/* * Dynamic DMA mapping support. * * This implementation is for IA-64 platforms that do not support * I/O TLBs (aka DMA address translation hardware). * Copyright (C) 2000 Asit Mallick * Copyright (C) 2000 Goutham Rao */ #include #include #include #include #include #include #include #include #include #ifdef CONFIG_SWIOTLB #include #include #define ALIGN(val, align) ((unsigned long) (((unsigned long) (val) + ((align) - 1)) & ~((align) - 1))) /* * log of the size of each IO TLB slab. The number of slabs is command line * controllable. */ #define IO_TLB_SHIFT 11 /* * Used to do a quick range check in pci_unmap_single and pci_sync_single, to see if the * memory was in fact allocated by this API. */ static char *io_tlb_start, *io_tlb_end; /* * The number of IO TLB blocks (in groups of 64) betweeen io_tlb_start and io_tlb_end. * This is command line adjustable via setup_io_tlb_npages. */ unsigned long io_tlb_nslabs = 1024; /* * This is a free list describing the number of free entries available from each index */ static unsigned int *io_tlb_list; static unsigned int io_tlb_index; /* * We need to save away the original address corresponding to a mapped entry for the sync * operations. */ static unsigned char **io_tlb_orig_addr; /* * Protect the above data structures in the map and unmap calls */ spinlock_t io_tlb_lock = SPIN_LOCK_UNLOCKED; static int __init setup_io_tlb_npages (char *str) { io_tlb_nslabs = simple_strtoul(str, NULL, 0) << (PAGE_SHIFT - IO_TLB_SHIFT); return 1; } __setup("swiotlb=", setup_io_tlb_npages); /* * Statically reserve bounce buffer space and initialize bounce buffer * data structures for the software IO TLB used to implement the PCI DMA API */ void setup_swiotlb (void) { int i; /* * Get IO TLB memory from the low pages */ io_tlb_start = alloc_bootmem_low_pages(io_tlb_nslabs * (1 << IO_TLB_SHIFT)); if (!io_tlb_start) BUG(); io_tlb_end = io_tlb_start + io_tlb_nslabs * (1 << IO_TLB_SHIFT); /* * Allocate and initialize the free list array. This array is used * to find contiguous free memory regions of size 2^IO_TLB_SHIFT between * io_tlb_start and io_tlb_end. */ io_tlb_list = alloc_bootmem(io_tlb_nslabs * sizeof(int)); for (i = 0; i < io_tlb_nslabs; i++) io_tlb_list[i] = io_tlb_nslabs - i; io_tlb_index = 0; io_tlb_orig_addr = alloc_bootmem(io_tlb_nslabs * sizeof(char *)); printk("Placing software IO TLB between 0x%p - 0x%p\n", (void *) io_tlb_start, (void *) io_tlb_end); } /* * Allocates bounce buffer and returns its kernel virtual address. */ static void * __pci_map_single (struct pci_dev *hwdev, char *buffer, size_t size, int direction) { unsigned long flags; char *dma_addr; unsigned int i, nslots, stride, index, wrap; /* * For mappings greater than a page size, we limit the stride (and hence alignment) * to a page size. */ nslots = ALIGN(size, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT; if (size > (1 << PAGE_SHIFT)) stride = (1 << (PAGE_SHIFT - IO_TLB_SHIFT)); else stride = nslots; if (!nslots) BUG(); /* * Find suitable number of IO TLB entries size that will fit this request and allocate a buffer * from that IO TLB pool. */ spin_lock_irqsave(&io_tlb_lock, flags); { wrap = index = ALIGN(io_tlb_index, stride); do { /* * If we find a slot that indicates we have 'nslots' number of * contiguous buffers, we allocate the buffers from that slot and mark the * entries as '0' indicating unavailable. */ if (io_tlb_list[index] >= nslots) { for (i = index; i < index + nslots; i++) io_tlb_list[i] = 0; dma_addr = io_tlb_start + (index << IO_TLB_SHIFT); /* * Update the indices to avoid searching in the next round. */ io_tlb_index = (index + nslots) < io_tlb_nslabs ? (index + nslots) : 0; goto found; } index += stride; if (index >= io_tlb_nslabs) index = 0; } while (index != wrap); /* * XXX What is a suitable recovery mechanism here? We cannot * sleep because we are called from with in interrupts! */ panic("__pci_map_single: could not allocate software IO TLB (%ld bytes)", size); found: } spin_unlock_irqrestore(&io_tlb_lock, flags); /* * Save away the mapping from the original address to the DMA address. This is needed * when we sync the memory. Then we sync the buffer if needed. */ io_tlb_orig_addr[index] = buffer; if (direction == PCI_DMA_TODEVICE || direction == PCI_DMA_BIDIRECTIONAL) memcpy(dma_addr, buffer, size); return dma_addr; } /* * dma_addr is the kernel virtual address of the bounce buffer to unmap. */ static void __pci_unmap_single (struct pci_dev *hwdev, char *dma_addr, size_t size, int direction) { unsigned long flags; int i, nslots = ALIGN(size, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT; int index = (dma_addr - io_tlb_start) >> IO_TLB_SHIFT; char *buffer = io_tlb_orig_addr[index]; /* * First, sync the memory before unmapping the entry */ if ((direction == PCI_DMA_FROMDEVICE) || (direction == PCI_DMA_BIDIRECTIONAL)) /* * bounce... copy the data back into the original buffer * and delete the bounce buffer. */ memcpy(buffer, dma_addr, size); /* * Return the buffer to the free list by setting the corresponding entries to indicate * the number of contigous entries available. * While returning the entries to the free list, we merge the entries with slots below * and above the pool being returned. */ spin_lock_irqsave(&io_tlb_lock, flags); { int count = ((index + nslots) < io_tlb_nslabs ? io_tlb_list[index + nslots] : 0); /* * Step 1: return the slots to the free list, merging the slots with superceeding slots */ for (i = index + nslots - 1; i >= index; i--) io_tlb_list[i] = ++count; /* * Step 2: merge the returned slots with the preceeding slots, if available (non zero) */ for (i = index - 1; (i >= 0) && io_tlb_list[i]; i--) io_tlb_list[i] += io_tlb_list[index]; } spin_unlock_irqrestore(&io_tlb_lock, flags); } static void __pci_sync_single (struct pci_dev *hwdev, char *dma_addr, size_t size, int direction) { int index = (dma_addr - io_tlb_start) >> IO_TLB_SHIFT; char *buffer = io_tlb_orig_addr[index]; /* * bounce... copy the data back into/from the original buffer * XXX How do you handle PCI_DMA_BIDIRECTIONAL here ? */ if (direction == PCI_DMA_FROMDEVICE) memcpy(buffer, dma_addr, size); else if (direction == PCI_DMA_TODEVICE) memcpy(dma_addr, buffer, size); else BUG(); } /* * Map a single buffer of the indicated size for DMA in streaming mode. * The PCI address to use is returned. * * Once the device is given the dma address, the device owns this memory * until either pci_unmap_single or pci_dma_sync_single is performed. */ dma_addr_t pci_map_single (struct pci_dev *hwdev, void *ptr, size_t size, int direction) { unsigned long pci_addr = virt_to_phys(ptr); if (direction == PCI_DMA_NONE) BUG(); /* * Check if the PCI device can DMA to ptr... if so, just return ptr */ if ((pci_addr & ~hwdev->dma_mask) == 0) /* * Device is bit capable of DMA'ing to the * buffer... just return the PCI address of ptr */ return pci_addr; /* * get a bounce buffer: */ pci_addr = virt_to_phys(__pci_map_single(hwdev, ptr, size, direction)); /* * Ensure that the address returned is DMA'ble: */ if ((pci_addr & ~hwdev->dma_mask) != 0) panic("__pci_map_single: bounce buffer is not DMA'ble"); return pci_addr; } /* * Unmap a single streaming mode DMA translation. The dma_addr and size * must match what was provided for in a previous pci_map_single call. All * other usages are undefined. * * After this call, reads by the cpu to the buffer are guarenteed to see * whatever the device wrote there. */ void pci_unmap_single (struct pci_dev *hwdev, dma_addr_t pci_addr, size_t size, int direction) { char *dma_addr = phys_to_virt(pci_addr); if (direction == PCI_DMA_NONE) BUG(); if (dma_addr >= io_tlb_start && dma_addr < io_tlb_end) __pci_unmap_single(hwdev, dma_addr, size, direction); } /* * Make physical memory consistent for a single * streaming mode DMA translation after a transfer. * * If you perform a pci_map_single() but wish to interrogate the * buffer using the cpu, yet do not wish to teardown the PCI dma * mapping, you must call this function before doing so. At the * next point you give the PCI dma address back to the card, the * device again owns the buffer. */ void pci_dma_sync_single (struct pci_dev *hwdev, dma_addr_t pci_addr, size_t size, int direction) { char *dma_addr = phys_to_virt(pci_addr); if (direction == PCI_DMA_NONE) BUG(); if (dma_addr >= io_tlb_start && dma_addr < io_tlb_end) __pci_sync_single(hwdev, dma_addr, size, direction); } /* * Map a set of buffers described by scatterlist in streaming * mode for DMA. This is the scather-gather version of the * above pci_map_single interface. Here the scatter gather list * elements are each tagged with the appropriate dma address * and length. They are obtained via sg_dma_{address,length}(SG). * * NOTE: An implementation may be able to use a smaller number of * DMA address/length pairs than there are SG table elements. * (for example via virtual mapping capabilities) * The routine returns the number of addr/length pairs actually * used, at most nents. * * Device ownership issues as mentioned above for pci_map_single are * the same here. */ int pci_map_sg (struct pci_dev *hwdev, struct scatterlist *sg, int nelems, int direction) { int i; if (direction == PCI_DMA_NONE) BUG(); for (i = 0; i < nelems; i++, sg++) { sg->orig_address = sg->address; if ((virt_to_phys(sg->address) & ~hwdev->dma_mask) != 