1#include <linux/prefetch.h>
2
3/**
4 * iommu_fill_pdir - Insert coalesced scatter/gather chunks into the I/O Pdir.
5 * @ioc: The I/O Controller.
6 * @startsg: The scatter/gather list of coalesced chunks.
7 * @nents: The number of entries in the scatter/gather list.
8 * @hint: The DMA Hint.
9 *
10 * This function inserts the coalesced scatter/gather list chunks into the
11 * I/O Controller's I/O Pdir.
12 */
13static inline unsigned int
14iommu_fill_pdir(struct ioc *ioc, struct scatterlist *startsg, int nents,
15		unsigned long hint,
16		void (*iommu_io_pdir_entry)(u64 *, space_t, unsigned long,
17					    unsigned long))
18{
19	struct scatterlist *dma_sg = startsg;	/* pointer to current DMA */
20	unsigned int n_mappings = 0;
21	unsigned long dma_offset = 0, dma_len = 0;
22	u64 *pdirp = NULL;
23
24	/* Horrible hack.  For efficiency's sake, dma_sg starts one
25	 * entry below the true start (it is immediately incremented
26	 * in the loop) */
27	 dma_sg--;
28
29	while (nents-- > 0) {
30		unsigned long vaddr;
31		long size;
32
33		DBG_RUN_SG(" %d : %08lx/%05x %p/%05x\n", nents,
34			   (unsigned long)sg_dma_address(startsg), cnt,
35			   sg_virt(startsg), startsg->length
36		);
37
38
39		/*
40		** Look for the start of a new DMA stream
41		*/
42
43		if (sg_dma_address(startsg) & PIDE_FLAG) {
44			u32 pide = sg_dma_address(startsg) & ~PIDE_FLAG;
45
46			BUG_ON(pdirp && (dma_len != sg_dma_len(dma_sg)));
47
48			dma_sg++;
49
50			dma_len = sg_dma_len(startsg);
51			sg_dma_len(startsg) = 0;
52			dma_offset = (unsigned long) pide & ~IOVP_MASK;
53			n_mappings++;
54#if defined(ZX1_SUPPORT)
55			/* Pluto IOMMU IO Virt Address is not zero based */
56			sg_dma_address(dma_sg) = pide | ioc->ibase;
57#else
58			/* SBA, ccio, and dino are zero based.
59			 * Trying to save a few CPU cycles for most users.
60			 */
61			sg_dma_address(dma_sg) = pide;
62#endif
63			pdirp = &(ioc->pdir_base[pide >> IOVP_SHIFT]);
64			prefetchw(pdirp);
65		}
66
67		BUG_ON(pdirp == NULL);
68
69		vaddr = (unsigned long)sg_virt(startsg);
70		sg_dma_len(dma_sg) += startsg->length;
71		size = startsg->length + dma_offset;
72		dma_offset = 0;
73#ifdef IOMMU_MAP_STATS
74		ioc->msg_pages += startsg->length >> IOVP_SHIFT;
75#endif
76		do {
77			iommu_io_pdir_entry(pdirp, KERNEL_SPACE,
78					    vaddr, hint);
79			vaddr += IOVP_SIZE;
80			size -= IOVP_SIZE;
81			pdirp++;
82		} while(unlikely(size > 0));
83		startsg++;
84	}
85	return(n_mappings);
86}
87
88
89/*
90** First pass is to walk the SG list and determine where the breaks are
91** in the DMA stream. Allocates PDIR entries but does not fill them.
92** Returns the number of DMA chunks.
93**
94** Doing the fill separate from the coalescing/allocation keeps the
95** code simpler. Future enhancement could make one pass through
96** the sglist do both.
97*/
98
99static inline unsigned int
100iommu_coalesce_chunks(struct ioc *ioc, struct device *dev,
101		struct scatterlist *startsg, int nents,
102		int (*iommu_alloc_range)(struct ioc *, struct device *, size_t))
103{
104	struct scatterlist *contig_sg;	   /* contig chunk head */
105	unsigned long dma_offset, dma_len; /* start/len of DMA stream */
106	unsigned int n_mappings = 0;
107	unsigned int max_seg_size = min(dma_get_max_seg_size(dev),
108					(unsigned)DMA_CHUNK_SIZE);
109	unsigned int max_seg_boundary = dma_get_seg_boundary(dev) + 1;
110	if (max_seg_boundary)	/* check if the addition above didn't overflow */
111		max_seg_size = min(max_seg_size, max_seg_boundary);
112
113	while (nents > 0) {
114
115		/*
116		** Prepare for first/next DMA stream
117		*/
118		contig_sg = startsg;
119		dma_len = startsg->length;
120		dma_offset = startsg->offset;
121
122		/* PARANOID: clear entries */
123		sg_dma_address(startsg) = 0;
124		sg_dma_len(startsg) = 0;
125
126		/*
127		** This loop terminates one iteration "early" since
128		** it's always looking one "ahead".
129		*/
130		while(--nents > 0) {
131			unsigned long prev_end, sg_start;
132
133			prev_end = (unsigned long)sg_virt(startsg) +
134							startsg->length;
135
136			startsg++;
137			sg_start = (unsigned long)sg_virt(startsg);
138
139			/* PARANOID: clear entries */
140			sg_dma_address(startsg) = 0;
141			sg_dma_len(startsg) = 0;
142
143			/*
144			** First make sure current dma stream won't
145			** exceed max_seg_size if we coalesce the
146			** next entry.
147			*/
148			if (unlikely(ALIGN(dma_len + dma_offset + startsg->length, IOVP_SIZE) >
149				     max_seg_size))
150				break;
151
152			/*
153			* Next see if we can append the next chunk (i.e.
154			* it must end on one page and begin on another, or
155			* it must start on the same address as the previous
156			* entry ended.
157			*/
158			if (unlikely((prev_end != sg_start) ||
159				((prev_end | sg_start) & ~PAGE_MASK)))
160				break;
161
162			dma_len += startsg->length;
163		}
164
165		/*
166		** End of DMA Stream
167		** Terminate last VCONTIG block.
168		** Allocate space for DMA stream.
169		*/
170		sg_dma_len(contig_sg) = dma_len;
171		dma_len = ALIGN(dma_len + dma_offset, IOVP_SIZE);
172		sg_dma_address(contig_sg) =
173			PIDE_FLAG
174			| (iommu_alloc_range(ioc, dev, dma_len) << IOVP_SHIFT)
175			| dma_offset;
176		n_mappings++;
177	}
178
179	return n_mappings;
180}
181
182