This driver makes use of regmap_mmio, but does not select the required
module.
Add the missing 'select REGMAP_MMIO'.

Fixes: 4d4b30526eb8 ("iio: dac: add support for stm32 DAC")
Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
---
 drivers/iio/dac/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
index f13daf0fd9f7..a5d083804b1c 100644
--- a/drivers/iio/dac/Kconfig
+++ b/drivers/iio/dac/Kconfig
@@ -485,6 +485,7 @@ config STM32_DAC
 
 config STM32_DAC_CORE
 	tristate
+	select REGMAP_MMIO
 
 config TI_DAC082S085
 	tristate "Texas Instruments 8/10/12-bit 2/4-channel DAC driver"

-- 
2.43.0