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iio: ti_am335x_adc: Add optional DT properties for tscadc

PATCH In review Vignesh R 2 participants 7 messages Mar 31, 2015 – May 13, 2015

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Device tree bindings IIO Input drivers
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Vignesh R

author
#0 lore raw

cover iio: ti_am335x_adc: Add optional DT properties for tscadc

Hi,

This patch adds optional DT properties for tscadc to set open delay, sample delay and number of averages per sample for each adc channel. Open delay, sample delay and averaging are some of the parameters that affect the sampling rate and accuracy of the tscadc. Decreasing delays and averaging helps to achieve higher sampling rates, while increasing this parameters provides greater accuracy. Hence, this patch provides DT properties to set the initial values for delays and number of averages per sample. User space control via sysfs can be added later.

Vignesh R (2):
iio: adc: ti_am335x_adc: refactor DT parsing into a function
iio: adc: ti_am335x_adc: make sample delay, open delay, averaging DT
parameters

 .../bindings/input/touchscreen/ti-tsc-adc.txt      | 24 +++++++
 drivers/iio/adc/ti_am335x_adc.c                    | 83 +++++++++++++++++-----
 2 files changed, 91 insertions(+), 16 deletions(-)
Signature · 1 line
1.9.1
author
#1 lore raw

PATCH 1/2 iio: adc: ti_am335x_adc: refactor DT parsing into a function

Refactor DT parsing into a separate function from probe() to help addition of more DT parameters later.

No functional changes.

Signed-off-by Vignesh R <[email protected]>
---
 drivers/iio/adc/ti_am335x_adc.c | 29 +++++++++++++++++++----------
 1 file changed, 19 insertions(+), 10 deletions(-)
drivers/iio/adc/ti_am335x_adc.c +19 -10
index 2e5cc4409f78..2f818405ffbe 100644
@@ -396,16 +396,30 @@ static const struct iio_info tiadc_info = {
 	.driver_module = THIS_MODULE,
 };
 
+static int tiadc_parse_dt(struct platform_device *pdev,
+			  struct tiadc_device *adc_dev)
+{
+	struct device_node *node = pdev->dev.of_node;
+	struct property *prop;
+	const __be32 *cur;
+	int channels = 0;
+	u32 val;
+
+	of_property_for_each_u32(node, "ti,adc-channels", prop, cur, val) {
+		adc_dev->channel_line[channels] = val;
+		channels++;
+	}
+
+	adc_dev->channels = channels;
+	return 0;
+}
+
 static int tiadc_probe(struct platform_device *pdev)
 {
 	struct iio_dev		*indio_dev;
 	struct tiadc_device	*adc_dev;
 	struct device_node	*node = pdev->dev.of_node;
-	struct property		*prop;
-	const __be32		*cur;
 	int			err;
-	u32			val;
-	int			channels = 0;
 
 	if (!node) {
 		dev_err(&pdev->dev, "Could not find valid DT data.\n");

@@ -421,12 +435,7 @@ static int tiadc_probe(struct platform_device *pdev)
 	adc_dev = iio_priv(indio_dev);
 
 	adc_dev->mfd_tscadc = ti_tscadc_dev_get(pdev);
-
-	of_property_for_each_u32(node, "ti,adc-channels", prop, cur, val) {
-		adc_dev->channel_line[channels] = val;
-		channels++;
-	}
-	adc_dev->channels = channels;
+	tiadc_parse_dt(pdev, adc_dev);
 
 	indio_dev->dev.parent = &pdev->dev;
 	indio_dev->name = dev_name(&pdev->dev);
Signature · 1 line
1.9.1
maintainer
#2 lore raw

Re: [PATCH 1/2] iio: adc: ti_am335x_adc: refactor DT parsing into a function

Quoted 6 lines · Vignesh R

Refactor DT parsing into a separate function from probe() to help addition of more DT parameters later.

No functional changes.

Signed-off-by Vignesh R <[email protected]>

Clearly going to need this whatever the outcome of the second patch being reviewed.

