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Subject[PATCH 4/6] nvmem: sunxi_sid: Read out data in native format
Date
From: Chen-Yu Tsai <wens@csie.org>

Originally the SID e-fuses were thought to be in big-endian format.
Later sources show that they are in fact native or little-endian.
The most compelling evidence is the thermal sensor calibration data,
which is a set of one to three 16-bit values. In native-endian they
are in 16-bit cells with increasing offsets, whereas with big-endian
they are in the wrong order, and a gap with no data will show if there
are one or three cells.

Switch to a native endian representation for the nvmem device. For the
H3, the register read-out method was already returning data in native
endian. This only affects the other SoCs.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
---
drivers/nvmem/sunxi_sid.c | 23 +----------------------
1 file changed, 1 insertion(+), 22 deletions(-)

diff --git a/drivers/nvmem/sunxi_sid.c b/drivers/nvmem/sunxi_sid.c
index 75c1f48cb3d0..14c114620ed6 100644
--- a/drivers/nvmem/sunxi_sid.c
+++ b/drivers/nvmem/sunxi_sid.c
@@ -46,33 +46,12 @@ struct sunxi_sid {
u32 value_offset;
};

-/* We read the entire key, due to a 32 bit read alignment requirement. Since we
- * want to return the requested byte, this results in somewhat slower code and
- * uses 4 times more reads as needed but keeps code simpler. Since the SID is
- * only very rarely probed, this is not really an issue.
- */
-static u8 sunxi_sid_read_byte(const struct sunxi_sid *sid,
- const unsigned int offset)
-{
- u32 sid_key;
-
- sid_key = ioread32be(sid->base + round_down(offset, 4));
- sid_key >>= (offset % 4) * 8;
-
- return sid_key; /* Only return the last byte */
-}
-
static int sunxi_sid_read(void *context, unsigned int offset,
void *val, size_t bytes)
{
struct sunxi_sid *sid = context;
- u8 *buf = val;
-
- /* Offset the read operation to the real position of SID */
- offset += sid->value_offset;

- while (bytes--)
- *buf++ = sunxi_sid_read_byte(sid, offset++);
+ memcpy_fromio(val, sid->base + sid->value_offset + offset, bytes);

return 0;
}
--
2.20.1
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