1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *  PowerPC version derived from arch/arm/mm/consistent.c
4  *    Copyright (C) 2001 Dan Malek (dmalek@jlc.net)
5  *
6  *  Copyright (C) 2000 Russell King
7  */
8 
9 #include <linux/kernel.h>
10 #include <linux/errno.h>
11 #include <linux/types.h>
12 #include <linux/highmem.h>
13 #include <linux/dma-direct.h>
14 #include <linux/dma-noncoherent.h>
15 
16 #include <asm/tlbflush.h>
17 #include <asm/dma.h>
18 
19 /*
20  * make an area consistent.
21  */
22 static void __dma_sync(void *vaddr, size_t size, int direction)
23 {
24 	unsigned long start = (unsigned long)vaddr;
25 	unsigned long end   = start + size;
26 
27 	switch (direction) {
28 	case DMA_NONE:
29 		BUG();
30 	case DMA_FROM_DEVICE:
31 		/*
32 		 * invalidate only when cache-line aligned otherwise there is
33 		 * the potential for discarding uncommitted data from the cache
34 		 */
35 		if ((start | end) & (L1_CACHE_BYTES - 1))
36 			flush_dcache_range(start, end);
37 		else
38 			invalidate_dcache_range(start, end);
39 		break;
40 	case DMA_TO_DEVICE:		/* writeback only */
41 		clean_dcache_range(start, end);
42 		break;
43 	case DMA_BIDIRECTIONAL:	/* writeback and invalidate */
44 		flush_dcache_range(start, end);
45 		break;
46 	}
47 }
48 
49 #ifdef CONFIG_HIGHMEM
50 /*
51  * __dma_sync_page() implementation for systems using highmem.
52  * In this case, each page of a buffer must be kmapped/kunmapped
53  * in order to have a virtual address for __dma_sync(). This must
54  * not sleep so kmap_atomic()/kunmap_atomic() are used.
55  *
56  * Note: yes, it is possible and correct to have a buffer extend
57  * beyond the first page.
58  */
59 static inline void __dma_sync_page_highmem(struct page *page,
60 		unsigned long offset, size_t size, int direction)
61 {
62 	size_t seg_size = min((size_t)(PAGE_SIZE - offset), size);
63 	size_t cur_size = seg_size;
64 	unsigned long flags, start, seg_offset = offset;
65 	int nr_segs = 1 + ((size - seg_size) + PAGE_SIZE - 1)/PAGE_SIZE;
66 	int seg_nr = 0;
67 
68 	local_irq_save(flags);
69 
70 	do {
71 		start = (unsigned long)kmap_atomic(page + seg_nr) + seg_offset;
72 
73 		/* Sync this buffer segment */
74 		__dma_sync((void *)start, seg_size, direction);
75 		kunmap_atomic((void *)start);
76 		seg_nr++;
77 
78 		/* Calculate next buffer segment size */
79 		seg_size = min((size_t)PAGE_SIZE, size - cur_size);
80 
81 		/* Add the segment size to our running total */
82 		cur_size += seg_size;
83 		seg_offset = 0;
84 	} while (seg_nr < nr_segs);
85 
86 	local_irq_restore(flags);
87 }
88 #endif /* CONFIG_HIGHMEM */
89 
90 /*
91  * __dma_sync_page makes memory consistent. identical to __dma_sync, but
92  * takes a struct page instead of a virtual address
93  */
94 static void __dma_sync_page(phys_addr_t paddr, size_t size, int dir)
95 {
96 	struct page *page = pfn_to_page(paddr >> PAGE_SHIFT);
97 	unsigned offset = paddr & ~PAGE_MASK;
98 
99 #ifdef CONFIG_HIGHMEM
100 	__dma_sync_page_highmem(page, offset, size, dir);
101 #else
102 	unsigned long start = (unsigned long)page_address(page) + offset;
103 	__dma_sync((void *)start, size, dir);
104 #endif
105 }
106 
107 void arch_sync_dma_for_device(phys_addr_t paddr, size_t size,
108 		enum dma_data_direction dir)
109 {
110 	__dma_sync_page(paddr, size, dir);
111 }
112 
113 void arch_sync_dma_for_cpu(phys_addr_t paddr, size_t size,
114 		enum dma_data_direction dir)
115 {
116 	__dma_sync_page(paddr, size, dir);
117 }
118 
119 void arch_dma_prep_coherent(struct page *page, size_t size)
120 {
121 	unsigned long kaddr = (unsigned long)page_address(page);
122 
123 	flush_dcache_range(kaddr, kaddr + size);
124 }
125