[PATCH v3 00/10] Support ROHM BD79105 ADC

[PATCH v3 00/10] Support ROHM BD79105 ADC

[Matti Vaittinen]

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Add support for the ROHM BD79105 ADC
(and do some minor simplifications to the ad7476 driver while at it).

The first 2 patches were originally sent as an RFC:
https://lore.kernel.org/all/cover.1754041258.git.mazziesaccount@gmail.com/

Revision history:
  v2 => v3:
   - Drop 5/10 "Limit the scope of the chip_info"
   - Add 5/10 "use *_cansleep GPIO APIs"
   - Multiple fixes as suggested during v2 review. More accurate
     changelog included in individual patches

  v1 => v2:
   - Two new patches:
     5/10 "Limit the scope of the chip_info" and
     6/10 "Drop convstart chan_spec"
     Please, let me know if you think some of the changes should be
     squashed.
   - Multiple fixes as suggested during v1 review. More accurate
     changelog included in individual patches

  Simplification RFC => ROHM BD79105 support series v1:
   - Use spi_get_device_match_data()
   - Fix uV to mV conversion
   - Rewording of commit message
   - Added patches 3 to 8.

Matti Vaittinen (10):
  iio: adc: ad7476: Simplify chip type detection
  iio: adc: ad7476: Simplify scale handling
  iio: adc: ad7476: Use mV for internal reference
  iio: adc: ad7476: Use correct channel for bit info
  iio: adc: ad7476: use *_cansleep GPIO APIs
  iio: adc: ad7476: Drop convstart chan_spec
  iio: adc: ad7476: Conditionally call convstart
  dt-bindings: iio: adc: ad7476: Add ROHM bd79105
  iio: adc: ad7476: Support ROHM BD79105
  MAINTAINERS: A driver for simple 1-channel SPI ADCs

 .../bindings/iio/adc/adi,ad7476.yaml          |  54 ++
 MAINTAINERS                                   |   5 +
 drivers/iio/adc/ad7476.c                      | 461 +++++++++---------
 3 files changed, 292 insertions(+), 228 deletions(-)

-- 
2.50.1


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[PATCH v3 01/10] iio: adc: ad7476: Simplify chip type detection

[Matti Vaittinen]

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The ad7476 driver uses a table of structures for defining the IC variant
specific data. Table is indexed using enum values, which are picked by
SPI ID.

Having the table and an enum adds extra complexity and may encourage
adding IC specific quircks in the code, instead of centralizing the IC
differences in one place, the chip-info.

Simplify this by dropping the table and using individual structures for
the IC specific data, and storing the IC specific structure's address
directly in the SPI ID data. Finally, switch to the
spi_get_device_match_data() and add a check for the return value.

Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
Reviewed-by: Nuno Sá <nuno.sa@analog.com>

---
Revision history:
 v1 =>
 - No changes

 This patch was originally sent as an RFC in 2 patch series:
 https://lore.kernel.org/all/cover.1754041258.git.mazziesaccount@gmail.com/
 Changes from the RFC => v1:
 - Use spi_get_device_match_data()
 - Slightly reword commit message
---
 drivers/iio/adc/ad7476.c | 296 +++++++++++++++++++--------------------
 1 file changed, 146 insertions(+), 150 deletions(-)

diff --git a/drivers/iio/adc/ad7476.c b/drivers/iio/adc/ad7476.c
index aea734aa06bd..9869526c1524 100644
--- a/drivers/iio/adc/ad7476.c
+++ b/drivers/iio/adc/ad7476.c
@@ -52,29 +52,6 @@ struct ad7476_state {
 	unsigned char data[ALIGN(2, sizeof(s64)) + sizeof(s64)] __aligned(IIO_DMA_MINALIGN);
 };
 
-enum ad7476_supported_device_ids {
-	ID_AD7091,
-	ID_AD7091R,
-	ID_AD7273,
-	ID_AD7274,
-	ID_AD7276,
-	ID_AD7277,
-	ID_AD7278,
-	ID_AD7466,
-	ID_AD7467,
-	ID_AD7468,
-	ID_AD7475,
-	ID_AD7495,
-	ID_AD7940,
-	ID_ADC081S,
-	ID_ADC101S,
-	ID_ADC121S,
-	ID_ADS7866,
-	ID_ADS7867,
-	ID_ADS7868,
-	ID_LTC2314_14,
-};
-
 static void ad7091_convst(struct ad7476_state *st)
 {
 	if (!st->convst_gpio)
@@ -190,102 +167,119 @@ static int ad7476_read_raw(struct iio_dev *indio_dev,
 #define ADS786X_CHAN(bits) _AD7476_CHAN((bits), 12 - (bits), \
 		BIT(IIO_CHAN_INFO_RAW))
 
-static const struct ad7476_chip_info ad7476_chip_info_tbl[] = {
-	[ID_AD7091] = {
-		.channel[0] = AD7091R_CHAN(12),
-		.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
-		.convst_channel[0] = AD7091R_CONVST_CHAN(12),
-		.convst_channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
-		.reset = ad7091_reset,
-	},
-	[ID_AD7091R] = {
-		.channel[0] = AD7091R_CHAN(12),
-		.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
-		.convst_channel[0] = AD7091R_CONVST_CHAN(12),
-		.convst_channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
-		.int_vref_uv = 2500000,
-		.has_vref = true,
-		.reset = ad7091_reset,
-	},
-	[ID_AD7273] = {
-		.channel[0] = AD7940_CHAN(10),
-		.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
-		.has_vref = true,
-	},
-	[ID_AD7274] = {
-		.channel[0] = AD7940_CHAN(12),
-		.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
-		.has_vref = true,
-	},
-	[ID_AD7276] = {
-		.channel[0] = AD7940_CHAN(12),
-		.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
-	},
-	[ID_AD7277] = {
-		.channel[0] = AD7940_CHAN(10),
-		.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
-	},
-	[ID_AD7278] = {
-		.channel[0] = AD7940_CHAN(8),
-		.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
-	},
-	[ID_AD7466] = {
-		.channel[0] = AD7476_CHAN(12),
-		.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
-	},
-	[ID_AD7467] = {
-		.channel[0] = AD7476_CHAN(10),
-		.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
-	},
-	[ID_AD7468] = {
-		.channel[0] = AD7476_CHAN(8),
-		.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
-	},
-	[ID_AD7475] = {
-		.channel[0] = AD7476_CHAN(12),
-		.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
-		.has_vref = true,
-		.has_vdrive = true,
-	},
-	[ID_AD7495] = {
-		.channel[0] = AD7476_CHAN(12),
-		.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
-		.int_vref_uv = 2500000,
-		.has_vdrive = true,
-	},
-	[ID_AD7940] = {
-		.channel[0] = AD7940_CHAN(14),
-		.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
-	},
-	[ID_ADC081S] = {
-		.channel[0] = ADC081S_CHAN(8),
-		.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
-	},
-	[ID_ADC101S] = {
-		.channel[0] = ADC081S_CHAN(10),
-		.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
-	},
-	[ID_ADC121S] = {
-		.channel[0] = ADC081S_CHAN(12),
-		.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
-	},
-	[ID_ADS7866] = {
-		.channel[0] = ADS786X_CHAN(12),
-		.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
-	},
-	[ID_ADS7867] = {
-		.channel[0] = ADS786X_CHAN(10),
-		.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
-	},
-	[ID_ADS7868] = {
-		.channel[0] = ADS786X_CHAN(8),
-		.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
-	},
-	[ID_LTC2314_14] = {
-		.channel[0] = AD7940_CHAN(14),
-		.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
-		.has_vref = true,
-	},
+static const struct ad7476_chip_info ad7091_chip_info = {
+	.channel[0] = AD7091R_CHAN(12),
+	.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
+	.convst_channel[0] = AD7091R_CONVST_CHAN(12),
+	.convst_channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
+	.reset = ad7091_reset,
+};
+
+static const struct ad7476_chip_info ad7091r_chip_info = {
+	.channel[0] = AD7091R_CHAN(12),
+	.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
+	.convst_channel[0] = AD7091R_CONVST_CHAN(12),
+	.convst_channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
+	.int_vref_uv = 2500000,
+	.has_vref = true,
+	.reset = ad7091_reset,
+};
+
+static const struct ad7476_chip_info ad7273_chip_info = {
+	.channel[0] = AD7940_CHAN(10),
+	.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
+	.has_vref = true,
+};
+
+static const struct ad7476_chip_info ad7274_chip_info = {
+	.channel[0] = AD7940_CHAN(12),
+	.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
+	.has_vref = true,
+};
+
+static const struct ad7476_chip_info ad7276_chip_info = {
+	.channel[0] = AD7940_CHAN(12),
+	.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
+};
+
+static const struct ad7476_chip_info ad7277_chip_info = {
+	.channel[0] = AD7940_CHAN(10),
+	.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
+};
+
+static const struct ad7476_chip_info ad7278_chip_info = {
+	.channel[0] = AD7940_CHAN(8),
+	.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
+};
+
+static const struct ad7476_chip_info ad7466_chip_info = {
+	.channel[0] = AD7476_CHAN(12),
+	.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
+};
+
+static const struct ad7476_chip_info ad7467_chip_info = {
+	.channel[0] = AD7476_CHAN(10),
+	.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
+};
+
+static const struct ad7476_chip_info ad7468_chip_info = {
+	.channel[0] = AD7476_CHAN(8),
+	.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
+};
+
+static const struct ad7476_chip_info ad7475_chip_info = {
+	.channel[0] = AD7476_CHAN(12),
+	.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
+	.has_vref = true,
+	.has_vdrive = true,
+};
+
+static const struct ad7476_chip_info ad7495_chip_info = {
+	.channel[0] = AD7476_CHAN(12),
+	.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
+	.int_vref_uv = 2500000,
+	.has_vdrive = true,
+};
+
+static const struct ad7476_chip_info ad7940_chip_info = {
+	.channel[0] = AD7940_CHAN(14),
+	.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
+};
+
+static const struct ad7476_chip_info adc081s_chip_info = {
+	.channel[0] = ADC081S_CHAN(8),
+	.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
+};
+
+static const struct ad7476_chip_info adc101s_chip_info = {
+	.channel[0] = ADC081S_CHAN(10),
+	.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
+};
+
+static const struct ad7476_chip_info adc121s_chip_info = {
+	.channel[0] = ADC081S_CHAN(12),
+	.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
+};
+
+static const struct ad7476_chip_info ads7866_chip_info = {
+	.channel[0] = ADS786X_CHAN(12),
+	.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
+};
+
+static const struct ad7476_chip_info ads7867_chip_info = {
+	.channel[0] = ADS786X_CHAN(10),
+	.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
+};
+
+static const struct ad7476_chip_info ads7868_chip_info = {
+	.channel[0] = ADS786X_CHAN(8),
+	.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
+};
+
+static const struct ad7476_chip_info ltc2314_14_chip_info = {
+	.channel[0] = AD7940_CHAN(14),
+	.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
+	.has_vref = true,
 };
 
