iio: adc: ti-ads7924: add Texas Instruments ADS7924 driver (4d82b2f9) · Commits · EulixOS / Software / Kernel

MAINTAINERS

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Original line number	Diff line number	Diff line
		@@ -20776,6 +20776,13 @@ M: Robert Richter <rric@kernel.org>
		S: Odd Fixes
		F: drivers/gpio/gpio-thunderx.c

		TI ADS7924 ADC DRIVER
		M: Hugo Villeneuve <hvilleneuve@dimonoff.com>
		L: linux-iio@vger.kernel.org
		S: Supported
		F: Documentation/devicetree/bindings/iio/adc/ti,ads7924.yaml
		F: drivers/iio/adc/ti-ads7924.c

		TI AM437X VPFE DRIVER
		M: "Lad, Prabhakar" <prabhakar.csengg@gmail.com>
		L: linux-media@vger.kernel.org

drivers/iio/adc/Kconfig

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		@@ -1208,6 +1208,17 @@ config TI_ADS1015
		This driver can also be built as a module. If so, the module will be
		called ti-ads1015.

		config TI_ADS7924
		tristate "Texas Instruments ADS7924 ADC"
		depends on I2C
		select REGMAP_I2C
		help
		If you say yes here you get support for Texas Instruments ADS7924
		4 channels, 12-bit I2C ADC chip.

		This driver can also be built as a module. If so, the module will be
		called ti-ads7924.

		config TI_ADS7950
		tristate "Texas Instruments ADS7950 ADC driver"
		depends on SPI && GPIOLIB

drivers/iio/adc/Makefile

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		@@ -107,6 +107,7 @@ obj-$(CONFIG_TI_ADC108S102) += ti-adc108s102.o
		obj-$(CONFIG_TI_ADC128S052) += ti-adc128s052.o
		obj-$(CONFIG_TI_ADC161S626) += ti-adc161s626.o
		obj-$(CONFIG_TI_ADS1015) += ti-ads1015.o
		obj-$(CONFIG_TI_ADS7924) += ti-ads7924.o
		obj-$(CONFIG_TI_ADS7950) += ti-ads7950.o
		obj-$(CONFIG_TI_ADS8344) += ti-ads8344.o
		obj-$(CONFIG_TI_ADS8688) += ti-ads8688.o

drivers/iio/adc/ti-ads7924.c

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		// SPDX-License-Identifier: GPL-2.0
		/*
		* IIO driver for Texas Instruments ADS7924 ADC, 12-bit, 4-Channels, I2C
		*
		* Author: Hugo Villeneuve <hvilleneuve@dimonoff.com>
		* Copyright 2022 DimOnOff
		*
		* based on iio/adc/ti-ads1015.c
		* Copyright (c) 2016, Intel Corporation.
		*
		* Datasheet: https://www.ti.com/lit/gpn/ads7924
		*/

		#include <linux/bitfield.h>
		#include <linux/delay.h>
		#include <linux/gpio/consumer.h>
		#include <linux/init.h>
		#include <linux/irq.h>
		#include <linux/i2c.h>
		#include <linux/module.h>
		#include <linux/mutex.h>
		#include <linux/regmap.h>
		#include <linux/regulator/consumer.h>

		#include <linux/iio/iio.h>
		#include <linux/iio/types.h>

		#define ADS7924_CHANNELS 4
		#define ADS7924_BITS 12
		#define ADS7924_DATA_SHIFT 4