Applied to the togreg branch of iio.git - initially pushed out as testing for the autobuilders to play with it.

Thanks,

Jonathan

Quoted 58 lines
---
 drivers/iio/adc/ti_am335x_adc.c | 29 +++++++++++++++++++----------
 1 file changed, 19 insertions(+), 10 deletions(-)
drivers/iio/adc/ti_am335x_adc.c +19 -10
index 2e5cc4409f78..2f818405ffbe 100644
@@ -396,16 +396,30 @@ static const struct iio_info tiadc_info = {
 	.driver_module = THIS_MODULE,
 };
 
+static int tiadc_parse_dt(struct platform_device *pdev,
+			  struct tiadc_device *adc_dev)
+{
+	struct device_node *node = pdev->dev.of_node;
+	struct property *prop;
+	const __be32 *cur;
+	int channels = 0;
+	u32 val;
+
+	of_property_for_each_u32(node, "ti,adc-channels", prop, cur, val) {
+		adc_dev->channel_line[channels] = val;
+		channels++;
+	}
+
+	adc_dev->channels = channels;
+	return 0;
+}
+
 static int tiadc_probe(struct platform_device *pdev)
 {
 	struct iio_dev		*indio_dev;
 	struct tiadc_device	*adc_dev;
 	struct device_node	*node = pdev->dev.of_node;
-	struct property		*prop;
-	const __be32		*cur;
 	int			err;
-	u32			val;
-	int			channels = 0;
 
 	if (!node) {
 		dev_err(&pdev->dev, "Could not find valid DT data.\n");

@@ -421,12 +435,7 @@ static int tiadc_probe(struct platform_device *pdev)
 	adc_dev = iio_priv(indio_dev);
 
 	adc_dev->mfd_tscadc = ti_tscadc_dev_get(pdev);
-
-	of_property_for_each_u32(node, "ti,adc-channels", prop, cur, val) {
-		adc_dev->channel_line[channels] = val;
-		channels++;
-	}
-	adc_dev->channels = channels;
+	tiadc_parse_dt(pdev, adc_dev);
 
 	indio_dev->dev.parent = &pdev->dev;
 	indio_dev->name = dev_name(&pdev->dev);
author
#3 lore raw

PATCH 2/2 iio: adc: ti_am335x_adc: make sample delay, open delay, averaging DT parameters

In reply to Vignesh R

Add optional DT properties to set open delay, sample delay and number of averages per sample for each adc step. Open delay, sample delay and averaging are some of the parameters that affect the sampling rate and accuracy of the sample. Making these parameters configurable via DT will help in balancing speed vs accuracy.

Signed-off-by Vignesh R <[email protected]>
---
 .../bindings/input/touchscreen/ti-tsc-adc.txt      | 24 ++++++++++
 drivers/iio/adc/ti_am335x_adc.c                    | 54 +++++++++++++++++++---
 2 files changed, 72 insertions(+), 6 deletions(-)
Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt +24 -0
index 6c4fb34823d3..8aafbe87f0eb 100644
@@ -42,6 +42,27 @@ Optional properties:
 			 hardware knob for adjusting the amount of "settling
 			 time".
 
+- child "adc"
+	ti,chan-step-opendelay: List of open delays for each channel of
+				ADC in the order of ti,adc-channels. The
+				value corresponds to the number of ADC
+				clock cycles to wait after applying the
+				step configuration registers and before
+				sending the start of ADC conversion.
+				Maximum value is 0x3FFFF.
+       ti,chan-step-sampledelay: List of sample delays for each channel
+				  of ADC in the order of ti,adc-channels.
+				  The value corresponds to the number of
+				  ADC clock cycles to sample (to hold
+				  start of conversion high).
+				  Maximum value is 0xFF.
+       ti,chan-step-avg: Number of averages to be performed for each
+			  channel of ADC. If average is 16 then input
+			  is sampled 16 times and averaged to get more
+			  accurate value. This increases the time taken
+			  by ADC to generate a sample. Valid range is 0
+			  average to 16 averages. Maximum value is 16.
+
 Example:
 	tscadc: tscadc@44e0d000 {
 		compatible = "ti,am3359-tscadc";

