[PATCH 0/5] meson_saradc fixes and minor improvements

[martin.blumenstingl@googlemail.com (Martin Blumenstingl)]

Meson8 and Meson8b require that the driver initializes the registers
correctly, while on GXBB and newer this is done by the firmware.
Thus the changes from this series are only relevant for Meson8 and
Meson8b.

The first two patches are bugfixes:
- the first patch fixes an issue where the SAR ADC would not work at
  all
- the second patch initializes the bandgrap register on Meson8 and
  Meson8b (which is required for the SAR ADC to operate)

The third patch is mainly a cosmetic fix because we don't want to
read/write registers that are not documented.

Patch four is purely cosmetic so the mainline driver uses the same
settings as Amlogic's vendor kernel driver.

The last patch initializes the channel muxes. There are sane defaults
for these in the hardware itself. However, some bootloaders are
setting strange values - the result is that reading the ADC gives
garbage values.
I did not tag this as "fix" since in my opinion it's a feature for
fixing broken bootloaders.

Tested on:
- a Meson8m2 board (compatible with Meson8)
- a Meson8b EC-100
- on a Khadas VIM to ensure that the newer SoCs are still working


Martin Blumenstingl (5):
  iio: adc: meson-saradc: fix the bit_idx of the adc_en clock
  iio: adc: meson-saradc: initialize the bandgap correctly on older SoCs
  iio: adc: meson-saradc: Meson8 and Meson8b do not have REG11 and REG13
  iio: adc: meson-saradc: fix the clock frequency on Meson8 and Meson8b
  iio: adc: meson-saradc: program the channel muxes during
    initialization

 drivers/iio/adc/meson_saradc.c | 92 +++++++++++++++++++++++++++++++++++-------
 1 file changed, 78 insertions(+), 14 deletions(-)

-- 
2.15.0