[PATCH 2/3] drivers: iio: adc: LTC2499 support

From: Ciprian Regus
Date: Mon Aug 22 2022 - 08:52:57 EST


The LTC2499 is a 16-channel (eight differential), 24-bit,
ADC with Easy Drive technology and a 2-wire, I2C interface.

Implement support for the LTC2499 ADC by extending the LTC2497
driver. A new chip_info struct is added to differentiate between
chip types and resolutions when reading data from the device.

Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/2499fe.pdf

Signed-off-by: Ciprian Regus <ciprian.regus@xxxxxxxxxx>
---
drivers/iio/adc/ltc2496.c | 8 +++++++-
drivers/iio/adc/ltc2497-core.c | 2 +-
drivers/iio/adc/ltc2497.c | 34 +++++++++++++++++++++++++++++-----
drivers/iio/adc/ltc2497.h | 13 ++++++++++++-
4 files changed, 49 insertions(+), 8 deletions(-)

diff --git a/drivers/iio/adc/ltc2496.c b/drivers/iio/adc/ltc2496.c
index dfb3bb5997e5..98338104c24a 100644
--- a/drivers/iio/adc/ltc2496.c
+++ b/drivers/iio/adc/ltc2496.c
@@ -14,6 +14,7 @@
#include <linux/iio/iio.h>
#include <linux/iio/driver.h>
#include <linux/module.h>
+#include <linux/property.h>
#include <linux/mod_devicetable.h>

#include "ltc2497.h"
@@ -74,6 +75,7 @@ static int ltc2496_probe(struct spi_device *spi)
spi_set_drvdata(spi, indio_dev);
st->spi = spi;
st->common_ddata.result_and_measure = ltc2496_result_and_measure;
+ st->common_ddata.chip_info = device_get_match_data(dev);

return ltc2497core_probe(dev, indio_dev);
}
@@ -85,8 +87,12 @@ static void ltc2496_remove(struct spi_device *spi)
ltc2497core_remove(indio_dev);
}

+static struct chip_info ltc2496_info = {
+ .resolution = 16,
+};
+
static const struct of_device_id ltc2496_of_match[] = {
- { .compatible = "lltc,ltc2496", },
+ { .compatible = "lltc,ltc2496", .data = (void *)&ltc2496_info },
{},
};
MODULE_DEVICE_TABLE(of, ltc2496_of_match);
diff --git a/drivers/iio/adc/ltc2497-core.c b/drivers/iio/adc/ltc2497-core.c
index 2a485c8a1940..b2752399402c 100644
--- a/drivers/iio/adc/ltc2497-core.c
+++ b/drivers/iio/adc/ltc2497-core.c
@@ -95,7 +95,7 @@ static int ltc2497core_read_raw(struct iio_dev *indio_dev,
return ret;

*val = ret / 1000;
- *val2 = 17;
+ *val2 = ddata->chip_info->resolution + 1;

return IIO_VAL_FRACTIONAL_LOG2;

diff --git a/drivers/iio/adc/ltc2497.c b/drivers/iio/adc/ltc2497.c
index f7c786f37ceb..bb5e0d4301e2 100644
--- a/drivers/iio/adc/ltc2497.c
+++ b/drivers/iio/adc/ltc2497.c
@@ -7,10 +7,14 @@
* Datasheet: http://cds.linear.com/docs/en/datasheet/2497fd.pdf
*/

+#include <linux/bitfield.h>
+#include <linux/bitops.h>
+
#include <linux/i2c.h>
#include <linux/iio/iio.h>
#include <linux/iio/driver.h>
#include <linux/module.h>
+#include <linux/property.h>
#include <linux/mod_devicetable.h>

#include "ltc2497.h"
@@ -19,6 +23,8 @@ struct ltc2497_driverdata {
/* this must be the first member */
struct ltc2497core_driverdata common_ddata;
struct i2c_client *client;
+ u32 recv_size;
+ u32 sub_lsb;
/*
* DMA (thus cache coherency maintenance) may require the
* transfer buffers to live in their own cache lines.
@@ -34,13 +40,14 @@ static int ltc2497_result_and_measure(struct ltc2497core_driverdata *ddata,
int ret;

if (val) {
- ret = i2c_master_recv(st->client, (char *)&st->buf, 3);
+ ret = i2c_master_recv(st->client, (char *)&st->buf, st->recv_size);
if (ret < 0) {
dev_err(&st->client->dev, "i2c_master_recv failed\n");
return ret;
}

- *val = (be32_to_cpu(st->buf) >> 14) - (1 << 17);
+ *val = (be32_to_cpu(st->buf) >> st->sub_lsb) -
+ BIT(ddata->chip_info->resolution + 1);
}

ret = i2c_smbus_write_byte(st->client,
@@ -54,6 +61,7 @@ static int ltc2497_result_and_measure(struct ltc2497core_driverdata *ddata,
static int ltc2497_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
+ u32 resolution;
struct iio_dev *indio_dev;
struct ltc2497_driverdata *st;
struct device *dev = &client->dev;
@@ -70,6 +78,11 @@ static int ltc2497_probe(struct i2c_client *client,
i2c_set_clientdata(client, indio_dev);
st->client = client;
st->common_ddata.result_and_measure = ltc2497_result_and_measure;
+ st->common_ddata.chip_info = device_get_match_data(dev);
+
+ resolution = st->common_ddata.chip_info->resolution;
+ st->sub_lsb = 31 - (resolution + 1);
+ st->recv_size = resolution / BITS_PER_BYTE + 1;

return ltc2497core_probe(dev, indio_dev);
}
@@ -83,15 +96,26 @@ static int ltc2497_remove(struct i2c_client *client)
return 0;
}

+static struct chip_info ltc2497_info[] = {
+ [TYPE_LTC2497] = {
+ .resolution = 16,
+ },
+ [TYPE_LTC2499] = {
+ .resolution = 24,
+ }
+};
+
static const struct i2c_device_id ltc2497_id[] = {
- { "ltc2497", 0 },
+ { "ltc2497", TYPE_LTC2497 },
+ { "ltc2499", TYPE_LTC2499 },
{ }
};
MODULE_DEVICE_TABLE(i2c, ltc2497_id);

static const struct of_device_id ltc2497_of_match[] = {
- { .compatible = "lltc,ltc2497", },
- {},
+ { .compatible = "lltc,ltc2497", .data = (void *)&ltc2497_info[TYPE_LTC2497] },
+ { .compatible = "lltc,ltc2499", .data = (void *)&ltc2497_info[TYPE_LTC2499] },
+ {}
};
MODULE_DEVICE_TABLE(of, ltc2497_of_match);

diff --git a/drivers/iio/adc/ltc2497.h b/drivers/iio/adc/ltc2497.h
index d0b42dd6b8ad..f4d939cfd48b 100644
--- a/drivers/iio/adc/ltc2497.h
+++ b/drivers/iio/adc/ltc2497.h
@@ -4,9 +4,20 @@
#define LTC2497_CONFIG_DEFAULT LTC2497_ENABLE
#define LTC2497_CONVERSION_TIME_MS 150ULL

+enum chip_type {
+ TYPE_LTC2496,
+ TYPE_LTC2497,
+ TYPE_LTC2499
+};
+
+struct chip_info {
+ u32 resolution;
+};
+
struct ltc2497core_driverdata {
struct regulator *ref;
- ktime_t time_prev;
+ ktime_t time_prev;
+ const struct chip_info *chip_info;
u8 addr_prev;
int (*result_and_measure)(struct ltc2497core_driverdata *ddata,
u8 address, int *val);
--
2.30.2