0) { sg->address = __pci_map_single(hwdev, sg->address, sg->length, direction); } } return nelems; } /* * Unmap a set of streaming mode DMA translations. * Again, cpu read rules concerning calls here are the same as for * pci_unmap_single() above. */ void pci_unmap_sg (struct pci_dev *hwdev, struct scatterlist *sg, int nelems, int direction) { int i; if (direction == PCI_DMA_NONE) BUG(); for (i = 0; i < nelems; i++, sg++) if (sg->orig_address != sg->address) { __pci_unmap_single(hwdev, sg->address, sg->length, direction); sg->address = sg->orig_address; } } /* * Make physical memory consistent for a set of streaming mode DMA * translations after a transfer. * * The same as pci_dma_sync_single but for a scatter-gather list, * same rules and usage. */ void pci_dma_sync_sg (struct pci_dev *hwdev, struct scatterlist *sg, int nelems, int direction) { int i; if (direction == PCI_DMA_NONE) BUG(); for (i = 0; i < nelems; i++, sg++) if (sg->orig_address != sg->address) __pci_sync_single(hwdev, sg->address, sg->length, direction); } #else /* * Map a single buffer of the indicated size for DMA in streaming mode. * The 32-bit bus address to use is returned. * * Once the device is given the dma address, the device owns this memory * until either pci_unmap_single or pci_dma_sync_single is performed. */ dma_addr_t pci_map_single (struct pci_dev *hwdev, void *ptr, size_t size, int direction) { if (direction == PCI_DMA_NONE) BUG(); return virt_to_bus(ptr); } /* * Unmap a single streaming mode DMA translation. The dma_addr and size * must match what was provided for in a previous pci_map_single call. All * other usages are undefined. * * After this call, reads by the cpu to the buffer are guarenteed to see * whatever the device wrote there. */ void pci_unmap_single (struct pci_dev *hwdev, dma_addr_t dma_addr, size_t size, int direction) { if (direction == PCI_DMA_NONE) BUG(); /* Nothing to do */ } /* * Map a set of buffers described by scatterlist in streaming * mode for DMA. This is the scather-gather version of the * above pci_map_single interface. Here the scatter gather list * elements are each tagged with the appropriate dma address * and length. They are obtained via sg_dma_{address,length}(SG). * * NOTE: An implementation may be able to use a smaller number of * DMA address/length pairs than there are SG table elements. * (for example via virtual mapping capabilities) * The routine returns the number of addr/length pairs actually * used, at most nents. * * Device ownership issues as mentioned above for pci_map_single are * the same here. */ int pci_map_sg (struct pci_dev *hwdev, struct scatterlist *sg, int nents, int direction) { if (direction == PCI_DMA_NONE) BUG(); return nents; } /* * Unmap a set of streaming mode DMA translations. * Again, cpu read rules concerning calls here are the same as for * pci_unmap_single() above. */ void pci_unmap_sg (struct pci_dev *hwdev, struct scatterlist *sg, int nents, int direction) { if (direction == PCI_DMA_NONE) BUG(); /* Nothing to do */ } /* * Make physical memory consistent for a single * streaming mode DMA translation after a transfer. * * If you perform a pci_map_single() but wish to interrogate the * buffer using the cpu, yet do not wish to teardown the PCI dma * mapping, you must call this function before doing so. At the * next point you give the PCI dma address back to the card, the * device again owns the buffer. */ void pci_dma_sync_single (struct pci_dev *hwdev, dma_addr_t dma_handle, size_t size, int direction) { if (direction == PCI_DMA_NONE) BUG(); /* Nothing to do */ } /* * Make physical memory consistent for a set of streaming mode DMA * translations after a transfer. * * The same as pci_dma_sync_single but for a scatter-gather list, * same rules and usage. */ void pci_dma_sync_sg (struct pci_dev *hwdev, struct scatterlist *sg, int nelems, int direction) { if (direction == PCI_DMA_NONE) BUG(); /* Nothing to do */ } #endif /* CONFIG_SWIOTLB */ void * pci_alloc_consistent (struct pci_dev *hwdev, size_t size, dma_addr_t *dma_handle) { unsigned long pci_addr; int gfp = GFP_ATOMIC; void *ret; if (!hwdev || hwdev->dma_mask <= 0xffffffff) gfp |= GFP_DMA; /* XXX fix me: should change this to GFP_32BIT or ZONE_32BIT */ ret = (void *)__get_free_pages(gfp, get_order(size)); if (!ret) return NULL; memset(ret, 0, size); pci_addr = virt_to_phys(ret); if ((pci_addr & ~hwdev->dma_mask) != 0) panic("pci_alloc_consistent: allocated memory is out of range for PCI device"); *dma_handle = pci_addr; return ret; } void pci_free_consistent (struct pci_dev *hwdev, size_t size, void *vaddr, dma_addr_t dma_handle) { free_pages((unsigned long) vaddr, get_order(size)); }