 static const struct iio_info ad7476_info = {
@@ -311,8 +305,10 @@ static int ad7476_probe(struct spi_device *spi)
 		return -ENOMEM;
 
 	st = iio_priv(indio_dev);
-	st->chip_info =
-		&ad7476_chip_info_tbl[spi_get_device_id(spi)->driver_data];
+
+	st->chip_info = spi_get_device_match_data(spi);
+	if (!st->chip_info)
+		return -ENODEV;
 
 	reg = devm_regulator_get(&spi->dev, "vcc");
 	if (IS_ERR(reg))
@@ -408,41 +404,41 @@ static int ad7476_probe(struct spi_device *spi)
 }
 
 static const struct spi_device_id ad7476_id[] = {
-	{ "ad7091", ID_AD7091 },
-	{ "ad7091r", ID_AD7091R },
-	{ "ad7273", ID_AD7273 },
-	{ "ad7274", ID_AD7274 },
-	{ "ad7276", ID_AD7276},
-	{ "ad7277", ID_AD7277 },
-	{ "ad7278", ID_AD7278 },
-	{ "ad7466", ID_AD7466 },
-	{ "ad7467", ID_AD7467 },
-	{ "ad7468", ID_AD7468 },
-	{ "ad7475", ID_AD7475 },
-	{ "ad7476", ID_AD7466 },
-	{ "ad7476a", ID_AD7466 },
-	{ "ad7477", ID_AD7467 },
-	{ "ad7477a", ID_AD7467 },
-	{ "ad7478", ID_AD7468 },
-	{ "ad7478a", ID_AD7468 },
-	{ "ad7495", ID_AD7495 },
-	{ "ad7910", ID_AD7467 },
-	{ "ad7920", ID_AD7466 },
-	{ "ad7940", ID_AD7940 },
-	{ "adc081s", ID_ADC081S },
-	{ "adc101s", ID_ADC101S },
-	{ "adc121s", ID_ADC121S },
-	{ "ads7866", ID_ADS7866 },
-	{ "ads7867", ID_ADS7867 },
-	{ "ads7868", ID_ADS7868 },
+	{ "ad7091", (kernel_ulong_t)&ad7091_chip_info },
+	{ "ad7091r", (kernel_ulong_t)&ad7091r_chip_info },
+	{ "ad7273", (kernel_ulong_t)&ad7273_chip_info },
+	{ "ad7274", (kernel_ulong_t)&ad7274_chip_info },
+	{ "ad7276", (kernel_ulong_t)&ad7276_chip_info },
+	{ "ad7277", (kernel_ulong_t)&ad7277_chip_info },
+	{ "ad7278", (kernel_ulong_t)&ad7278_chip_info },
+	{ "ad7466", (kernel_ulong_t)&ad7466_chip_info },
+	{ "ad7467", (kernel_ulong_t)&ad7467_chip_info },
+	{ "ad7468", (kernel_ulong_t)&ad7468_chip_info },
+	{ "ad7475", (kernel_ulong_t)&ad7475_chip_info },
+	{ "ad7476", (kernel_ulong_t)&ad7466_chip_info },
+	{ "ad7476a", (kernel_ulong_t)&ad7466_chip_info },
+	{ "ad7477", (kernel_ulong_t)&ad7467_chip_info },
+	{ "ad7477a", (kernel_ulong_t)&ad7467_chip_info },
+	{ "ad7478", (kernel_ulong_t)&ad7468_chip_info },
+	{ "ad7478a", (kernel_ulong_t)&ad7468_chip_info },
+	{ "ad7495", (kernel_ulong_t)&ad7495_chip_info },
+	{ "ad7910", (kernel_ulong_t)&ad7467_chip_info },
+	{ "ad7920", (kernel_ulong_t)&ad7466_chip_info },
+	{ "ad7940", (kernel_ulong_t)&ad7940_chip_info },
+	{ "adc081s", (kernel_ulong_t)&adc081s_chip_info },
+	{ "adc101s", (kernel_ulong_t)&adc101s_chip_info },
+	{ "adc121s", (kernel_ulong_t)&adc121s_chip_info },
+	{ "ads7866", (kernel_ulong_t)&ads7866_chip_info },
+	{ "ads7867", (kernel_ulong_t)&ads7867_chip_info },
+	{ "ads7868", (kernel_ulong_t)&ads7868_chip_info },
 	/*
 	 * The ROHM BU79100G is identical to the TI's ADS7866 from the software
 	 * point of view. The binding document mandates the ADS7866 to be
 	 * marked as a fallback for the BU79100G, but we still need the SPI ID
 	 * here to make the module loading work.
 	 */
-	{ "bu79100g", ID_ADS7866 },
-	{ "ltc2314-14", ID_LTC2314_14 },
+	{ "bu79100g", (kernel_ulong_t)&ads7866_chip_info },
+	{ "ltc2314-14", (kernel_ulong_t)&ltc2314_14_chip_info },
 	{ }
 };
 MODULE_DEVICE_TABLE(spi, ad7476_id);
-- 
2.50.1


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[PATCH v3 02/10] iio: adc: ad7476: Simplify scale handling

[Matti Vaittinen]

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The ad7476 driver supports variants with different amount of supply
regulators. On some variants there is only VCC, which is used as a
reference voltage. Others have separate VREF regulator, and some rely on
internal VREF. Some have both internal VREF and option to connect
external one.

The ad7476 driver reads the regulator voltage only when the user asks to
get the scale. This means the driver needs to do some dancing while
picking the correct reference regulator (or internal reference), and
store it for the later use.

According to the discussion [1] variable voltage references are rare,
making it hard to justify the added complexity for supporting those.

Drop the support for the variable voltage references and simplify things
by using the managed regulator get and enable interfaces.

Link: https://lore.kernel.org/linux-iio/20250331122247.05c6b09d@jic23-huawei/ #1
Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
Reviewed-by: Nuno Sá <nuno.sa@analog.com>

---
Revision history:
 v2 => :
 - No changes

 v1 => v2:
 - use link-tag

 This patch was originally sent as an RFC in 2 patch series:
 https://lore.kernel.org/all/cover.1754041258.git.mazziesaccount@gmail.com/
 Changes from the RFC:
 - Fix the faulty conversion from  uV to mV as pointed out by David.
---
 drivers/iio/adc/ad7476.c | 84 ++++++++++------------------------------
 1 file changed, 21 insertions(+), 63 deletions(-)

diff --git a/drivers/iio/adc/ad7476.c b/drivers/iio/adc/ad7476.c
index 9869526c1524..f117aafd8fad 100644
--- a/drivers/iio/adc/ad7476.c
+++ b/drivers/iio/adc/ad7476.c
@@ -39,10 +39,10 @@ struct ad7476_chip_info {
 struct ad7476_state {
 	struct spi_device		*spi;
 	const struct ad7476_chip_info	*chip_info;
-	struct regulator		*ref_reg;
 	struct gpio_desc		*convst_gpio;
 	struct spi_transfer		xfer;
 	struct spi_message		msg;
+	int				scale_mv;
 	/*
 	 * DMA (thus cache coherency maintenance) may require the
 	 * transfer buffers to live in their own cache lines.
@@ -111,7 +111,6 @@ static int ad7476_read_raw(struct iio_dev *indio_dev,
 {
 	int ret;
 	struct ad7476_state *st = iio_priv(indio_dev);
-	int scale_uv;
 
 	switch (m) {
 	case IIO_CHAN_INFO_RAW:
@@ -126,14 +125,7 @@ static int ad7476_read_raw(struct iio_dev *indio_dev,
 			GENMASK(st->chip_info->channel[0].scan_type.realbits - 1, 0);
 		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_SCALE:
-		if (st->ref_reg) {
-			scale_uv = regulator_get_voltage(st->ref_reg);
-			if (scale_uv < 0)
-				return scale_uv;
-		} else {
-			scale_uv = st->chip_info->int_vref_uv;
-		}
-		*val = scale_uv / 1000;
+		*val = st->scale_mv;
 		*val2 = chan->scan_type.realbits;
 		return IIO_VAL_FRACTIONAL_LOG2;
 	}
@@ -286,18 +278,10 @@ static const struct iio_info ad7476_info = {
 	.read_raw = &ad7476_read_raw,
 };
 
-static void ad7476_reg_disable(void *data)
-{
-	struct regulator *reg = data;
-
-	regulator_disable(reg);
-}
-
 static int ad7476_probe(struct spi_device *spi)
 {
 	struct ad7476_state *st;
 	struct iio_dev *indio_dev;
-	struct regulator *reg;
 	int ret;
 
