[PATCH v3 1/2] dt-bindings: iio: adc: add TI LMP92064 controller

[PATCH v3 1/2] dt-bindings: iio: adc: add TI LMP92064 controller

[Leonard Göhrs]

Add binding documentation for the TI LMP92064 dual channel SPI ADC.

Signed-off-by: Leonard Göhrs <l.goehrs@pengutronix.de>
---

Changes from v2 -> v3:

 - Use unevaluatedProperties: false instead of additionalProperties: false

Changes from v1 -> v2:

 - Rename the "shunt-resistor" devicetree property to
   "shunt-resistor-micro-ohms".
 - Add supply regulator support for the two voltage domains of the chip
   (vdd and vdig).
 - Add reference to spi-peripheral-props.yaml


 .../bindings/iio/adc/ti,lmp92064.yaml         | 70 +++++++++++++++++++
 1 file changed, 70 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/ti,lmp92064.yaml

diff --git a/Documentation/devicetree/bindings/iio/adc/ti,lmp92064.yaml b/Documentation/devicetree/bindings/iio/adc/ti,lmp92064.yaml
new file mode 100644
index 0000000000000..5fb65bf7749d0
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/adc/ti,lmp92064.yaml
@@ -0,0 +1,70 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/adc/ti,lmp92064.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Texas Instruments LMP92064 Precision Current and Voltage Sensor.
+
+maintainers:
+  - Leonard Göhrs <l.goehrs@pengutronix.de>
+
+description: |
+  The LMP92064 is a two channel ADC intended for combined voltage and current
+  measurements.
+
+  The device contains two ADCs to allow simultaneous sampling of voltage and
+  current and thus of instantaneous power consumption.
+
+properties:
+  compatible:
+    enum:
+      - ti,lmp92064
+
+  reg:
+    maxItems: 1
+
+  vdd-supply:
+    description: Regulator that provides power to the main part of the chip
+
+  vdig-supply:
+    description: |
+      Regulator that provides power to the digital I/O part of the chip
+
+  shunt-resistor-micro-ohms:
+    description: |
+      Value of the shunt resistor (in µΩ) connected between INCP and INCN,
+      across which current is measured. Used to provide correct scaling of the
+      raw ADC measurement.
+
+  reset-gpios:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+  - shunt-resistor-micro-ohms
+
+allOf:
+  - $ref: /schemas/spi/spi-peripheral-props.yaml#
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    spi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        adc@0 {
+            compatible = "ti,lmp92064";
+            reg = <0>;
+            vdd-supply = <&vdd>;
+            vdig-supply = <&vdd>;
+            spi-max-frequency = <20000000>;
+            shunt-resistor-micro-ohms = <15000>;
+            reset-gpios = <&gpio1 16 GPIO_ACTIVE_HIGH>;
+        };
+    };
+...

base-commit: b7b275e60bcd5f89771e865a8239325f86d9927d
-- 
2.30.2

[PATCH v3 2/2] iio: adc: add ADC driver for the TI LMP92064 controller

[Leonard Göhrs]

The TI LMP92064 is a dual 12 Bit ADC connected via SPI.
The two channels are intended for simultaneous measurements of the voltage
across- and current through a load to allow accurate instantaneous power
measurements.
The driver does not yet take advantage of this feature, as buffering is not
yet implemented.

Signed-off-by: Leonard Göhrs <l.goehrs@pengutronix.de>
---

Changes from v2 -> v3:

 - Set lmp92064_adc_driver.id_table to lmp92064_id_table
 - Add comments on what the INV/INC names taken from the datasheet
   mean (INput Voltage and INput Current).
 - Improve comments regarding reset timing

Changes from v1 -> v2:

 - Rebase from 6.0 to 6.1-rc2 to get access to devm_regulator_get_enable.
 - Use regmap instead of raw SPI commands.
   This fixes multiple issues in the v1:
   - Remove need to assemble register address using bit shifts.
   - Remove non DMA-safe stack-allocated buffers.
   - Regmap has internal lock handling, removing the need for locking in the
     driver read code using mlock.
 - Use be16_to_cpu() instead of manually assembling values using bit shifts.
 - Use generic device_property_read_u32() instead of devicetree specific
   of_property_read_u32().
 - Rename the "shunt-resistor" device property to "shunt-resistor-micro-ohms".
 - Add supply regulator support for the two voltage domains of the chip
   (vdd and vdig).
 - Only perform soft reset if no GPIO line for hard resets is available.
 - Change the error returned if the device does not respond after a reset
   from "EBUSY" to "ENXIO" to indicate that this is likely a persistent
   error (like a broken connection).
 - Don't set the SPI mode manually.
 - Provide a spi_device_id table.
 - Declare local variables in reverse christmas tree order.
 - Fix formatting of multi-line comments and some whitespace issues.


