
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ACPI: Maintain a list of ACPI memory mapped I/O remappings 



For memory mapped I/O (MMIO) remappings, add a list to maintain the
remappings and augment the corresponding mapping and unmapping interface
routines (acpi_os_map_memory() and acpi_os_unmap_memory()) to
dynamically add to, and delete from, the list.

The current ACPI I/O accessing methods - acpi_read() and acpi_write() -
end up calling ioremap() when accessing MMIO.  This prevents use of these
methods within interrupt context (IRQ and/or NMI), since ioremap() may
block to allocate memory.  Maintaining a list of MMIO remappings enables
accesses to such areas from within interrupt context provided they have
been pre-mapped.

Signed-off-by: default avatarMyron Stowe <myron.stowe@hp.com>
Signed-off-by: default avatarLen Brown <len.brown@intel.com>
parent b3ba1efe

drivers/acpi/osl.c

+113 −15
Original line number Diff line number Diff line
@@ -95,6 +95,20 @@ struct acpi_res_list { 
static LIST_HEAD(resource_list_head);

static DEFINE_SPINLOCK(acpi_res_lock);



/*

 * This list of permanent mappings is for memory that may be accessed from

 * interrupt context, where we can't do the ioremap().

 */

struct acpi_ioremap {

	struct list_head list;

	void __iomem *virt;

	acpi_physical_address phys;

	acpi_size size;

};



static LIST_HEAD(acpi_ioremaps);

static DEFINE_SPINLOCK(acpi_ioremap_lock);



#define	OSI_STRING_LENGTH_MAX 64	/* arbitrary */

static char osi_additional_string[OSI_STRING_LENGTH_MAX];
@@ -260,29 +274,95 @@ acpi_physical_address __init acpi_os_get_root_pointer(void) 
	}

}



/* Must be called with 'acpi_ioremap_lock' lock held. */

static void __iomem *

acpi_map_vaddr_lookup(acpi_physical_address phys, acpi_size size)

{

	struct acpi_ioremap *map;



	list_for_each_entry(map, &acpi_ioremaps, list)

		if (map->phys <= phys &&

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

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



	return NULL;

}



/* Must be called with 'acpi_ioremap_lock' lock held. */

static struct acpi_ioremap *

acpi_map_lookup_virt(void __iomem *virt, acpi_size size)

{

	struct acpi_ioremap *map;



	list_for_each_entry(map, &acpi_ioremaps, list)

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

			return map;



	return NULL;

}



void __iomem *__init_refok

acpi_os_map_memory(acpi_physical_address phys, acpi_size size)

{

	struct acpi_ioremap *map;

	unsigned long flags;

	void __iomem *virt;



	if (phys > ULONG_MAX) {

		printk(KERN_ERR PREFIX "Cannot map memory that high\n");

		return NULL;

	}

	if (acpi_gbl_permanent_mmap)

		/*

		* ioremap checks to ensure this is in reserved space

		*/

		return ioremap((unsigned long)phys, size);

	else



	if (!acpi_gbl_permanent_mmap)

		return __acpi_map_table((unsigned long)phys, size);



	map = kzalloc(sizeof(*map), GFP_KERNEL);

	if (!map)

		return NULL;



	virt = ioremap(phys, size);

	if (!virt) {

		kfree(map);

		return NULL;

	}



	INIT_LIST_HEAD(&map->list);

	map->virt = virt;

	map->phys = phys;

	map->size = size;



	spin_lock_irqsave(&acpi_ioremap_lock, flags);

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

	spin_unlock_irqrestore(&acpi_ioremap_lock, flags);



	return virt;

}

EXPORT_SYMBOL_GPL(acpi_os_map_memory);



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

{

	if (acpi_gbl_permanent_mmap)

		iounmap(virt);

	else

	struct acpi_ioremap *map;

	unsigned long flags;



	if (!acpi_gbl_permanent_mmap) {

		__acpi_unmap_table(virt, size);

		return;

	}



	spin_lock_irqsave(&acpi_ioremap_lock, flags);

	map = acpi_map_lookup_virt(virt, size);

	if (!map) {

		spin_unlock_irqrestore(&acpi_ioremap_lock, flags);

		printk(KERN_ERR PREFIX "%s: bad address %p\n", __func__, virt);

		dump_stack();

		return;

	}



	list_del(&map->list);

	spin_unlock_irqrestore(&acpi_ioremap_lock, flags);



	iounmap(map->virt);

	kfree(map);

}

EXPORT_SYMBOL_GPL(acpi_os_unmap_memory);
@@ -495,8 +575,16 @@ acpi_os_read_memory(acpi_physical_address phys_addr, u32 * value, u32 width) 
{

	u32 dummy;

	void __iomem *virt_addr;

	int size = width / 8, unmap = 0;

	unsigned long flags;



	virt_addr = ioremap(phys_addr, width / 8);

	spin_lock_irqsave(&acpi_ioremap_lock, flags);

	virt_addr = acpi_map_vaddr_lookup(phys_addr, size);

	spin_unlock_irqrestore(&acpi_ioremap_lock, flags);

	if (!virt_addr) {

		virt_addr = ioremap(phys_addr, size);

		unmap = 1;

	}

	if (!value)

		value = &dummy;
@@ -514,6 +602,7 @@ acpi_os_read_memory(acpi_physical_address phys_addr, u32 * value, u32 width) 
		BUG();

	}



	if (unmap)

		iounmap(virt_addr);



	return AE_OK;
@@ -523,8 +612,16 @@ acpi_status 
acpi_os_write_memory(acpi_physical_address phys_addr, u32 value, u32 width)

{

	void __iomem *virt_addr;

	int size = width / 8, unmap = 0;

	unsigned long flags;



	virt_addr = ioremap(phys_addr, width / 8);

	spin_lock_irqsave(&acpi_ioremap_lock, flags);

	virt_addr = acpi_map_vaddr_lookup(phys_addr, size);

	spin_unlock_irqrestore(&acpi_ioremap_lock, flags);

	if (!virt_addr) {

		virt_addr = ioremap(phys_addr, size);

		unmap = 1;

	}



	switch (width) {

	case 8:
@@ -540,6 +637,7 @@ acpi_os_write_memory(acpi_physical_address phys_addr, u32 value, u32 width) 
		BUG();

	}



	if (unmap)

		iounmap(virt_addr);



	return AE_OK;