 	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
@@ -310,58 +294,32 @@ static int ad7476_probe(struct spi_device *spi)
 	if (!st->chip_info)
 		return -ENODEV;
 
-	reg = devm_regulator_get(&spi->dev, "vcc");
-	if (IS_ERR(reg))
-		return PTR_ERR(reg);
-
-	ret = regulator_enable(reg);
-	if (ret)
-		return ret;
-
-	ret = devm_add_action_or_reset(&spi->dev, ad7476_reg_disable, reg);
-	if (ret)
-		return ret;
-
-	/* Either vcc or vref (below) as appropriate */
-	if (!st->chip_info->int_vref_uv)
-		st->ref_reg = reg;
+	/* Use VCC for reference voltage if vref / internal vref aren't used */
+	if (!st->chip_info->int_vref_uv && !st->chip_info->has_vref) {
+		ret = devm_regulator_get_enable_read_voltage(&spi->dev, "vcc");
+		if (ret < 0)
+			return ret;
+		st->scale_mv = ret / 1000;
+	} else {
+		ret = devm_regulator_get_enable(&spi->dev, "vcc");
+		if (ret < 0)
+			return ret;
+	}
 
 	if (st->chip_info->has_vref) {
-
-		/* If a device has an internal reference vref is optional */
-		if (st->chip_info->int_vref_uv) {
-			reg = devm_regulator_get_optional(&spi->dev, "vref");
-			if (IS_ERR(reg) && (PTR_ERR(reg) != -ENODEV))
-				return PTR_ERR(reg);
-		} else {
-			reg = devm_regulator_get(&spi->dev, "vref");
-			if (IS_ERR(reg))
-				return PTR_ERR(reg);
-		}
-
-		if (!IS_ERR(reg)) {
-			ret = regulator_enable(reg);
-			if (ret)
+		ret = devm_regulator_get_enable_read_voltage(&spi->dev, "vref");
+		if (ret < 0) {
+			/* Vref is optional if a device has an internal reference */
+			if (!st->chip_info->int_vref_uv || ret != -ENODEV)
 				return ret;
-
-			ret = devm_add_action_or_reset(&spi->dev,
-						       ad7476_reg_disable,
-						       reg);
-			if (ret)
-				return ret;
-			st->ref_reg = reg;
 		} else {
-			/*
-			 * Can only get here if device supports both internal
-			 * and external reference, but the regulator connected
-			 * to the external reference is not connected.
-			 * Set the reference regulator pointer to NULL to
-			 * indicate this.
-			 */
-			st->ref_reg = NULL;
+			st->scale_mv = ret / 1000;
 		}
 	}
 
+	if (!st->scale_mv)
+		st->scale_mv = st->chip_info->int_vref_uv / 1000;
+
 	if (st->chip_info->has_vdrive) {
 		ret = devm_regulator_get_enable(&spi->dev, "vdrive");
 		if (ret)
-- 
2.50.1


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[PATCH v3 03/10] iio: adc: ad7476: Use mV for internal reference

[Matti Vaittinen]

[-- Attachment #1: Type: text/plain, Size: 2814 bytes --]

The ad7476 supports some ICs with an internal reference voltage. For
those ICs the reference voltage has been hard-coded as micro volts, but
the value which is later used in code needs to be milli volts. This
results the need to divide hard coded voltage by 1000 before using it.

Simplify code by changing the hard-coded voltage to millivolts and by
dropping the division.

Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
Reviewed-by: Nuno Sá <nuno.sa@analog.com>
---
Revision history:
 v1 => :
 - No changes
---
 drivers/iio/adc/ad7476.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/iio/adc/ad7476.c b/drivers/iio/adc/ad7476.c
index f117aafd8fad..7b6d36999afc 100644
--- a/drivers/iio/adc/ad7476.c
+++ b/drivers/iio/adc/ad7476.c
@@ -27,7 +27,7 @@
 struct ad7476_state;
 
 struct ad7476_chip_info {
-	unsigned int			int_vref_uv;
+	unsigned int			int_vref_mv;
 	struct iio_chan_spec		channel[2];
 	/* channels used when convst gpio is defined */
 	struct iio_chan_spec		convst_channel[2];
@@ -172,7 +172,7 @@ static const struct ad7476_chip_info ad7091r_chip_info = {
 	.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
 	.convst_channel[0] = AD7091R_CONVST_CHAN(12),
 	.convst_channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
-	.int_vref_uv = 2500000,
+	.int_vref_mv = 2500,
 	.has_vref = true,
 	.reset = ad7091_reset,
 };
@@ -229,7 +229,7 @@ static const struct ad7476_chip_info ad7475_chip_info = {
 static const struct ad7476_chip_info ad7495_chip_info = {
 	.channel[0] = AD7476_CHAN(12),
 	.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
-	.int_vref_uv = 2500000,
+	.int_vref_mv = 2500,
 	.has_vdrive = true,
 };
 
@@ -295,7 +295,7 @@ static int ad7476_probe(struct spi_device *spi)
 		return -ENODEV;
 
 	/* Use VCC for reference voltage if vref / internal vref aren't used */
-	if (!st->chip_info->int_vref_uv && !st->chip_info->has_vref) {
+	if (!st->chip_info->int_vref_mv && !st->chip_info->has_vref) {
 		ret = devm_regulator_get_enable_read_voltage(&spi->dev, "vcc");
 		if (ret < 0)
 			return ret;
@@ -310,7 +310,7 @@ static int ad7476_probe(struct spi_device *spi)
 		ret = devm_regulator_get_enable_read_voltage(&spi->dev, "vref");
 		if (ret < 0) {
 			/* Vref is optional if a device has an internal reference */
-			if (!st->chip_info->int_vref_uv || ret != -ENODEV)
+			if (!st->chip_info->int_vref_mv || ret != -ENODEV)
 				return ret;
 		} else {
 			st->scale_mv = ret / 1000;
@@ -318,7 +318,7 @@ static int ad7476_probe(struct spi_device *spi)
 	}
 
 	if (!st->scale_mv)
-		st->scale_mv = st->chip_info->int_vref_uv / 1000;
+		st->scale_mv = st->chip_info->int_vref_mv;
 
 	if (st->chip_info->has_vdrive) {
 		ret = devm_regulator_get_enable(&spi->dev, "vdrive");
-- 
2.50.1


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[PATCH v3 04/10] iio: adc: ad7476: Use correct channel for bit info

[Matti Vaittinen]

[-- Attachment #1: Type: text/plain, Size: 1844 bytes --]

The ad7476 supports ADCs which use separate GPIO for starting the
conversion. For such devices, the driver uses different channel
information if the GPIO is found. The bit information is still always
used from the original (non 'convstart') channels.

This has not been causing problems because the bit information for the
'convstart' -channel and the 'normal' -channel is identical. It,
however, will cause issues if an IC has different characteristics for an
'convstart' -channel and regular channel. Furthermore, this will cause
problems if a device always requires the convstart GPIO and thus only
defines the convstart channel.

Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
Reviewed-by: Nuno Sá <nuno.sa@analog.com>
---
Revision history:
 v1 => :
 - No changes
---
 drivers/iio/adc/ad7476.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/adc/ad7476.c b/drivers/iio/adc/ad7476.c
index 7b6d36999afc..fc701267358e 100644
--- a/drivers/iio/adc/ad7476.c
+++ b/drivers/iio/adc/ad7476.c
@@ -121,8 +121,8 @@ static int ad7476_read_raw(struct iio_dev *indio_dev,
 
 		if (ret < 0)
 			return ret;
-		*val = (ret >> st->chip_info->channel[0].scan_type.shift) &
-			GENMASK(st->chip_info->channel[0].scan_type.realbits - 1, 0);
+		*val = (ret >> chan->scan_type.shift) &
+			GENMASK(chan->scan_type.realbits - 1, 0);
 		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_SCALE:
 		*val = st->scale_mv;
@@ -345,7 +345,7 @@ static int ad7476_probe(struct spi_device *spi)
 	/* Setup default message */
 
 	st->xfer.rx_buf = &st->data;
-	st->xfer.len = st->chip_info->channel[0].scan_type.storagebits / 8;
+	st->xfer.len = indio_dev->channels[0].scan_type.storagebits / 8;
 
 	spi_message_init(&st->msg);
 	spi_message_add_tail(&st->xfer, &st->msg);
-- 
2.50.1


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[PATCH v3 05/10] iio: adc: ad7476: use *_cansleep GPIO APIs

[Matti Vaittinen]

[-- Attachment #1: Type: text/plain, Size: 1460 bytes --]

The ad7476 driver supports ADCs which require a GPIO pin to be used to
start conversion. The GPIO line status seems to be always toggled from
a process context, either from the user-initiated "raw-read conversion",
or from a threaded IRQ handler. Furthermore, these ICs are connected via
SPI bus, which is usually implemented in a way that the access to the
device can sleep. The GPIO here is toggled from the same context which
is reading the results over SPI.

Thus it seems very likely these GPIOs are toggled from a context which
can sleep.

Swap the gpiod_set_value() to gpiod_set_value_cansleep() accordinlgy.

