[PATCH v6 1/3] dt-bindings: iio: amplifiers: add ada4250 doc

[PATCH v6 1/3] dt-bindings: iio: amplifiers: add ada4250 doc

[Antoniu Miclaus]

Add device tree bindings for the ADA4250 driver.

Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
---
changes in v6:
 - add space before `{` in the amplifier node example
 .../bindings/iio/amplifiers/adi,ada4250.yaml  | 50 +++++++++++++++++++
 1 file changed, 50 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/amplifiers/adi,ada4250.yaml

diff --git a/Documentation/devicetree/bindings/iio/amplifiers/adi,ada4250.yaml b/Documentation/devicetree/bindings/iio/amplifiers/adi,ada4250.yaml
new file mode 100644
index 000000000000..5277479be382
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/amplifiers/adi,ada4250.yaml
@@ -0,0 +1,50 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/amplifiers/adi,ada4250.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: ADA4250 Programmable Gain Instrumentation Amplifier
+
+maintainers:
+  - Antoniu Miclaus <antoniu.miclaus@analog.com>
+
+description: |
+  Precision Low Power, 110kHz, 26uA, Programmable Gain Instrumentation Amplifier.
+
+properties:
+  compatible:
+    enum:
+      - adi,ada4250
+
+  reg:
+    maxItems: 1
+
+  avdd-supply: true
+
+  adi,refbuf-enable:
+    description:
+      Enable internal buffer to drive the reference pin.
+    type: boolean
+
+  spi-max-frequency: true
+
+required:
+  - compatible
+  - reg
+  - avdd-supply
+
+additionalProperties: false
+
+examples:
+  - |
+    spi {
+      #address-cells = <1>;
+      #size-cells = <0>;
+      amplifier@0 {
+        compatible = "adi,ada4250";
+        reg = <0>;
+        avdd-supply = <&avdd>;
+      };
+    };
+...
-- 
2.35.1

[PATCH v6 2/3] iio: amplifiers: ada4250: add support for ADA4250

[Antoniu Miclaus]

The ADA4250 is an instrumentation amplifier with SPI/pin-strap
progammable gains that is optimized for ultra-low power systems.
With a minimum supply voltage of 1.7V, 26uA of quiescent current,
a shutdown mode, a sleep mode, and a fast wake up settling time,
ADA4250 can be power cycled on a battery powered system for even
futher savings.

Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
---
 drivers/iio/amplifiers/Kconfig   |  11 +
 drivers/iio/amplifiers/Makefile  |   1 +
 drivers/iio/amplifiers/ada4250.c | 403 +++++++++++++++++++++++++++++++
 3 files changed, 415 insertions(+)
 create mode 100644 drivers/iio/amplifiers/ada4250.c

diff --git a/drivers/iio/amplifiers/Kconfig b/drivers/iio/amplifiers/Kconfig
index 5eb1357a9c78..f217a2a1e958 100644
--- a/drivers/iio/amplifiers/Kconfig
+++ b/drivers/iio/amplifiers/Kconfig
@@ -23,6 +23,17 @@ config AD8366
 	  To compile this driver as a module, choose M here: the
 	  module will be called ad8366.
 
+config ADA4250
+	tristate "Analog Devices ADA4250 Instrumentation Amplifier"
+	depends on SPI
+	help
+	  Say yes here to build support for Analog Devices ADA4250
+	  SPI Amplifier's support. The driver provides direct access via
+	  sysfs.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called ada4250.
+
 config HMC425
 	tristate "Analog Devices HMC425A and similar GPIO Gain Amplifiers"
 	depends on GPIOLIB
diff --git a/drivers/iio/amplifiers/Makefile b/drivers/iio/amplifiers/Makefile
index cb551d82f56b..2126331129cf 100644
--- a/drivers/iio/amplifiers/Makefile
+++ b/drivers/iio/amplifiers/Makefile
@@ -5,4 +5,5 @@
 
