diff mbox series

[v4,9/9] iio: adc: mcp3911: add support to set PGA

Message ID 20220722130726.7627-10-marcus.folkesson@gmail.com (mailing list archive)
State Changes Requested
Headers show
Series Improve MCP3911 driver | expand

Commit Message

Marcus Folkesson July 22, 2022, 1:07 p.m. UTC 
Add support for setting the Programmable Gain Amplifiers by adjust the
scale value.

Signed-off-by: Marcus Folkesson <marcus.folkesson@gmail.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
---
 drivers/iio/adc/mcp3911.c | 107 +++++++++++++++++++++++++++++---------
 1 file changed, 83 insertions(+), 24 deletions(-)

Comments

Jonathan Cameron July 31, 2022, 4:53 p.m. UTC | #1 
On Fri, 22 Jul 2022 15:07:26 +0200
Marcus Folkesson <marcus.folkesson@gmail.com> wrote:

> Add support for setting the Programmable Gain Amplifiers by adjust the
> scale value.
> 
> Signed-off-by: Marcus Folkesson <marcus.folkesson@gmail.com>
> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>

This and other patches I haven't commented on all look good to me.

> ---
>  drivers/iio/adc/mcp3911.c | 107 +++++++++++++++++++++++++++++---------
>  1 file changed, 83 insertions(+), 24 deletions(-)
> 
> diff --git a/drivers/iio/adc/mcp3911.c b/drivers/iio/adc/mcp3911.c
> index 30c91ccc5fb6..22a43d3fe402 100644
> --- a/drivers/iio/adc/mcp3911.c
> +++ b/drivers/iio/adc/mcp3911.c
> @@ -27,6 +27,8 @@
>  #define MCP3911_REG_MOD			0x06
>  #define MCP3911_REG_PHASE		0x07
>  #define MCP3911_REG_GAIN		0x09
> +#define MCP3911_GAIN_MASK(ch)		(GENMASK(2, 0) << 3 * ch)
> +#define MCP3911_GAIN_VAL(ch, val)      ((val << 3 * ch) & MCP3911_GAIN_MASK(ch))
>  
>  #define MCP3911_REG_STATUSCOM		0x0a
>  #define MCP3911_STATUSCOM_DRHIZ         BIT(12)
> @@ -57,8 +59,10 @@
>  #define MCP3911_REG_WRITE(reg, id)	((((reg) << 1) | ((id) << 5) | (0 << 0)) & 0xff)
>  
>  #define MCP3911_NUM_CHANNELS		2
> +#define MCP3911_NUM_SCALES		6
>  
>  static const int mcp3911_osr_table[] = { 32, 64, 128, 256, 512, 1024, 2048, 4096 };
> +static u32 mcp3911_scale_table[MCP3911_NUM_SCALES][2];
>  
>  struct mcp3911 {
>  	struct spi_device *spi;
> @@ -67,6 +71,7 @@ struct mcp3911 {
>  	struct clk *clki;
>  	u32 dev_addr;
>  	struct iio_trigger *trig;
> +	u32 gain[MCP3911_NUM_CHANNELS];
>  	struct {
>  		u32 channels[MCP3911_NUM_CHANNELS];
>  		s64 ts __aligned(8);
> @@ -143,6 +148,11 @@ static int mcp3911_read_avail(struct iio_dev *indio_dev,
>  		*vals = mcp3911_osr_table;
>  		*length = ARRAY_SIZE(mcp3911_osr_table);
>  		return IIO_AVAIL_LIST;
> +	case IIO_CHAN_INFO_SCALE:
> +		*type = IIO_VAL_INT_PLUS_NANO;
> +		*vals = (int *)mcp3911_scale_table;
> +		*length = ARRAY_SIZE(mcp3911_scale_table) * 2;
> +		return IIO_AVAIL_LIST;
>  	default:
>  		return -EINVAL;
>  	}
> @@ -187,29 +197,9 @@ static int mcp3911_read_raw(struct iio_dev *indio_dev,
>  		break;
>  
>  	case IIO_CHAN_INFO_SCALE:
> -		if (adc->vref) {
> -			ret = regulator_get_voltage(adc->vref);
> -			if (ret < 0) {
> -				dev_err(indio_dev->dev.parent,
> -					"failed to get vref voltage: %d\n",
> -				       ret);
> -				goto out;
> -			}
> -
> -			*val = ret / 1000;
> -		} else {
> -			*val = MCP3911_INT_VREF_MV;
> -		}
> -
> -		/*
> -		 * For 24bit Conversion
> -		 * Raw = ((Voltage)/(Vref) * 2^23 * Gain * 1.5
