drivers: adc: Remove channel_count property for Renesas driver

Currently, in Renesas adc driver, channel_count is used
as the maximum index of the channels can be supported.
However, the value input in dts of "channel_count"
represents the total number of supported channels.

After consideration, we have decided to remove this
reduntant property.

Signed-off-by: Khoa Nguyen <khoa.nguyen.xh@renesas.com>

drivers/adc/adc_renesas_ra.c

@@ -36,8 +36,6 @@ void adc_scan_end_isr(void);
  * This structure contains constant data for given instance of RA ADC.
  */
 struct adc_ra_config {
-	/** Number of supported channels */
-	uint8_t num_channels;
 	/** Mask for channels existed in each board */
 	uint32_t channel_available_mask;
 	/** pinctrl configs */
@@ -155,16 +153,10 @@ static void adc_ra_isr(const struct device *dev)
  */
 static int adc_ra_check_buffer_size(const struct device *dev, const struct adc_sequence *sequence)
 {
-	const struct adc_ra_config *config = dev->config;
 	uint8_t channels = 0;
 	size_t needed;
-	uint32_t mask;
 
-	for (mask = BIT(config->num_channels - 1); mask != 0; mask >>= 1) {
-		if (mask & sequence->channels) {
-			channels++;
-		}
-	}
+	channels = POPCOUNT(sequence->channels);
 
 	needed = channels * sizeof(uint16_t);
 	if (sequence->options) {
@@ -202,7 +194,7 @@ static int adc_ra_start_read(const struct device *dev, const struct adc_sequence
 		return -ENOTSUP;
 	}
 
-	if (find_msb_set(sequence->channels) > config->num_channels) {
+	if ((sequence->channels & ~config->channel_available_mask) != 0) {
 		LOG_ERR("unsupported channels in mask: 0x%08x", sequence->channels);
 		return -ENOTSUP;
 	}
@@ -355,7 +347,6 @@ static int adc_ra_init(const struct device *dev)
 		.ref_internal = DT_INST_PROP(idx, vref_mv),                                        \
 		IF_ENABLED(CONFIG_ADC_ASYNC, (.read_async = adc_ra_read_async))};                  \
 	static const struct adc_ra_config adc_ra_config_##idx = {                                  \
-		.num_channels = DT_INST_PROP(idx, channel_count),                                  \
 		.channel_available_mask = DT_INST_PROP(idx, channel_available_mask),               \
 		.pcfg = PINCTRL_DT_INST_DEV_CONFIG_GET(idx),                                       \
 		IRQ_CONFIGURE_DEFINE(idx),                                                         \

dts/bindings/adc/renesas,ra-adc.yaml

@@ -16,11 +16,6 @@ properties:
     required: true
     description: ADC reference voltage (Unit:mV)
 
-  channel-count:
-    type: int
-    required: true
-    description: The number of ADC channels
-
   "#io-channel-cells":
     const: 1