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);
