[PATCH v2 1/2] dt-bindings: iio: adc: add TI LMP92064 controller

[PATCH v2 1/2] dt-bindings: iio: adc: add TI LMP92064 controller

[Leonard Göhrs]

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

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

Signed-off-by: Leonard Göhrs <l.goehrs@pengutronix.de>
---
 .../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 000000000000..357b15ebd897
--- /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#
+
+additionalProperties: 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>;
+        };
+    };
+...
-- 
2.30.2

[PATCH v2 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.

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.

Signed-off-by: Leonard Göhrs <l.goehrs@pengutronix.de>
---
 MAINTAINERS                   |   8 +
 drivers/iio/adc/Kconfig       |  10 ++
 drivers/iio/adc/Makefile      |   1 +
 drivers/iio/adc/ti-lmp92064.c | 316 ++++++++++++++++++++++++++++++++++
 4 files changed, 335 insertions(+)
 create mode 100644 drivers/iio/adc/ti-lmp92064.c

diff --git a/MAINTAINERS b/MAINTAINERS
index e04d944005ba..e716f4596d56 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -20608,6 +20608,14 @@ 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 791612ca6012..6875fecc6360 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 46caba7a010c..e8175c97ebeb 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 000000000000..0e49e0c2c9db
--- /dev/null
+++ b/drivers/iio/adc/ti-lmp92064.c
@@ -0,0 +1,316 @@
+// 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
+
+#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 */
+		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 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 */
+	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", 0 },
+	{}
+};
+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,
+};
+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 v2 2/2] iio: adc: add ADC driver for the TI LMP92064 controller

[Jonathan Cameron]

On Tue, 1 Nov 2022 18:36:14 +0800
kernel test robot <lkp@intel.com> wrote:

> Hi Leonard,
> 
> I love your patch! Perhaps something to improve:
> 
> [auto build test WARNING on jic23-iio/togreg]
> [also build test WARNING on linus/master v6.1-rc3 next-20221101]
> [If your patch is applied to the wrong git tree, kindly drop us a note.
> And when submitting patch, we suggest to use '--base' as documented in
> https://git-scm.com/docs/git-format-patch#_base_tree_information]
> 
> url:    https://github.com/intel-lab-lkp/linux/commits/Leonard-G-hrs/dt-bindings-iio-adc-add-TI-LMP92064-controller/20221101-145036
> base:   https://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio.git togreg
> patch link:    https://lore.kernel.org/r/20221101064804.720050-2-l.goehrs%40pengutronix.de
> patch subject: [PATCH v2 2/2] iio: adc: add ADC driver for the TI LMP92064 controller
> config: x86_64-allyesconfig
> compiler: gcc-11 (Debian 11.3.0-8) 11.3.0
> reproduce (this is a W=1 build):
>         # https://github.com/intel-lab-lkp/linux/commit/4b264b5bc9425f051a3ce5c5a9a30a66d3a0a477
>         git remote add linux-review https://github.com/intel-lab-lkp/linux
>         git fetch --no-tags linux-review Leonard-G-hrs/dt-bindings-iio-adc-add-TI-LMP92064-controller/20221101-145036
>         git checkout 4b264b5bc9425f051a3ce5c5a9a30a66d3a0a477
>         # save the config file
>         mkdir build_dir && cp config build_dir/.config
>         make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash drivers/iio/adc/
> 
> If you fix the issue, kindly add following tag where applicable
> | Reported-by: kernel test robot <lkp@intel.com>
> 
> All warnings (new ones prefixed by >>):
> 
>    drivers/iio/adc/ti-lmp92064.c: In function 'lmp92064_adc_probe':
>    drivers/iio/adc/ti-lmp92064.c:267:15: error: implicit declaration of function 'devm_regulator_get_enable'; did you mean 'devm_regulator_get_optional'? [-Werror=implicit-function-declaration]
>      267 |         ret = devm_regulator_get_enable(dev, "vdd");
>          |               ^~~~~~~~~~~~~~~~~~~~~~~~~
>          |               devm_regulator_get_optional

That's odd. it's definitely in the trees referenced above and there are stubs
for when regulator support isn't built.  No idea... 


>    At top level:
> >> drivers/iio/adc/ti-lmp92064.c:293:35: warning: 'lmp92064_id_table' defined but not used [-Wunused-const-variable=]  
>      293 | static const struct spi_device_id lmp92064_id_table[] = {
>          |                                   ^~~~~~~~~~~~~~~~~
>    cc1: some warnings being treated as errors

This one is obvious though as the relevant entry in the struct spi_driver
is not set.
 
> 
> 
> vim +/lmp92064_id_table +293 drivers/iio/adc/ti-lmp92064.c
> 
>    292	
>  > 293	static const struct spi_device_id lmp92064_id_table[] = {  
>    294		{ "lmp92064", 0 },
>    295		{}
>    296	};
>    297	MODULE_DEVICE_TABLE(spi, lmp92064_id_table);
>    298	
> 

Re: [PATCH v2 2/2] iio: adc: add ADC driver for the TI LMP92064 controller

[Jonathan Cameron]

On Tue,  1 Nov 2022 07:48:04 +0100
Leonard Göhrs <l.goehrs@pengutronix.de> wrote:

> 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.
> 
> Changes from v1 -> v2:

Hi Leonard,

As with the previous patch, please move the change logs below the ---

> 
>  - 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.
> 
> Signed-off-by: Leonard Göhrs <l.goehrs@pengutronix.de>
> ---
If you weren't going to need to do a v3 anyway for the DT binding, I'd
probably just have fixed up the comments inline and applied it.
Ah well, will be easy to pick up as v3!  We have a few more weeks this
cycle, so hopefully you can do a quick update in next week or so.