@@ -55,5 +76,8 @@ Example:
 
 		adc {
 			ti,adc-channels = <4 5 6 7>;
+			ti,chan-step-opendelay = <0x098 0x3ffff 0x098 0x0>;
+			ti,chan-step-sampledelay = <0xff 0x0 0xf 0x0>;
+			ti,chan-step-avg = <16 2 4 8>;
 		};
 	}
drivers/iio/adc/ti_am335x_adc.c +48 -6

89 lines not on this page · raw message

Signature · 1 line
1.9.1
maintainer
#4 lore raw

Re: [PATCH 2/2] iio: adc: ti_am335x_adc: make sample delay, open delay, averaging DT parameters

Quoted 7 lines · Vignesh R

Add optional DT properties to set open delay, sample delay and number of averages per sample for each adc step. Open delay, sample delay and averaging are some of the parameters that affect the sampling rate and accuracy of the sample. Making these parameters configurable via DT will help in balancing speed vs accuracy.

Signed-off-by Vignesh R <[email protected]>

All looks fine to me, but I would ideally like a devicetree ack on this one.

Jonathan

Quoted 160 lines
---
 .../bindings/input/touchscreen/ti-tsc-adc.txt      | 24 ++++++++++
 drivers/iio/adc/ti_am335x_adc.c                    | 54 +++++++++++++++++++---
 2 files changed, 72 insertions(+), 6 deletions(-)
Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt +24 -0
index 6c4fb34823d3..8aafbe87f0eb 100644
@@ -42,6 +42,27 @@ Optional properties:
 			 hardware knob for adjusting the amount of "settling
 			 time".
 
+- child "adc"
+	ti,chan-step-opendelay: List of open delays for each channel of
+				ADC in the order of ti,adc-channels. The
+				value corresponds to the number of ADC
+				clock cycles to wait after applying the
+				step configuration registers and before
+				sending the start of ADC conversion.
+				Maximum value is 0x3FFFF.
+       ti,chan-step-sampledelay: List of sample delays for each channel
+				  of ADC in the order of ti,adc-channels.
+				  The value corresponds to the number of
+				  ADC clock cycles to sample (to hold
+				  start of conversion high).
+				  Maximum value is 0xFF.
+       ti,chan-step-avg: Number of averages to be performed for each
+			  channel of ADC. If average is 16 then input
+			  is sampled 16 times and averaged to get more
+			  accurate value. This increases the time taken
+			  by ADC to generate a sample. Valid range is 0
+			  average to 16 averages. Maximum value is 16.
+
 Example:
 	tscadc: tscadc@44e0d000 {
 		compatible = "ti,am3359-tscadc";

@@ -55,5 +76,8 @@ Example:
 
 		adc {
 			ti,adc-channels = <4 5 6 7>;
+			ti,chan-step-opendelay = <0x098 0x3ffff 0x098 0x0>;
+			ti,chan-step-sampledelay = <0xff 0x0 0xf 0x0>;
+			ti,chan-step-avg = <16 2 4 8>;
 		};
 	}
drivers/iio/adc/ti_am335x_adc.c +64 -6
index 2f818405ffbe..5ee597b4a1af 100644
@@ -37,6 +37,7 @@ struct tiadc_device {
 	u8 channel_step[8];
 	int buffer_en_ch_steps;
 	u16 data[8];
+	u32 open_delay[8], sample_delay[8], step_avg[8];
 };
 
 static unsigned int tiadc_readl(struct tiadc_device *adc, unsigned int reg)

@@ -85,6 +86,7 @@ static u32 get_adc_step_bit(struct tiadc_device *adc_dev, int chan)
 static void tiadc_step_config(struct iio_dev *indio_dev)
 {
 	struct tiadc_device *adc_dev = iio_priv(indio_dev);
+	struct device *dev = adc_dev->mfd_tscadc->dev;
 	unsigned int stepconfig;
 	int i, steps = 0;
 

