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1// SPDX-License-Identifier: (GPL-2.0-only OR BSD-3-Clause)2//3// This file is provided under a dual BSD/GPLv2 license. When using or4// redistributing this file, you may do so under either license.5//6// Copyright(c) 2018-2022 Intel Corporation7//8// Author: Keyon Jie <yang.jie@linux.intel.com>9//10 11#include <linux/unaligned.h>12#include <linux/io-64-nonatomic-lo-hi.h>13#include <linux/device.h>14#include <sound/memalloc.h>15#include <linux/module.h>16#include "sof-utils.h"17 18/*19 * Generic buffer page table creation.20 * Take the each physical page address and drop the least significant unused21 * bits from each (based on PAGE_SIZE). Then pack valid page address bits22 * into compressed page table.23 */24 25int snd_sof_create_page_table(struct device *dev,26 struct snd_dma_buffer *dmab,27 unsigned char *page_table, size_t size)28{29 int i, pages;30 31 pages = snd_sgbuf_aligned_pages(size);32 33 dev_dbg(dev, "generating page table for %p size 0x%zx pages %d\n",34 dmab->area, size, pages);35 36 for (i = 0; i < pages; i++) {37 /*38 * The number of valid address bits for each page is 20.39 * idx determines the byte position within page_table40 * where the current page's address is stored41 * in the compressed page_table.42 * This can be calculated by multiplying the page number by 2.5.43 */44 u32 idx = (5 * i) >> 1;45 u32 pfn = snd_sgbuf_get_addr(dmab, i * PAGE_SIZE) >> PAGE_SHIFT;46 u8 *pg_table;47 48 pg_table = (u8 *)(page_table + idx);49 50 /*51 * pagetable compression:52 * byte 0 byte 1 byte 2 byte 3 byte 4 byte 553 * ___________pfn 0__________ __________pfn 1___________ _pfn 2...54 * .... .... .... .... .... .... .... .... .... .... ....55 * It is created by:56 * 1. set current location to 0, PFN index i to 057 * 2. put pfn[i] at current location in Little Endian byte order58 * 3. calculate an intermediate value as59 * x = (pfn[i+1] << 4) | (pfn[i] & 0xf)60 * 4. put x at offset (current location + 2) in LE byte order61 * 5. increment current location by 5 bytes, increment i by 262 * 6. continue to (2)63 */64 if (i & 1)65 put_unaligned_le32((pg_table[0] & 0xf) | pfn << 4,66 pg_table);67 else68 put_unaligned_le32(pfn, pg_table);69 }70 71 return pages;72}73EXPORT_SYMBOL(snd_sof_create_page_table);74 75MODULE_LICENSE("Dual BSD/GPL");76MODULE_DESCRIPTION("SOF utils");77