1/* 2 * Copyright (c) 2004 Hewlett-Packard Development Company, L.P. 3 * Contributed by David Mosberger-Tang <davidm@hpl.hp.com> 4 * 5 * This is a pseudo I/O MMU which dispatches to the hardware I/O MMU 6 * whenever possible. We assume that the hardware I/O MMU requires 7 * full 32-bit addressability, as is the case, e.g., for HP zx1-based 8 * systems (there, the I/O MMU window is mapped at 3-4GB). If a 9 * device doesn't provide full 32-bit addressability, we fall back on 10 * the sw I/O TLB. This is good enough to let us support broken 11 * hardware such as soundcards which have a DMA engine that can 12 * address only 28 bits. 13 */ 14 15#include <linux/device.h> 16#include <linux/dma-mapping.h> 17#include <linux/swiotlb.h> 18#include <asm/machvec.h> 19 20extern struct dma_map_ops sba_dma_ops, swiotlb_dma_ops; 21 22/* swiotlb declarations & definitions: */ 23extern int swiotlb_late_init_with_default_size (size_t size); 24 25/* 26 * Note: we need to make the determination of whether or not to use 27 * the sw I/O TLB based purely on the device structure. Anything else 28 * would be unreliable or would be too intrusive. 29 */ 30static inline int use_swiotlb(struct device *dev) 31{ 32 return dev && dev->dma_mask && 33 !sba_dma_ops.dma_supported(dev, *dev->dma_mask); 34} 35 36struct dma_map_ops *hwsw_dma_get_ops(struct device *dev) 37{ 38 if (use_swiotlb(dev)) 39 return &swiotlb_dma_ops; 40 return &sba_dma_ops; 41} 42EXPORT_SYMBOL(hwsw_dma_get_ops); 43 44void __init 45hwsw_init (void) 46{ 47 /* default to a smallish 2MB sw I/O TLB */ 48 if (swiotlb_late_init_with_default_size (2 * (1<<20)) != 0) { 49#ifdef CONFIG_IA64_GENERIC 50 /* Better to have normal DMA than panic */ 51 printk(KERN_WARNING "%s: Failed to initialize software I/O TLB," 52 " reverting to hpzx1 platform vector\n", __func__); 53 machvec_init("hpzx1"); 54#else 55 panic("Unable to initialize software I/O TLB services"); 56#endif 57 } 58} 59