@@ -98,20 +100,47 @@ static void tiadc_step_config(struct iio_dev *indio_dev)
 	 * needs to be given to ADC to digitalize data.
 	 */
 
-	if (iio_buffer_enabled(indio_dev))
-		stepconfig = STEPCONFIG_AVG_16 | STEPCONFIG_FIFO1
-					| STEPCONFIG_MODE_SWCNT;
-	else
-		stepconfig = STEPCONFIG_AVG_16 | STEPCONFIG_FIFO1;
 
 	for (i = 0; i < adc_dev->channels; i++) {
 		int chan;
 
 		chan = adc_dev->channel_line[i];
+
+		if (adc_dev->step_avg[i] > STEPCONFIG_AVG_16) {
+			dev_warn(dev, "chan %d step_avg truncating to %d\n",
+				 chan, STEPCONFIG_AVG_16);
+			adc_dev->step_avg[i] = STEPCONFIG_AVG_16;
+		}
+
+		if (adc_dev->step_avg[i])
+			stepconfig =
+			STEPCONFIG_AVG(ffs(adc_dev->step_avg[i]) - 1) |
+			STEPCONFIG_FIFO1;
+		else
+			stepconfig = STEPCONFIG_FIFO1;
+
+		if (iio_buffer_enabled(indio_dev))
+			stepconfig |= STEPCONFIG_MODE_SWCNT;
+
 		tiadc_writel(adc_dev, REG_STEPCONFIG(steps),
 				stepconfig | STEPCONFIG_INP(chan));
+
+		if (adc_dev->open_delay[i] > STEPDELAY_OPEN_MASK)alue corresponds to the number of ADC
+				clock cycles to wait after applying the
+				step configuration registers and before
+				sending the start of ADC conversion.
+				Maximum value is 0x3FFFF.
+       ti,chan-step-sampledelay: List of sample delays for each channel
+				  of ADC in the order of ti,adc-channels.
+				  The value corresponds to the number of
+				  ADC clock cycles to sample (to hold
+				  start of conversion high).
+				  Maximum value is 0xFF.
+       ti,chan-step-avg: Number of averages to be performed for each
+			  channel of ADC. If average is 16 then input
+			  is sampled 16 times and averaged to get more
+			  accurate value. This increases the time taken
+			  by ADC to generate a sample. Valid range is 0
+			  average to 16 averages. Maximum value is 16. {
+			dev_warn(dev, "chan %d open delay truncating to 0x3FFFF\n",
+				 chan);
+			adc_dev->open_delay[i] = STEPDELAY_OPEN_MASK;
+		}
+
+		if (adc_dev->sample_delay[i] > 0xFF) {
+			dev_warn(dev, "chan %d sample delay truncating to 0xFF\n",
+				 chan);
+			adc_dev->sample_delay[i] = 0xFF;
+		}
+
 		tiadc_writel(adc_dev, REG_STEPDELAY(steps),
-				STEPCONFIG_OPENDLY);
+				STEPDELAY_OPEN(adc_dev->open_delay[i]) |
+				STEPDELAY_SAMPLE(adc_dev->sample_delay[i]));
+
 		adc_dev->channel_step[i] = steps;
 		steps++;
 	}

@@ -407,9 +436,22 @@ static int tiadc_parse_dt(struct platform_device *pdev,
 
 	of_property_for_each_u32(node, "ti,adc-channels", prop, cur, val) {
 		adc_dev->channel_line[channels] = val;
+
+		/* Set Default values for optional DT parameters */
+		adc_dev->open_delay[channels] = STEPCONFIG_OPENDLY;
+		adc_dev->sample_delay[channels] = STEPCONFIG_SAMPLEDLY;
+		adc_dev->step_avg[channels] = 16;
+
 		channels++;
 	}
 
+	of_property_read_u32_array(node, "ti,chan-step-avg",
+				   adc_dev->step_avg, channels);
+	of_property_read_u32_array(node, "ti,chan-step-opendelay",
+				   adc_dev->open_delay, channels);
+	of_property_read_u32_array(node, "ti,chan-step-sampledelay",
+				   adc_dev->sample_delay, channels);
+
 	adc_dev->channels = channels;
 	return 0;
 }
author
#5 lore raw