 MAINTAINERS                   |   8 +
 drivers/iio/adc/Kconfig       |  10 +
 drivers/iio/adc/Makefile      |   1 +
 drivers/iio/adc/ti-lmp92064.c | 332 ++++++++++++++++++++++++++++++++++
 4 files changed, 351 insertions(+)
 create mode 100644 drivers/iio/adc/ti-lmp92064.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 69565ac0c2244..3223ef36862c5 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -20640,6 +20640,14 @@ S:	Maintained
 F:	sound/soc/codecs/isabelle*
 F:	sound/soc/codecs/lm49453*
 
+TI LMP92064 ADC DRIVER
+M:	Leonard Göhrs <l.goehrs@pengutronix.de>
+R:	kernel@pengutronix.de
+L:	linux-iio@vger.kernel.org
+S:	Maintained
+F:	Documentation/devicetree/bindings/iio/adc/ti,lmp92064.yaml
+F:	drivers/iio/adc/ti-lmp92064.c
+
 TI PCM3060 ASoC CODEC DRIVER
 M:	Kirill Marinushkin <kmarinushkin@birdec.com>
 L:	alsa-devel@alsa-project.org (moderated for non-subscribers)
diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 791612ca60120..6875fecc63603 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -1234,6 +1234,16 @@ config TI_AM335X_ADC
 	  To compile this driver as a module, choose M here: the module will be
 	  called ti_am335x_adc.
 
