1/* SPDX-License-Identifier: GPL-2.0 */
2#include <linux/prefetch.h>
3
4/**
5 * iommu_fill_pdir - Insert coalesced scatter/gather chunks into the I/O Pdir.
6 * @ioc: The I/O Controller.
7 * @startsg: The scatter/gather list of coalesced chunks.
8 * @nents: The number of entries in the scatter/gather list.
9 * @hint: The DMA Hint.
10 *
11 * This function inserts the coalesced scatter/gather list chunks into the
12 * I/O Controller's I/O Pdir.
13 */
14static inline unsigned int
15iommu_fill_pdir(struct ioc *ioc, struct scatterlist *startsg, int nents,
16		unsigned long hint,
17		void (*iommu_io_pdir_entry)(__le64 *, space_t, unsigned long,
18					    unsigned long))
19{
20	struct scatterlist *dma_sg = startsg;	/* pointer to current DMA */
21	unsigned int n_mappings = 0;
22	unsigned long dma_offset = 0, dma_len = 0;
23	__le64 *pdirp = NULL;
24
25	/* Horrible hack.  For efficiency's sake, dma_sg starts one
26	 * entry below the true start (it is immediately incremented
27	 * in the loop) */
28	 dma_sg--;
29
30	while (nents-- > 0) {
31		unsigned long vaddr;
32		long size;
33
34		DBG_RUN_SG(" %d : %08lx %p/%05x\n", nents,
35			   (unsigned long)sg_dma_address(startsg),
36			   sg_virt(startsg), startsg->length
37		);
38
39
40		/*
41		** Look for the start of a new DMA stream
42		*/
43
44		if (sg_dma_address(startsg) & PIDE_FLAG) {
45			u32 pide = sg_dma_address(startsg) & ~PIDE_FLAG;
46
47			BUG_ON(pdirp && (dma_len != sg_dma_len(dma_sg)));
48
49			dma_sg++;
50
51			dma_len = sg_dma_len(startsg);
52			sg_dma_len(startsg) = 0;
53			dma_offset = (unsigned long) pide & ~IOVP_MASK;
54			n_mappings++;
55#if defined(ZX1_SUPPORT)
56			/* Pluto IOMMU IO Virt Address is not zero based */
57			sg_dma_address(dma_sg) = pide | ioc->ibase;
58#else
59			/* SBA, ccio, and dino are zero based.
60			 * Trying to save a few CPU cycles for most users.
61			 */
62			sg_dma_address(dma_sg) = pide;
63#endif
64			pdirp = &(ioc->pdir_base[pide >> IOVP_SHIFT]);
65			prefetchw(pdirp);
66		}
67
68		BUG_ON(pdirp == NULL);
69
70		vaddr = (unsigned long)sg_virt(startsg);
71		sg_dma_len(dma_sg) += startsg->length;
72		size = startsg->length + dma_offset;
73		dma_offset = 0;
74#ifdef IOMMU_MAP_STATS
75		ioc->msg_pages += startsg->length >> IOVP_SHIFT;
76#endif
77		do {
78			iommu_io_pdir_entry(pdirp, KERNEL_SPACE,
79					    vaddr, hint);
80			vaddr += IOVP_SIZE;
81			size -= IOVP_SIZE;
82			pdirp++;
83		} while(unlikely(size > 0));
84		startsg++;
85	}
86	return(n_mappings);
87}
88
89
90/*
91** First pass is to walk the SG list and determine where the breaks are
92** in the DMA stream. Allocates PDIR entries but does not fill them.
93** Returns the number of DMA chunks.
94**
95** Doing the fill separate from the coalescing/allocation keeps the
96** code simpler. Future enhancement could make one pass through
97** the sglist do both.
98*/
99
100static inline unsigned int
101iommu_coalesce_chunks(struct ioc *ioc, struct device *dev,
102		struct scatterlist *startsg, int nents,
103		int (*iommu_alloc_range)(struct ioc *, struct device *, size_t))
104{
105	struct scatterlist *contig_sg;	   /* contig chunk head */
106	unsigned long dma_offset, dma_len; /* start/len of DMA stream */
107	unsigned int n_mappings = 0;
108	unsigned int max_seg_size = min(dma_get_max_seg_size(dev),
109					(unsigned)DMA_CHUNK_SIZE);
110	unsigned int max_seg_boundary = dma_get_seg_boundary(dev) + 1;
111	if (max_seg_boundary)	/* check if the addition above didn't overflow */
112		max_seg_size = min(max_seg_size, max_seg_boundary);
113
114	while (nents > 0) {
115
116		/*
117		** Prepare for first/next DMA stream
118		*/
119		contig_sg = startsg;
120		dma_len = startsg->length;
121		dma_offset = startsg->offset;
122
123		/* PARANOID: clear entries */
124		sg_dma_address(startsg) = 0;
125		sg_dma_len(startsg) = 0;
126
127		/*
128		** This loop terminates one iteration "early" since
129		** it's always looking one "ahead".
130		*/
131		while(--nents > 0) {
132			unsigned long prev_end, sg_start;
133
134			prev_end = (unsigned long)sg_virt(startsg) +
135							startsg->length;
136
137			startsg++;
138			sg_start = (unsigned long)sg_virt(startsg);
139
140			/* PARANOID: clear entries */
141			sg_dma_address(startsg) = 0;
142			sg_dma_len(startsg) = 0;
143
144			/*
145			** First make sure current dma stream won't
146			** exceed max_seg_size if we coalesce the
147			** next entry.
148			*/
149			if (unlikely(ALIGN(dma_len + dma_offset + startsg->length, IOVP_SIZE) >
150				     max_seg_size))
151				break;
152
153			/*
154			* Next see if we can append the next chunk (i.e.
155			* it must end on one page and begin on another, or
156			* it must start on the same address as the previous
157			* entry ended.
158			*/
159			if (unlikely((prev_end != sg_start) ||
160				((prev_end | sg_start) & ~PAGE_MASK)))
161				break;
162
163			dma_len += startsg->length;
164		}
165
166		/*
167		** End of DMA Stream
168		** Terminate last VCONTIG block.
169		** Allocate space for DMA stream.
170		*/
171		sg_dma_len(contig_sg) = dma_len;
172		dma_len = ALIGN(dma_len + dma_offset, IOVP_SIZE);
173		sg_dma_address(contig_sg) =
174			PIDE_FLAG
175			| (iommu_alloc_range(ioc, dev, dma_len) << IOVP_SHIFT)
176			| dma_offset;
177		n_mappings++;
178	}
179
180	return n_mappings;
181}
182
183