On Mon, 8 May 2023 13:30:28 +0300 Matti Vaittinen <mazziesaccount@xxxxxxxxx> wrote: > Add support for ROHM BU27008 RGB sensor. Series applied to the togreg branch of iio.git and pushed out initially as testing for all the normal reasons. Thanks, Jonathan > > The ROHM BU27008 is a sensor with 5 photodiodes (red, green, blue, clear > and IR) with four configurable channels. Red and green being always > available and two out of the rest three (blue, clear, IR) can be > selected to be simultaneously measured. Typical application is adjusting > LCD backlight of TVs, mobile phones and tablet PCs. > > This series supports reading the RGBC and IR channels using IIO > framework. However, only two of the BC+IR can be enabled at the same > time. Series adds also support for scale and integration time > configuration, where scale consists of impact of both the integration > time and hardware gain. The gain and time support is backed by the newly > introduced IIO GTS helper. This series depends on GTS helper patches > added in BU27034 support series which is already merged in iio/togreg > which this series is based on. > > The hardware allows configuring gain setting by writing a 5-bit gain > selector value to a register. Part of the gain setting is common for all > channels (RGBC + IR) but part of the selector value can be set > separately for RGBC and IR: > > MODE_CONTROL2 REG: > bit 7 6 5 4 3 2 1 0 > ----------------------------------------------------------------- > | RGB selector | > +---------------------------------------+ > ----------------------------------------------------------------- > | high bits IR | | low bits IR selector | > +---------------+ +-----------------------+ > > In theory it would be possible to set certain separate gain values for > RGBC and IR channels, but this gets pretty confusing because there are a > few 'unsupported' selector values. If only RGBC or IR was set, some > extra handling should be done to prevent the other channel from getting > unsupported value due to change in high-bits. Furthermore, allowing the > channels to be set different gain values (in some cases when gains are > such the HW supports it) would make the cases where also integration > time is changed to achieve correct scale ... interesting. It might also > be confusing for user to try predicting when setting different scales > succeeds and when it does not. Furthermore, if for example the scale > setting for RGBC caused IR selector to be invalid - it could also cause > the IR scale to "jump" very far from previous value. > > To make the code simpler and more predictable for users, the current > logic is as follows: > > 1. Prevent setting IR scale. (My assumption is IR is less used than > RGBC) > 2. When RGBC scale is set, set also the IR-selector to the same value. > This prevents unsupported selector values and makes the IR scale changes > predictable. > > The 2) could mean we effectively have the same scale for all channels. > Unfortunately, the HW design is slightly peculiar and selector 0 means > gain 1X on RGBC but gain 2X on IR. Rest of the selectors equal same gain > values on RGBC and IR. The result is that while changin selector from 0 > => 1 causes RGBC gain to go from 1X => 4X, it causes IR gain to go from > 2X => 4X. > > So, the driver provides separate scale entries for all channels (also > RGB and C will have separate gain entries because these channels are of > same type as IR channel). This makes it possible for user applications > to go read the scales for all channels after setting scale for one (in > order to detect the IR scale difference). > > Having the separate IR scale entry which applications can read to detect > "arbitrary scale changes" makes it possible for applications to be > written so they can cope if we need to implement the 'allow setting some > different gains for IR and RGBC' - later. > > Finally, the scales_available is also provided for all other channels > except the IR channel, which does not allow the scale to be changed. > > The sensor provides a data-ready IRQ and the driver implements a > triggered buffer mode using this IRQ as a trigger. > > Finally, the series introduces generic iio_validate_own_trigger() helper > which can be used as a validate_trigger callback for drivers which > require the trigger and iio-device to be parented by same device. The > KX022A driver is converted to use this new callback instead of rolling > it's own function. The new helper and KX022A can be merged in as > independent changes if need be. > > > Revision history > v3 => v4: > iio_validate_own_trigger: > - kernel-doc fix > bu27008 driver fixes: > - re-enable IRQ in trigger renable-callback > - do trigger setup on own function > - drop regmap lock > - configure channels in appropriate callback > v3 => v4: > bu27008 driver fixes: > - Drop thread from device IRQ handler > - Styling and some minor improvements > - Use kernel-doc for enums > - Correctly order entries in Makefile > v2 => v3: > dt-bindings: > - No changes > iio_validate_own_trigger: > - subject fix > bu27008: > - Mostly styling based on comments from Andy and Andi > > More accurate changelog in individual patches > > v1 => v2: > dt-bindings: > - Fix issues pointed by Krzysztof. > bu27008 driver: > - Fix issues pointed by Jonathan > Add new helper for validating own trigger > > More accurate changelog in individual patches > > --- > > Matti Vaittinen (5): > dt-bindings: iio: light: ROHM BU27008 > iio: trigger: Add simple trigger_validation helper > iio: kx022a: Use new iio_validate_own_trigger() > iio: light: ROHM BU27008 color sensor > MAINTAINERS: Add ROHM BU27008 > > .../bindings/iio/light/rohm,bu27008.yaml | 49 + > MAINTAINERS | 3 +- > drivers/iio/accel/kionix-kx022a.c | 13 +- > drivers/iio/industrialio-trigger.c | 22 +- > drivers/iio/light/Kconfig | 14 + > drivers/iio/light/Makefile | 1 + > drivers/iio/light/rohm-bu27008.c | 1026 +++++++++++++++++ > include/linux/iio/trigger.h | 1 + > 8 files changed, 1115 insertions(+), 14 deletions(-) > create mode 100644 Documentation/devicetree/bindings/iio/light/rohm,bu27008.yaml > create mode 100644 drivers/iio/light/rohm-bu27008.c >