Suggested-by: Nuno Sá <noname.nuno@gmail.com>
Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>

---
Revision history:
 v2 => v3:
 - New patch
---
 drivers/iio/adc/ad7476.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/adc/ad7476.c b/drivers/iio/adc/ad7476.c
index fc701267358e..1445f0f599d9 100644
--- a/drivers/iio/adc/ad7476.c
+++ b/drivers/iio/adc/ad7476.c
@@ -57,9 +57,9 @@ static void ad7091_convst(struct ad7476_state *st)
 	if (!st->convst_gpio)
 		return;
 
-	gpiod_set_value(st->convst_gpio, 0);
+	gpiod_set_value_cansleep(st->convst_gpio, 0);
 	udelay(1); /* CONVST pulse width: 10 ns min */
-	gpiod_set_value(st->convst_gpio, 1);
+	gpiod_set_value_cansleep(st->convst_gpio, 1);
 	udelay(1); /* Conversion time: 650 ns max */
 }
 
-- 
2.50.1


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Re: [PATCH v3 05/10] iio: adc: ad7476: use *_cansleep GPIO APIs

[Nuno Sá]

On Fri, Aug 08, 2025 at 11:52:13AM +0300, Matti Vaittinen wrote:
> The ad7476 driver supports ADCs which require a GPIO pin to be used to
> start conversion. The GPIO line status seems to be always toggled from
> a process context, either from the user-initiated "raw-read conversion",
> or from a threaded IRQ handler. Furthermore, these ICs are connected via
> SPI bus, which is usually implemented in a way that the access to the
> device can sleep. The GPIO here is toggled from the same context which
> is reading the results over SPI.
> 
> Thus it seems very likely these GPIOs are toggled from a context which
> can sleep.
> 
> Swap the gpiod_set_value() to gpiod_set_value_cansleep() accordinlgy.
> 
> Suggested-by: Nuno Sá <noname.nuno@gmail.com>
> Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
> 
> ---
> Revision history:
>  v2 => v3:
>  - New patch
> ---

Reviewed-by: Nuno Sá <nuno.sa@analog.com>

>  drivers/iio/adc/ad7476.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iio/adc/ad7476.c b/drivers/iio/adc/ad7476.c
> index fc701267358e..1445f0f599d9 100644
> --- a/drivers/iio/adc/ad7476.c
> +++ b/drivers/iio/adc/ad7476.c
> @@ -57,9 +57,9 @@ static void ad7091_convst(struct ad7476_state *st)
>  	if (!st->convst_gpio)
>  		return;
>  
> -	gpiod_set_value(st->convst_gpio, 0);
> +	gpiod_set_value_cansleep(st->convst_gpio, 0);
>  	udelay(1); /* CONVST pulse width: 10 ns min */
> -	gpiod_set_value(st->convst_gpio, 1);
> +	gpiod_set_value_cansleep(st->convst_gpio, 1);
>  	udelay(1); /* Conversion time: 650 ns max */
>  }
>  
> -- 
> 2.50.1
> 

[PATCH v3 06/10] iio: adc: ad7476: Drop convstart chan_spec

[Matti Vaittinen]

[-- Attachment #1: Type: text/plain, Size: 4656 bytes --]

The ad7476 driver defines separate chan_spec structures for operation
with and without convstart GPIO. At quick glance this may seem as if the
driver did provide more than 1 data-channel to users - one for the
regular data, other for the data obtained with the convstart GPIO.

The only difference between the 'convstart' and 'non convstart'
-channels is presence / absence of the BIT(IIO_CHAN_INFO_RAW) in
channel's flags.

We can drop the convstart channel spec, and related convstart macro, by
allocating a mutable per driver instance channel spec and adding the flag
in probe if needed. This will simplify the driver with the cost of added
memory consumption.

Assuming there aren't systems with very many ADCs and very few
resources, this tradeoff seems worth making.

Simplify the driver by dropping the 'convstart' channel spec and
allocating the channel spec for each driver instance.

Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>

---
Revision history:
 v2 => v3:
 - Use __set_bit() instead of |=
 - Swicth BUILD_BUG_ON to static_assert
 - Clarify a comment
 - Improve commit message

 v1 => v2:
 - New patch
---
 drivers/iio/adc/ad7476.c | 31 +++++++++++++++++++------------
 1 file changed, 19 insertions(+), 12 deletions(-)

diff --git a/drivers/iio/adc/ad7476.c b/drivers/iio/adc/ad7476.c
index 1445f0f599d9..ad9e629f0cbd 100644
--- a/drivers/iio/adc/ad7476.c
+++ b/drivers/iio/adc/ad7476.c
@@ -6,6 +6,7 @@
  * Copyright 2010 Analog Devices Inc.
  */
 
+#include <linux/bitops.h>
 #include <linux/device.h>
 #include <linux/kernel.h>
 #include <linux/slab.h>
@@ -29,8 +30,6 @@ struct ad7476_state;
 struct ad7476_chip_info {
 	unsigned int			int_vref_mv;
 	struct iio_chan_spec		channel[2];
-	/* channels used when convst gpio is defined */
-	struct iio_chan_spec		convst_channel[2];
 	void (*reset)(struct ad7476_state *);
 	bool				has_vref;
 	bool				has_vdrive;
@@ -42,6 +41,7 @@ struct ad7476_state {
 	struct gpio_desc		*convst_gpio;
 	struct spi_transfer		xfer;
 	struct spi_message		msg;
+	struct iio_chan_spec		channel[2];
 	int				scale_mv;
 	/*
 	 * DMA (thus cache coherency maintenance) may require the
@@ -154,24 +154,18 @@ static int ad7476_read_raw(struct iio_dev *indio_dev,
 #define AD7940_CHAN(bits) _AD7476_CHAN((bits), 15 - (bits), \
 		BIT(IIO_CHAN_INFO_RAW))
 #define AD7091R_CHAN(bits) _AD7476_CHAN((bits), 16 - (bits), 0)
-#define AD7091R_CONVST_CHAN(bits) _AD7476_CHAN((bits), 16 - (bits), \
-		BIT(IIO_CHAN_INFO_RAW))
 #define ADS786X_CHAN(bits) _AD7476_CHAN((bits), 12 - (bits), \
 		BIT(IIO_CHAN_INFO_RAW))
 
 static const struct ad7476_chip_info ad7091_chip_info = {
 	.channel[0] = AD7091R_CHAN(12),
 	.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
-	.convst_channel[0] = AD7091R_CONVST_CHAN(12),
-	.convst_channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
 	.reset = ad7091_reset,
 };
 
 static const struct ad7476_chip_info ad7091r_chip_info = {
 	.channel[0] = AD7091R_CHAN(12),
 	.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
-	.convst_channel[0] = AD7091R_CONVST_CHAN(12),
-	.convst_channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
 	.int_vref_mv = 2500,
 	.has_vref = true,
 	.reset = ad7091_reset,
@@ -282,6 +276,7 @@ static int ad7476_probe(struct spi_device *spi)
 {
 	struct ad7476_state *st;
 	struct iio_dev *indio_dev;
+	unsigned int i;
 	int ret;
 
 	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
@@ -332,16 +327,28 @@ static int ad7476_probe(struct spi_device *spi)
 	if (IS_ERR(st->convst_gpio))
 		return PTR_ERR(st->convst_gpio);
 
+	/*
+	 * This will never happen. Unless someone changes the channel specs
+	 * in this driver. And if someone does, without changing the loop
+	 * below, then we'd better immediately produce a big fat error, before
+	 * the change proceeds from that developer's table.
+	 */
+	static_assert(ARRAY_SIZE(st->channel) == ARRAY_SIZE(st->chip_info->channel));
+	for (i = 0; i < ARRAY_SIZE(st->channel); i++) {
+		st->channel[i] = st->chip_info->channel[i];
+		if (st->convst_gpio)
+			__set_bit(IIO_CHAN_INFO_RAW,
+				  &st->channel[i].info_mask_separate);
+	}
+
 	st->spi = spi;
 
 	indio_dev->name = spi_get_device_id(spi)->name;
 	indio_dev->modes = INDIO_DIRECT_MODE;
-	indio_dev->channels = st->chip_info->channel;
-	indio_dev->num_channels = 2;
+	indio_dev->channels = st->channel;
+	indio_dev->num_channels = ARRAY_SIZE(st->channel);
 	indio_dev->info = &ad7476_info;
 
-	if (st->convst_gpio)
-		indio_dev->channels = st->chip_info->convst_channel;
 	/* Setup default message */
 
 	st->xfer.rx_buf = &st->data;
-- 
2.50.1


[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]

Re: [PATCH v3 06/10] iio: adc: ad7476: Drop convstart chan_spec

[Nuno Sá]

On Fri, Aug 08, 2025 at 11:53:29AM +0300, Matti Vaittinen wrote:
> The ad7476 driver defines separate chan_spec structures for operation
> with and without convstart GPIO. At quick glance this may seem as if the
> driver did provide more than 1 data-channel to users - one for the
> regular data, other for the data obtained with the convstart GPIO.
> 
> The only difference between the 'convstart' and 'non convstart'
> -channels is presence / absence of the BIT(IIO_CHAN_INFO_RAW) in
> channel's flags.
> 
> We can drop the convstart channel spec, and related convstart macro, by
> allocating a mutable per driver instance channel spec and adding the flag
> in probe if needed. This will simplify the driver with the cost of added
> memory consumption.
> 
> Assuming there aren't systems with very many ADCs and very few
> resources, this tradeoff seems worth making.
> 
> Simplify the driver by dropping the 'convstart' channel spec and
> allocating the channel spec for each driver instance.
> 
> Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
> 
> ---
> Revision history:
>  v2 => v3:
>  - Use __set_bit() instead of |=
>  - Swicth BUILD_BUG_ON to static_assert
>  - Clarify a comment
>  - Improve commit message
> 
>  v1 => v2:
>  - New patch
> ---

