Re: [PATCH 2/3 v2] iio: adc: break out common code from SPMI VADC

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On 15/12/16 22:48, Linus Walleij wrote:
> The SPMI VADC and the earlier XOADC share a subset of
> common code, so to be able to use the same code in both
> drivers, we break out a separate file with the common code,
> prefix exported functions that are no longer static with
> qcom_* and bake an object qcom-vadc.o that contains both
> files: qcom-vadc-common.o and qcom-spmi-vadc.o.
> 
> Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> Cc: linux-arm-msm@xxxxxxxxxxxxxxx
> Cc: Ivan T. Ivanov <iivanov.xz@xxxxxxxxx>
> Cc: Andy Gross <andy.gross@xxxxxxxxxx>
> Cc: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>
> Cc: Stephen Boyd <sboyd@xxxxxxxxxxxxxx>
> Cc: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>
> Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
Looks superficially fine, but I'm guessing will need a respin
as we have a fair bit of new stuff (and a couple of fixes) going
through this driver at the moment.

All but the two fixes I posted a few mins ago are in my testing
branch and should go to Greg once I have confirmed testing on
those two fixes.

Jonathan
> ---
> ChangeLog v1->v2:
> - No changes just reposting
> ---
>  drivers/iio/adc/Makefile           |  3 +-
>  drivers/iio/adc/qcom-spmi-vadc.c   | 95 +++-----------------------------------
>  drivers/iio/adc/qcom-vadc-common.c | 38 +++++++++++++++
>  drivers/iio/adc/qcom-vadc-common.h | 69 +++++++++++++++++++++++++++
>  4 files changed, 116 insertions(+), 89 deletions(-)
>  create mode 100644 drivers/iio/adc/qcom-vadc-common.c
>  create mode 100644 drivers/iio/adc/qcom-vadc-common.h
> 
> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> index 7a40c04c311f..f9468d228b1e 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -38,7 +38,8 @@ obj-$(CONFIG_MXS_LRADC) += mxs-lradc.o
>  obj-$(CONFIG_NAU7802) += nau7802.o
>  obj-$(CONFIG_PALMAS_GPADC) += palmas_gpadc.o
>  obj-$(CONFIG_QCOM_SPMI_IADC) += qcom-spmi-iadc.o
> -obj-$(CONFIG_QCOM_SPMI_VADC) += qcom-spmi-vadc.o
> +qcom-vadc-y := qcom-vadc-common.o
> +obj-$(CONFIG_QCOM_SPMI_VADC) += qcom-vadc.o qcom-spmi-vadc.o
>  obj-$(CONFIG_ROCKCHIP_SARADC) += rockchip_saradc.o
>  obj-$(CONFIG_STX104) += stx104.o
>  obj-$(CONFIG_TI_ADC081C) += ti-adc081c.o
> diff --git a/drivers/iio/adc/qcom-spmi-vadc.c b/drivers/iio/adc/qcom-spmi-vadc.c
> index c2babe50a0d8..74d21afa34a9 100644
> --- a/drivers/iio/adc/qcom-spmi-vadc.c
> +++ b/drivers/iio/adc/qcom-spmi-vadc.c
> @@ -28,6 +28,8 @@
>  
>  #include <dt-bindings/iio/qcom,spmi-vadc.h>
>  
> +#include "qcom-vadc-common.h"
> +
>  /* VADC register and bit definitions */
>  #define VADC_REVISION2				0x1
>  #define VADC_REVISION2_SUPPORTED_VADC		1
> @@ -75,69 +77,9 @@
>  
>  #define VADC_DATA				0x60	/* 16 bits */
>  
> -#define VADC_CONV_TIME_MIN_US			2000
> -#define VADC_CONV_TIME_MAX_US			2100
> -
> -/* Min ADC code represents 0V */
> -#define VADC_MIN_ADC_CODE			0x6000
> -/* Max ADC code represents full-scale range of 1.8V */
> -#define VADC_MAX_ADC_CODE			0xa800
> -
> -#define VADC_ABSOLUTE_RANGE_UV			625000
> -#define VADC_RATIOMETRIC_RANGE_UV		1800000
> -
> -#define VADC_DEF_PRESCALING			0 /* 1:1 */
> -#define VADC_DEF_DECIMATION			0 /* 512 */
> -#define VADC_DEF_HW_SETTLE_TIME			0 /* 0 us */
> -#define VADC_DEF_AVG_SAMPLES			0 /* 1 sample */
> -#define VADC_DEF_CALIB_TYPE			VADC_CALIB_ABSOLUTE
> -
> -#define VADC_DECIMATION_MIN			512
> -#define VADC_DECIMATION_MAX			4096
> -
> -#define VADC_HW_SETTLE_DELAY_MAX		10000
> -#define VADC_AVG_SAMPLES_MAX			512
> -
> -#define KELVINMIL_CELSIUSMIL			273150
> -
>  #define VADC_CHAN_MIN			VADC_USBIN
>  #define VADC_CHAN_MAX			VADC_LR_MUX3_BUF_PU1_PU2_XO_THERM
>  
> -/*
> - * VADC_CALIB_ABSOLUTE: uses the 625mV and 1.25V as reference channels.
