From: Russ Weight russell.h.weight@intel.com
[ Upstream commit c8e796895e2310b6130e7577248da1d771431a77 ]
The max_raw_write member of the regmap_spi_avmm_bus structure is defined as: .max_raw_write = SPI_AVMM_VAL_SIZE * MAX_WRITE_CNT
SPI_AVMM_VAL_SIZE == 4 and MAX_WRITE_CNT == 1 so this results in a maximum write transfer size of 4 bytes which provides only enough space to transfer the address of the target register. It provides no space for the value to be transferred. This bug became an issue (divide-by-zero in _regmap_raw_write()) after the following was accepted into mainline:
commit 3981514180c9 ("regmap: Account for register length when chunking")
Change max_raw_write to include space (4 additional bytes) for both the register address and value:
.max_raw_write = SPI_AVMM_REG_SIZE + SPI_AVMM_VAL_SIZE * MAX_WRITE_CNT
Fixes: 7f9fb67358a2 ("regmap: add Intel SPI Slave to AVMM Bus Bridge support") Reviewed-by: Matthew Gerlach matthew.gerlach@linux.intel.com Signed-off-by: Russ Weight russell.h.weight@intel.com Link: https://lore.kernel.org/r/20230620202824.380313-1-russell.h.weight@intel.com Signed-off-by: Mark Brown broonie@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/base/regmap/regmap-spi-avmm.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/base/regmap/regmap-spi-avmm.c b/drivers/base/regmap/regmap-spi-avmm.c index 4c2b94b3e30be..6af692844c196 100644 --- a/drivers/base/regmap/regmap-spi-avmm.c +++ b/drivers/base/regmap/regmap-spi-avmm.c @@ -660,7 +660,7 @@ static const struct regmap_bus regmap_spi_avmm_bus = { .reg_format_endian_default = REGMAP_ENDIAN_NATIVE, .val_format_endian_default = REGMAP_ENDIAN_NATIVE, .max_raw_read = SPI_AVMM_VAL_SIZE * MAX_READ_CNT, - .max_raw_write = SPI_AVMM_VAL_SIZE * MAX_WRITE_CNT, + .max_raw_write = SPI_AVMM_REG_SIZE + SPI_AVMM_VAL_SIZE * MAX_WRITE_CNT, .free_context = spi_avmm_bridge_ctx_free, };