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-rw-r--r--drivers/mtd/nand/gpmi-nand/gpmi-lib.c153
-rw-r--r--drivers/mtd/nand/gpmi-nand/gpmi-nand.h4
2 files changed, 157 insertions, 0 deletions
diff --git a/drivers/mtd/nand/gpmi-nand/gpmi-lib.c b/drivers/mtd/nand/gpmi-nand/gpmi-lib.c
index 87e658ce23ef..27f272ed502a 100644
--- a/drivers/mtd/nand/gpmi-nand/gpmi-lib.c
+++ b/drivers/mtd/nand/gpmi-nand/gpmi-lib.c
@@ -1353,3 +1353,156 @@ int gpmi_read_page(struct gpmi_nand_data *this,
set_dma_type(this, DMA_FOR_READ_ECC_PAGE);
return start_dma_with_bch_irq(this, desc);
}
+
+/**
+ * gpmi_copy_bits - copy bits from one memory region to another
+ * @dst: destination buffer
+ * @dst_bit_off: bit offset we're starting to write at
+ * @src: source buffer
+ * @src_bit_off: bit offset we're starting to read from
+ * @nbits: number of bits to copy
+ *
+ * This functions copies bits from one memory region to another, and is used by
+ * the GPMI driver to copy ECC sections which are not guaranteed to be byte
+ * aligned.
+ *
+ * src and dst should not overlap.
+ *
+ */
+void gpmi_copy_bits(u8 *dst, size_t dst_bit_off,
+ const u8 *src, size_t src_bit_off,
+ size_t nbits)
+{
+ size_t i;
+ size_t nbytes;
+ u32 src_buffer = 0;
+ size_t bits_in_src_buffer = 0;
+
+ if (!nbits)
+ return;
+
+ /*
+ * Move src and dst pointers to the closest byte pointer and store bit
+ * offsets within a byte.
+ */
+ src += src_bit_off / 8;
+ src_bit_off %= 8;
+
+ dst += dst_bit_off / 8;
+ dst_bit_off %= 8;
+
+ /*
+ * Initialize the src_buffer value with bits available in the first
+ * byte of data so that we end up with a byte aligned src pointer.
+ */
+ if (src_bit_off) {
+ src_buffer = src[0] >> src_bit_off;
+ if (nbits >= (8 - src_bit_off)) {
+ bits_in_src_buffer += 8 - src_bit_off;
+ } else {
+ src_buffer &= GENMASK(nbits - 1, 0);
+ bits_in_src_buffer += nbits;
+ }
+ nbits -= bits_in_src_buffer;
+ src++;
+ }
+
+ /* Calculate the number of bytes that can be copied from src to dst. */
+ nbytes = nbits / 8;
+
+ /* Try to align dst to a byte boundary. */
+ if (dst_bit_off) {
+ if (bits_in_src_buffer < (8 - dst_bit_off) && nbytes) {
+ src_buffer |= src[0] << bits_in_src_buffer;
+ bits_in_src_buffer += 8;
+ src++;
+ nbytes--;
+ }
+
+ if (bits_in_src_buffer >= (8 - dst_bit_off)) {
+ dst[0] &= GENMASK(dst_bit_off - 1, 0);
+ dst[0] |= src_buffer << dst_bit_off;
+ src_buffer >>= (8 - dst_bit_off);
+ bits_in_src_buffer -= (8 - dst_bit_off);
+ dst_bit_off = 0;
+ dst++;
+ if (bits_in_src_buffer > 7) {
+ bits_in_src_buffer -= 8;
+ dst[0] = src_buffer;
+ dst++;
+ src_buffer >>= 8;
+ }
+ }
+ }
+
+ if (!bits_in_src_buffer && !dst_bit_off) {
+ /*
+ * Both src and dst pointers are byte aligned, thus we can
+ * just use the optimized memcpy function.
+ */
+ if (nbytes)
+ memcpy(dst, src, nbytes);
+ } else {
+ /*
+ * src buffer is not byte aligned, hence we have to copy each
+ * src byte to the src_buffer variable before extracting a byte
+ * to store in dst.
+ */
+ for (i = 0; i < nbytes; i++) {
+ src_buffer |= src[i] << bits_in_src_buffer;
+ dst[i] = src_buffer;
+ src_buffer >>= 8;
+ }
+ }
+ /* Update dst and src pointers */
+ dst += nbytes;
+ src += nbytes;
+
+ /*
+ * nbits is the number of remaining bits. It should not exceed 8 as
+ * we've already copied as much bytes as possible.
+ */
+ nbits %= 8;
+
+ /*
+ * If there's no more bits to copy to the destination and src buffer
+ * was already byte aligned, then we're done.
+ */
+ if (!nbits && !bits_in_src_buffer)
+ return;
+
+ /* Copy the remaining bits to src_buffer */
+ if (nbits)
+ src_buffer |= (*src & GENMASK(nbits - 1, 0)) <<
+ bits_in_src_buffer;
+ bits_in_src_buffer += nbits;
+
+ /*
+ * In case there were not enough bits to get a byte aligned dst buffer
+ * prepare the src_buffer variable to match the dst organization (shift
+ * src_buffer by dst_bit_off and retrieve the least significant bits
+ * from dst).
+ */
+ if (dst_bit_off)
+ src_buffer = (src_buffer << dst_bit_off) |
+ (*dst & GENMASK(dst_bit_off - 1, 0));
+ bits_in_src_buffer += dst_bit_off;
+
+ /*
+ * Keep most significant bits from dst if we end up with an unaligned
+ * number of bits.
+ */
+ nbytes = bits_in_src_buffer / 8;
+ if (bits_in_src_buffer % 8) {
+ src_buffer |= (dst[nbytes] &
+ GENMASK(7, bits_in_src_buffer % 8)) <<
+ (nbytes * 8);
+ nbytes++;
+ }
+
+ /* Copy the remaining bytes to dst */
+ for (i = 0; i < nbytes; i++) {
+ dst[i] = src_buffer;
+ src_buffer >>= 8;
+ }
+}
diff --git a/drivers/mtd/nand/gpmi-nand/gpmi-nand.h b/drivers/mtd/nand/gpmi-nand/gpmi-nand.h
index 32c6ba49f986..20da1f139853 100644
--- a/drivers/mtd/nand/gpmi-nand/gpmi-nand.h
+++ b/drivers/mtd/nand/gpmi-nand/gpmi-nand.h
@@ -290,6 +290,10 @@ extern int gpmi_send_page(struct gpmi_nand_data *,
extern int gpmi_read_page(struct gpmi_nand_data *,
dma_addr_t payload, dma_addr_t auxiliary);
+void gpmi_copy_bits(u8 *dst, size_t dst_bit_off,
+ const u8 *src, size_t src_bit_off,
+ size_t nbits);
+
/* BCH : Status Block Completion Codes */
#define STATUS_GOOD 0x00
#define STATUS_ERASED 0xff