From: Dmitry Baryshkov dmitry.baryshkov@linaro.org
[ Upstream commit 7a06ef75107799675ea6e4d73b9df37e18e352a8 ]
If the NVMEM specifies a stride to access data, reading particular cell might require bit offset that is bigger than one byte. Rework NVMEM core code to support bit offsets of more than 8 bits.
Signed-off-by: Dmitry Baryshkov dmitry.baryshkov@linaro.org Signed-off-by: Srinivas Kandagatla srinivas.kandagatla@linaro.org Link: https://lore.kernel.org/r/20250411112251.68002-9-srinivas.kandagatla@linaro.... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/nvmem/core.c | 24 +++++++++++++++++------- 1 file changed, 17 insertions(+), 7 deletions(-)
diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c index fff85bbf0ecd0..7872903c08a11 100644 --- a/drivers/nvmem/core.c +++ b/drivers/nvmem/core.c @@ -837,7 +837,9 @@ static int nvmem_add_cells_from_dt(struct nvmem_device *nvmem, struct device_nod if (addr && len == (2 * sizeof(u32))) { info.bit_offset = be32_to_cpup(addr++); info.nbits = be32_to_cpup(addr); - if (info.bit_offset >= BITS_PER_BYTE || info.nbits < 1) { + if (info.bit_offset >= BITS_PER_BYTE * info.bytes || + info.nbits < 1 || + info.bit_offset + info.nbits > BITS_PER_BYTE * info.bytes) { dev_err(dev, "nvmem: invalid bits on %pOF\n", child); of_node_put(child); return -EINVAL; @@ -1630,21 +1632,29 @@ 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, extra, bytes_offset; + int bit_offset = cell->bit_offset;
p = b = buf; - if (bit_offset) { + + bytes_offset = bit_offset / BITS_PER_BYTE; + b += bytes_offset; + bit_offset %= BITS_PER_BYTE; + + if (bit_offset % BITS_PER_BYTE) { /* First shift */ - *b++ >>= bit_offset; + *p = *b++ >> bit_offset;
/* setup rest of the bytes if any */ for (i = 1; i < cell->bytes; i++) { /* Get bits from next byte and shift them towards msb */ - *p |= *b << (BITS_PER_BYTE - bit_offset); + *p++ |= *b << (BITS_PER_BYTE - bit_offset);
- p = b; - *b++ >>= bit_offset; + *p = *b++ >> bit_offset; } + } else if (p != b) { + memmove(p, b, cell->bytes - bytes_offset); + p += cell->bytes - 1; } else { /* point to the msb */ p += cell->bytes - 1;