		/* Registers. */
		#define ADS7924_MODECNTRL_REG 0x00
		#define ADS7924_INTCNTRL_REG 0x01
		#define ADS7924_DATA0_U_REG 0x02
		#define ADS7924_DATA0_L_REG 0x03
		#define ADS7924_DATA1_U_REG 0x04
		#define ADS7924_DATA1_L_REG 0x05
		#define ADS7924_DATA2_U_REG 0x06
		#define ADS7924_DATA2_L_REG 0x07
		#define ADS7924_DATA3_U_REG 0x08
		#define ADS7924_DATA3_L_REG 0x09
		#define ADS7924_ULR0_REG 0x0A
		#define ADS7924_LLR0_REG 0x0B
		#define ADS7924_ULR1_REG 0x0C
		#define ADS7924_LLR1_REG 0x0D
		#define ADS7924_ULR2_REG 0x0E
		#define ADS7924_LLR2_REG 0x0F
		#define ADS7924_ULR3_REG 0x10
		#define ADS7924_LLR3_REG 0x11
		#define ADS7924_INTCONFIG_REG 0x12
		#define ADS7924_SLPCONFIG_REG 0x13
		#define ADS7924_ACQCONFIG_REG 0x14
		#define ADS7924_PWRCONFIG_REG 0x15
		#define ADS7924_RESET_REG 0x16

		/*
		* Register address INC bit: when set to '1', the register address is
		* automatically incremented after every register read which allows convenient
		* reading of multiple registers. Set INC to '0' when reading a single register.
		*/
		#define ADS7924_AUTO_INCREMENT_BIT BIT(7)

		#define ADS7924_MODECNTRL_MODE_MASK GENMASK(7, 2)

		#define ADS7924_MODECNTRL_SEL_MASK GENMASK(1, 0)

		#define ADS7924_CFG_INTPOL_BIT 1
		#define ADS7924_CFG_INTTRIG_BIT 0

		#define ADS7924_CFG_INTPOL_MASK BIT(ADS7924_CFG_INTPOL_BIT)
		#define ADS7924_CFG_INTTRIG_MASK BIT(ADS7924_CFG_INTTRIG_BIT)

		/* Interrupt pin polarity */
		#define ADS7924_CFG_INTPOL_LOW 0
		#define ADS7924_CFG_INTPOL_HIGH 1

		/* Interrupt pin signaling */
		#define ADS7924_CFG_INTTRIG_LEVEL 0
		#define ADS7924_CFG_INTTRIG_EDGE 1

		/* Mode control values */
		#define ADS7924_MODECNTRL_IDLE 0x00
		#define ADS7924_MODECNTRL_AWAKE 0x20
		#define ADS7924_MODECNTRL_MANUAL_SINGLE 0x30
		#define ADS7924_MODECNTRL_MANUAL_SCAN 0x32
		#define ADS7924_MODECNTRL_AUTO_SINGLE 0x31
		#define ADS7924_MODECNTRL_AUTO_SCAN 0x33
		#define ADS7924_MODECNTRL_AUTO_SINGLE_SLEEP 0x39
		#define ADS7924_MODECNTRL_AUTO_SCAN_SLEEP 0x3B
		#define ADS7924_MODECNTRL_AUTO_BURST_SLEEP 0x3F

		#define ADS7924_ACQTIME_MASK GENMASK(4, 0)

		#define ADS7924_PWRUPTIME_MASK GENMASK(4, 0)

		/*
		* The power-up time is allowed to elapse whenever the device has been shutdown
		* in idle mode. Power-up time can allow external circuits, such as an
		* operational amplifier, between the MUXOUT and ADCIN pins to turn on.
		* The nominal time programmed by the PUTIME[4:0] register bits is given by:
		* t PU = PWRUPTIME[4:0] × 2 μs
		* If a power-up time is not required, set the bits to '0' to effectively bypass.
		*/
		#define ADS7924_PWRUPTIME_US 0 /* Bypass (0us). */

		/*
		* Acquisition Time according to ACQTIME[4:0] register bits.
		* The Acquisition Time is given by:
		* t ACQ = (ACQTIME[4:0] × 2 μs) + 6 μs
		* Using default value of 0 for ACQTIME[4:0] results in a minimum acquisition
		* time of 6us.
		*/
		#define ADS7924_ACQTIME_US 6

		/* The conversion time is always 4μs and cannot be programmed by the user. */
		#define ADS7924_CONVTIME_US 4

