nvmem: allow bit offset > 8

Signed-off-by: Sven Peter <sven@svenpeter.dev>

Author: svenpeter42

drivers/nvmem/core.c

@@ -1622,15 +1622,23 @@ 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);
 
@@ -1643,7 +1651,7 @@ 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;