[RESEND v4 14/15] iio: adc: aspeed: Support battery sensing.

Billy Tsai
2021-08-25T01:57:29Z

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
higher voltage than reference voltage.

Signed-off-by: Billy Tsai <billy_tsai@aspeedtech.com>
---
drivers/iio/adc/aspeed_adc.c | 62 +++++++++++++++++++++++++++++++++---
1 file changed, 57 insertions(+), 5 deletions(-)

diff --git a/drivers/iio/adc/aspeed_adc.c b/drivers/iio/adc/aspeed_adc.c
index 20caf28dff18..0c5d84e82561 100644
--- a/drivers/iio/adc/aspeed_adc.c
+++ b/drivers/iio/adc/aspeed_adc.c
@@ -79,10 +79,16 @@ struct aspeed_adc_model_data {
unsigned int vref_fixed; // mV
bool wait_init_sequence;
bool need_prescaler;
+ bool bat_sense_sup;
u8 scaler_bit_width;
unsigned int num_channels;
};

+struct adc_gain {
+ u8 mult;
+ u8 div;
+};
+
struct aspeed_adc_data {
struct device *dev;
const struct aspeed_adc_model_data *model_data;
@@ -96,6 +102,8 @@ 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) { \
@@ -103,10 +111,10 @@ struct aspeed_adc_data {
.indexed = 1, \
.channel = (_idx), \
.address = (_data_reg_addr), \
- .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
- .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) | \
- BIT(IIO_CHAN_INFO_SAMP_FREQ) | \
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
BIT(IIO_CHAN_INFO_OFFSET), \
+ .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) | \
+ BIT(IIO_CHAN_INFO_SAMP_FREQ), \
}

static const struct iio_chan_spec aspeed_adc_iio_channels[] = {
@@ -196,14 +204,39 @@ 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);
+ 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 |
+ FIELD_PREP(ASPEED_ADC_CH7_MODE,
+ ASPEED_ADC_CH7_BAT) |
+ ASPEED_ADC_BAT_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);
+ *val = (*val * data->battery_mode_gain.mult) /
+ data->battery_mode_gain.div;
+ /* Restore control register value */
+ writel(adc_engine_control_reg_val,
+ data->base + ASPEED_REG_ENGINE_CONTROL);
+ } else
+ *val = readw(data->base + chan->address);
return IIO_VAL_INT;

case IIO_CHAN_INFO_OFFSET:
- *val = data->cv;
+ if (data->battery_sensing && chan->channel == 7)
+ *val = (data->cv * data->battery_mode_gain.mult) /
+ data->battery_mode_gain.div;
+ else
+ *val = data->cv;
return IIO_VAL_INT;

case IIO_CHAN_INFO_SCALE:
@@ -473,6 +506,23 @@ static int aspeed_adc_probe(struct platform_device *pdev)
if (ret)
return ret;

+ if (of_find_property(data->dev->of_node, "aspeed,battery-sensing",
+ NULL)) {
+ if (data->model_data->bat_sense_sup) {
+ data->battery_sensing = 1;
+ if (readl(data->base + ASPEED_REG_ENGINE_CONTROL) &
+ ASPEED_ADC_BAT_SENSING_DIV) {
+ 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 (data->model_data->wait_init_sequence) {
adc_engine_control_reg_val =
readl(data->base + ASPEED_REG_ENGINE_CONTROL);
@@ -555,6 +605,7 @@ static const struct aspeed_adc_model_data ast2600_adc0_model_data = {
.min_sampling_rate = 10000,
.max_sampling_rate = 500000,
.wait_init_sequence = true,
+ .bat_sense_sup = true,
.scaler_bit_width = 16,
.num_channels = 8,
};
@@ -564,6 +615,7 @@ static const struct aspeed_adc_model_data ast2600_adc1_model_data = {
.min_sampling_rate = 10000,
.max_sampling_rate = 500000,
.wait_init_sequence = true,
+ .bat_sense_sup = true,
.scaler_bit_width = 16,
.num_channels = 8,
};