+config TI_LMP92064
+	tristate "Texas Instruments LMP92064 ADC driver"
+	depends on SPI
+	help
+	  Say yes here to build support for the LMP92064 Precision Current and Voltage
+	  sensor.
+
+	  This driver can also be built as a module. If so, the module will be called
+	  ti-lmp92064.
+
 config TI_TLC4541
 	tristate "Texas Instruments TLC4541 ADC driver"
 	depends on SPI
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index 46caba7a010c9..e8175c97ebeb6 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -110,6 +110,7 @@ obj-$(CONFIG_TI_ADS8688) += ti-ads8688.o
 obj-$(CONFIG_TI_ADS124S08) += ti-ads124s08.o
 obj-$(CONFIG_TI_ADS131E08) += ti-ads131e08.o
 obj-$(CONFIG_TI_AM335X_ADC) += ti_am335x_adc.o
+obj-$(CONFIG_TI_LMP92064) += ti-lmp92064.o
 obj-$(CONFIG_TI_TLC4541) += ti-tlc4541.o
 obj-$(CONFIG_TI_TSC2046) += ti-tsc2046.o
 obj-$(CONFIG_TWL4030_MADC) += twl4030-madc.o
diff --git a/drivers/iio/adc/ti-lmp92064.c b/drivers/iio/adc/ti-lmp92064.c
new file mode 100644
index 0000000000000..c30ed824924f3
--- /dev/null
+++ b/drivers/iio/adc/ti-lmp92064.c
@@ -0,0 +1,332 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Texas Instruments LMP92064 SPI ADC driver
+ *
+ * Copyright (c) 2022 Leonard Göhrs <kernel@pengutronix.de>, Pengutronix
+ *
+ * Based on linux/drivers/iio/adc/ti-tsc2046.c
+ * Copyright (c) 2021 Oleksij Rempel <kernel@pengutronix.de>, Pengutronix
+ */
+
+#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
+#include <linux/spi/spi.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/driver.h>
+
+#define TI_LMP92064_REG_CONFIG_A 0x0000
+#define TI_LMP92064_REG_CONFIG_B 0x0001
+#define TI_LMP92064_REG_CHIP_REV 0x0006
+
+#define TI_LMP92064_REG_MFR_ID1 0x000C
+#define TI_LMP92064_REG_MFR_ID2 0x000D
+
+#define TI_LMP92064_REG_REG_UPDATE 0x000F
+#define TI_LMP92064_REG_CONFIG_REG 0x0100
+#define TI_LMP92064_REG_STATUS 0x0103
+
+#define TI_LMP92064_REG_DATA_VOUT_LSB 0x0200
+#define TI_LMP92064_REG_DATA_VOUT_MSB 0x0201
+#define TI_LMP92064_REG_DATA_COUT_LSB 0x0202
+#define TI_LMP92064_REG_DATA_COUT_MSB 0x0203
+
+#define TI_LMP92064_VAL_CONFIG_A 0x99
+#define TI_LMP92064_VAL_CONFIG_B 0x00
+#define TI_LMP92064_VAL_STATUS_OK 0x01
+
+/*
+ * Channel number definitions for the two channels of the device
+ * - IN Current (INC)
+ * - IN Voltage (INV)
+ */
+#define TI_LMP92064_CHAN_INC 0
+#define TI_LMP92064_CHAN_INV 1
+
+static const struct regmap_range lmp92064_readable_reg_ranges[] = {
+	regmap_reg_range(TI_LMP92064_REG_CONFIG_A, TI_LMP92064_REG_CHIP_REV),
+	regmap_reg_range(TI_LMP92064_REG_MFR_ID1, TI_LMP92064_REG_MFR_ID2),
+	regmap_reg_range(TI_LMP92064_REG_REG_UPDATE, TI_LMP92064_REG_REG_UPDATE),
+	regmap_reg_range(TI_LMP92064_REG_CONFIG_REG, TI_LMP92064_REG_CONFIG_REG),
+	regmap_reg_range(TI_LMP92064_REG_STATUS, TI_LMP92064_REG_STATUS),
+	regmap_reg_range(TI_LMP92064_REG_DATA_VOUT_LSB, TI_LMP92064_REG_DATA_COUT_MSB),
+};
+
+static const struct regmap_access_table lmp92064_readable_regs = {
+	.yes_ranges = lmp92064_readable_reg_ranges,
+	.n_yes_ranges = ARRAY_SIZE(lmp92064_readable_reg_ranges),
+};
+
+static const struct regmap_range lmp92064_writable_reg_ranges[] = {
+	regmap_reg_range(TI_LMP92064_REG_CONFIG_A, TI_LMP92064_REG_CONFIG_B),
+	regmap_reg_range(TI_LMP92064_REG_REG_UPDATE, TI_LMP92064_REG_REG_UPDATE),
+	regmap_reg_range(TI_LMP92064_REG_CONFIG_REG, TI_LMP92064_REG_CONFIG_REG),
+};
+
+static const struct regmap_access_table lmp92064_writable_regs = {
+	.yes_ranges = lmp92064_writable_reg_ranges,
+	.n_yes_ranges = ARRAY_SIZE(lmp92064_writable_reg_ranges),
+};
+
+static const struct regmap_config lmp92064_spi_regmap_config = {
+	.reg_bits = 16,
+	.val_bits = 8,
+	.max_register = TI_LMP92064_REG_DATA_COUT_MSB,
+	.rd_table = &lmp92064_readable_regs,
+	.wr_table = &lmp92064_writable_regs,
+};
+
+struct lmp92064_adc_priv {
+	int shunt_resistor_uohm;
+	struct spi_device *spi;