Reviewed-by: Nuno Sá <nuno.sa@analog.com>

>  drivers/iio/adc/ad7476.c | 31 +++++++++++++++++++------------
>  1 file changed, 19 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/iio/adc/ad7476.c b/drivers/iio/adc/ad7476.c
> index 1445f0f599d9..ad9e629f0cbd 100644
> --- a/drivers/iio/adc/ad7476.c
> +++ b/drivers/iio/adc/ad7476.c
> @@ -6,6 +6,7 @@
>   * Copyright 2010 Analog Devices Inc.
>   */
>  
> +#include <linux/bitops.h>
>  #include <linux/device.h>
>  #include <linux/kernel.h>
>  #include <linux/slab.h>
> @@ -29,8 +30,6 @@ struct ad7476_state;
>  struct ad7476_chip_info {
>  	unsigned int			int_vref_mv;
>  	struct iio_chan_spec		channel[2];
> -	/* channels used when convst gpio is defined */
> -	struct iio_chan_spec		convst_channel[2];
>  	void (*reset)(struct ad7476_state *);
>  	bool				has_vref;
>  	bool				has_vdrive;
> @@ -42,6 +41,7 @@ struct ad7476_state {
>  	struct gpio_desc		*convst_gpio;
>  	struct spi_transfer		xfer;
>  	struct spi_message		msg;
> +	struct iio_chan_spec		channel[2];
>  	int				scale_mv;
>  	/*
>  	 * DMA (thus cache coherency maintenance) may require the
> @@ -154,24 +154,18 @@ static int ad7476_read_raw(struct iio_dev *indio_dev,
>  #define AD7940_CHAN(bits) _AD7476_CHAN((bits), 15 - (bits), \
>  		BIT(IIO_CHAN_INFO_RAW))
>  #define AD7091R_CHAN(bits) _AD7476_CHAN((bits), 16 - (bits), 0)
> -#define AD7091R_CONVST_CHAN(bits) _AD7476_CHAN((bits), 16 - (bits), \
> -		BIT(IIO_CHAN_INFO_RAW))
>  #define ADS786X_CHAN(bits) _AD7476_CHAN((bits), 12 - (bits), \
>  		BIT(IIO_CHAN_INFO_RAW))
>  
>  static const struct ad7476_chip_info ad7091_chip_info = {
>  	.channel[0] = AD7091R_CHAN(12),
>  	.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
> -	.convst_channel[0] = AD7091R_CONVST_CHAN(12),
> -	.convst_channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
>  	.reset = ad7091_reset,
>  };
>  
>  static const struct ad7476_chip_info ad7091r_chip_info = {
>  	.channel[0] = AD7091R_CHAN(12),
>  	.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
> -	.convst_channel[0] = AD7091R_CONVST_CHAN(12),
> -	.convst_channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
>  	.int_vref_mv = 2500,
>  	.has_vref = true,
>  	.reset = ad7091_reset,
> @@ -282,6 +276,7 @@ static int ad7476_probe(struct spi_device *spi)
>  {
>  	struct ad7476_state *st;
>  	struct iio_dev *indio_dev;
> +	unsigned int i;
>  	int ret;
>  
>  	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
> @@ -332,16 +327,28 @@ static int ad7476_probe(struct spi_device *spi)
>  	if (IS_ERR(st->convst_gpio))
>  		return PTR_ERR(st->convst_gpio);
>  
> +	/*
> +	 * This will never happen. Unless someone changes the channel specs
> +	 * in this driver. And if someone does, without changing the loop
> +	 * below, then we'd better immediately produce a big fat error, before
> +	 * the change proceeds from that developer's table.
> +	 */
> +	static_assert(ARRAY_SIZE(st->channel) == ARRAY_SIZE(st->chip_info->channel));
> +	for (i = 0; i < ARRAY_SIZE(st->channel); i++) {
> +		st->channel[i] = st->chip_info->channel[i];
> +		if (st->convst_gpio)
> +			__set_bit(IIO_CHAN_INFO_RAW,
> +				  &st->channel[i].info_mask_separate);
> +	}
> +
>  	st->spi = spi;
>  
>  	indio_dev->name = spi_get_device_id(spi)->name;
>  	indio_dev->modes = INDIO_DIRECT_MODE;
> -	indio_dev->channels = st->chip_info->channel;
> -	indio_dev->num_channels = 2;
> +	indio_dev->channels = st->channel;
> +	indio_dev->num_channels = ARRAY_SIZE(st->channel);
>  	indio_dev->info = &ad7476_info;
>  
> -	if (st->convst_gpio)
> -		indio_dev->channels = st->chip_info->convst_channel;
>  	/* Setup default message */
>  
>  	st->xfer.rx_buf = &st->data;
> -- 
> 2.50.1
> 

[PATCH v3 07/10] iio: adc: ad7476: Conditionally call convstart

[Matti Vaittinen]

[-- Attachment #1: Type: text/plain, Size: 3107 bytes --]

The ad7476 supports two IC variants which may have a 'convstart' -GPIO
for starting the conversion. Currently the driver calls a function which
tries to access the GPIO for all of the IC variants, whether they
support 'convstart' or not. This is not an error because this function
returns early if GPIO information is not populated.

We can do a tad better by calling this function only for the ICs which
have the 'convstart' by providing a function pointer to the convstart
function from the chip_info structure, and calling this function only
for the ICs which have the function pointer set.

This does also allow to support ICs which require different convstart
handling than the currently supported ICs.

Call convstart function only on the ICs which can support it and allow
IC-specific convstart functions for the ICs which require different
handling.

Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
---
Revision history:
 v2 => v3:
 - Use indirect call to convstart (via function pointer) also from the
   ad7476_scan_direct().
 - Adapt to the change which returned the chip_info pointer back to the
   driver's state structure.

 v1 => v2:
 - Adapt to the change which removed the chip_info pointer from the
  driver's state structure.

The follow-up patch adding support for the ROHM BD79105 will bring
different 'convstart' functions in use. The IC specific pointer will
also prepare the way for this.
---
 drivers/iio/adc/ad7476.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/adc/ad7476.c b/drivers/iio/adc/ad7476.c
index ad9e629f0cbd..6cb2cbeafbd3 100644
--- a/drivers/iio/adc/ad7476.c
+++ b/drivers/iio/adc/ad7476.c
@@ -31,6 +31,7 @@ struct ad7476_chip_info {
 	unsigned int			int_vref_mv;
 	struct iio_chan_spec		channel[2];
 	void (*reset)(struct ad7476_state *);
+	void (*conversion_pre_op)(struct ad7476_state *st);
 	bool				has_vref;
 	bool				has_vdrive;
 };
@@ -70,7 +71,8 @@ static irqreturn_t ad7476_trigger_handler(int irq, void  *p)
 	struct ad7476_state *st = iio_priv(indio_dev);
 	int b_sent;
 
-	ad7091_convst(st);
+	if (st->chip_info->conversion_pre_op)
+		st->chip_info->conversion_pre_op(st);
 
 	b_sent = spi_sync(st->spi, &st->msg);
 	if (b_sent < 0)
@@ -94,7 +96,8 @@ static int ad7476_scan_direct(struct ad7476_state *st)
 {
 	int ret;
 
-	ad7091_convst(st);
+	if (st->chip_info->conversion_pre_op)
+		st->chip_info->conversion_pre_op(st);
 
 	ret = spi_sync(st->spi, &st->msg);
 	if (ret)
@@ -160,12 +163,14 @@ static int ad7476_read_raw(struct iio_dev *indio_dev,
 static const struct ad7476_chip_info ad7091_chip_info = {
 	.channel[0] = AD7091R_CHAN(12),
 	.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
+	.conversion_pre_op = ad7091_convst,
 	.reset = ad7091_reset,
 };
 
 static const struct ad7476_chip_info ad7091r_chip_info = {
 	.channel[0] = AD7091R_CHAN(12),
 	.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
+	.conversion_pre_op = ad7091_convst,
 	.int_vref_mv = 2500,
 	.has_vref = true,
 	.reset = ad7091_reset,
-- 
2.50.1


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Re: [PATCH v3 07/10] iio: adc: ad7476: Conditionally call convstart

[Nuno Sá]

On Fri, Aug 08, 2025 at 11:54:09AM +0300, Matti Vaittinen wrote:
> The ad7476 supports two IC variants which may have a 'convstart' -GPIO
> for starting the conversion. Currently the driver calls a function which
> tries to access the GPIO for all of the IC variants, whether they
> support 'convstart' or not. This is not an error because this function
> returns early if GPIO information is not populated.
> 
> We can do a tad better by calling this function only for the ICs which
> have the 'convstart' by providing a function pointer to the convstart
> function from the chip_info structure, and calling this function only
> for the ICs which have the function pointer set.
> 
> This does also allow to support ICs which require different convstart
> handling than the currently supported ICs.
> 
> Call convstart function only on the ICs which can support it and allow
> IC-specific convstart functions for the ICs which require different
> handling.
> 
> Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
> ---
> Revision history:
>  v2 => v3:
>  - Use indirect call to convstart (via function pointer) also from the
>    ad7476_scan_direct().
>  - Adapt to the change which returned the chip_info pointer back to the
>    driver's state structure.
> 
>  v1 => v2:
>  - Adapt to the change which removed the chip_info pointer from the
>   driver's state structure.
> 
> The follow-up patch adding support for the ROHM BD79105 will bring
> different 'convstart' functions in use. The IC specific pointer will
> also prepare the way for this.
> ---

