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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162636465666768697071727374757677// 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");