1 files changed, 70 insertions, 4 deletions

diff --git a/drivers/iio/adc/at91_adc.c b/drivers/iio/adc/at91_adc.c
index 6fc43c15f028..3fb3fe48a98c 100644
--- a/drivers/iio/adc/at91_adc.c
+++ b/drivers/iio/adc/at91_adc.c
@@ -57,6 +57,8 @@ struct at91_adc_state {
 	u32			trigger_number;
 	bool			use_external;
 	u32			vref_mv;
+	u32			res;		/* resolution used for convertions */
+	bool			low_res;	/* the resolution corresponds to the lowest one */
 	wait_queue_head_t	wq_data_avail;
 };
 
@@ -138,7 +140,7 @@ static int at91_adc_channel_init(struct iio_dev *idev)
 		chan->channel = bit;
 		chan->scan_index = idx;
 		chan->scan_type.sign = 'u';
-		chan->scan_type.realbits = 10;
+		chan->scan_type.realbits = st->res;
 		chan->scan_type.storagebits = 16;
 		chan->info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE);
 		chan->info_mask_separate = BIT(IIO_CHAN_INFO_RAW);
@@ -372,6 +374,59 @@ static int at91_adc_read_raw(struct iio_dev *idev,
 	return -EINVAL;
 }
 
+static int at91_adc_of_get_resolution(struct at91_adc_state *st,
+				      struct platform_device *pdev)
+{
+	struct iio_dev *idev = iio_priv_to_dev(st);
+	struct device_node *np = pdev->dev.of_node;
+	int count, i, ret = 0;
+	char *res_name, *s;
+	u32 *resolutions;
+
+	count = of_property_count_strings(np, "atmel,adc-res-names");
+	if (count < 2) {
+		dev_err(&idev->dev, "You must specified at least two resolution names for "
+				    "adc-res-names property in the DT\n");
+		return count;
+	}
+
+	resolutions = kmalloc(count * sizeof(*resolutions), GFP_KERNEL);
+	if (!resolutions)
+		return -ENOMEM;
+
+	if (of_property_read_u32_array(np, "atmel,adc-res", resolutions, count)) {
+		dev_err(&idev->dev, "Missing adc-res property in the DT.\n");
+		ret = -ENODEV;
+		goto ret;
+	}
+
+	if (of_property_read_string(np, "atmel,adc-use-res", (const char **)&res_name))
+		res_name = "highres";
+
+	for (i = 0; i < count; i++) {
+		if (of_property_read_string_index(np, "atmel,adc-res-names", i, (const char **)&s))
+			continue;
+
+		if (strcmp(res_name, s))
+			continue;
+
+		st->res = resolutions[i];
+		if (!strcmp(res_name, "lowres"))
+			st->low_res = true;
+		else
+			st->low_res = false;
+
+		dev_info(&idev->dev, "Resolution used: %u bits\n", st->res);
+		goto ret;
+	}
+
+	dev_err(&idev->dev, "There is no resolution for %s\n", res_name);
+
+ret:
+	kfree(resolutions);
+	return ret;
+}
+
 static int at91_adc_probe_dt(struct at91_adc_state *st,
 			     struct platform_device *pdev)
 {
@@ -415,6 +470,10 @@ static int at91_adc_probe_dt(struct at91_adc_state *st,
 	}
 	st->vref_mv = prop;
 
+	ret = at91_adc_of_get_resolution(st, pdev);
+	if (ret)
+		goto error_ret;
+
 	st->registers = devm_kzalloc(&idev->dev,
 				     sizeof(struct at91_adc_reg_desc),
 				     GFP_KERNEL);
@@ -628,9 +687,16 @@ static int at91_adc_probe(struct platform_device *pdev)
 	 */
 	ticks = round_up((st->startup_time * adc_clk /
 			  1000000) - 1, 8) / 8;
-	at91_adc_writel(st, AT91_ADC_MR,
-			(AT91_ADC_PRESCAL_(prsc) & AT91_ADC_PRESCAL) |
-			(AT91_ADC_STARTUP_(ticks) & AT91_ADC_STARTUP));
+
+	if (st->low_res)
+		at91_adc_writel(st, AT91_ADC_MR,
+				AT91_ADC_LOWRES |
+				(AT91_ADC_PRESCAL_(prsc) & AT91_ADC_PRESCAL) |
+				(AT91_ADC_STARTUP_(ticks) & AT91_ADC_STARTUP));
+	else
+		at91_adc_writel(st, AT91_ADC_MR,
+				(AT91_ADC_PRESCAL_(prsc) & AT91_ADC_PRESCAL) |
+				(AT91_ADC_STARTUP_(ticks) & AT91_ADC_STARTUP));
 
 	/* Setup the ADC channels available on the board */
 	ret = at91_adc_channel_init(idev);