Reviewed-by: Nuno Sá <nuno.sa@analog.com>

>  drivers/iio/adc/ad7476.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iio/adc/ad7476.c b/drivers/iio/adc/ad7476.c
> index ad9e629f0cbd..6cb2cbeafbd3 100644
> --- a/drivers/iio/adc/ad7476.c
> +++ b/drivers/iio/adc/ad7476.c
> @@ -31,6 +31,7 @@ struct ad7476_chip_info {
>  	unsigned int			int_vref_mv;
>  	struct iio_chan_spec		channel[2];
>  	void (*reset)(struct ad7476_state *);
> +	void (*conversion_pre_op)(struct ad7476_state *st);
>  	bool				has_vref;
>  	bool				has_vdrive;
>  };
> @@ -70,7 +71,8 @@ static irqreturn_t ad7476_trigger_handler(int irq, void  *p)
>  	struct ad7476_state *st = iio_priv(indio_dev);
>  	int b_sent;
>  
> -	ad7091_convst(st);
> +	if (st->chip_info->conversion_pre_op)
> +		st->chip_info->conversion_pre_op(st);
>  
>  	b_sent = spi_sync(st->spi, &st->msg);
>  	if (b_sent < 0)
> @@ -94,7 +96,8 @@ static int ad7476_scan_direct(struct ad7476_state *st)
>  {
>  	int ret;
>  
> -	ad7091_convst(st);
> +	if (st->chip_info->conversion_pre_op)
> +		st->chip_info->conversion_pre_op(st);
>  
>  	ret = spi_sync(st->spi, &st->msg);
>  	if (ret)
> @@ -160,12 +163,14 @@ static int ad7476_read_raw(struct iio_dev *indio_dev,
>  static const struct ad7476_chip_info ad7091_chip_info = {
>  	.channel[0] = AD7091R_CHAN(12),
>  	.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
> +	.conversion_pre_op = ad7091_convst,
>  	.reset = ad7091_reset,
>  };
>  
>  static const struct ad7476_chip_info ad7091r_chip_info = {
>  	.channel[0] = AD7091R_CHAN(12),
>  	.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
> +	.conversion_pre_op = ad7091_convst,
>  	.int_vref_mv = 2500,
>  	.has_vref = true,
>  	.reset = ad7091_reset,
> -- 
> 2.50.1
> 

[PATCH v3 08/10] dt-bindings: iio: adc: ad7476: Add ROHM bd79105

[Matti Vaittinen]

[-- Attachment #1: Type: text/plain, Size: 4430 bytes --]

The ROHM BD79105 is a simple, 16-bit, 1-channel ADC with a 'CONVSTART'
pin used to start the ADC conversion. Other than the 'CONVSTART', there
are 3 supply pins (one used as a reference), analog inputs, ground and
communication pins. It's worth noting that the pin somewhat confusingly
labeled as 'DIN', is a pin which should be used as a chip-select. The IC
does not have any writable registers.

The device is designed so that the output pin can, in addition to
outputting the data, be used as a 'data-ready'-IRQ. This, however, would
require the IRQ to be masked from host side for the duration of the data
reads - and it wouldn't also work when the SPI is shared. (As access to
the other SPI devices would cause data line changes to be detected as
IRQs - and the BD79105 provides no means to detect if it has generated
an IRQ).

Hence the device-tree does not contain any IRQ properties.

Add a compatible for the bd79105.

Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>

---
Revision history:
 v2 => :
 - No changes

 v1 => v2:
 - BD79105 can provide data-ready IRQ (or GPIO) via DOUT-pin.
---
 .../bindings/iio/adc/adi,ad7476.yaml          | 54 +++++++++++++++++++
 1 file changed, 54 insertions(+)

diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad7476.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad7476.yaml
index d0cb32f136e5..c411a7467651 100644
--- a/Documentation/devicetree/bindings/iio/adc/adi,ad7476.yaml
+++ b/Documentation/devicetree/bindings/iio/adc/adi,ad7476.yaml
@@ -41,6 +41,7 @@ properties:
               - adi,ad7910
               - adi,ad7920
               - adi,ad7940
+              - rohm,bd79105
               - ti,adc081s
               - ti,adc101s
               - ti,adc121s
@@ -55,6 +56,11 @@ properties:
   reg:
     maxItems: 1
 
+  interrupts:
+    description:
+      The data-ready interrupt. Provided via DOUT pin.
+    maxItems: 1
+
   vcc-supply:
     description:
       Main powersupply voltage for the chips, sometimes referred to as VDD on
@@ -75,6 +81,10 @@ properties:
     description: A GPIO used to trigger the start of a conversion
     maxItems: 1
 
+  rdy-gpios:
+    description: A GPIO for detecting the data-ready.
+    maxItems: 1
+
 required:
   - compatible
   - reg
@@ -82,6 +92,20 @@ required:
 allOf:
   - $ref: /schemas/spi/spi-peripheral-props.yaml#
 
+# Devices with an IRQ
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - rohm,bd79105
+    then:
+      properties:
+        interrupts: true
+    else:
+      properties:
+        interrupts: false
+
   # Devices where reference is vcc
   - if:
       properties:
@@ -115,6 +139,7 @@ allOf:
               - adi,ad7274
               - adi,ad7475
               - lltc,ltc2314-14
+              - rohm,bd79105
     then:
       properties:
         vref-supply: true
@@ -131,6 +156,7 @@ allOf:
               - adi,ad7274
               - adi,ad7475
               - lltc,ltc2314-14
+              - rohm,bd79105
     then:
       required:
         - vref-supply
@@ -141,12 +167,28 @@ allOf:
             enum:
               - adi,ad7475
               - adi,ad7495
+              - rohm,bd79105
     then:
       properties:
         vdrive-supply: true
     else:
       properties:
         vdrive-supply: false
+
+  # Devices which support polling the data-ready via GPIO
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - rohm,bd79105
+    then:
+      properties:
+        rdy-gpios: true
+    else:
+      properties:
+        rdy-gpios: false
+
   - if:
       properties:
         compatible:
@@ -154,6 +196,7 @@ allOf:
             enum:
               - adi,ad7091
               - adi,ad7091r
+              - rohm,bd79105
     then:
       properties:
         adi,conversion-start-gpios: true
@@ -161,6 +204,17 @@ allOf:
       properties:
         adi,conversion-start-gpios: false
 
+  # Devices with a convstart GPIO where it is not optional
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - rohm,bd79105
+    then:
+      required:
+        - adi,conversion-start-gpios
+
 unevaluatedProperties: false
 
 examples:
-- 
2.50.1


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Re: [PATCH v3 08/10] dt-bindings: iio: adc: ad7476: Add ROHM bd79105

[Jonathan Cameron]

On Fri, 8 Aug 2025 11:54:25 +0300
Matti Vaittinen <mazziesaccount@gmail.com> wrote:

> The ROHM BD79105 is a simple, 16-bit, 1-channel ADC with a 'CONVSTART'
> pin used to start the ADC conversion. Other than the 'CONVSTART', there
> are 3 supply pins (one used as a reference), analog inputs, ground and
> communication pins. It's worth noting that the pin somewhat confusingly
> labeled as 'DIN', is a pin which should be used as a chip-select. The IC
> does not have any writable registers.
> 
> The device is designed so that the output pin can, in addition to
> outputting the data, be used as a 'data-ready'-IRQ. This, however, would
> require the IRQ to be masked from host side for the duration of the data
> reads - and it wouldn't also work when the SPI is shared. (As access to
> the other SPI devices would cause data line changes to be detected as
> IRQs - and the BD79105 provides no means to detect if it has generated
> an IRQ).
> 
> Hence the device-tree does not contain any IRQ properties.

Commit message needs an update as it now allows for IRQ properties.


> 
> Add a compatible for the bd79105.
> 
> Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
> 
> ---
> Revision history:
>  v2 => :
>  - No changes
> 
>  v1 => v2:
>  - BD79105 can provide data-ready IRQ (or GPIO) via DOUT-pin.
> ---
>  .../bindings/iio/adc/adi,ad7476.yaml          | 54 +++++++++++++++++++
>  1 file changed, 54 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad7476.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad7476.yaml
> index d0cb32f136e5..c411a7467651 100644
> --- a/Documentation/devicetree/bindings/iio/adc/adi,ad7476.yaml
> +++ b/Documentation/devicetree/bindings/iio/adc/adi,ad7476.yaml
> @@ -41,6 +41,7 @@ properties:
>                - adi,ad7910
>                - adi,ad7920
>                - adi,ad7940
> +              - rohm,bd79105
>                - ti,adc081s
>                - ti,adc101s
>                - ti,adc121s
> @@ -55,6 +56,11 @@ properties:
>    reg:
>      maxItems: 1
>  
> +  interrupts:
> +    description:
> +      The data-ready interrupt. Provided via DOUT pin.
> +    maxItems: 1
> +
>    vcc-supply:
>      description:
>        Main powersupply voltage for the chips, sometimes referred to as VDD on
> @@ -75,6 +81,10 @@ properties:
>      description: A GPIO used to trigger the start of a conversion
>      maxItems: 1
>  
> +  rdy-gpios:
> +    description: A GPIO for detecting the data-ready.
> +    maxItems: 1
> +
>  required:
>    - compatible
>    - reg
> @@ -82,6 +92,20 @@ required:
>  allOf:
>    - $ref: /schemas/spi/spi-peripheral-props.yaml#
>  
> +# Devices with an IRQ
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            enum:
> +              - rohm,bd79105
> +    then:
> +      properties:
> +        interrupts: true

It's been a while since I wrote one of these, but do we need
the true bit given we have already specified the interrupts
property.  I think we only need to do the setting to false
on an if: not: 

> +    else:
> +      properties:
> +        interrupts: false
> +
>    # Devices where reference is vcc
>    - if:
>        properties:
> @@ -115,6 +139,7 @@ allOf:
>                - adi,ad7274
>                - adi,ad7475
>                - lltc,ltc2314-14
> +              - rohm,bd79105
>      then:
>        properties:
>          vref-supply: true
> @@ -131,6 +156,7 @@ allOf:
>                - adi,ad7274
>                - adi,ad7475
>                - lltc,ltc2314-14
> +              - rohm,bd79105
>      then:
>        required:
>          - vref-supply
> @@ -141,12 +167,28 @@ allOf:
>              enum:
>                - adi,ad7475
>                - adi,ad7495
> +              - rohm,bd79105
>      then:
>        properties:
>          vdrive-supply: true
>      else:
>        properties:
>          vdrive-supply: false
> +
> +  # Devices which support polling the data-ready via GPIO
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            enum:
> +              - rohm,bd79105
> +    then:
> +      properties:
> +        rdy-gpios: true

As above, I believe we only need the not case.