> -		 * Voltage = Raw * (Vref)/(2^23 * Gain * 1.5)
> -		 */
> -
> -		/* val2 = (2^23 * 1.5) */
> -		*val2 = 12582912;
> -		ret = IIO_VAL_FRACTIONAL;
> +		*val = mcp3911_scale_table[ilog2(adc->gain[channel->channel])][0];
> +		*val2 = mcp3911_scale_table[ilog2(adc->gain[channel->channel])][1];
> +		ret = IIO_VAL_INT_PLUS_NANO;
>  		break;
>  	}
>  
> @@ -227,6 +217,18 @@ static int mcp3911_write_raw(struct iio_dev *indio_dev,
>  
>  	mutex_lock(&adc->lock);
>  	switch (mask) {
> +	case IIO_CHAN_INFO_SCALE:
> +		for (int i = 0; i < MCP3911_NUM_SCALES; i++) {
> +			if (val == mcp3911_scale_table[i][0] &&
> +				val2 == mcp3911_scale_table[i][1]) {
> +
> +				adc->gain[channel->channel] = BIT(i);
> +				ret = mcp3911_update(adc, MCP3911_REG_GAIN,
> +						MCP3911_GAIN_MASK(channel->channel),
> +						MCP3911_GAIN_VAL(channel->channel, i), 1);
> +			}
> +		}
> +		break;
>  	case IIO_CHAN_INFO_OFFSET:
>  		if (val2 != 0) {
>  			ret = -EINVAL;
> @@ -262,6 +264,47 @@ static int mcp3911_write_raw(struct iio_dev *indio_dev,
>  	return ret;
>  }
>  
> +static int mcp3911_calc_scale_table(struct mcp3911 *adc)
> +{
> +	u32 ref = MCP3911_INT_VREF_MV;
> +	u32 div;
> +	int ret;
> +	int tmp0, tmp1;
> +	s64 tmp2;
> +
> +	if (adc->vref) {
> +		ret = regulator_get_voltage(adc->vref);
> +		if (ret < 0) {
> +			dev_err(&adc->spi->dev,
> +				"failed to get vref voltage: %d\n",
> +			       ret);
> +			return ret;
> +		}
> +
> +		ref = ret / 1000;
> +	}
> +
> +	/*
> +	 * For 24-bit Conversion
> +	 * Raw = ((Voltage)/(Vref) * 2^23 * Gain * 1.5
> +	 * Voltage = Raw * (Vref)/(2^23 * Gain * 1.5)
> +	 *
> +	 * ref = Reference voltage
> +	 * div = (2^23 * 1.5 * gain) = 12582912 * gain
> +	 */
> +	for (int i = 0; i < MCP3911_NUM_SCALES; i++) {
> +		div = 12582912 * BIT(i);
> +		tmp2 = div_s64((s64)ref * 1000000000LL, div);
> +		tmp1 = div;
> +		tmp0 = (int)div_s64_rem(tmp2, 1000000000, &tmp1);
> +
> +		mcp3911_scale_table[i][0] = 0;
> +		mcp3911_scale_table[i][1] = tmp1;
> +	}
> +
> +	return 0;
> +}
> +
>  #define MCP3911_CHAN(idx) {					\
>  		.type = IIO_VOLTAGE,				\
>  		.indexed = 1,					\
> @@ -271,8 +314,10 @@ static int mcp3911_write_raw(struct iio_dev *indio_dev,
>  		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |	\
>  			BIT(IIO_CHAN_INFO_OFFSET) |		\
>  			BIT(IIO_CHAN_INFO_SCALE),		\
> -		.info_mask_shared_by_type_available =		\
> +		.info_mask_shared_by_type_available =           \
>  			BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),	\
> +		.info_mask_separate_available =			\
> +			BIT(IIO_CHAN_INFO_SCALE),		\
>  		.scan_type = {					\
>  			.sign = 's',				\
>  			.realbits = 24,				\
> @@ -495,6 +540,20 @@ static int mcp3911_probe(struct spi_device *spi)
>  	if (ret)
>  		return ret;
>  
> +	ret = mcp3911_calc_scale_table(adc);
> +	if (ret)
> +		return ret;
> +
> +       /* Set gain to 1 for all channels */
> +	for (int i = 0; i < MCP3911_NUM_CHANNELS; i++) {
> +		adc->gain[i] = 1;
> +		ret = mcp3911_update(adc, MCP3911_REG_GAIN,
> +				MCP3911_GAIN_MASK(i),
> +				MCP3911_GAIN_VAL(i, 0), 1);
> +		if (ret)
> +			return ret;
> +	}
> +
>  	indio_dev->name = spi_get_device_id(spi)->name;
>  	indio_dev->modes = INDIO_DIRECT_MODE;
>  	indio_dev->info = &mcp3911_info;
diff mbox series

