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-rw-r--r--sound/soc/sof/sof-utils.c75
1 files changed, 75 insertions, 0 deletions
diff --git a/sound/soc/sof/sof-utils.c b/sound/soc/sof/sof-utils.c
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+++ b/sound/soc/sof/sof-utils.c
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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");