> +    else:
> +      properties:
> +        rdy-gpios: false
> +
>    - if:
>        properties:
>          compatible:
> @@ -154,6 +196,7 @@ allOf:
>              enum:
>                - adi,ad7091
>                - adi,ad7091r
> +              - rohm,bd79105
>      then:
>        properties:
>          adi,conversion-start-gpios: true
> @@ -161,6 +204,17 @@ allOf:
>        properties:
>          adi,conversion-start-gpios: false
>  
> +  # Devices with a convstart GPIO where it is not optional
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            enum:
> +              - rohm,bd79105
> +    then:
> +      required:
> +        - adi,conversion-start-gpios
> +
>  unevaluatedProperties: false
>  
>  examples:

Re: [PATCH v3 08/10] dt-bindings: iio: adc: ad7476: Add ROHM bd79105

[Matti Vaittinen]

On 09/08/2025 22:21, Jonathan Cameron wrote:
> On Fri, 8 Aug 2025 11:54:25 +0300
> Matti Vaittinen <mazziesaccount@gmail.com> wrote:
> 
>> The ROHM BD79105 is a simple, 16-bit, 1-channel ADC with a 'CONVSTART'
>> pin used to start the ADC conversion. Other than the 'CONVSTART', there
>> are 3 supply pins (one used as a reference), analog inputs, ground and
>> communication pins. It's worth noting that the pin somewhat confusingly
>> labeled as 'DIN', is a pin which should be used as a chip-select. The IC
>> does not have any writable registers.
>>
>> The device is designed so that the output pin can, in addition to
>> outputting the data, be used as a 'data-ready'-IRQ. This, however, would
>> require the IRQ to be masked from host side for the duration of the data
>> reads - and it wouldn't also work when the SPI is shared. (As access to
>> the other SPI devices would cause data line changes to be detected as
>> IRQs - and the BD79105 provides no means to detect if it has generated
>> an IRQ).
>>
>> Hence the device-tree does not contain any IRQ properties.
> 
> Commit message needs an update as it now allows for IRQ properties.

Ah, true. Thanks :)

> 
>>
>> Add a compatible for the bd79105.
>>
>> Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
>>
>> ---
>> Revision history:
>>   v2 => :
>>   - No changes
>>
>>   v1 => v2:
>>   - BD79105 can provide data-ready IRQ (or GPIO) via DOUT-pin.
>> ---
>>   .../bindings/iio/adc/adi,ad7476.yaml          | 54 +++++++++++++++++++
>>   1 file changed, 54 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad7476.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad7476.yaml
>> index d0cb32f136e5..c411a7467651 100644
>> --- a/Documentation/devicetree/bindings/iio/adc/adi,ad7476.yaml
>> +++ b/Documentation/devicetree/bindings/iio/adc/adi,ad7476.yaml
>> @@ -41,6 +41,7 @@ properties:
>>                 - adi,ad7910
>>                 - adi,ad7920
>>                 - adi,ad7940
>> +              - rohm,bd79105
>>                 - ti,adc081s
>>                 - ti,adc101s
>>                 - ti,adc121s
>> @@ -55,6 +56,11 @@ properties:
>>     reg:
>>       maxItems: 1
>>   
>> +  interrupts:
>> +    description:
>> +      The data-ready interrupt. Provided via DOUT pin.
>> +    maxItems: 1
>> +
>>     vcc-supply:
>>       description:
>>         Main powersupply voltage for the chips, sometimes referred to as VDD on
>> @@ -75,6 +81,10 @@ properties:
>>       description: A GPIO used to trigger the start of a conversion
>>       maxItems: 1
>>   
>> +  rdy-gpios:
>> +    description: A GPIO for detecting the data-ready.
>> +    maxItems: 1
>> +
>>   required:
>>     - compatible
>>     - reg
>> @@ -82,6 +92,20 @@ required:
>>   allOf:
>>     - $ref: /schemas/spi/spi-peripheral-props.yaml#
>>   
>> +# Devices with an IRQ
>> +  - if:
>> +      properties:
>> +        compatible:
>> +          contains:
>> +            enum:
>> +              - rohm,bd79105
>> +    then:
>> +      properties:
>> +        interrupts: true
> 
> It's been a while since I wrote one of these, but do we need
> the true bit given we have already specified the interrupts
> property.  I think we only need to do the setting to false
> on an if: not:

I think you're right. I just used same approach that had already been 
used throughout this binding. I'll try dropping the 'true'-branches, but 
then also the other 'true'-branches should be dropped from the binding.

I'll just do that and send v4. Let's see what Rob/Krzk/Conor have to say :)

Yours,
	-- Matti

[PATCH v3 09/10] iio: adc: ad7476: Support ROHM BD79105

[Matti Vaittinen]

[-- Attachment #1: Type: text/plain, Size: 4720 bytes --]

The ROHM BD79105 is a simple 16-bit ADC accessible via SPI*.

The BD79105 has a CONVSTART pin, which must be set high to start the ADC
conversion. Unlike with the ad7091 and ad7091r which also have a
CONVSTART pin, the BD79105 requires that the pin must remain high also
for the duration of the SPI access.

(*) Couple of words about the SPI. The BD79105 has pins named as
CONVSTART, SCLK, DIN and DOUT. For the curious reader, DIN is not SPI
MISO.

DIN is a signal which can be used as a chip-select. When DIN is pulled
low, the ADC will output the completed measurement via DOUT as SCLK is
clocked. According to the data-sheet, the DIN can also be used for
daisy-chaining multiple ADCs. Furthermore, DOUT can be used also for a
'data-ready' -IRQ. These modes aren't supported by this driver.

Support reading ADC scale and data from the BD79105 using SPI, when DIN
is used as a chip-select.

Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
---
Revision history:
 v2 => v3:
 - Check for missing convstart GPIO at probe.
 - Use indirect call to convstart (via function pointer) also from the
   ad7476_scan_direct().

 v1 => v2:
 - Fix the conversion delay for the BD79105
 - Drop unnecessary GPIO check from the convstart disable
 - Drop unintended whitespace change
 - Fix spelling
---
 drivers/iio/adc/ad7476.c | 39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/drivers/iio/adc/ad7476.c b/drivers/iio/adc/ad7476.c
index 6cb2cbeafbd3..1bec6657394c 100644
--- a/drivers/iio/adc/ad7476.c
+++ b/drivers/iio/adc/ad7476.c
@@ -32,8 +32,10 @@ struct ad7476_chip_info {
 	struct iio_chan_spec		channel[2];
 	void (*reset)(struct ad7476_state *);
 	void (*conversion_pre_op)(struct ad7476_state *st);
+	void (*conversion_post_op)(struct ad7476_state *st);
 	bool				has_vref;
 	bool				has_vdrive;
+	bool				convstart_required;
 };
 
 struct ad7476_state {
@@ -64,6 +66,18 @@ static void ad7091_convst(struct ad7476_state *st)
 	udelay(1); /* Conversion time: 650 ns max */
 }
 
+static void bd79105_convst_disable(struct ad7476_state *st)
+{
+	gpiod_set_value_cansleep(st->convst_gpio, 0);
+}
+
+static void bd79105_convst_enable(struct ad7476_state *st)
+{
+	gpiod_set_value_cansleep(st->convst_gpio, 1);
+	/* Worst case, 2790 ns required for conversion */
+	ndelay(2790);
+}
+
 static irqreturn_t ad7476_trigger_handler(int irq, void  *p)
 {
 	struct iio_poll_func *pf = p;
@@ -81,6 +95,8 @@ static irqreturn_t ad7476_trigger_handler(int irq, void  *p)
 	iio_push_to_buffers_with_ts(indio_dev, st->data, sizeof(st->data),
 				    iio_get_time_ns(indio_dev));
 done:
+	if (st->chip_info->conversion_post_op)
+		st->chip_info->conversion_post_op(st);
 	iio_trigger_notify_done(indio_dev->trig);
 
 	return IRQ_HANDLED;
@@ -103,6 +119,9 @@ static int ad7476_scan_direct(struct ad7476_state *st)
 	if (ret)
 		return ret;
 
+	if (st->chip_info->conversion_post_op)
+		st->chip_info->conversion_post_op(st);
+
 	return be16_to_cpup((__be16 *)st->data);
 }
 
@@ -273,6 +292,22 @@ static const struct ad7476_chip_info ltc2314_14_chip_info = {
 	.has_vref = true,
 };
 
+static const struct ad7476_chip_info bd79105_chip_info = {
+	.channel[0] = AD7091R_CHAN(16),
+	.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
+	/*
+	 * The BD79105 starts ADC data conversion when the CONVSTART line is
+	 * set HIGH. The CONVSTART must be kept HIGH until the data has been
+	 * read from the ADC.
+	 */
+	.conversion_pre_op = bd79105_convst_enable,
+	.conversion_post_op = bd79105_convst_disable,
+	/* BD79105 won't do conversion without convstart */
+	.convstart_required = true,
+	.has_vref = true,
+	.has_vdrive = true,
+};
+
 static const struct iio_info ad7476_info = {
 	.read_raw = &ad7476_read_raw,
 };
@@ -332,6 +367,9 @@ static int ad7476_probe(struct spi_device *spi)
 	if (IS_ERR(st->convst_gpio))
 		return PTR_ERR(st->convst_gpio);
 