Some of the comments are more for reference (probably by me)
a later date than suggestions for changes.

Thanks,

Jonathan


> diff --git a/drivers/iio/adc/ti-lmp92064.c b/drivers/iio/adc/ti-lmp92064.c
> new file mode 100644
> index 000000000000..0e49e0c2c9db
> --- /dev/null
> +++ b/drivers/iio/adc/ti-lmp92064.c
> @@ -0,0 +1,316 @@

> +
> +#define TI_LMP92064_CHAN_INC 0
> +#define TI_LMP92064_CHAN_INV 1

These abbreviations are a bit unfortunate as INC commonly means increment
and INV commonly means invert. Still they are used on the datasheet so
perhaps better to leave them as you have it.

> +
> +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));

Hmm. I've been a bit overly strict on this in the past.
The underlying SPI bus bulk accessors require DMA safe buffers - but the
reads are actually done use spi_write_then_read() which bounce buffers.
There is the added complication that regmap actually bounced everything
for other reasons at the moment but might not do so in future (fairly sure
it didn't a while back).  Anyhow upshot is this is (I think) fine but you'll
see me fairly recently commenting on need for DMA safe buffers for
regmap_bulk_reads(). Going forwards I'll probably only raise this for
bulk writes.

> +
> +	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)

Extra space before processed?

> +			 * 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 */
> +		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 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 */

Good to add a comment here on why these particular time parameters.
At minimum say how long the reset is documented to take.

> +	for (i = 0; i < 10; i++) {
> +		ret = regmap_read(priv->regmap, TI_LMP92064_REG_STATUS, &status);
> +

For style consistency no blank line here (to keep the error handler and function
call visually in one block.

> +		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", 0 },

I would not set the data until you need it (i.e. when adding support for other
parts.  Setting it explicitly gives the impression we are using it.

> +	{}
> +};
> +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,

Missing the id_table being set as per the 0-day bot mail.

> +};
> +module_spi_driver(lmp92064_adc_driver);
> +
> +MODULE_AUTHOR("Leonard Göhrs <kernel@pengutronix.de>");
> +MODULE_DESCRIPTION("TI LMP92064 ADC");
> +MODULE_LICENSE("GPL");

Re: [PATCH v2 1/2] dt-bindings: iio: adc: add TI LMP92064 controller

[Rob Herring]

On Tue, 01 Nov 2022 07:48:03 +0100, Leonard Göhrs wrote:
> Add binding documentation for the TI LMP92064 dual channel SPI ADC.
> 
> 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
> 
> Signed-off-by: Leonard Göhrs <l.goehrs@pengutronix.de>
> ---
>  .../bindings/iio/adc/ti,lmp92064.yaml         | 70 +++++++++++++++++++
>  1 file changed, 70 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iio/adc/ti,lmp92064.yaml
> 

My bot found errors running 'make DT_CHECKER_FLAGS=-m dt_binding_check'
on your patch (DT_CHECKER_FLAGS is new in v5.13):

yamllint warnings/errors:

dtschema/dtc warnings/errors:
/builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/iio/adc/ti,lmp92064.example.dtb: adc@0: 'spi-max-frequency' does not match any of the regexes: 'pinctrl-[0-9]+'
	From schema: /builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/iio/adc/ti,lmp92064.yaml

doc reference errors (make refcheckdocs):

See https://patchwork.ozlabs.org/patch/

This check can fail if there are any dependencies. The base for a patch
series is generally the most recent rc1.

If you already ran 'make dt_binding_check' and didn't see the above
error(s), then make sure 'yamllint' is installed and dt-schema is up to
date:

pip3 install dtschema --upgrade

Please check and re-submit.

Re: [PATCH v2 1/2] dt-bindings: iio: adc: add TI LMP92064 controller

[Rob Herring]

On Tue, Nov 01, 2022 at 07:48:03AM +0100, Leonard Göhrs wrote:
> Add binding documentation for the TI LMP92064 dual channel SPI ADC.
> 
> 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
> 
> Signed-off-by: Leonard Göhrs <l.goehrs@pengutronix.de>
> ---
>  .../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 000000000000..357b15ebd897
> --- /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#
> +
> +additionalProperties: false

This should be unevaluatedProperties instead.

> +
> +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>;
> +        };
> +    };
> +...
> -- 
> 2.30.2
> 
> 

Re: [PATCH v2 1/2] dt-bindings: iio: adc: add TI LMP92064 controller

[Jonathan Cameron]

On Tue, 1 Nov 2022 07:28:24 -0500
Rob Herring <robh@kernel.org> wrote:

> On Tue, Nov 01, 2022 at 07:48:03AM +0100, Leonard Göhrs wrote:
> > Add binding documentation for the TI LMP92064 dual channel SPI ADC.
> > 
> > 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

Change log should be below the ---
We don't want to directly capture in the git tree - though I will apply
a link tag so people can find the thread on lore.kernel.org if they want
this information.

I'm aware that for some parts of the kernel the policy is different but in IIO
we assume the link tag is sufficient.

> > 
> > Signed-off-by: Leonard Göhrs <l.goehrs@pengutronix.de>
> > ---
> >  .../bindings/iio/adc/ti,lmp92064.yaml         | 70 +++++++++++++++++++
> >  1 file changed, 70 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/iio/adc/ti,lmp92064.yaml
> >