		#define ADS7924_TOTAL_CONVTIME_US (ADS7924_PWRUPTIME_US + ADS7924_ACQTIME_US + \
		ADS7924_CONVTIME_US)

		#define ADS7924_V_CHAN(_chan, _addr) { \
		.type = IIO_VOLTAGE, \
		.indexed = 1, \
		.channel = _chan, \
		.address = _addr, \
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
		.datasheet_name = "AIN"#_chan, \
		}

		struct ads7924_data {
		struct device *dev;
		struct regmap *regmap;
		struct regulator *vref_reg;

		/* GPIO descriptor for device hard-reset pin. */
		struct gpio_desc *reset_gpio;

		/*
		* Protects ADC ops, e.g: concurrent sysfs/buffered
		* data reads, configuration updates
		*/
		struct mutex lock;

		/*
		* Set to true when the ADC is switched to the continuous-conversion
		* mode and exits from a power-down state. This flag is used to avoid
		* getting the stale result from the conversion register.
		*/
		bool conv_invalid;
		};

		static bool ads7924_is_writeable_reg(struct device *dev, unsigned int reg)
		{
		switch (reg) {
		case ADS7924_MODECNTRL_REG:
		case ADS7924_INTCNTRL_REG:
		case ADS7924_ULR0_REG:
		case ADS7924_LLR0_REG:
		case ADS7924_ULR1_REG:
		case ADS7924_LLR1_REG:
		case ADS7924_ULR2_REG:
		case ADS7924_LLR2_REG:
		case ADS7924_ULR3_REG:
		case ADS7924_LLR3_REG:
		case ADS7924_INTCONFIG_REG:
		case ADS7924_SLPCONFIG_REG:
		case ADS7924_ACQCONFIG_REG:
		case ADS7924_PWRCONFIG_REG:
		case ADS7924_RESET_REG:
		return true;
		default:
		return false;
		}
		}

		static const struct regmap_config ads7924_regmap_config = {
		.reg_bits = 8,
		.val_bits = 8,
		.max_register = ADS7924_RESET_REG,
		.writeable_reg = ads7924_is_writeable_reg,
		};

		static const struct iio_chan_spec ads7924_channels[] = {
		ADS7924_V_CHAN(0, ADS7924_DATA0_U_REG),
		ADS7924_V_CHAN(1, ADS7924_DATA1_U_REG),
		ADS7924_V_CHAN(2, ADS7924_DATA2_U_REG),
		ADS7924_V_CHAN(3, ADS7924_DATA3_U_REG),
		};

		static int ads7924_get_adc_result(struct ads7924_data *data,
		struct iio_chan_spec const chan, int val)
		{
		int ret;
		__be16 be_val;

		if (chan->channel < 0 \|\| chan->channel >= ADS7924_CHANNELS)
		return -EINVAL;

		if (data->conv_invalid) {
		int conv_time;

		conv_time = ADS7924_TOTAL_CONVTIME_US;
		/* Allow 10% for internal clock inaccuracy. */
		conv_time += conv_time / 10;
		usleep_range(conv_time, conv_time + 1);
		data->conv_invalid = false;
		}

		ret = regmap_raw_read(data->regmap, ADS7924_AUTO_INCREMENT_BIT \|
		chan->address, &be_val, sizeof(be_val));
		if (ret)
		return ret;

		*val = be16_to_cpu(be_val) >> ADS7924_DATA_SHIFT;

		return 0;
		}

		static int ads7924_read_raw(struct iio_dev *indio_dev,
		struct iio_chan_spec const chan, int val,
		int *val2, long mask)
		{
		int ret, vref_uv;
		struct ads7924_data *data = iio_priv(indio_dev);

		switch (mask) {
		case IIO_CHAN_INFO_RAW:
		mutex_lock(&data->lock);
		ret = ads7924_get_adc_result(data, chan, val);
		mutex_unlock(&data->lock);
		if (ret < 0)
		return ret;

