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- // SPDX-License-Identifier: (GPL-2.0-only OR BSD-3-Clause)
- //
- // This file is provided under a dual BSD/GPLv2 license. When using or
- // redistributing this file, you may do so under either license.
- //
- // Copyright(c) 2018-2022 Intel Corporation. All rights reserved.
- //
- // Author: Keyon Jie <[email protected]>
- //
- #include <asm/unaligned.h>
- #include <linux/io-64-nonatomic-lo-hi.h>
- #include <linux/device.h>
- #include <sound/memalloc.h>
- #include <linux/module.h>
- #include "sof-utils.h"
- /*
- * Generic buffer page table creation.
- * Take the each physical page address and drop the least significant unused
- * bits from each (based on PAGE_SIZE). Then pack valid page address bits
- * into compressed page table.
- */
- int snd_sof_create_page_table(struct device *dev,
- struct snd_dma_buffer *dmab,
- unsigned char *page_table, size_t size)
- {
- int i, pages;
- pages = snd_sgbuf_aligned_pages(size);
- dev_dbg(dev, "generating page table for %p size 0x%zx pages %d\n",
- dmab->area, size, pages);
- for (i = 0; i < pages; i++) {
- /*
- * The number of valid address bits for each page is 20.
- * idx determines the byte position within page_table
- * where the current page's address is stored
- * in the compressed page_table.
- * This can be calculated by multiplying the page number by 2.5.
- */
- u32 idx = (5 * i) >> 1;
- u32 pfn = snd_sgbuf_get_addr(dmab, i * PAGE_SIZE) >> PAGE_SHIFT;
- u8 *pg_table;
- pg_table = (u8 *)(page_table + idx);
- /*
- * pagetable compression:
- * byte 0 byte 1 byte 2 byte 3 byte 4 byte 5
- * ___________pfn 0__________ __________pfn 1___________ _pfn 2...
- * .... .... .... .... .... .... .... .... .... .... ....
- * It is created by:
- * 1. set current location to 0, PFN index i to 0
- * 2. put pfn[i] at current location in Little Endian byte order
- * 3. calculate an intermediate value as
- * x = (pfn[i+1] << 4) | (pfn[i] & 0xf)
- * 4. put x at offset (current location + 2) in LE byte order
- * 5. increment current location by 5 bytes, increment i by 2
- * 6. continue to (2)
- */
- if (i & 1)
- put_unaligned_le32((pg_table[0] & 0xf) | pfn << 4,
- pg_table);
- else
- put_unaligned_le32(pfn, pg_table);
- }
- return pages;
- }
- EXPORT_SYMBOL(snd_sof_create_page_table);
- MODULE_LICENSE("Dual BSD/GPL");
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