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linux/drivers/iio/adc/ti-lmp92064.c
Leonard Göhrs 6c7bc1d27b iio: adc: ti-lmp92064: add buffering support 
Enable buffered reading of samples from the LMP92064 ADC.
The main benefit of this change is being able to read out current and
voltage measurements in a single transfer, allowing instantaneous power
measurements.

Reads into the buffer can be triggered by any software triggers, e.g.
the iio-trig-hrtimer:

    $ mkdir /sys/kernel/config/iio/triggers/hrtimer/my-trigger
    $ cat /sys/bus/iio/devices/iio\:device3/name
    lmp92064
    $ iio_readdev -t my-trigger -b 16 iio:device3 | hexdump
    WARNING: High-speed mode not enabled
    0000000 0000 0176 0101 0001 5507 abd5 7645 1768
    0000010 0000 016d 0101 0001 ee1e ac6b 7645 1768
    ...

Signed-off-by: Leonard Göhrs <l.goehrs@pengutronix.de>
Reviewed-by: Nuno Sa <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20230707063635.1496437-1-l.goehrs@pengutronix.de
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
2023-07-20 19:21:30 +01:00

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// 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/buffer.h>
#include <linux/iio/driver.h>
#include <linux/iio/triggered_buffer.h>
#include <linux/iio/trigger_consumer.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),
.scan_index = TI_LMP92064_CHAN_INC,
.scan_type = {
.sign = 'u',
.realbits = 12,
.storagebits = 16,
},
.datasheet_name = "INC",
},
{
.type = IIO_VOLTAGE,
.address = TI_LMP92064_CHAN_INV,
.info_mask_separate =
BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
.scan_index = TI_LMP92064_CHAN_INV,
.scan_type = {
.sign = 'u',
.realbits = 12,
.storagebits = 16,
},
.datasheet_name = "INV",
},
IIO_CHAN_SOFT_TIMESTAMP(2),
};
static const unsigned long lmp92064_scan_masks[] = {
BIT(TI_LMP92064_CHAN_INC) | BIT(TI_LMP92064_CHAN_INV),
0
};
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 irqreturn_t lmp92064_trigger_handler(int irq, void *p)
{
struct iio_poll_func *pf = p;
struct iio_dev *indio_dev = pf->indio_dev;
struct lmp92064_adc_priv *priv = iio_priv(indio_dev);
struct {
u16 values[2];
int64_t timestamp __aligned(8);
} data;
int ret;
memset(&data, 0, sizeof(data));
ret = lmp92064_read_meas(priv, data.values);
if (ret)
goto err;
iio_push_to_buffers_with_timestamp(indio_dev, &data,
iio_get_time_ns(indio_dev));
err:
iio_trigger_notify_done(indio_dev->trig);
return IRQ_HANDLED;
}
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;
indio_dev->available_scan_masks = lmp92064_scan_masks;
ret = devm_iio_triggered_buffer_setup(dev, indio_dev, NULL,
lmp92064_trigger_handler, NULL);
if (ret)
return dev_err_probe(dev, ret, "Failed to setup buffered read\n");
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");
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