		return IIO_VAL_INT;
		case IIO_CHAN_INFO_SCALE:
		vref_uv = regulator_get_voltage(data->vref_reg);
		if (vref_uv < 0)
		return vref_uv;

		val = vref_uv / 1000; / Convert reg voltage to mV */
		*val2 = ADS7924_BITS;
		return IIO_VAL_FRACTIONAL_LOG2;
		default:
		return -EINVAL;
		}
		}

		static const struct iio_info ads7924_info = {
		.read_raw = ads7924_read_raw,
		};

		static int ads7924_get_channels_config(struct i2c_client *client,
		struct iio_dev *indio_dev)
		{
		struct ads7924_data *priv = iio_priv(indio_dev);
		struct device *dev = priv->dev;
		struct fwnode_handle *node;
		int num_channels = 0;

		device_for_each_child_node(dev, node) {
		u32 pval;
		unsigned int channel;

		if (fwnode_property_read_u32(node, "reg", &pval)) {
		dev_err(dev, "invalid reg on %pfw\n", node);
		continue;
		}

		channel = pval;
		if (channel >= ADS7924_CHANNELS) {
		dev_err(dev, "invalid channel index %d on %pfw\n",
		channel, node);
		continue;
		}

		num_channels++;
		}

		if (!num_channels)
		return -EINVAL;

		return 0;
		}

		static int ads7924_set_conv_mode(struct ads7924_data *data, int mode)
		{
		int ret;
		unsigned int mode_field;
		struct device *dev = data->dev;

		/*
		* When switching between modes, be sure to first select the Awake mode
		* and then switch to the desired mode. This procedure ensures the
		* internal control logic is properly synchronized.
		*/
		if (mode != ADS7924_MODECNTRL_IDLE) {
		mode_field = FIELD_PREP(ADS7924_MODECNTRL_MODE_MASK,
		ADS7924_MODECNTRL_AWAKE);

		ret = regmap_update_bits(data->regmap, ADS7924_MODECNTRL_REG,
		ADS7924_MODECNTRL_MODE_MASK,
		mode_field);
		if (ret) {
		dev_err(dev, "failed to set awake mode (%pe)\n",
		ERR_PTR(ret));
		return ret;
		}
		}

		mode_field = FIELD_PREP(ADS7924_MODECNTRL_MODE_MASK, mode);

		ret = regmap_update_bits(data->regmap, ADS7924_MODECNTRL_REG,
		ADS7924_MODECNTRL_MODE_MASK, mode_field);
		if (ret)
		dev_err(dev, "failed to set mode %d (%pe)\n", mode,
		ERR_PTR(ret));

		return ret;
		}

		static int ads7924_reset(struct iio_dev *indio_dev)
		{
		struct ads7924_data *data = iio_priv(indio_dev);

		if (data->reset_gpio) {
		gpiod_set_value(data->reset_gpio, 1); /* Assert. */
		/* Educated guess: assert time not specified in datasheet... */
		mdelay(100);
		gpiod_set_value(data->reset_gpio, 0); /* Deassert. */
		return 0;
		}

		/*
		* A write of 10101010 to this register will generate a
		* software reset of the ADS7924.
		*/
		return regmap_write(data->regmap, ADS7924_RESET_REG, 0b10101010);
		};

		static void ads7924_reg_disable(void *data)
		{
		regulator_disable(data);
		}

		static void ads7924_set_idle_mode(void *data)
		{
		ads7924_set_conv_mode(data, ADS7924_MODECNTRL_IDLE);
		}

		static int ads7924_probe(struct i2c_client *client)
		{
		struct iio_dev *indio_dev;
		struct ads7924_data *data;
		struct device *dev = &client->dev;
		int ret;

		indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
		if (!indio_dev)
		return dev_err_probe(dev, -ENOMEM,
		"failed to allocate iio device\n");

		data = iio_priv(indio_dev);

		data->dev = dev;