Re: [PATCH 2/2] iio: adc: ti_am335x_adc: make sample delay, open delay, averaging DT parameters

Quoted 7 lines · Jonathan Cameron
Quoted 6 lines · Vignesh R

Add optional DT properties to set open delay, sample delay and number of averages per sample for each adc step. Open delay, sample delay and averaging are some of the parameters that affect the sampling rate and accuracy of the sample. Making these parameters configurable via DT will help in balancing speed vs accuracy.

Quoted 5 lines
Quoted 1 line
Signed-off-by Vignesh R <[email protected]>

All looks fine to me, but I would ideally like a devicetree ack on this one.

Jonathan

Gentle ping...

Regards
Vignesh

Quoted 161 lines
Quoted 160 lines
---
 .../bindings/input/touchscreen/ti-tsc-adc.txt      | 24 ++++++++++
 drivers/iio/adc/ti_am335x_adc.c                    | 54 +++++++++++++++++++---
 2 files changed, 72 insertions(+), 6 deletions(-)
Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt +24 -0
index 6c4fb34823d3..8aafbe87f0eb 100644
@@ -42,6 +42,27 @@ Optional properties:
 			 hardware knob for adjusting the amount of "settling
 			 time".
 
+- child "adc"
+	ti,chan-step-opendelay: List of open delays for each channel of
+				ADC in the order of ti,adc-channels. The
+				value corresponds to the number of ADC
+				clock cycles to wait after applying the
+				step configuration registers and before
+				sending the start of ADC conversion.
+				Maximum value is 0x3FFFF.
+       ti,chan-step-sampledelay: List of sample delays for each channel
+				  of ADC in the order of ti,adc-channels.
+				  The value corresponds to the number of
+				  ADC clock cycles to sample (to hold
+				  start of conversion high).
+				  Maximum value is 0xFF.
+       ti,chan-step-avg: Number of averages to be performed for each
+			  channel of ADC. If average is 16 then input
+			  is sampled 16 times and averaged to get more
+			  accurate value. This increases the time taken
+			  by ADC to generate a sample. Valid range is 0
+			  average to 16 averages. Maximum value is 16.
+
 Example:
 	tscadc: tscadc@44e0d000 {
 		compatible = "ti,am3359-tscadc";

@@ -55,5 +76,8 @@ Example:
 
 		adc {
 			ti,adc-channels = <4 5 6 7>;
+			ti,chan-step-opendelay = <0x098 0x3ffff 0x098 0x0>;
+			ti,chan-step-sampledelay = <0xff 0x0 0xf 0x0>;
+			ti,chan-step-avg = <16 2 4 8>;
 		};
 	}
drivers/iio/adc/ti_am335x_adc.c +64 -6
index 2f818405ffbe..5ee597b4a1af 100644
@@ -37,6 +37,7 @@ struct tiadc_device {
 	u8 channel_step[8];
 	int buffer_en_ch_steps;
 	u16 data[8];
+	u32 open_delay[8], sample_delay[8], step_avg[8];
 };
 
 static unsigned int tiadc_readl(struct tiadc_device *adc, unsigned int reg)

@@ -85,6 +86,7 @@ static u32 get_adc_step_bit(struct tiadc_device *adc_dev, int chan)
 static void tiadc_step_config(struct iio_dev *indio_dev)
 {
 	struct tiadc_device *adc_dev = iio_priv(indio_dev);
+	struct device *dev = adc_dev->mfd_tscadc->dev;
 	unsigned int stepconfig;
 	int i, steps = 0;
 

@@ -98,20 +100,47 @@ static void tiadc_step_config(struct iio_dev *indio_dev)
 	 * needs to be given to ADC to digitalize data.
 	 */
 
