From: Alexandru Tachici <alexandru.tachici@xxxxxxxxxx> Currently AD7124-8 driver cannot use more than 8 IIO channels because it was assigning the channel configurations bijectively to channels specified in the device-tree. This is not possible to do when using more than 8 channels as AD7124-8 has only 8 configuration registers. All configurations are marked as live if they are programmed on the device. Any change that happens from userspace (sampling rate, filters etc.) will invalidate them. To allow the user to use all channels at once the driver will keep in memory configurations for all channels but will program only 8 of them at a time on the device. If multiple channels have the same configuration, only one configuration register will be used. If there are more configurations needed than available registers only the last 8 used configurations will be allowed to exist on the device in a LRU fashion. (in case of raw reads). If a read is requested on a channel whose configuration is not programmed: - check if there are similar configurations already programmed if yes: - point channel to that config if no: - check if there are empty config slots - if yes: write config, push into queue of LRU configs - if no: pop one config, get it's config slot nr, write new config on the old slot, push new config in queue of LRU configs. Alexandru Tachici (1): iio: adc: ad7124: allow more than 8 channels Changelog v3 -> v4: - fixed multi-line comments - moved locking and unlocking out of the switch/case in write_raw - check if there were any actual changes in write_raw to the sample frequency/filter/scale by comparing old/new values before marking a config. as changed - maintain a bitmap in order to keep track of empty slots on the device drivers/iio/adc/ad7124.c | 470 ++++++++++++++++++++++++++------------- 1 file changed, 313 insertions(+), 157 deletions(-) -- 2.20.1
