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linux-zen-server/drivers/iio/adc/ti-ads7924.c

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Initial commit
2023-08-30 17:53:23 +02:00
// 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");