blob: 0310078a95f8a8a78bf360cc7aa7d0f6680a11a0 [file] [log] [blame]
* Copyright (c) 2004 Hewlett-Packard Development Company, L.P.
* Contributed by David Mosberger-Tang <>
* This is a pseudo I/O MMU which dispatches to the hardware I/O MMU
* whenever possible. We assume that the hardware I/O MMU requires
* full 32-bit addressability, as is the case, e.g., for HP zx1-based
* systems (there, the I/O MMU window is mapped at 3-4GB). If a
* device doesn't provide full 32-bit addressability, we fall back on
* the sw I/O TLB. This is good enough to let us support broken
* hardware such as soundcards which have a DMA engine that can
* address only 28 bits.
#include <linux/device.h>
#include <linux/dma-mapping.h>
#include <linux/swiotlb.h>
#include <linux/export.h>
#include <asm/machvec.h>
extern const struct dma_map_ops sba_dma_ops, swiotlb_dma_ops;
/* swiotlb declarations & definitions: */
extern int swiotlb_late_init_with_default_size (size_t size);
* Note: we need to make the determination of whether or not to use
* the sw I/O TLB based purely on the device structure. Anything else
* would be unreliable or would be too intrusive.
static inline int use_swiotlb(struct device *dev)
return dev && dev->dma_mask &&
!sba_dma_ops.dma_supported(dev, *dev->dma_mask);
const struct dma_map_ops *hwsw_dma_get_ops(struct device *dev)
if (use_swiotlb(dev))
return &swiotlb_dma_ops;
return &sba_dma_ops;
void __init
hwsw_init (void)
/* default to a smallish 2MB sw I/O TLB */
if (swiotlb_late_init_with_default_size (2 * (1<<20)) != 0) {
/* Better to have normal DMA than panic */
printk(KERN_WARNING "%s: Failed to initialize software I/O TLB,"
" reverting to hpzx1 platform vector\n", __func__);
panic("Unable to initialize software I/O TLB services");