diff options
Diffstat (limited to 'sound/soc/sof/utils.c')
| -rw-r--r-- | sound/soc/sof/utils.c | 60 |
1 files changed, 60 insertions, 0 deletions
diff --git a/sound/soc/sof/utils.c b/sound/soc/sof/utils.c index 2ac4c3da0320..9831eb57df6c 100644 --- a/sound/soc/sof/utils.c +++ b/sound/soc/sof/utils.c @@ -10,6 +10,7 @@ #include <linux/io-64-nonatomic-lo-hi.h> #include <linux/platform_device.h> +#include <asm/unaligned.h> #include <sound/soc.h> #include <sound/sof.h> #include "sof-priv.h" @@ -110,3 +111,62 @@ void sof_block_read(struct snd_sof_dev *sdev, u32 bar, u32 offset, void *dest, memcpy_fromio(dest, src, size); } EXPORT_SYMBOL(sof_block_read); + +/* + * 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; + + dev_vdbg(dev, "pfn i %i idx %d pfn %x\n", i, idx, pfn); + + 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); |