-	if (iio_buffer_enabled(indio_dev))
-		stepconfig = STEPCONFIG_AVG_16 | STEPCONFIG_FIFO1
-					| STEPCONFIG_MODE_SWCNT;
-	else
-		stepconfig = STEPCONFIG_AVG_16 | STEPCONFIG_FIFO1;
 
 	for (i = 0; i < adc_dev->channels; i++) {
 		int chan;
 
 		chan = adc_dev->channel_line[i];
+
+		if (adc_dev->step_avg[i] > STEPCONFIG_AVG_16) {
+			dev_warn(dev, "chan %d step_avg truncating to %d\n",
+				 chan, STEPCONFIG_AVG_16);
+			adc_dev->step_avg[i] = STEPCONFIG_AVG_16;
+		}
+
+		if (adc_dev->step_avg[i])
+			stepconfig =
+			STEPCONFIG_AVG(ffs(adc_dev->step_avg[i]) - 1) |
+			STEPCONFIG_FIFO1;
+		else
+			stepconfig = STEPCONFIG_FIFO1;
+
+		if (iio_buffer_enabled(indio_dev))
+			stepconfig |= STEPCONFIG_MODE_SWCNT;
+
 		tiadc_writel(adc_dev, REG_STEPCONFIG(steps),
 				stepconfig | STEPCONFIG_INP(chan));
+
+		if (adc_dev->open_delay[i] > STEPDELAY_OPEN_MASK)alue corresponds to the number of ADC
+				clock cycles to wait after applying the
+				step configuration registers and before
+				sending the start of ADC conversion.
+				Maximum value is 0x3FFFF.
+       ti,chan-step-sampledelay: List of sample delays for each channel
+				  of ADC in the order of ti,adc-channels.
+				  The value corresponds to the number of
+				  ADC clock cycles to sample (to hold
+				  start of conversion high).
+				  Maximum value is 0xFF.
+       ti,chan-step-avg: Number of averages to be performed for each
+			  channel of ADC. If average is 16 then input
+			  is sampled 16 times and averaged to get more
+			  accurate value. This increases the time taken
+			  by ADC to generate a sample. Valid range is 0
+			  average to 16 averages. Maximum value is 16. {
+			dev_warn(dev, "chan %d open delay truncating to 0x3FFFF\n",
+				 chan);
+			adc_dev->open_delay[i] = STEPDELAY_OPEN_MASK;
+		}
+
+		if (adc_dev->sample_delay[i] > 0xFF) {
+			dev_warn(dev, "chan %d sample delay truncating to 0xFF\n",
+				 chan);
+			adc_dev->sample_delay[i] = 0xFF;
+		}
+
 		tiadc_writel(adc_dev, REG_STEPDELAY(steps),
-				STEPCONFIG_OPENDLY);
+				STEPDELAY_OPEN(adc_dev->open_delay[i]) |
+				STEPDELAY_SAMPLE(adc_dev->sample_delay[i]));
+
 		adc_dev->channel_step[i] = steps;
 		steps++;
 	}

@@ -407,9 +436,22 @@ static int tiadc_parse_dt(struct platform_device *pdev,
 
 	of_property_for_each_u32(node, "ti,adc-channels", prop, cur, val) {
 		adc_dev->channel_line[channels] = val;
+
+		/* Set Default values for optional DT parameters */
+		adc_dev->open_delay[channels] = STEPCONFIG_OPENDLY;
+		adc_dev->sample_delay[channels] = STEPCONFIG_SAMPLEDLY;
+		adc_dev->step_avg[channels] = 16;
+
 		channels++;
 	}
 
+	of_property_read_u32_array(node, "ti,chan-step-avg",
+				   adc_dev->step_avg, channels);
+	of_property_read_u32_array(node, "ti,chan-step-opendelay",
+				   adc_dev->open_delay, channels);
+	of_property_read_u32_array(node, "ti,chan-step-sampledelay",
+				   adc_dev->sample_delay, channels);
+
 	adc_dev->channels = channels;
 	return 0;
 }
maintainer
#6 lore raw

Re: [PATCH 2/2] iio: adc: ti_am335x_adc: make sample delay, open delay, averaging DT parameters

Quoted 10 lines · Vignesh R
Quoted 7 lines · Jonathan Cameron
Quoted 6 lines · Vignesh R

Add optional DT properties to set open delay, sample delay and number of averages per sample for each adc step. Open delay, sample delay and averaging are some of the parameters that affect the sampling rate and accuracy of the sample. Making these parameters configurable via DT will help in balancing speed vs accuracy.