 # When adding new entries keep the list in alphabetical order
 obj-$(CONFIG_AD8366) += ad8366.o
+obj-$(CONFIG_ADA4250) += ada4250.o
 obj-$(CONFIG_HMC425) += hmc425a.o
diff --git a/drivers/iio/amplifiers/ada4250.c b/drivers/iio/amplifiers/ada4250.c
new file mode 100644
index 000000000000..4b32d350dc5d
--- /dev/null
+++ b/drivers/iio/amplifiers/ada4250.c
@@ -0,0 +1,403 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * ADA4250 driver
+ *
+ * Copyright 2022 Analog Devices Inc.
+ */
+
+#include <linux/bitfield.h>
+#include <linux/bits.h>
+#include <linux/device.h>
+#include <linux/iio/iio.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
+#include <linux/spi/spi.h>
+
+#include <asm/unaligned.h>
+
+/* ADA4250 Register Map */
+#define ADA4250_REG_GAIN_MUX        0x00
+#define ADA4250_REG_REFBUF_EN       0x01
+#define ADA4250_REG_RESET           0x02
+#define ADA4250_REG_SNSR_CAL_VAL    0x04
+#define ADA4250_REG_SNSR_CAL_CNFG   0x05
+#define ADA4250_REG_DIE_REV         0x18
+#define ADA4250_REG_CHIP_ID         0x19
+
+/* ADA4250_REG_GAIN_MUX Map */
+#define ADA4250_GAIN_MUX_MSK        GENMASK(2, 0)
+
+/* ADA4250_REG_REFBUF Map */
+#define ADA4250_REFBUF_MSK          BIT(0)
+
+/* ADA4250_REG_RESET Map */
+#define ADA4250_RESET_MSK           BIT(0)
+
+/* ADA4250_REG_SNSR_CAL_VAL Map */
+#define ADA4250_CAL_CFG_BIAS_MSK    GENMASK(7, 0)
+
+/* ADA4250_REG_SNSR_CAL_CNFG Bit Definition */
+#define ADA4250_BIAS_SET_MSK        GENMASK(3, 2)
+#define ADA4250_RANGE_SET_MSK       GENMASK(1, 0)
+
+/* Miscellaneous definitions */
+#define ADA4250_CHIP_ID             0x4250
+#define ADA4250_RANGE1              0
+#define	ADA4250_RANGE4              3
+
+/* ADA4250 current bias set */
+enum ada4250_current_bias {
+	ADA4250_BIAS_DISABLED,
+	ADA4250_BIAS_BANDGAP,
+	ADA4250_BIAS_AVDD,
+};
+
+struct ada4250_state {
+	struct spi_device	*spi;
+	struct regmap		*regmap;
+	struct regulator	*reg;
+	/* Protect against concurrent accesses to the device and data content */
+	struct mutex		lock;
+	u8			bias;
+	u8			gain;
+	int			offset_uv;
+	bool			refbuf_en;
+};
+
+/* ADA4250 Current Bias Source Settings: Disabled, Bandgap Reference, AVDD */
+static const int calibbias_table[] = {0, 1, 2};
+
+/* ADA4250 Gain (V/V) values: 1, 2, 4, 8, 16, 32, 64, 128 */
+static const int hwgain_table[] = {1, 2, 4, 8, 16, 32, 64, 128};
+
+static const struct regmap_config ada4250_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.read_flag_mask = BIT(7),
+	.max_register = 0x1A,
+};
+
+static int ada4250_set_offset_uv(struct iio_dev *indio_dev,
+				 const struct iio_chan_spec *chan,
+				 int offset_uv)
+{
+	struct ada4250_state *st = iio_priv(indio_dev);
+
+	int i, ret, x[8], max_vos, min_vos, voltage_v, vlsb = 0;
+	u8 offset_raw, range = ADA4250_RANGE1;
+	u32 lsb_coeff[6] = {1333, 2301, 4283, 8289, 16311, 31599};
+
+	if (st->bias == 0 || st->bias == 3)
+		return -EINVAL;
+
+	voltage_v = regulator_get_voltage(st->reg);
+	voltage_v = DIV_ROUND_CLOSEST(voltage_v, 1000000);
+
+	if (st->bias == ADA4250_BIAS_AVDD)
+		x[0] = voltage_v;
+	else
+		x[0] = 5;
+
+	x[1] = 126 * (x[0] - 1);
+
+	for (i = 0; i < 6; i++)
+		x[i + 2] = DIV_ROUND_CLOSEST(x[1] * 1000, lsb_coeff[i]);
+
+	if (st->gain == 0)
+		return -EINVAL;
+
+	/*
+	 * Compute Range and Voltage per LSB for the Sensor Offset Calibration
+	 * Example of computation for Range 1 and Range 2 (Curren Bias Set = AVDD):
+	 *                     Range 1                            Range 2
+	 *   Gain   | Max Vos(mV) |   LSB(mV)        |  Max Vos(mV)  | LSB(mV) |
+	 *    2     |    X1*127   | X1=0.126(AVDD-1) |   X1*3*127    |  X1*3   |