+	struct regmap *regmap;
+};
+
+static const struct iio_chan_spec lmp92064_adc_channels[] = {
+	{
+		.type = IIO_CURRENT,
+		.address = TI_LMP92064_CHAN_INC,
+		.info_mask_separate =
+			BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
+		.datasheet_name = "INC",
+	},
+	{
+		.type = IIO_VOLTAGE,
+		.address = TI_LMP92064_CHAN_INV,
+		.info_mask_separate =
+			BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
+		.datasheet_name = "INV",
+	},
+};
+
+static int lmp92064_read_meas(struct lmp92064_adc_priv *priv, u16 *res)
+{
+	__be16 raw[2];
+	int ret;
+
+	/*
+	 * The ADC only latches in new samples if all DATA registers are read
+	 * in descending sequential order.
+	 * The ADC auto-decrements the register index with each clocked byte.
+	 * Read both channels in single SPI transfer by selecting the highest
+	 * register using the command below and clocking out all four data
+	 * bytes.
+	 */
+
+	ret = regmap_bulk_read(priv->regmap, TI_LMP92064_REG_DATA_COUT_MSB,
+			 &raw, sizeof(raw));
+
+	if (ret) {
+		dev_err(&priv->spi->dev, "regmap_bulk_read failed: %pe\n",
+			ERR_PTR(ret));
+		return ret;
+	}
+
+	res[0] = be16_to_cpu(raw[0]);
+	res[1] = be16_to_cpu(raw[1]);
+
+	return 0;
+}
+
+static int lmp92064_read_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan, int *val,
+			     int *val2, long mask)
+{
+	struct lmp92064_adc_priv *priv = iio_priv(indio_dev);
+	u16 raw[2];
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		ret = lmp92064_read_meas(priv, raw);
+		if (ret < 0)
+			return ret;
+
+		*val = (chan->address == TI_LMP92064_CHAN_INC) ? raw[0] : raw[1];
+
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		if (chan->address == TI_LMP92064_CHAN_INC) {
+			/*
+			 * processed (mA) = raw * current_lsb (mA)
+			 * current_lsb (mA) = shunt_voltage_lsb (nV) / shunt_resistor (uOhm)
+			 * shunt_voltage_lsb (nV) = 81920000 / 4096 = 20000
+			 */
+			*val = 20000;
+			*val2 = priv->shunt_resistor_uohm;
+		} else {
+			/*
+			 * processed (mV) = raw * voltage_lsb (mV)
+			 * voltage_lsb (mV) = 2048 / 4096
+			 */
+			*val = 2048;
+			*val2 = 4096;
+		}
+		return IIO_VAL_FRACTIONAL;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int lmp92064_reset(struct lmp92064_adc_priv *priv,
+			  struct gpio_desc *gpio_reset)
+{
+	unsigned int status;
+	int ret, i;
+
+	if (gpio_reset) {
+		/*
+		 * Perform a hard reset if gpio_reset is available.
+		 * The datasheet specifies a very low 3.5ns reset pulse duration and does not
+		 * specify how long to wait after a reset to access the device.
+		 * Use more conservative pulse lengths to allow analog RC filtering of the
+		 * reset line at the board level (as recommended in the datasheet).
+		 */
+		gpiod_set_value_cansleep(gpio_reset, 1);
+		usleep_range(1, 10);
+		gpiod_set_value_cansleep(gpio_reset, 0);
+		usleep_range(500, 750);
+	} else {
+		/*
+		 * Perform a soft-reset if not.
+		 * Also write default values to the config registers that are not
+		 * affected by soft reset.
+		 */
+		ret = regmap_write(priv->regmap, TI_LMP92064_REG_CONFIG_A,
+				   TI_LMP92064_VAL_CONFIG_A);
+		if (ret < 0)
+			return ret;
+
+		ret = regmap_write(priv->regmap, TI_LMP92064_REG_CONFIG_B,
+				   TI_LMP92064_VAL_CONFIG_B);
+		if (ret < 0)
+			return ret;
+	}
+
+	/*
+	 * Wait for the device to signal readiness to prevent reading bogus data
+	 * and make sure device is actually connected.
+	 * The datasheet does not specify how long this takes but usually it is
+	 * not more than 3-4 iterations of this loop.
+	 */
+	for (i = 0; i < 10; i++) {
+		ret = regmap_read(priv->regmap, TI_LMP92064_REG_STATUS, &status);
+		if (ret < 0)
+			return ret;
+
+		if (status == TI_LMP92064_VAL_STATUS_OK)
+			return 0;
+
+		usleep_range(1000, 2000);
+	}
+
+	/*
+	 * No (correct) response received.
+	 * Device is mostly likely not connected to the bus.