Patch

diff --git a/drivers/iio/adc/mcp3911.c b/drivers/iio/adc/mcp3911.c
index 30c91ccc5fb6..22a43d3fe402 100644
--- a/drivers/iio/adc/mcp3911.c
+++ b/drivers/iio/adc/mcp3911.c
@@ -27,6 +27,8 @@ 
 #define MCP3911_REG_MOD			0x06
 #define MCP3911_REG_PHASE		0x07
 #define MCP3911_REG_GAIN		0x09
+#define MCP3911_GAIN_MASK(ch)		(GENMASK(2, 0) << 3 * ch)
+#define MCP3911_GAIN_VAL(ch, val)      ((val << 3 * ch) & MCP3911_GAIN_MASK(ch))
 
 #define MCP3911_REG_STATUSCOM		0x0a
 #define MCP3911_STATUSCOM_DRHIZ         BIT(12)
@@ -57,8 +59,10 @@ 
 #define MCP3911_REG_WRITE(reg, id)	((((reg) << 1) | ((id) << 5) | (0 << 0)) & 0xff)
 
 #define MCP3911_NUM_CHANNELS		2
+#define MCP3911_NUM_SCALES		6
 
 static const int mcp3911_osr_table[] = { 32, 64, 128, 256, 512, 1024, 2048, 4096 };
+static u32 mcp3911_scale_table[MCP3911_NUM_SCALES][2];
 
 struct mcp3911 {
 	struct spi_device *spi;
@@ -67,6 +71,7 @@  struct mcp3911 {
 	struct clk *clki;
 	u32 dev_addr;
 	struct iio_trigger *trig;
+	u32 gain[MCP3911_NUM_CHANNELS];
 	struct {
 		u32 channels[MCP3911_NUM_CHANNELS];
 		s64 ts __aligned(8);
@@ -143,6 +148,11 @@  static int mcp3911_read_avail(struct iio_dev *indio_dev,
 		*vals = mcp3911_osr_table;
 		*length = ARRAY_SIZE(mcp3911_osr_table);
 		return IIO_AVAIL_LIST;
+	case IIO_CHAN_INFO_SCALE:
+		*type = IIO_VAL_INT_PLUS_NANO;
+		*vals = (int *)mcp3911_scale_table;
+		*length = ARRAY_SIZE(mcp3911_scale_table) * 2;
+		return IIO_AVAIL_LIST;
 	default:
 		return -EINVAL;
 	}
@@ -187,29 +197,9 @@  static int mcp3911_read_raw(struct iio_dev *indio_dev,
 		break;
 
 	case IIO_CHAN_INFO_SCALE:
-		if (adc->vref) {
-			ret = regulator_get_voltage(adc->vref);
-			if (ret < 0) {
-				dev_err(indio_dev->dev.parent,
-					"failed to get vref voltage: %d\n",
-				       ret);
-				goto out;
-			}
-
-			*val = ret / 1000;
-		} else {
-			*val = MCP3911_INT_VREF_MV;
-		}
-
-		/*
-		 * For 24bit Conversion
-		 * Raw = ((Voltage)/(Vref) * 2^23 * Gain * 1.5
-		 * Voltage = Raw * (Vref)/(2^23 * Gain * 1.5)
-		 */
-
-		/* val2 = (2^23 * 1.5) */
-		*val2 = 12582912;
-		ret = IIO_VAL_FRACTIONAL;
+		*val = mcp3911_scale_table[ilog2(adc->gain[channel->channel])][0];
+		*val2 = mcp3911_scale_table[ilog2(adc->gain[channel->channel])][1];
+		ret = IIO_VAL_INT_PLUS_NANO;
 		break;
 	}
 
