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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 <yang.jie@linux.intel.com>
//
#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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