Some nvmem controllers like Apple's eFuses or Nintendo's OTP have a cell
size that's larger than one byte. Consumers may however still need
access to a subset of bits that start after the first byte. Handle this
inside nvmem_shift_read_buffer_in_place().
Signed-off-by: Sven Peter <[email protected]>
---
drivers/nvmem/core.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)
diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index 321d7d63e068..a5b8d6989f8e 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -1379,15 +1379,23 @@ EXPORT_SYMBOL_GPL(nvmem_cell_put);
static void nvmem_shift_read_buffer_in_place(struct nvmem_cell_entry *cell, void *buf)
{
u8 *p, *b;
- int i, extra, bit_offset = cell->bit_offset;
+ int i, padding, extra, bit_offset = cell->bit_offset;
+ int bytes = cell->bytes;
p = b = buf;
if (bit_offset) {
+ padding = bit_offset/8;
+ if (padding) {
+ memmove(buf, buf + padding, bytes - padding);
+ bit_offset -= BITS_PER_BYTE * padding;
+ bytes -= padding;
+ }
+
/* First shift */
*b++ >>= bit_offset;
/* setup rest of the bytes if any */
- for (i = 1; i < cell->bytes; i++) {
+ for (i = 1; i < bytes; i++) {
/* Get bits from next byte and shift them towards msb */
*p |= *b << (BITS_PER_BYTE - bit_offset);
@@ -1400,7 +1408,7 @@ static void nvmem_shift_read_buffer_in_place(struct nvmem_cell_entry *cell, void
}
/* result fits in less bytes */
- extra = cell->bytes - DIV_ROUND_UP(cell->nbits, BITS_PER_BYTE);
+ extra = bytes - DIV_ROUND_UP(cell->nbits, BITS_PER_BYTE);
while (--extra >= 0)
*p-- = 0;
--
2.25.1