arch/ia64/hp/common/hwsw_iommu.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (c) 2004 Hewlett-Packard Development Company, L.P.
   4  *   Contributed by David Mosberger-Tang <davidm@hpl.hp.com>
   5  *
   6  * This is a pseudo I/O MMU which dispatches to the hardware I/O MMU
   7  * whenever possible.  We assume that the hardware I/O MMU requires
   8  * full 32-bit addressability, as is the case, e.g., for HP zx1-based
   9  * systems (there, the I/O MMU window is mapped at 3-4GB).  If a
  10  * device doesn't provide full 32-bit addressability, we fall back on
  11  * the sw I/O TLB.  This is good enough to let us support broken
  12  * hardware such as soundcards which have a DMA engine that can
  13  * address only 28 bits.
  14  */
  15
  16 #include <linux/device.h>
  17 #include <linux/dma-mapping.h>
  18 #include <linux/swiotlb.h>
  19 #include <linux/export.h>
  20 #include <asm/machvec.h>
  21
  22 extern const struct dma_map_ops sba_dma_ops, swiotlb_dma_ops;
  23
  24 /* swiotlb declarations & definitions: */
  25 extern int swiotlb_late_init_with_default_size (size_t size);
  26
  27 /*
  28  * Note: we need to make the determination of whether or not to use
  29  * the sw I/O TLB based purely on the device structure.  Anything else
  30  * would be unreliable or would be too intrusive.
  31  */
  32 static inline int use_swiotlb(struct device *dev)
  33 {
  34         return dev && dev->dma_mask &&
  35                 !sba_dma_ops.dma_supported(dev, *dev->dma_mask);
  36 }
  37
  38 const struct dma_map_ops *hwsw_dma_get_ops(struct device *dev)
  39 {
  40         if (use_swiotlb(dev))
  41                 return &swiotlb_dma_ops;
  42         return &sba_dma_ops;
  43 }
  44 EXPORT_SYMBOL(hwsw_dma_get_ops);
  45
  46 void __init
  47 hwsw_init (void)
  48 {
  49         /* default to a smallish 2MB sw I/O TLB */
  50         if (swiotlb_late_init_with_default_size (2 * (1<<20)) != 0) {
  51 #ifdef CONFIG_IA64_GENERIC
  52                 /* Better to have normal DMA than panic */
  53                 printk(KERN_WARNING "%s: Failed to initialize software I/O TLB,"
  54                        " reverting to hpzx1 platform vector\n", __func__);
  55                 machvec_init("hpzx1");
  56 #else
  57                 panic("Unable to initialize software I/O TLB services");
  58 #endif
  59         }
  60 }