Re: [PATCH 2/7] iio: adc: qcom-spmi-adc5-gen3: Add support for QCOM PMIC5 Gen4 ADC

[Andy Shevchenko]

On Fri, Jul 31, 2026 at 11:36:15PM +0530, Jishnu Prakash wrote:
> PMIC5 Gen4 ADC is similar to PMIC5 Gen3 ADC, with several changes made
> for improved performance, mostly at the hardware level.
> 
> One significant software change is that ratiometric conversion resolution
> has been increased from 14 bits to 16 bits, so the maximum value of
> these measurements needs to be updated for Gen4. Add a new scaling
> function for thermistor channels which use this type of conversion.
> 
> In the latest PMIC arbiter version (v8), there can be up to 4 buses
> under the PMIC arbiter and 32 PMICs under each bus. In order to
> support communication between ADC on the master PMIC and ADCs on any
> of the other PMICs, a field of width 2 bits is added for bus index
> and the bits for SID are extended from 4 to 5 bits, in the SID
> register. Add support for this.
> 
> In addition, it is possible that the master PMIC has ADC of one generation
> and it needs to communicate with another PMIC with ADC of a different
> generation. Add new DT properties "qcom,adc5-gen3" and "qcom,adc5-gen4",
> to distinguish Gen3 channels under a Gen4 master and Gen4 channels
> under a Gen3 master respectively, to ensure that their conversions are handled
> correctly.

...

> +static const struct adc5_channels adc5_gen4_chans_pmic[ADC5_MAX_CHANNEL] = {
> +	[ADC5_GEN4_OFFSET_REF]		= ADC5_CHAN_VOLT(0,
> +						SCALE_HW_CALIB_DEFAULT)

Always nice to see a macro with the embedded comma...

> +	[ADC5_GEN4_1P25VREF]		= ADC5_CHAN_VOLT(0,
> +						SCALE_HW_CALIB_DEFAULT)
> +	[ADC5_GEN4_VPH_PWR]		= ADC5_CHAN_VOLT(1,
> +						SCALE_HW_CALIB_DEFAULT)
> +	[ADC5_GEN4_VBAT_SNS_QBG]	= ADC5_CHAN_VOLT(1,
> +						SCALE_HW_CALIB_DEFAULT)
> +	[ADC5_GEN4_DIE_TEMP]		= ADC5_CHAN_TEMP(0,
> +						SCALE_HW_CALIB_PMIC_THERM_PM7)
> +	[ADC5_GEN4_AMUX1_THM_100K_PU]	= ADC5_CHAN_TEMP(0,
> +						SCALE_HW_CALIB_THERM_100K_PU_GEN4)
> +	[ADC5_GEN4_AMUX2_THM_100K_PU]	= ADC5_CHAN_TEMP(0,
> +						SCALE_HW_CALIB_THERM_100K_PU_GEN4)
> +	[ADC5_GEN4_AMUX3_THM_100K_PU]	= ADC5_CHAN_TEMP(0,
> +						SCALE_HW_CALIB_THERM_100K_PU_GEN4)
> +	[ADC5_GEN4_AMUX4_THM_100K_PU]	= ADC5_CHAN_TEMP(0,
> +						SCALE_HW_CALIB_THERM_100K_PU_GEN4)
> +	[ADC5_GEN4_AMUX5_THM_100K_PU]	= ADC5_CHAN_TEMP(0,
> +						SCALE_HW_CALIB_THERM_100K_PU_GEN4)
> +	[ADC5_GEN4_AMUX6_THM_100K_PU]	= ADC5_CHAN_TEMP(0,
> +						SCALE_HW_CALIB_THERM_100K_PU_GEN4)
> +	[ADC5_GEN4_AMUX1_GPIO_100K_PU]	= ADC5_CHAN_TEMP(0,
> +						SCALE_HW_CALIB_THERM_100K_PU_GEN4)
> +	[ADC5_GEN4_AMUX2_GPIO_100K_PU]	= ADC5_CHAN_TEMP(0,
> +						SCALE_HW_CALIB_THERM_100K_PU_GEN4)
> +	[ADC5_GEN4_AMUX3_GPIO_100K_PU]	= ADC5_CHAN_TEMP(0,
> +						SCALE_HW_CALIB_THERM_100K_PU_GEN4)
> +	[ADC5_GEN4_AMUX4_GPIO_100K_PU]	= ADC5_CHAN_TEMP(0,
> +						SCALE_HW_CALIB_THERM_100K_PU_GEN4)
> +	[ADC5_GEN4_AMUX5_GPIO_100K_PU]	= ADC5_CHAN_TEMP(0,
> +						SCALE_HW_CALIB_THERM_100K_PU_GEN4)
> +};

...

>  enum adc5_cal_method {
>  	ADC5_NO_CAL = 0,

(here as well, see below)

>  	ADC5_RATIOMETRIC_CAL,

>  };
>  
> +enum adc_generation {
> +	ADC5_GEN3 = 0,

Why is this assignment? What's wrong with the C standard?

> +	ADC5_GEN4,

If these are related to HW communication protocol or bit fields, all of them
must be explicitly assigned (to make code robust against changes in the middle
of enum).

> +};

-- 
With Best Regards,
Andy Shevchenko