// 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//// Author: Keyon Jie <yang.jie@linux.intel.com>// #include <linux/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");MODULE_DESCRIPTION("SOF utils");