+	 */
+	return -ENXIO;
+}
+
+static const struct iio_info lmp92064_adc_info = {
+	.read_raw = lmp92064_read_raw,
+};
+
+static int lmp92064_adc_probe(struct spi_device *spi)
+{
+	struct device *dev = &spi->dev;
+	struct lmp92064_adc_priv *priv;
+	struct gpio_desc *gpio_reset;
+	struct iio_dev *indio_dev;
+	u32 shunt_resistor_uohm;
+	struct regmap *regmap;
+	int ret;
+
+	ret = spi_setup(spi);
+	if (ret < 0)
+		return dev_err_probe(dev, ret, "Error in SPI setup\n");
+
+	regmap = devm_regmap_init_spi(spi, &lmp92064_spi_regmap_config);
+	if (IS_ERR(regmap))
+		return dev_err_probe(dev, PTR_ERR(regmap),
+				     "Failed to set up SPI regmap\n");
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*priv));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	priv = iio_priv(indio_dev);
+
+	priv->spi = spi;
+	priv->regmap = regmap;
+
+	ret = device_property_read_u32(dev, "shunt-resistor-micro-ohms",
+				       &shunt_resistor_uohm);
+	if (ret < 0)
+		return dev_err_probe(dev, ret,
+				     "Failed to get shunt-resistor value\n");
+
+	/*
+	 * The shunt resistance is passed to userspace as the denominator of an iio
+	 * fraction. Make sure it is in range for that.
+	 */
+	if (shunt_resistor_uohm == 0 || shunt_resistor_uohm > INT_MAX) {
+		dev_err(dev, "Shunt resistance is out of range\n");
+		return -EINVAL;
+	}
+
+	priv->shunt_resistor_uohm = shunt_resistor_uohm;
+
+	ret = devm_regulator_get_enable(dev, "vdd");
+	if (ret)
+		return ret;
+
+	ret = devm_regulator_get_enable(dev, "vdig");
+	if (ret)
+		return ret;
+
+	gpio_reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
+	if (IS_ERR(gpio_reset))
+		return dev_err_probe(dev, PTR_ERR(gpio_reset),
+				     "Failed to get GPIO reset pin\n");
+
+	ret = lmp92064_reset(priv, gpio_reset);
+	if (ret < 0)
+		return dev_err_probe(dev, ret, "Failed to reset device\n");
+
+	indio_dev->name = "lmp92064";
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = lmp92064_adc_channels;
+	indio_dev->num_channels = ARRAY_SIZE(lmp92064_adc_channels);
+	indio_dev->info = &lmp92064_adc_info;
+
+	return devm_iio_device_register(dev, indio_dev);
+}
+
+static const struct spi_device_id lmp92064_id_table[] = {
+	{ "lmp92064" },
+	{}
+};
+MODULE_DEVICE_TABLE(spi, lmp92064_id_table);
+
+static const struct of_device_id lmp92064_of_table[] = {
+	{ .compatible = "ti,lmp92064" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, lmp92064_of_table);
+
+static struct spi_driver lmp92064_adc_driver = {
+	.driver = {
+		.name = "lmp92064",
+		.of_match_table = lmp92064_of_table,
+	},
+	.probe = lmp92064_adc_probe,
+	.id_table = lmp92064_id_table,
+};
+module_spi_driver(lmp92064_adc_driver);
+
+MODULE_AUTHOR("Leonard Göhrs <kernel@pengutronix.de>");
+MODULE_DESCRIPTION("TI LMP92064 ADC");
+MODULE_LICENSE("GPL");
-- 
2.30.2

Re: [PATCH v3 1/2] dt-bindings: iio: adc: add TI LMP92064 controller

[Krzysztof Kozlowski]

On 28/11/2022 14:35, Leonard Göhrs wrote:
> Add binding documentation for the TI LMP92064 dual channel SPI ADC.
> 
> Signed-off-by: Leonard Göhrs <l.goehrs@pengutronix.de>
> ---
> 



Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

Best regards,
Krzysztof

Re: [PATCH v3 1/2] dt-bindings: iio: adc: add TI LMP92064 controller

[Jonathan Cameron]

On Mon, 28 Nov 2022 22:25:20 +0100
Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> wrote:

> On 28/11/2022 14:35, Leonard Göhrs wrote:
> > Add binding documentation for the TI LMP92064 dual channel SPI ADC.
> > 
> > Signed-off-by: Leonard Göhrs <l.goehrs@pengutronix.de>
> > ---
> >   
> 
> 
> 
> Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

Series applied to the togreg branch of iio.git. This is now 6.3 material
as the merge window will open soon so we've missed this cycle.

For now I'll push out as testing to let 0-day look at it prior to rebasing
the branch on rc1.

Thanks,

Jonathan
>