Quoted 7 lines
Quoted 5 lines
Quoted 1 line
Signed-off-by Vignesh R <[email protected]>

All looks fine to me, but I would ideally like a devicetree ack on this one.

Jonathan

Gentle ping...

Thanks. Had forgotten about this one. Ah well, no device tree response...

Applied to the togreg branch of iio.git, initially pushed out as testing.

Thanks,

Jonathan

Quoted 169 lines

Regards
Vignesh

Quoted 149 lines
Quoted 149 lines
---
 .../bindings/input/touchscreen/ti-tsc-adc.txt      | 24 ++++++++++
 drivers/iio/adc/ti_am335x_adc.c                    | 54 +++++++++++++++++++---
 2 files changed, 72 insertions(+), 6 deletions(-)
Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt +24 -0
index 6c4fb34823d3..8aafbe87f0eb 100644
@@ -42,6 +42,27 @@ Optional properties:
 			 hardware knob for adjusting the amount of "settling
 			 time".
 
+- child "adc"
+	ti,chan-step-opendelay: List of open delays for each channel of
+				ADC in the order of ti,adc-channels. The
+				value corresponds to the number of ADC
+				clock cycles to wait after applying the
+				step configuration registers and before
+				sending the start of ADC conversion.
+				Maximum value is 0x3FFFF.
+       ti,chan-step-sampledelay: List of sample delays for each channel
+				  of ADC in the order of ti,adc-channels.
+				  The value corresponds to the number of
+				  ADC clock cycles to sample (to hold
+				  start of conversion high).
+				  Maximum value is 0xFF.
+       ti,chan-step-avg: Number of averages to be performed for each
+			  channel of ADC. If average is 16 then input
+			  is sampled 16 times and averaged to get more
+			  accurate value. This increases the time taken
+			  by ADC to generate a sample. Valid range is 0
+			  average to 16 averages. Maximum value is 16.
+
 Example:
 	tscadc: tscadc@44e0d000 {
 		compatible = "ti,am3359-tscadc";

@@ -55,5 +76,8 @@ Example:
 
 		adc {
 			ti,adc-channels = <4 5 6 7>;
+			ti,chan-step-opendelay = <0x098 0x3ffff 0x098 0x0>;
+			ti,chan-step-sampledelay = <0xff 0x0 0xf 0x0>;
+			ti,chan-step-avg = <16 2 4 8>;
 		};
 	}
drivers/iio/adc/ti_am335x_adc.c +57 -6
index 2f818405ffbe..5ee597b4a1af 100644
@@ -37,6 +37,7 @@ struct tiadc_device {
 	u8 channel_step[8];
 	int buffer_en_ch_steps;
 	u16 data[8];
+	u32 open_delay[8], sample_delay[8], step_avg[8];
 };
 
 static unsigned int tiadc_readl(struct tiadc_device *adc, unsigned int reg)

@@ -85,6 +86,7 @@ static u32 get_adc_step_bit(struct tiadc_device *adc_dev, int chan)
 static void tiadc_step_config(struct iio_dev *indio_dev)
 {
 	struct tiadc_device *adc_dev = iio_priv(indio_dev);
+	struct device *dev = adc_dev->mfd_tscadc->dev;
 	unsigned int stepconfig;
 	int i, steps = 0;
 

@@ -98,20 +100,47 @@ static void tiadc_step_config(struct iio_dev *indio_dev)
 	 * needs to be given to ADC to digitalize data.
 	 */
 
