dm: adc: add uclass's mask and conversion helpers

Add two functions to ADC uclass's:
- adc_raw_to_uV() to ease ADC raw value conversion to microvolts
- adc_channel_mask() to get channels on consumer side

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

drivers/adc/adc-uclass.c

@@ -6,6 +6,7 @@
 
 #include <common.h>
 #include <errno.h>
+#include <div64.h>
 #include <dm.h>
 #include <dm/lists.h>
 #include <dm/device-internal.h>
@@ -77,6 +78,18 @@ int adc_data_mask(struct udevice *dev, unsigned int *data_mask)
 	return 0;
 }
 
+int adc_channel_mask(struct udevice *dev, unsigned int *channel_mask)
+{
+	struct adc_uclass_platdata *uc_pdata = dev_get_uclass_platdata(dev);
+
+	if (!uc_pdata)
+		return -ENOSYS;
+
+	*channel_mask = uc_pdata->channel_mask;
+
+	return 0;
+}
+
 int adc_stop(struct udevice *dev)
 {
 	const struct adc_ops *ops = dev_get_driver_ops(dev);
@@ -329,6 +342,30 @@ int adc_vss_value(struct udevice *dev, int *uV)
 	return 0;
 }
 
+int adc_raw_to_uV(struct udevice *dev, unsigned int raw, int *uV)
+{
+	unsigned int data_mask;
+	int ret, val, vref;
+	u64 raw64 = raw;
+
+	ret = adc_vdd_value(dev, &vref);
+	if (ret)
+		return ret;
+
+	if (!adc_vss_value(dev, &val))
+		vref -= val;
+
+	ret = adc_data_mask(dev, &data_mask);
+	if (ret)
+		return ret;
+
+	raw64 *= vref;
+	do_div(raw64, data_mask);
+	*uV = raw64;
+
+	return 0;
+}
+
 static int adc_vdd_platdata_set(struct udevice *dev)
 {
 	struct adc_uclass_platdata *uc_pdata = dev_get_uclass_platdata(dev);

include/adc.h

@@ -218,6 +218,17 @@ int adc_channels_data(struct udevice *dev, unsigned int channel_mask,
  */
 int adc_data_mask(struct udevice *dev, unsigned int *data_mask);
 
+/**
+ * adc_channel_mask() - get channel mask for given ADC device
+ *
+ * This can be used if adc uclass platform data is filled.
+ *
+ * @dev:       ADC device to check
+ * @channel_mask: pointer to the returned channel bitmask
+ * @return: 0 if OK, -ve on error
+ */
+int adc_channel_mask(struct udevice *dev, unsigned int *channel_mask);
+
 /**
  * adc_channel_single_shot() - get output data of conversion for the ADC
  * device's channel. This function searches for the device with the given name,
@@ -284,4 +295,14 @@ int adc_vss_value(struct udevice *dev, int *uV);
  */
 int adc_stop(struct udevice *dev);
 
+/**
+ * adc_raw_to_uV() - converts raw value to microvolts for given ADC device.
+ *
+ * @dev:     ADC device used from conversion
+ * @raw:     raw value to convert
+ * @uV:	     converted value in microvolts
+ * @return:  0 on success or -ve on error
+ */
+int adc_raw_to_uV(struct udevice *dev, unsigned int raw, int *uV);
+
 #endif

test/dm/adc.c

@@ -22,10 +22,14 @@
 static int dm_test_adc_bind(struct unit_test_state *uts)
 {
 	struct udevice *dev;
+	unsigned int channel_mask;
 
 	ut_assertok(uclass_get_device_by_name(UCLASS_ADC, "adc", &dev));
 	ut_asserteq_str(SANDBOX_ADC_DEVNAME, dev->name);
 
+	ut_assertok(adc_channel_mask(dev, &channel_mask));
+	ut_asserteq((1 << SANDBOX_ADC_CHANNELS) - 1, channel_mask);
+
 	return 0;
 }
 DM_TEST(dm_test_adc_bind, DM_TESTF_SCAN_FDT);
@@ -160,3 +164,34 @@ static int dm_test_adc_multi_channel_shot(struct unit_test_state *uts)
 	return 0;
 }
 DM_TEST(dm_test_adc_multi_channel_shot, DM_TESTF_SCAN_FDT);
+
+static const int dm_test_adc_uV_data[SANDBOX_ADC_CHANNELS] = {
+	((u64)SANDBOX_ADC_CHANNEL0_DATA * SANDBOX_BUCK2_INITIAL_EXPECTED_UV) /
+		SANDBOX_ADC_DATA_MASK,
+	((u64)SANDBOX_ADC_CHANNEL1_DATA * SANDBOX_BUCK2_INITIAL_EXPECTED_UV) /
+		SANDBOX_ADC_DATA_MASK,
+	((u64)SANDBOX_ADC_CHANNEL2_DATA * SANDBOX_BUCK2_INITIAL_EXPECTED_UV) /
+		SANDBOX_ADC_DATA_MASK,
+	((u64)SANDBOX_ADC_CHANNEL3_DATA * SANDBOX_BUCK2_INITIAL_EXPECTED_UV) /
+		SANDBOX_ADC_DATA_MASK,
+};
+
+static int dm_test_adc_raw_to_uV(struct unit_test_state *uts)
+{
+	struct adc_channel *tdata = adc_channel_test_data;
+	unsigned int i, data;
+	struct udevice *dev;
+	int uV;
+
+	ut_assertok(uclass_get_device_by_name(UCLASS_ADC, "adc", &dev));
+	/* Test each ADC channel's value in microvolts */
+	for (i = 0; i < SANDBOX_ADC_CHANNELS; i++, tdata++) {
+		ut_assertok(adc_start_channel(dev, tdata->id));
+		ut_assertok(adc_channel_data(dev, tdata->id, &data));
+		ut_assertok(adc_raw_to_uV(dev, data, &uV));
+		ut_asserteq(dm_test_adc_uV_data[i], uV);
+	}
+
+	return 0;
+}
+DM_TEST(dm_test_adc_raw_to_uV, DM_TESTF_SCAN_FDT);