Re: [v2 8/8] iio: adc: aspeed: Support battery sensing.

[Billy Tsai]

On 2021/7/23, 11:57 PM, "Jonathan Cameron" <Jonathan.Cameron@xxxxxxxxxx> wrote:

    On Fri, 23 Jul 2021 16:16:21 +0800
    Billy Tsai <billy_tsai@xxxxxxxxxxxxxx> wrote:

    >   > In ast2600, ADC integrate dividing circuit at last input channel for
    >   > battery sensing. This patch use the dts property "battery-sensing" to
    >   > enable this feature makes the last channel of each adc can tolerance

    >   this feature allows the last channel of each ADC to tolerate a higher
    >   voltage than the reference voltage.

    >   > higher voltage than reference voltage.
    >   > 
    >   > Signed-off-by: Billy Tsai <billy_tsai@xxxxxxxxxxxxxx>
    >   This looks fine otherwise, but one more general question inline.

Hi Jonathan,

I reply the question inline.

Thanks,

Best Regards,
Billy Tsai

    >   Thanks,

    >   Jonathan

    >   > ---
    >   >  drivers/iio/adc/aspeed_adc.c | 60 +++++++++++++++++++++++++++++++++---
    >   >  1 file changed, 55 insertions(+), 5 deletions(-)
    >   > 
    >   > diff --git a/drivers/iio/adc/aspeed_adc.c b/drivers/iio/adc/aspeed_adc.c
    >   > index 7e674b607e36..6c7e2bb7b1ac 100644
    >   > --- a/drivers/iio/adc/aspeed_adc.c
    >   > +++ b/drivers/iio/adc/aspeed_adc.c
    >   > @@ -45,6 +45,9 @@
    >   >  #define ASPEED_ADC_REF_VOLTAGE_1200mV		FIELD_PREP(ASPEED_ADC_REF_VOLTAGE, 1)
    >   >  #define ASPEED_ADC_REF_VOLTAGE_EXT_HIGH		FIELD_PREP(ASPEED_ADC_REF_VOLTAGE, 2)
    >   >  #define ASPEED_ADC_REF_VOLTAGE_EXT_LOW		FIELD_PREP(ASPEED_ADC_REF_VOLTAGE, 3)
    >   > +#define ASPEED_ADC_BATTERY_SENSING_DIV		BIT(6)
    >   > +#define ASPEED_ADC_BATTERY_SENSING_DIV_2_3	FIELD_PREP(ASPEED_ADC_BATTERY_SENSING_DIV, 0)
    >   > +#define ASPEED_ADC_BATTERY_SENSING_DIV_1_3	FIELD_PREP(ASPEED_ADC_BATTERY_SENSING_DIV, 1)
    >   >  #define ASPEED_ADC_CTRL_INIT_RDY		BIT(8)
    >   >  #define ASPEED_ADC_CH7_MODE			BIT(12)
    >   >  #define ASPEED_ADC_CH7_NORMAL			FIELD_PREP(ASPEED_ADC_CH7_MODE, 0)
    >   > @@ -76,6 +79,11 @@ struct aspeed_adc_model_data {
    >   >  	unsigned int num_channels;
    >   >  };
    >   >  
    >   > +struct adc_gain {
    >   > +	u8 mult;
    >   > +	u8 div;
    >   > +};
    >   > +
    >   >  struct aspeed_adc_data {
    >   >  	struct device		*dev;
    >   >  	void __iomem		*base;
    >   > @@ -87,6 +95,8 @@ struct aspeed_adc_data {
    >   >  	int			vref;
    >   >  	u32			sample_period_ns;
    >   >  	int			cv;
    >   > +	bool			battery_sensing;
    >   > +	struct adc_gain		battery_mode_gain;
    >   >  };
    >   >  
    >   >  #define ASPEED_CHAN(_idx, _data_reg_addr) {			\
    >   > @@ -185,14 +195,38 @@ static int aspeed_adc_read_raw(struct iio_dev *indio_dev,
    >   >  			       int *val, int *val2, long mask)
    >   >  {
    >   >  	struct aspeed_adc_data *data = iio_priv(indio_dev);
    >   > +	u32 adc_engine_control_reg_val;
    >   >  
    >   >  	switch (mask) {
    >   >  	case IIO_CHAN_INFO_RAW:
    >   > -		*val = readw(data->base + chan->address) + data->cv;
    >   > -		if (*val < 0)
    >   > -			*val = 0;
    >   > -		else if (*val >= ASPEED_ADC_MAX_RAW_DATA)
    >   > -			*val = ASPEED_ADC_MAX_RAW_DATA;