		/* Initialize the reset GPIO as output with an initial value of 0. */
		data->reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW);
		if (IS_ERR(data->reset_gpio))
		return dev_err_probe(dev, PTR_ERR(data->reset_gpio),
		"failed to get request reset GPIO\n");

		mutex_init(&data->lock);

		indio_dev->name = "ads7924";
		indio_dev->modes = INDIO_DIRECT_MODE;

		indio_dev->channels = ads7924_channels;
		indio_dev->num_channels = ARRAY_SIZE(ads7924_channels);
		indio_dev->info = &ads7924_info;

		ret = ads7924_get_channels_config(client, indio_dev);
		if (ret < 0)
		return dev_err_probe(dev, ret,
		"failed to get channels configuration\n");

		data->regmap = devm_regmap_init_i2c(client, &ads7924_regmap_config);
		if (IS_ERR(data->regmap))
		return dev_err_probe(dev, PTR_ERR(data->regmap),
		"failed to init regmap\n");

		data->vref_reg = devm_regulator_get(dev, "vref");
		if (IS_ERR(data->vref_reg))
		return dev_err_probe(dev, PTR_ERR(data->vref_reg),
		"failed to get vref regulator\n");

		ret = regulator_enable(data->vref_reg);
		if (ret)
		return dev_err_probe(dev, ret,
		"failed to enable regulator\n");

		ret = devm_add_action_or_reset(dev, ads7924_reg_disable, data->vref_reg);
		if (ret)
		return dev_err_probe(dev, ret,
		"failed to add regulator disable action\n");

		ret = ads7924_reset(indio_dev);
		if (ret < 0)
		return dev_err_probe(dev, ret,
		"failed to reset device\n");

		ret = ads7924_set_conv_mode(data, ADS7924_MODECNTRL_AUTO_SCAN);
		if (ret)
		return dev_err_probe(dev, ret,
		"failed to set conversion mode\n");

		ret = devm_add_action_or_reset(dev, ads7924_set_idle_mode, data);
		if (ret)
		return dev_err_probe(dev, ret,
		"failed to add idle mode action\n");

		/* Use minimum signal acquire time. */
		ret = regmap_update_bits(data->regmap, ADS7924_ACQCONFIG_REG,
		ADS7924_ACQTIME_MASK,
		FIELD_PREP(ADS7924_ACQTIME_MASK, 0));
		if (ret < 0)
		return dev_err_probe(dev, ret,
		"failed to configure signal acquire time\n");

		/* Disable power-up time. */
		ret = regmap_update_bits(data->regmap, ADS7924_PWRCONFIG_REG,
		ADS7924_PWRUPTIME_MASK,
		FIELD_PREP(ADS7924_PWRUPTIME_MASK, 0));
		if (ret < 0)
		return dev_err_probe(dev, ret,
		"failed to configure power-up time\n");

		data->conv_invalid = true;

		ret = devm_iio_device_register(dev, indio_dev);
		if (ret < 0)
		return dev_err_probe(dev, ret,
		"failed to register IIO device\n");

		return 0;
		}

		static const struct i2c_device_id ads7924_id[] = {
		{ "ads7924", 0 },
		{}
		};
		MODULE_DEVICE_TABLE(i2c, ads7924_id);

		static const struct of_device_id ads7924_of_match[] = {
		{ .compatible = "ti,ads7924", },
		{}
		};
		MODULE_DEVICE_TABLE(of, ads7924_of_match);

		static struct i2c_driver ads7924_driver = {
		.driver = {
		.name = "ads7924",
		.of_match_table = ads7924_of_match,
		},
		.probe_new = ads7924_probe,
		.id_table = ads7924_id,
		};

		module_i2c_driver(ads7924_driver);

		MODULE_AUTHOR("Hugo Villeneuve <hvilleneuve@dimonoff.com>");
		MODULE_DESCRIPTION("Texas Instruments ADS7924 ADC I2C driver");
		MODULE_LICENSE("GPL");