+	 *    4     |    X2*127   | X2=X1/1.3333     |   X2*3*127    |  X2*3   |
+	 *    8     |    X3*127   | X3=X1/2.301      |   X3*3*127    |  X3*3   |
+	 *    16    |    X4*127   | X4=X1/4.283      |   X4*3*127    |  X4*3   |
+	 *    32    |    X5*127   | X5=X1/8.289      |   X5*3*127    |  X5*3   |
+	 *    64    |    X6*127   | X6=X1/16.311     |   X6*3*127    |  X6*3   |
+	 *    128   |    X7*127   | X7=X1/31.599     |   X7*3*127    |  X7*3   |
+	 */
+	for (i = ADA4250_RANGE1; i <= ADA4250_RANGE4; i++) {
+		max_vos = x[st->gain] *  127 * ((1 << (i + 1)) - 1);
+		min_vos = -1 * max_vos;
+		if (offset_uv > min_vos && offset_uv < max_vos) {
+			range = i;
+			vlsb = x[st->gain] * ((1 << (i + 1)) - 1);
+			break;
+		}
+	}
+
+	if (vlsb <= 0)
+		return -EINVAL;
+
+	offset_raw = DIV_ROUND_CLOSEST(abs(offset_uv), vlsb);
+
+	mutex_lock(&st->lock);
+	ret = regmap_update_bits(st->regmap, ADA4250_REG_SNSR_CAL_CNFG,
+				 ADA4250_RANGE_SET_MSK,
+				 FIELD_PREP(ADA4250_RANGE_SET_MSK, range));
+	if (ret)
+		goto exit;
+
+	st->offset_uv = offset_raw * vlsb;
+
+	/*
+	 * To set the offset calibration value, use bits [6:0] and bit 7 as the
+	 * polarity bit (set to "0" for a negative offset and "1" for a positive
+	 * offset).
+	 */
+	if (offset_uv < 0) {
+		offset_raw |= BIT(7);
+		st->offset_uv *= (-1);
+	}
+
+	ret = regmap_write(st->regmap, ADA4250_REG_SNSR_CAL_VAL, offset_raw);
+
+exit:
+	mutex_unlock(&st->lock);
+
+	return ret;
+}
+
+static int ada4250_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan,
+			    int *val, int *val2, long info)
+{
+	struct ada4250_state *st = iio_priv(indio_dev);
+	int ret;
+
+	switch (info) {
+	case IIO_CHAN_INFO_HARDWAREGAIN:
+		ret = regmap_read(st->regmap, ADA4250_REG_GAIN_MUX, val);
+		if (ret)
+			return ret;
+
+		*val = BIT(*val);
+
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_OFFSET:
+		*val = st->offset_uv;
+
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_CALIBBIAS:
+		ret = regmap_read(st->regmap, ADA4250_REG_SNSR_CAL_CNFG, val);
+		if (ret)
+			return ret;
+
+		*val = FIELD_GET(ADA4250_BIAS_SET_MSK, *val);
+
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		*val = 1;
+		*val2 = 1000000;
+
+		return IIO_VAL_FRACTIONAL;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int ada4250_write_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     int val, int val2, long info)
+{
+	struct ada4250_state *st = iio_priv(indio_dev);
+	int ret;
+
+	switch (info) {
+	case IIO_CHAN_INFO_HARDWAREGAIN:
+		ret = regmap_write(st->regmap, ADA4250_REG_GAIN_MUX,
+				   FIELD_PREP(ADA4250_GAIN_MUX_MSK, ilog2(val)));
+		if (ret)
+			return ret;
+
+		st->gain = ilog2(val);
+
+		return ret;
+	case IIO_CHAN_INFO_OFFSET:
+		return ada4250_set_offset_uv(indio_dev, chan, val);
+	case IIO_CHAN_INFO_CALIBBIAS:
+		ret = regmap_update_bits(st->regmap, ADA4250_REG_SNSR_CAL_CNFG,
+					 ADA4250_BIAS_SET_MSK,
+					 FIELD_PREP(ADA4250_BIAS_SET_MSK, val));
+		if (ret)
+			return ret;
+
+		st->bias = val;
+
+		return ret;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int ada4250_read_avail(struct iio_dev *indio_dev,
+			      struct iio_chan_spec const *chan,
+			      const int **vals, int *type, int *length,
+			      long mask)
+{
+	switch (mask) {
+	case IIO_CHAN_INFO_CALIBBIAS:
+		*vals = calibbias_table;
+		*type = IIO_VAL_INT;
+		*length = ARRAY_SIZE(calibbias_table);
+
+		return IIO_AVAIL_LIST;
+	case IIO_CHAN_INFO_HARDWAREGAIN:
+		*vals = hwgain_table;
+		*type = IIO_VAL_INT;
+		*length = ARRAY_SIZE(hwgain_table);
+
