@@ -224,6 +224,48 @@ static int check_offs_len(struct nand_chip *chip, loff_t ofs, uint64_t len)
return ret;
}
+/** nand_extract_bits - Copy unaligned bits from one buffer to another one
+ * @dst: destination buffer
+ * @dst_off: bit offset at which the writing starts
+ * @src: source buffer
+ * @src_off: bit offset at which the reading starts
+ * @nbits: number of bits to copy from @src to @dst
+ *
+ * Copy bits from one memory region to another (overlap authorized).
+ */
+void nand_extract_bits(u8 *dst, unsigned int dst_off, const u8 *src,
+ unsigned int src_off, unsigned int nbits)
+{
+ unsigned int tmp, n;
+
+ dst += dst_off / 8;
+ dst_off %= 8;
+ src += src_off / 8;
+ src_off %= 8;
+
+ while (nbits) {
+ n = min3(8 - dst_off, 8 - src_off, nbits);
+
+ tmp = (*src >> src_off) & GENMASK(n - 1, 0);
+ *dst &= ~GENMASK(n - 1 + dst_off, dst_off);
+ *dst |= tmp << dst_off;
+
+ dst_off += n;
+ if (dst_off >= 8) {
+ dst++;
+ dst_off -= 8;
+ }
+
+ src_off += n;
+ if (src_off >= 8) {
+ src++;
+ src_off -= 8;
+ }
+
+ nbits -= n;
+ }
+}
+
/**
* nand_select_target() - Select a NAND target (A.K.A. die)
* @chip: NAND chip object
@@ -1404,6 +1404,10 @@ int nand_gpio_waitrdy(struct nand_chip *chip, struct gpio_desc *gpiod,
void nand_select_target(struct nand_chip *chip, unsigned int cs);
void nand_deselect_target(struct nand_chip *chip);
+/* Bitops */
+void nand_extract_bits(u8 *dst, unsigned int dst_off, const u8 *src,
+ unsigned int src_off, unsigned int nbits);
+
/**
* nand_get_data_buf() - Get the internal page buffer
* @chip: NAND chip object
There are cases where ECC bytes are not byte-aligned. Indeed, BCH implies using a number of ECC bits, which are not always a multiple of 8. We then need a helper like nand_extract_bits() to extract these syndromes from a buffer. Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com> --- drivers/mtd/nand/raw/nand_base.c | 42 ++++++++++++++++++++++++++++++++ include/linux/mtd/rawnand.h | 4 +++ 2 files changed, 46 insertions(+)