iio: adc: stm32-dfsdm: make spi_master_freq more accurate

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Current ckout divider may be set to a value that makes ckout to exceed
spi-max-frequency. Rather use lower value (e.g. round up divider when
ckout isn't accurate).

Also when the SPI clock isn't accurate, 'spi_master_freq' is filled in
with expected frequency. Use computed value instead to be more accurate:
- e.g. source clock / (CKOUTDIV + 1)

Enforce checks on the divider: ckoutdiv range can be from 1-255 to provide
divider of 2-256.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

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Fabrice Gasnier 2019-03-21 17:47:22 +01:00 • committed by Jonathan Cameron

parent 57565828ad

commit 2e19ba661e

1 changed files with 12 additions and 5 deletions

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drivers/iio/adc/stm32-dfsdm-core.c

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