-	if (iio_buffer_enabled(indio_dev))
-		stepconfig = STEPCONFIG_AVG_16 | STEPCONFIG_FIFO1
-					| STEPCONFIG_MODE_SWCNT;
-	else
-		stepconfig = STEPCONFIG_AVG_16 | STEPCONFIG_FIFO1;
 
 	for (i = 0; i < adc_dev->channels; i++) {
 		int chan;
 
 		chan = adc_dev->channel_line[i];
+
+		if (adc_dev->step_avg[i] > STEPCONFIG_AVG_16) {
+			dev_warn(dev, "chan %d step_avg truncating to %d\n",
+				 chan, STEPCONFIG_AVG_16);
+			adc_dev->step_avg[i] = STEPCONFIG_AVG_16;
+		}
+
+		if (adc_dev->step_avg[i])
+			stepconfig =
+			STEPCONFIG_AVG(ffs(adc_dev->step_avg[i]) - 1) |
+			STEPCONFIG_FIFO1;
+		else
+			stepconfig = STEPCONFIG_FIFO1;
+
+		if (iio_buffer_enabled(indio_dev))
+			stepconfig |= STEPCONFIG_MODE_SWCNT;
+
 		tiadc_writel(adc_dev, REG_STEPCONFIG(steps),
 				stepconfig | STEPCONFIG_INP(chan));
+
+		if (adc_dev->open_delay[i] > STEPDELAY_OPEN_MASK)alue corresponds to the number of ADC
+				clock cycles to wait after applying the
+				step configuration registers and before
+				sending the start of ADC conversion.
+				Maximum value is 0x3FFFF.
+       ti,chan-step-sampledelay: List of sample delays for each channel
+				  of ADC in the order of ti,adc-channels.
+				  The value corresponds to the number of
+				  ADC clock cycles to sample (to hold
+				  start of conversion high).
+				  Maximum value is 0xFF.
+       ti,chan-step-avg: Number of averages to be performed for each
+			  channel of ADC. If average is 16 then input
+			  is sampled 16 times and averaged to get more
+			  accurate value. This increases the time taken
+			  by ADC to generate a sample. Valid range is 0
+			  average to 16 averages. Maximum value is 16. {
+			dev_warn(dev, "chan %d open delay truncating to 0x3FFFF\n",
+				 chan);
+			adc_dev->open_delay[i] = STEPDELAY_OPEN_MASK;
+		}
+
+		if (adc_dev->sample_delay[i] > 0xFF) {
+			dev_warn(dev, "chan %d sample delay truncating to 0xFF\n",
+				 chan);
+			adc_dev->sample_delay[i] = 0xFF;
+		}
+
 		tiadc_writel(adc_dev, REG_STEPDELAY(steps),
-				STEPCONFIG_OPENDLY);
+				STEPDELAY_OPEN(adc_dev->open_delay[i]) |
+				STEPDELAY_SAMPLE(adc_dev->sample_delay[i]));
+
 		adc_dev->channel_step[i] = steps;
 		steps++;
 	}

@@ -407,9 +436,22 @@ static int tiadc_parse_dt(struct platform_device *pdev,
 
 	of_property_for_each_u32(node, "ti,adc-channels", prop, cur, val) {
 		adc_dev->channel_line[channels] = val;
+
+		/* Set Default values for optional DT parameters */
+		adc_dev->open_delay[channels] = STEPCONFIG_OPENDLY;
+		adc_dev->sample_delay[channels] = STEPCONFIG_SAMPLEDLY;
+		adc_dev->step_avg[channels] = 16;
+
 		channels++;
 	}
Quoted 12 lines

drivers/iio/adc/ti_am335x_adc.c static int tiadc_parse_dt(struct platform_device *pdev, · line 457

Quoted 11 lines
drivers/iio/adc/ti_am335x_adc.c +7 -0
+	of_property_read_u32_array(node, "ti,chan-step-avg",
+				   adc_dev->step_avg, channels);
+	of_property_read_u32_array(node, "ti,chan-step-opendelay",
+				   adc_dev->open_delay, channels);
+	of_property_read_u32_array(node, "ti,chan-step-sampledelay",
+				   adc_dev->sample_delay, channels);
+
 	adc_dev->channels = channels;
 	return 0;
 }

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