    >   Not related to this patch, but can the device support a per channel
    >   reference selection? I.e. some channels use different internal references or
    >   external references from others?

No, the device can only choice one reference voltage for all of the channels.

    >   If so we should consider if it is necessary to expose that functionality
    >   in the dt-binding.

    >   > +		if (data->battery_sensing && chan->channel == 7) {
    >   > +			adc_engine_control_reg_val =
    >   > +				readl(data->base + ASPEED_REG_ENGINE_CONTROL);
    >   > +			writel(adc_engine_control_reg_val |
    >   > +				       ASPEED_ADC_CH7_BATTERY |
    >   > +				       ASPEED_ADC_BATTERY_SENSING_ENABLE,
    >   > +			       data->base + ASPEED_REG_ENGINE_CONTROL);
    >   > +			/*
    >   > +			 * After enable battery sensing mode need to wait some time for adc stable
    >   > +			 * Experiment result is 1ms.
    >   > +			 */
    >   > +			mdelay(1);
    >   > +			*val = readw(data->base + chan->address) + data->cv;
    >   > +			if (*val < 0)
    >   > +				*val = 0;
    >   > +			else if (*val >= ASPEED_ADC_MAX_RAW_DATA)
    >   > +				*val = ASPEED_ADC_MAX_RAW_DATA;
    >   > +			*val = (*val * data->battery_mode_gain.mult) /
    >   > +			       data->battery_mode_gain.div;
    >   > +			writel(adc_engine_control_reg_val,
    >   > +			       data->base + ASPEED_REG_ENGINE_CONTROL);
    >   > +		} else {
    >   > +			*val = readw(data->base + chan->address) + data->cv;
    >   > +			if (*val < 0)
    >   > +				*val = 0;
    >   > +			else if (*val >= ASPEED_ADC_MAX_RAW_DATA)
    >   > +				*val = ASPEED_ADC_MAX_RAW_DATA;
    >   > +		}
    >   >  		return IIO_VAL_INT;
    >   >  
    >   >  	case IIO_CHAN_INFO_SCALE:
    >   > @@ -392,6 +426,22 @@ static int aspeed_adc_probe(struct platform_device *pdev)
    >   >  	if (ret)
    >   >  		goto vref_config_error;
    >   >  
    >   > +	if (of_find_property(data->dev->of_node, "battery-sensing", NULL)) {
    >   > +		if (model_data->version >= aspeed_adc_ast2600) {
    >   > +			data->battery_sensing = 1;
    >   > +			if (readl(data->base + ASPEED_REG_ENGINE_CONTROL) &
    >   > +			    ASPEED_ADC_BATTERY_SENSING_DIV_1_3) {
    >   > +				data->battery_mode_gain.mult = 3;
    >   > +				data->battery_mode_gain.div = 1;
    >   > +			} else {
    >   > +				data->battery_mode_gain.mult = 3;
    >   > +				data->battery_mode_gain.div = 2;
    >   > +			}
    >   > +		} else
    >   > +			dev_warn(&pdev->dev,
    >   > +				 "Failed to enable battey-sensing mode\n");
    >   > +	}
    >   > +
    >   >  	if (model_data->wait_init_sequence) {
    >   >  		adc_engine_control_reg_val =
    >   >  			readl(data->base + ASPEED_REG_ENGINE_CONTROL);