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Commit 576d2f25 authored by Nicolas Pitre's avatar Nicolas Pitre
Browse files

ARM: add generic ioremap optimization by reusing static mappings 



Now that we have all the static mappings from iotable_init() located
in the vmalloc area, it is trivial to optimize ioremap by reusing those
static mappings when the requested physical area fits in one of them,
and so in a generic way for all platforms.

Signed-off-by: default avatarNicolas Pitre <nicolas.pitre@linaro.org>
Tested-by: default avatarStephen Warren <swarren@nvidia.com>
Tested-by: default avatarKevin Hilman <khilman@ti.com>
Tested-by: default avatarJamie Iles <jamie@jamieiles.com>
parent 6ee723a6

arch/arm/mm/ioremap.c

+48 −24
Original line number Diff line number Diff line
@@ -36,12 +36,6 @@ 
#include <asm/mach/map.h>

#include "mm.h"



/*

 * Used by ioremap() and iounmap() code to mark (super)section-mapped

 * I/O regions in vm_struct->flags field.

 */

#define VM_ARM_SECTION_MAPPING	0x80000000



int ioremap_page(unsigned long virt, unsigned long phys,

		 const struct mem_type *mtype)

{
@@ -201,12 +195,6 @@ void __iomem * __arm_ioremap_pfn_caller(unsigned long pfn, 
	if (pfn >= 0x100000 && (__pfn_to_phys(pfn) & ~SUPERSECTION_MASK))

		return NULL;



	/*

	 * Don't allow RAM to be mapped - this causes problems with ARMv6+

	 */

	if (WARN_ON(pfn_valid(pfn)))

		return NULL;



	type = get_mem_type(mtype);

	if (!type)

		return NULL;
@@ -216,6 +204,34 @@ void __iomem * __arm_ioremap_pfn_caller(unsigned long pfn, 
	 */

	size = PAGE_ALIGN(offset + size);



	/*

	 * Try to reuse one of the static mapping whenever possible.

	 */

	read_lock(&vmlist_lock);

	for (area = vmlist; area; area = area->next) {

		if (!size || (sizeof(phys_addr_t) == 4 && pfn >= 0x100000))

			break;

		if (!(area->flags & VM_ARM_STATIC_MAPPING))

			continue;

		if ((area->flags & VM_ARM_MTYPE_MASK) != VM_ARM_MTYPE(mtype))

			continue;

		if (__phys_to_pfn(area->phys_addr) > pfn ||

		    __pfn_to_phys(pfn) + size-1 > area->phys_addr + area->size-1)

			continue;

		/* we can drop the lock here as we know *area is static */

		read_unlock(&vmlist_lock);

		addr = (unsigned long)area->addr;

		addr += __pfn_to_phys(pfn) - area->phys_addr;

		return (void __iomem *) (offset + addr);

	}

	read_unlock(&vmlist_lock);



	/*

	 * Don't allow RAM to be mapped - this causes problems with ARMv6+

	 */

	if (WARN_ON(pfn_valid(pfn)))

		return NULL;



	area = get_vm_area_caller(size, VM_IOREMAP, caller);

 	if (!area)

 		return NULL;
@@ -313,26 +329,34 @@ __arm_ioremap_exec(unsigned long phys_addr, size_t size, bool cached) 
void __iounmap(volatile void __iomem *io_addr)

{

	void *addr = (void *)(PAGE_MASK & (unsigned long)io_addr);

#ifndef CONFIG_SMP

	struct vm_struct *vm;



	read_lock(&vmlist_lock);

	for (vm = vmlist; vm; vm = vm->next) {

		if (vm->addr > addr)

			break;

		if (!(vm->flags & VM_IOREMAP))

			continue;

		/* If this is a static mapping we must leave it alone */

		if ((vm->flags & VM_ARM_STATIC_MAPPING) &&

		    (vm->addr <= addr) && (vm->addr + vm->size > addr)) {

			read_unlock(&vmlist_lock);

			return;

		}

#ifndef CONFIG_SMP

		/*

		 * If this is a section based mapping we need to handle it

		 * specially as the VM subsystem does not know how to handle

		 * such a beast.

		 */

	read_lock(&vmlist_lock);

	for (vm = vmlist; vm; vm = vm->next) {

		if ((vm->flags & VM_IOREMAP) && (vm->addr == addr)) {

			if (vm->flags & VM_ARM_SECTION_MAPPING) {

				unmap_area_sections((unsigned long)vm->addr,

						    vm->size);

			}

		if ((vm->addr == addr) &&

		    (vm->flags & VM_ARM_SECTION_MAPPING)) {

			unmap_area_sections((unsigned long)vm->addr, vm->size);

			break;

		}

#endif

	}

	read_unlock(&vmlist_lock);

#endif



	vunmap(addr);

}

arch/arm/mm/mm.h

+14 −0
Original line number Diff line number Diff line
@@ -21,6 +21,20 @@ const struct mem_type *get_mem_type(unsigned int type); 


extern void __flush_dcache_page(struct address_space *mapping, struct page *page);



/*

 * ARM specific vm_struct->flags bits.

 */



/* (super)section-mapped I/O regions used by ioremap()/iounmap() */

#define VM_ARM_SECTION_MAPPING	0x80000000



/* permanent static mappings from iotable_init() */

#define VM_ARM_STATIC_MAPPING	0x40000000



/* mapping type (attributes) for permanent static mappings */

#define VM_ARM_MTYPE(mt)		((mt) << 20)

#define VM_ARM_MTYPE_MASK	(0x1f << 20)



#endif



#ifdef CONFIG_ZONE_DMA

arch/arm/mm/mmu.c

+2 −1
Original line number Diff line number Diff line
@@ -749,7 +749,8 @@ void __init iotable_init(struct map_desc *io_desc, int nr) 
		vm->addr = (void *)(md->virtual & PAGE_MASK);

		vm->size = PAGE_ALIGN(md->length + (md->virtual & ~PAGE_MASK));

		vm->phys_addr = __pfn_to_phys(md->pfn); 

		vm->flags = VM_IOREMAP;

		vm->flags = VM_IOREMAP | VM_ARM_STATIC_MAPPING; 

		vm->flags |= VM_ARM_MTYPE(md->type);

		vm->caller = iotable_init;

		vm_area_add_early(vm++);

	}