@@ -227,6 +217,18 @@  static int mcp3911_write_raw(struct iio_dev *indio_dev,
 
 	mutex_lock(&adc->lock);
 	switch (mask) {
+	case IIO_CHAN_INFO_SCALE:
+		for (int i = 0; i < MCP3911_NUM_SCALES; i++) {
+			if (val == mcp3911_scale_table[i][0] &&
+				val2 == mcp3911_scale_table[i][1]) {
+
+				adc->gain[channel->channel] = BIT(i);
+				ret = mcp3911_update(adc, MCP3911_REG_GAIN,
+						MCP3911_GAIN_MASK(channel->channel),
+						MCP3911_GAIN_VAL(channel->channel, i), 1);
+			}
+		}
+		break;
 	case IIO_CHAN_INFO_OFFSET:
 		if (val2 != 0) {
 			ret = -EINVAL;
@@ -262,6 +264,47 @@  static int mcp3911_write_raw(struct iio_dev *indio_dev,
 	return ret;
 }
 
+static int mcp3911_calc_scale_table(struct mcp3911 *adc)
+{
+	u32 ref = MCP3911_INT_VREF_MV;
+	u32 div;
+	int ret;
+	int tmp0, tmp1;
+	s64 tmp2;
+
+	if (adc->vref) {
+		ret = regulator_get_voltage(adc->vref);
+		if (ret < 0) {
+			dev_err(&adc->spi->dev,
+				"failed to get vref voltage: %d\n",
+			       ret);
+			return ret;
+		}
+
+		ref = ret / 1000;
+	}
+
+	/*
+	 * For 24-bit Conversion
+	 * Raw = ((Voltage)/(Vref) * 2^23 * Gain * 1.5
+	 * Voltage = Raw * (Vref)/(2^23 * Gain * 1.5)
+	 *
+	 * ref = Reference voltage
+	 * div = (2^23 * 1.5 * gain) = 12582912 * gain
+	 */
+	for (int i = 0; i < MCP3911_NUM_SCALES; i++) {
+		div = 12582912 * BIT(i);
+		tmp2 = div_s64((s64)ref * 1000000000LL, div);
+		tmp1 = div;
+		tmp0 = (int)div_s64_rem(tmp2, 1000000000, &tmp1);
+
+		mcp3911_scale_table[i][0] = 0;
+		mcp3911_scale_table[i][1] = tmp1;
+	}
+
+	return 0;
+}
+
 #define MCP3911_CHAN(idx) {					\
 		.type = IIO_VOLTAGE,				\
 		.indexed = 1,					\
@@ -271,8 +314,10 @@  static int mcp3911_write_raw(struct iio_dev *indio_dev,
 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |	\
 			BIT(IIO_CHAN_INFO_OFFSET) |		\
 			BIT(IIO_CHAN_INFO_SCALE),		\
-		.info_mask_shared_by_type_available =		\
+		.info_mask_shared_by_type_available =           \
 			BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),	\
+		.info_mask_separate_available =			\
+			BIT(IIO_CHAN_INFO_SCALE),		\
 		.scan_type = {					\
 			.sign = 's',				\
 			.realbits = 24,				\
@@ -495,6 +540,20 @@  static int mcp3911_probe(struct spi_device *spi)
 	if (ret)
 		return ret;
 
+	ret = mcp3911_calc_scale_table(adc);
+	if (ret)
+		return ret;
+
+       /* Set gain to 1 for all channels */
+	for (int i = 0; i < MCP3911_NUM_CHANNELS; i++) {
+		adc->gain[i] = 1;
+		ret = mcp3911_update(adc, MCP3911_REG_GAIN,
+				MCP3911_GAIN_MASK(i),
+				MCP3911_GAIN_VAL(i, 0), 1);
+		if (ret)
+			return ret;
+	}
+
 	indio_dev->name = spi_get_device_id(spi)->name;
 	indio_dev->modes = INDIO_DIRECT_MODE;
 	indio_dev->info = &mcp3911_info;