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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: Nicolas Pitre <nicolas.pitre@linaro.org>
Tested-by: Stephen Warren <swarren@nvidia.com>
Tested-by: Kevin Hilman <khilman@ti.com>
Tested-by: Jamie Iles <jamie@jamieiles.com>
This commit is contained in:
Nicolas Pitre 2011-09-16 01:14:23 -04:00 committed by Nicolas Pitre
parent 6ee723a657
commit 576d2f2525
3 changed files with 64 additions and 25 deletions
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72
arch/arm/mm/ioremap.c
View File

@ -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;
/*
* 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)
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.
*/
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);
}

14
arch/arm/mm/mm.h
View File

@ -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

3
arch/arm/mm/mmu.c
View File

@ -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++);
}