+	if (st->chip_info->convstart_required && !st->convst_gpio)
+		return dev_err_probe(&spi->dev, -EINVAL, "No convstart GPIO\n");
+
 	/*
 	 * This will never happen. Unless someone changes the channel specs
 	 * in this driver. And if someone does, without changing the loop
@@ -401,6 +439,7 @@ static const struct spi_device_id ad7476_id[] = {
 	{ "ads7866", (kernel_ulong_t)&ads7866_chip_info },
 	{ "ads7867", (kernel_ulong_t)&ads7867_chip_info },
 	{ "ads7868", (kernel_ulong_t)&ads7868_chip_info },
+	{ "bd79105", (kernel_ulong_t)&bd79105_chip_info },
 	/*
 	 * The ROHM BU79100G is identical to the TI's ADS7866 from the software
 	 * point of view. The binding document mandates the ADS7866 to be
-- 
2.50.1


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Re: [PATCH v3 09/10] iio: adc: ad7476: Support ROHM BD79105

[Nuno Sá]

On Fri, Aug 08, 2025 at 11:55:48AM +0300, Matti Vaittinen wrote:
> The ROHM BD79105 is a simple 16-bit ADC accessible via SPI*.
> 
> The BD79105 has a CONVSTART pin, which must be set high to start the ADC
> conversion. Unlike with the ad7091 and ad7091r which also have a
> CONVSTART pin, the BD79105 requires that the pin must remain high also
> for the duration of the SPI access.
> 
> (*) Couple of words about the SPI. The BD79105 has pins named as
> CONVSTART, SCLK, DIN and DOUT. For the curious reader, DIN is not SPI
> MISO.
> 
> DIN is a signal which can be used as a chip-select. When DIN is pulled
> low, the ADC will output the completed measurement via DOUT as SCLK is
> clocked. According to the data-sheet, the DIN can also be used for
> daisy-chaining multiple ADCs. Furthermore, DOUT can be used also for a
> 'data-ready' -IRQ. These modes aren't supported by this driver.
> 
> Support reading ADC scale and data from the BD79105 using SPI, when DIN
> is used as a chip-select.
> 
> Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
> ---

Reviewed-by: Nuno Sá <nuno.sa@analog.com>

> Revision history:
>  v2 => v3:
>  - Check for missing convstart GPIO at probe.
>  - Use indirect call to convstart (via function pointer) also from the
>    ad7476_scan_direct().
> 
>  v1 => v2:
>  - Fix the conversion delay for the BD79105
>  - Drop unnecessary GPIO check from the convstart disable
>  - Drop unintended whitespace change
>  - Fix spelling
> ---
>  drivers/iio/adc/ad7476.c | 39 +++++++++++++++++++++++++++++++++++++++
>  1 file changed, 39 insertions(+)
> 
> diff --git a/drivers/iio/adc/ad7476.c b/drivers/iio/adc/ad7476.c
> index 6cb2cbeafbd3..1bec6657394c 100644
> --- a/drivers/iio/adc/ad7476.c
> +++ b/drivers/iio/adc/ad7476.c
> @@ -32,8 +32,10 @@ struct ad7476_chip_info {
>  	struct iio_chan_spec		channel[2];
>  	void (*reset)(struct ad7476_state *);
>  	void (*conversion_pre_op)(struct ad7476_state *st);
> +	void (*conversion_post_op)(struct ad7476_state *st);
>  	bool				has_vref;
>  	bool				has_vdrive;
> +	bool				convstart_required;
>  };
>  
>  struct ad7476_state {
> @@ -64,6 +66,18 @@ static void ad7091_convst(struct ad7476_state *st)
>  	udelay(1); /* Conversion time: 650 ns max */
>  }
>  
> +static void bd79105_convst_disable(struct ad7476_state *st)
> +{
> +	gpiod_set_value_cansleep(st->convst_gpio, 0);
> +}
> +
> +static void bd79105_convst_enable(struct ad7476_state *st)
> +{
> +	gpiod_set_value_cansleep(st->convst_gpio, 1);
> +	/* Worst case, 2790 ns required for conversion */
> +	ndelay(2790);
> +}
> +
>  static irqreturn_t ad7476_trigger_handler(int irq, void  *p)
>  {
>  	struct iio_poll_func *pf = p;
> @@ -81,6 +95,8 @@ static irqreturn_t ad7476_trigger_handler(int irq, void  *p)
>  	iio_push_to_buffers_with_ts(indio_dev, st->data, sizeof(st->data),
>  				    iio_get_time_ns(indio_dev));
>  done:
> +	if (st->chip_info->conversion_post_op)
> +		st->chip_info->conversion_post_op(st);
>  	iio_trigger_notify_done(indio_dev->trig);
>  
>  	return IRQ_HANDLED;
> @@ -103,6 +119,9 @@ static int ad7476_scan_direct(struct ad7476_state *st)
>  	if (ret)
>  		return ret;
>  
> +	if (st->chip_info->conversion_post_op)
> +		st->chip_info->conversion_post_op(st);
> +
>  	return be16_to_cpup((__be16 *)st->data);
>  }
>  
> @@ -273,6 +292,22 @@ static const struct ad7476_chip_info ltc2314_14_chip_info = {
>  	.has_vref = true,
>  };
>  
> +static const struct ad7476_chip_info bd79105_chip_info = {
> +	.channel[0] = AD7091R_CHAN(16),
> +	.channel[1] = IIO_CHAN_SOFT_TIMESTAMP(1),
> +	/*
> +	 * The BD79105 starts ADC data conversion when the CONVSTART line is
> +	 * set HIGH. The CONVSTART must be kept HIGH until the data has been
> +	 * read from the ADC.
> +	 */
> +	.conversion_pre_op = bd79105_convst_enable,
> +	.conversion_post_op = bd79105_convst_disable,
> +	/* BD79105 won't do conversion without convstart */
> +	.convstart_required = true,
> +	.has_vref = true,
> +	.has_vdrive = true,
> +};
> +
>  static const struct iio_info ad7476_info = {
>  	.read_raw = &ad7476_read_raw,
>  };
> @@ -332,6 +367,9 @@ static int ad7476_probe(struct spi_device *spi)
>  	if (IS_ERR(st->convst_gpio))
>  		return PTR_ERR(st->convst_gpio);
>  
> +	if (st->chip_info->convstart_required && !st->convst_gpio)
> +		return dev_err_probe(&spi->dev, -EINVAL, "No convstart GPIO\n");
> +
>  	/*
>  	 * This will never happen. Unless someone changes the channel specs
>  	 * in this driver. And if someone does, without changing the loop
> @@ -401,6 +439,7 @@ static const struct spi_device_id ad7476_id[] = {
>  	{ "ads7866", (kernel_ulong_t)&ads7866_chip_info },
>  	{ "ads7867", (kernel_ulong_t)&ads7867_chip_info },
>  	{ "ads7868", (kernel_ulong_t)&ads7868_chip_info },
> +	{ "bd79105", (kernel_ulong_t)&bd79105_chip_info },
>  	/*
>  	 * The ROHM BU79100G is identical to the TI's ADS7866 from the software
>  	 * point of view. The binding document mandates the ADS7866 to be
> -- 
> 2.50.1
> 

[PATCH v3 10/10] MAINTAINERS: A driver for simple 1-channel SPI ADCs

[Matti Vaittinen]

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Add undersigned as a maintainer for the ad7476.c which supports a few
simple 1-channel ADC connected to SPI.

Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>

---
Revision history:
 v1 => :
 - No changes.

I'll try to keep this on eye.

I only have access to the ROHM BD79105 and BU79100g. I would welcome
anyone with access to other supported ADCs (and time, energy and the
knowledge) to join me. :)
---
 MAINTAINERS | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index f8c8f682edf6..36fa6333f7b5 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -455,6 +455,11 @@ F:	Documentation/devicetree/bindings/iio/adc/adi,ad7380.yaml
 F:	Documentation/iio/ad7380.rst
 F:	drivers/iio/adc/ad7380.c
 
+AD7476 ADC DRIVER FOR VARIOUS SIMPLE 1-CHANNEL SPI ADCs
+M:	Matti Vaittinen <mazziesaccount@gmail.com>
+S:	Maintained
+F:	drivers/iio/adc/ad7476.c
+
 AD7877 TOUCHSCREEN DRIVER
 M:	Michael Hennerich <michael.hennerich@analog.com>
 S:	Supported
-- 
2.50.1


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Re: [PATCH v3 00/10] Support ROHM BD79105 ADC

[Andy Shevchenko]

On Fri, Aug 8, 2025 at 10:50 AM Matti Vaittinen
<mazziesaccount@gmail.com> wrote:
>
> Add support for the ROHM BD79105 ADC
> (and do some minor simplifications to the ad7476 driver while at it).
>
> The first 2 patches were originally sent as an RFC:
> https://lore.kernel.org/all/cover.1754041258.git.mazziesaccount@gmail.com/

This version LGTM
Reviewed-by: Andy Shevchenko <andy@kernel.org>
with the exception of patches for DT and MAINTAINERS, I haven't even
looked at them.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v3 00/10] Support ROHM BD79105 ADC

[Jonathan Cameron]

On Fri, 8 Aug 2025 14:42:47 +0200
Andy Shevchenko <andy.shevchenko@gmail.com> wrote:

> On Fri, Aug 8, 2025 at 10:50 AM Matti Vaittinen
> <mazziesaccount@gmail.com> wrote:
> >
> > Add support for the ROHM BD79105 ADC
> > (and do some minor simplifications to the ad7476 driver while at it).
> >
> > The first 2 patches were originally sent as an RFC:
> > https://lore.kernel.org/all/cover.1754041258.git.mazziesaccount@gmail.com/  
> 
> This version LGTM
> Reviewed-by: Andy Shevchenko <andy@kernel.org>
> with the exception of patches for DT and MAINTAINERS, I haven't even
> looked at them.
> 

I took another quick look and just a few comments on the DT patch
which also need a DT maintainer review.


Jonathan