+		return IIO_AVAIL_LIST;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int ada4250_reg_access(struct iio_dev *indio_dev,
+			      unsigned int reg,
+			      unsigned int write_val,
+			      unsigned int *read_val)
+{
+	struct ada4250_state *st = iio_priv(indio_dev);
+
+	if (read_val)
+		return regmap_read(st->regmap, reg, read_val);
+	else
+		return regmap_write(st->regmap, reg, write_val);
+}
+
+static const struct iio_info ada4250_info = {
+	.read_raw = ada4250_read_raw,
+	.write_raw = ada4250_write_raw,
+	.read_avail = &ada4250_read_avail,
+	.debugfs_reg_access = &ada4250_reg_access,
+};
+
+static const struct iio_chan_spec ada4250_channels[] = {
+	{
+		.type = IIO_VOLTAGE,
+		.output = 1,
+		.indexed = 1,
+		.channel = 0,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_HARDWAREGAIN) |
+				BIT(IIO_CHAN_INFO_OFFSET) |
+				BIT(IIO_CHAN_INFO_CALIBBIAS) |
+				BIT(IIO_CHAN_INFO_SCALE),
+		.info_mask_separate_available = BIT(IIO_CHAN_INFO_CALIBBIAS) |
+						BIT(IIO_CHAN_INFO_HARDWAREGAIN),
+	}
+};
+
+static void ada4250_reg_disable(void *data)
+{
+	regulator_disable(data);
+}
+
+static int ada4250_init(struct ada4250_state *st)
+{
+	int ret;
+	u16 chip_id;
+	u8 data[2] __aligned(8) = {};
+	struct spi_device *spi = st->spi;
+
+	st->refbuf_en = device_property_read_bool(&spi->dev, "adi,refbuf-enable");
+
+	st->reg = devm_regulator_get(&spi->dev, "avdd");
+	if (IS_ERR(st->reg))
+		return dev_err_probe(&spi->dev, PTR_ERR(st->reg),
+				     "failed to get the AVDD voltage\n");
+
+	ret = regulator_enable(st->reg);
+	if (ret) {
+		dev_err(&spi->dev, "Failed to enable specified AVDD supply\n");
+		return ret;
+	}
+
+	ret = devm_add_action_or_reset(&spi->dev, ada4250_reg_disable, st->reg);
+	if (ret)
+		return ret;
+
+	ret = regmap_write(st->regmap, ADA4250_REG_RESET,
+			   FIELD_PREP(ADA4250_RESET_MSK, 1));
+	if (ret)
+		return ret;
+
+	ret = regmap_bulk_read(st->regmap, ADA4250_REG_CHIP_ID, data, 2);
+	if (ret)
+		return ret;
+
+	chip_id = get_unaligned_le16(data);
+
+	if (chip_id != ADA4250_CHIP_ID) {
+		dev_err(&spi->dev, "Invalid chip ID.\n");
+		return -EINVAL;
+	}
+
+	return regmap_write(st->regmap, ADA4250_REG_REFBUF_EN,
+			    FIELD_PREP(ADA4250_REFBUF_MSK, st->refbuf_en));
+}
+
+static int ada4250_probe(struct spi_device *spi)
+{
+	struct iio_dev *indio_dev;
+	struct regmap *regmap;
+	struct ada4250_state *st;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	regmap = devm_regmap_init_spi(spi, &ada4250_regmap_config);
+	if (IS_ERR(regmap))
+		return PTR_ERR(regmap);
+
+	st = iio_priv(indio_dev);
+	st->regmap = regmap;
+	st->spi = spi;
+
+	indio_dev->info = &ada4250_info;
+	indio_dev->name = "ada4250";
+	indio_dev->channels = ada4250_channels;
+	indio_dev->num_channels = ARRAY_SIZE(ada4250_channels);
+
+	mutex_init(&st->lock);
+
+	ret = ada4250_init(st);
+	if (ret) {
+		dev_err(&spi->dev, "ADA4250 init failed\n");
+		return ret;
+	}
+
+	return devm_iio_device_register(&spi->dev, indio_dev);
+}
+
+static const struct spi_device_id ada4250_id[] = {
+	{ "ada4250", 0 },
+	{}
+};
+MODULE_DEVICE_TABLE(spi, ada4250_id);
+
+static const struct of_device_id ada4250_of_match[] = {
+	{ .compatible = "adi,ada4250" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, ada4250_of_match);
+
+static struct spi_driver ada4250_driver = {
+	.driver = {
+			.name = "ada4250",
+			.of_match_table = ada4250_of_match,
+		},
+	.probe = ada4250_probe,
+	.id_table = ada4250_id,
+};
+module_spi_driver(ada4250_driver);
+
+MODULE_AUTHOR("Antoniu Miclaus <antoniu.miclaus@analog.com");
+MODULE_DESCRIPTION("Analog Devices ADA4250");
+MODULE_LICENSE("GPL v2");
-- 
2.35.1