> - * VADC_CALIB_RATIOMETRIC: uses the reference voltage (1.8V) and GND for
> - * calibration.
> - */
> -enum vadc_calibration {
> -	VADC_CALIB_ABSOLUTE = 0,
> -	VADC_CALIB_RATIOMETRIC
> -};
> -
> -/**
> - * struct vadc_linear_graph - Represent ADC characteristics.
> - * @dy: numerator slope to calculate the gain.
> - * @dx: denominator slope to calculate the gain.
> - * @gnd: A/D word of the ground reference used for the channel.
> - *
> - * Each ADC device has different offset and gain parameters which are
> - * computed to calibrate the device.
> - */
> -struct vadc_linear_graph {
> -	s32 dy;
> -	s32 dx;
> -	s32 gnd;
> -};
> -
> -/**
> - * struct vadc_prescale_ratio - Represent scaling ratio for ADC input.
> - * @num: the inverse numerator of the gain applied to the input channel.
> - * @den: the inverse denominator of the gain applied to the input channel.
> - */
> -struct vadc_prescale_ratio {
> -	u32 num;
> -	u32 den;
> -};
> -
>  /**
>   * struct vadc_channel_prop - VADC channel property.
>   * @channel: channel number, refer to the channel list.
> @@ -471,33 +413,10 @@ static int vadc_measure_ref_points(struct vadc_priv *vadc)
>  static s32 vadc_calibrate(struct vadc_priv *vadc,
>  			  const struct vadc_channel_prop *prop, u16 adc_code)
>  {
> -	const struct vadc_prescale_ratio *prescale;
> -	s64 voltage;
> -
> -	voltage = adc_code - vadc->graph[prop->calibration].gnd;
> -	voltage *= vadc->graph[prop->calibration].dx;
> -	voltage = div64_s64(voltage, vadc->graph[prop->calibration].dy);
> -
> -	if (prop->calibration == VADC_CALIB_ABSOLUTE)
> -		voltage += vadc->graph[prop->calibration].dx;
> -
> -	if (voltage < 0)
> -		voltage = 0;
> -
> -	prescale = &vadc_prescale_ratios[prop->prescale];
> -
> -	voltage = voltage * prescale->den;
> -
> -	return div64_s64(voltage, prescale->num);
> -}
> -
> -static int vadc_decimation_from_dt(u32 value)
> -{
> -	if (!is_power_of_2(value) || value < VADC_DECIMATION_MIN ||
> -	    value > VADC_DECIMATION_MAX)
> -		return -EINVAL;
> -
> -	return __ffs64(value / VADC_DECIMATION_MIN);
> +	return qcom_vadc_calibrate(&vadc_prescale_ratios[prop->prescale],
> +				   &vadc->graph[prop->calibration],
> +				   (prop->calibration == VADC_CALIB_ABSOLUTE),
> +				   adc_code);
>  }
>  
>  static int vadc_prescaling_from_dt(u32 num, u32 den)
> @@ -752,7 +671,7 @@ static int vadc_get_dt_channel_data(struct device *dev,
>  
>  	ret = of_property_read_u32(node, "qcom,decimation", &value);
>  	if (!ret) {
> -		ret = vadc_decimation_from_dt(value);
> +		ret = qcom_vadc_decimation_from_dt(value);
>  		if (ret < 0) {
>  			dev_err(dev, "%02x invalid decimation %d\n",
>  				chan, value);
> diff --git a/drivers/iio/adc/qcom-vadc-common.c b/drivers/iio/adc/qcom-vadc-common.c
> new file mode 100644
> index 000000000000..f67fc5e2a702
> --- /dev/null
> +++ b/drivers/iio/adc/qcom-vadc-common.c
> @@ -0,0 +1,38 @@
> +#include <linux/kernel.h>
> +#include <linux/bitops.h>
> +#include <linux/math64.h>
> +#include <linux/log2.h>
> +#include <linux/err.h>
> +
> +#include "qcom-vadc-common.h"
> +
