linux/arch/x86/kernel/pci-swiotlb.c
Akinobu Mita 9c5a362142 x86: enable DMA CMA with swiotlb
The DMA Contiguous Memory Allocator support on x86 is disabled when
swiotlb config option is enabled.  So DMA CMA is always disabled on
x86_64 because swiotlb is always enabled.  This attempts to support for
DMA CMA with enabling swiotlb config option.

The contiguous memory allocator on x86 is integrated in the function
dma_generic_alloc_coherent() which is .alloc callback in nommu_dma_ops
for dma_alloc_coherent().

x86_swiotlb_alloc_coherent() which is .alloc callback in swiotlb_dma_ops
tries to allocate with dma_generic_alloc_coherent() firstly and then
swiotlb_alloc_coherent() is called as a fallback.

The main part of supporting DMA CMA with swiotlb is that changing
x86_swiotlb_free_coherent() which is .free callback in swiotlb_dma_ops
for dma_free_coherent() so that it can distinguish memory allocated by
dma_generic_alloc_coherent() from one allocated by
swiotlb_alloc_coherent() and release it with dma_generic_free_coherent()
which can handle contiguous memory.  This change requires making
is_swiotlb_buffer() global function.

This also needs to change .free callback in the dma_map_ops for amd_gart
and sta2x11, because these dma_ops are also using
dma_generic_alloc_coherent().

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Don Dutile <ddutile@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04 16:53:57 -07:00

113 lines
2.7 KiB
C

/* Glue code to lib/swiotlb.c */
#include <linux/pci.h>
#include <linux/cache.h>
#include <linux/module.h>
#include <linux/swiotlb.h>
#include <linux/bootmem.h>
#include <linux/dma-mapping.h>
#include <asm/iommu.h>
#include <asm/swiotlb.h>
#include <asm/dma.h>
#include <asm/xen/swiotlb-xen.h>
#include <asm/iommu_table.h>
int swiotlb __read_mostly;
void *x86_swiotlb_alloc_coherent(struct device *hwdev, size_t size,
dma_addr_t *dma_handle, gfp_t flags,
struct dma_attrs *attrs)
{
void *vaddr;
vaddr = dma_generic_alloc_coherent(hwdev, size, dma_handle, flags,
attrs);
if (vaddr)
return vaddr;
return swiotlb_alloc_coherent(hwdev, size, dma_handle, flags);
}
void x86_swiotlb_free_coherent(struct device *dev, size_t size,
void *vaddr, dma_addr_t dma_addr,
struct dma_attrs *attrs)
{
if (is_swiotlb_buffer(dma_to_phys(dev, dma_addr)))
swiotlb_free_coherent(dev, size, vaddr, dma_addr);
else
dma_generic_free_coherent(dev, size, vaddr, dma_addr, attrs);
}
static struct dma_map_ops swiotlb_dma_ops = {
.mapping_error = swiotlb_dma_mapping_error,
.alloc = x86_swiotlb_alloc_coherent,
.free = x86_swiotlb_free_coherent,
.sync_single_for_cpu = swiotlb_sync_single_for_cpu,
.sync_single_for_device = swiotlb_sync_single_for_device,
.sync_sg_for_cpu = swiotlb_sync_sg_for_cpu,
.sync_sg_for_device = swiotlb_sync_sg_for_device,
.map_sg = swiotlb_map_sg_attrs,
.unmap_sg = swiotlb_unmap_sg_attrs,
.map_page = swiotlb_map_page,
.unmap_page = swiotlb_unmap_page,
.dma_supported = NULL,
};
/*
* pci_swiotlb_detect_override - set swiotlb to 1 if necessary
*
* This returns non-zero if we are forced to use swiotlb (by the boot
* option).
*/
int __init pci_swiotlb_detect_override(void)
{
int use_swiotlb = swiotlb | swiotlb_force;
if (swiotlb_force)
swiotlb = 1;
return use_swiotlb;
}
IOMMU_INIT_FINISH(pci_swiotlb_detect_override,
pci_xen_swiotlb_detect,
pci_swiotlb_init,
pci_swiotlb_late_init);
/*
* if 4GB or more detected (and iommu=off not set) return 1
* and set swiotlb to 1.
*/
int __init pci_swiotlb_detect_4gb(void)
{
/* don't initialize swiotlb if iommu=off (no_iommu=1) */
#ifdef CONFIG_X86_64
if (!no_iommu && max_pfn > MAX_DMA32_PFN)
swiotlb = 1;
#endif
return swiotlb;
}
IOMMU_INIT(pci_swiotlb_detect_4gb,
pci_swiotlb_detect_override,
pci_swiotlb_init,
pci_swiotlb_late_init);
void __init pci_swiotlb_init(void)
{
if (swiotlb) {
swiotlb_init(0);
dma_ops = &swiotlb_dma_ops;
}
}
void __init pci_swiotlb_late_init(void)
{
/* An IOMMU turned us off. */
if (!swiotlb)
swiotlb_free();
else {
printk(KERN_INFO "PCI-DMA: "
"Using software bounce buffering for IO (SWIOTLB)\n");
swiotlb_print_info();
}
}