iio: adc: aspeed: Restructure the model data

This patch refactors the model data structure to distinguish the
function form different versions of aspeed ADC.
- Rename the vref_voltage to vref_fixed_mv and add vref_mv driver data
When driver probe will check vref_fixed_mv value and store it to vref_mv
which isn't const value.
- Add num_channels
Make num_channles of iio device can be changed by different model_data
- Add need_prescaler flag and scaler_bit_width
The need_prescaler flag is used to tell the driver the clock divider needs
another Prescaler and the scaler_bit_width to set the clock divider
bitfield width.

Signed-off-by: Billy Tsai <billy_tsai@aspeedtech.com>
Link: https://lore.kernel.org/r/20210922081520.30580-3-billy_tsai@aspeedtech.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/aspeed_adc.c

@@ -71,8 +71,11 @@ struct aspeed_adc_model_data {
 	const char *model_name;
 	unsigned int min_sampling_rate;	// Hz
 	unsigned int max_sampling_rate;	// Hz
-	unsigned int vref_voltage;	// mV
+	unsigned int vref_fixed_mv;
 	bool wait_init_sequence;
+	bool need_prescaler;
+	u8 scaler_bit_width;
+	unsigned int num_channels;
 };
 
 struct aspeed_adc_data {
@@ -83,6 +86,7 @@ struct aspeed_adc_data {
 	struct clk_hw		*clk_prescaler;
 	struct clk_hw		*clk_scaler;
 	struct reset_control	*rst;
+	int			vref_mv;
 };
 
 #define ASPEED_CHAN(_idx, _data_reg_addr) {			\
@@ -126,7 +130,7 @@ static int aspeed_adc_read_raw(struct iio_dev *indio_dev,
 		return IIO_VAL_INT;
 
 	case IIO_CHAN_INFO_SCALE:
-		*val = data->model_data->vref_voltage;
+		*val = data->model_data->vref_fixed_mv;
 		*val2 = ASPEED_RESOLUTION_BITS;
 		return IIO_VAL_FRACTIONAL_LOG2;
 
@@ -279,7 +283,7 @@ static int aspeed_adc_probe(struct platform_device *pdev)
 	indio_dev->info = &aspeed_adc_iio_info;
 	indio_dev->modes = INDIO_DIRECT_MODE;
 	indio_dev->channels = aspeed_adc_iio_channels;
-	indio_dev->num_channels = ARRAY_SIZE(aspeed_adc_iio_channels);
+	indio_dev->num_channels = data->model_data->num_channels;
 
 	ret = iio_device_register(indio_dev);
 	if (ret)
@@ -319,17 +323,23 @@ static int aspeed_adc_remove(struct platform_device *pdev)
 
 static const struct aspeed_adc_model_data ast2400_model_data = {
 	.model_name = "ast2400-adc",
-	.vref_voltage = 2500, // mV
+	.vref_fixed_mv = 2500,
 	.min_sampling_rate = 10000,
 	.max_sampling_rate = 500000,
+	.need_prescaler = true,
+	.scaler_bit_width = 10,
+	.num_channels = 16,
 };
 
 static const struct aspeed_adc_model_data ast2500_model_data = {
 	.model_name = "ast2500-adc",
-	.vref_voltage = 1800, // mV
+	.vref_fixed_mv = 1800,
 	.min_sampling_rate = 1,
 	.max_sampling_rate = 1000000,
 	.wait_init_sequence = true,
+	.need_prescaler = true,
+	.scaler_bit_width = 10,
+	.num_channels = 16,
 };
 
 static const struct of_device_id aspeed_adc_matches[] = {