> +s32 qcom_vadc_calibrate(const struct vadc_prescale_ratio *prescale,
> +			const struct vadc_linear_graph *graph,
> +			bool absolute,
> +			u16 adc_code)
> +{
> +	s64 voltage;
> +
> +	voltage = adc_code - graph->gnd;
> +	voltage *= graph->dx;
> +	voltage = div64_s64(voltage, graph->dy);
> +
> +	if (absolute)
> +		voltage += graph->dx;
> +
> +	if (voltage < 0)
> +		voltage = 0;
> +
> +	voltage = voltage * prescale->den;
> +
> +	return div64_s64(voltage, prescale->num);
> +}
> +
> +int qcom_vadc_decimation_from_dt(u32 value)
> +{
> +	if (!is_power_of_2(value) || value < VADC_DECIMATION_MIN ||
> +	    value > VADC_DECIMATION_MAX)
> +		return -EINVAL;
> +
> +	return __ffs64(value / VADC_DECIMATION_MIN);
> +}
> diff --git a/drivers/iio/adc/qcom-vadc-common.h b/drivers/iio/adc/qcom-vadc-common.h
> new file mode 100644
> index 000000000000..b41cb501eef8
> --- /dev/null
> +++ b/drivers/iio/adc/qcom-vadc-common.h
> @@ -0,0 +1,69 @@
> +/*
> + * Code shared between the different Qualcomm PMIC voltage ADCs
> + */
> +
> +#define VADC_CONV_TIME_MIN_US			2000
> +#define VADC_CONV_TIME_MAX_US			2100
> +
> +/* Min ADC code represents 0V */
> +#define VADC_MIN_ADC_CODE			0x6000
> +/* Max ADC code represents full-scale range of 1.8V */
> +#define VADC_MAX_ADC_CODE			0xa800
> +
> +#define VADC_ABSOLUTE_RANGE_UV			625000
> +#define VADC_RATIOMETRIC_RANGE_UV		1800000
> +
> +#define VADC_DEF_PRESCALING			0 /* 1:1 */
> +#define VADC_DEF_DECIMATION			0 /* 512 */
> +#define VADC_DEF_HW_SETTLE_TIME			0 /* 0 us */
> +#define VADC_DEF_AVG_SAMPLES			0 /* 1 sample */
> +#define VADC_DEF_CALIB_TYPE			VADC_CALIB_ABSOLUTE
> +
> +#define VADC_DECIMATION_MIN			512
> +#define VADC_DECIMATION_MAX			4096
> +
> +#define VADC_HW_SETTLE_DELAY_MAX		10000
> +#define VADC_AVG_SAMPLES_MAX			512
> +
> +#define KELVINMIL_CELSIUSMIL			273150
> +
> +/*
> + * VADC_CALIB_ABSOLUTE: uses the 625mV and 1.25V as reference channels.
> + * VADC_CALIB_RATIOMETRIC: uses the reference voltage (1.8V) and GND for
> + * calibration.
> + */
> +enum vadc_calibration {
> +	VADC_CALIB_ABSOLUTE = 0,
> +	VADC_CALIB_RATIOMETRIC
> +};
> +
> +/**
> + * struct vadc_linear_graph - Represent ADC characteristics.
> + * @dy: numerator slope to calculate the gain.
> + * @dx: denominator slope to calculate the gain.
> + * @gnd: A/D word of the ground reference used for the channel.
> + *
> + * Each ADC device has different offset and gain parameters which are
> + * computed to calibrate the device.
> + */
> +struct vadc_linear_graph {
> +	s32 dy;
> +	s32 dx;
> +	s32 gnd;
> +};
> +
> +/**
> + * struct vadc_prescale_ratio - Represent scaling ratio for ADC input.
> + * @num: the inverse numerator of the gain applied to the input channel.
> + * @den: the inverse denominator of the gain applied to the input channel.
> + */
> +struct vadc_prescale_ratio {
> +	u32 num;
> +	u32 den;
> +};
> +
> +s32 qcom_vadc_calibrate(const struct vadc_prescale_ratio *prescale,
> +			const struct vadc_linear_graph *graph,
> +			bool absolute,
> +			u16 adc_code);
> +int qcom_vadc_decimation_from_dt(u32 value);
> 

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