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| 11 | #include <linux/unaligned.h>
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| 12 | #include <linux/io-64-nonatomic-lo-hi.h>
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| 13 | #include <linux/device.h>
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| 14 | #include <sound/memalloc.h>
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| 15 | #include <linux/module.h>
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| 16 | #include "sof-utils.h"
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| 17 |
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| 18 | |
| 19 | * Generic buffer page table creation.
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| 20 | * Take the each physical page address and drop the least significant unused
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| 21 | * bits from each (based on PAGE_SIZE). Then pack valid page address bits
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| 22 | * into compressed page table.
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| 23 |
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| 24 |
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| 25 | int snd_sof_create_page_table(struct device *dev,
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| 26 | struct snd_dma_buffer *dmab,
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| 27 | unsigned char *page_table, size_t size)
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| 28 | {
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| 29 | int i, pages;
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| 30 |
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| 31 | pages = snd_sgbuf_aligned_pages(size);
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| 32 |
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| 33 | dev_dbg(dev, "generating page table for %p size 0x%zx pages %d\n",
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| 34 | dmab->area, size, pages);
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| 35 |
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| 36 | for (i = 0; i < pages; i++) {
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| 37 | |
| 38 | * The number of valid address bits for each page is 20.
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| 39 | * idx determines the byte position within page_table
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| 40 | * where the current page's address is stored
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| 41 | * in the compressed page_table.
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| 42 | * This can be calculated by multiplying the page number by 2.5.
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| 43 |
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| 44 | u32 idx = (5 * i) >> 1;
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| 45 | u32 pfn = snd_sgbuf_get_addr(dmab, i * PAGE_SIZE) >> PAGE_SHIFT;
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| 46 | u8 *pg_table;
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| 47 |
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| 48 | pg_table = (u8 *)(page_table + idx);
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| 49 |
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| 50 | |
| 51 | * pagetable compression:
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| 52 | * byte 0 byte 1 byte 2 byte 3 byte 4 byte 5
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| 53 | * ___________pfn 0__________ __________pfn 1___________ _pfn 2...
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| 54 | * .... .... .... .... .... .... .... .... .... .... ....
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| 55 | * It is created by:
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| 56 | * 1. set current location to 0, PFN index i to 0
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| 57 | * 2. put pfn[i] at current location in Little Endian byte order
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| 58 | * 3. calculate an intermediate value as
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| 59 | * x = (pfn[i+1] << 4) | (pfn[i] & 0xf)
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| 60 | * 4. put x at offset (current location + 2) in LE byte order
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| 61 | * 5. increment current location by 5 bytes, increment i by 2
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| 62 | * 6. continue to (2)
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| 63 |
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| 64 | if (i & 1)
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| 65 | put_unaligned_le32((pg_table[0] & 0xf) | pfn << 4,
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| 66 | pg_table);
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| 67 | else
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| 68 | put_unaligned_le32(pfn, pg_table);
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| 69 | }
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| 70 |
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| 71 | return pages;
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| 72 | }
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| 73 | EXPORT_SYMBOL(snd_sof_create_page_table);
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| 74 |
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| 75 | MODULE_LICENSE("Dual BSD/GPL");
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| 76 | MODULE_DESCRIPTION("SOF utils");
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