Add IOCTL to initialize the I2C expander and SPI
initialization for ADS ADC. Clients issue a request
to initialize and enable the device before issuing
requests to perform an ADC read.
The file interface is necessary since it takes
considerable amount of time to initialize the
I2C expander and the ADS ADC device for every
ADC read transaction.
Change-Id: I9e830232592288cbc41554070c70882f05c842ce
Signed-off-by: Siddartha Mohanadoss <smohanad@codeaurora.org>
External Power Monitor(EPM) uses the external ADS1158 ADC
to measure voltage and current. Each ADS1158 ADC supports
measuring 16 Analog input channels.
APQ8064 has support for 2ADS ADC and can measure upto 32
analog input channels. The power to the EPM uses a
SX1509 I2C expander to enable the ADS ADC. Depending on
the input channel the appropriate chip select is de-asserted
to select the ADS ADC to measure the input signal. The
ADS1158 chip is configured through the SPI interface.
Signed-off-by: Siddartha Mohanadoss <smohanad@codeaurora.org>
Change-Id: Ib9f36606b6b183f75754b7763dbe45455c779327