[PATCH v6 3/3] MAINTAINERS: add maintainer for ADA4250 driver

[Antoniu Miclaus]

Add myself as maintainer for the ADA4250 driver.

Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
---
 MAINTAINERS | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index fb18ce7168aa..0410054a7bf5 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1075,6 +1075,14 @@ L:	linux-media@vger.kernel.org
 S:	Maintained
 F:	drivers/media/i2c/ad9389b*
 
+ANALOG DEVICES INC ADA4250 DRIVER
+M:	Antoniu Miclaus <antoniu.miclaus@analog.com>
+L:	linux-iio@vger.kernel.org
+S:	Supported
+W:	https://ez.analog.com/linux-software-drivers
+F:	Documentation/devicetree/bindings/iio/amplifiers/adi,ada4250.yaml
+F:	drivers/iio/amplifiers/ada4250.c
+
 ANALOG DEVICES INC ADGS1408 DRIVER
 M:	Mircea Caprioru <mircea.caprioru@analog.com>
 S:	Supported
-- 
2.35.1

Re: [PATCH v6 1/3] dt-bindings: iio: amplifiers: add ada4250 doc

[Rob Herring]

On Wed, 23 Feb 2022 14:01:10 +0200, Antoniu Miclaus wrote:
> Add device tree bindings for the ADA4250 driver.
> 
> Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
> Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
> ---
> changes in v6:
>  - add space before `{` in the amplifier node example
>  .../bindings/iio/amplifiers/adi,ada4250.yaml  | 50 +++++++++++++++++++
>  1 file changed, 50 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iio/amplifiers/adi,ada4250.yaml
> 

Reviewed-by: Rob Herring <robh@kernel.org>

Re: [PATCH v6 1/3] dt-bindings: iio: amplifiers: add ada4250 doc

[Jonathan Cameron]

On Thu, 24 Feb 2022 10:31:17 -0600
Rob Herring <robh@kernel.org> wrote:

> On Wed, 23 Feb 2022 14:01:10 +0200, Antoniu Miclaus wrote:
> > Add device tree bindings for the ADA4250 driver.
> > 
> > Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
> > Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
> > ---
> > changes in v6:
> >  - add space before `{` in the amplifier node example
> >  .../bindings/iio/amplifiers/adi,ada4250.yaml  | 50 +++++++++++++++++++
> >  1 file changed, 50 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/iio/amplifiers/adi,ada4250.yaml
> >   
> 
> Reviewed-by: Rob Herring <robh@kernel.org>

Series applied to the togreg branch of iio.git and pushed out as testing for
0-day to take a quick look before I go making a mess of linux-next.

One side comment though - when there are lots of revisions in a short timescale
and people haven't had time to get back to the intermediate ones, it is particularly
helpful to give a multi version change log.

i.e. tell us what happened in at least the last couple of revisions to save
on having to go find the earlier threads to find out what changed in v5 and v4!

Also, I always prefer a cover letter for a series even if brief. It give somewhere
to reply to if there are discussions covering multiple patches, or if someone wants
to give a tag for the whole series that I can trivially pick up with b4.
Obviously no point for single patch series though!
I don't normally moan about this, but I was moaning anyway so why not get
everything off my chest! :)

Thanks,

Jonathan