Commit 2187cfeb authored by Ciprian Regus's avatar Ciprian Regus Committed by Jonathan Cameron
Browse files

drivers: iio: adc: ltc2497: LTC2499 support 

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: default avatarCiprian Regus <ciprian.regus@analog.com>
Link: https://lore.kernel.org/r/20220916140922.2506248-5-ciprian.regus@analog.com


Signed-off-by: default avatarJonathan Cameron <Jonathan.Cameron@huawei.com>
parent cc6fbf26

drivers/iio/adc/ltc2496.c

+7 −1
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ 
#include <linux/iio/driver.h>

#include <linux/module.h>

#include <linux/mod_devicetable.h>

#include <linux/property.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 const struct ltc2497_chip_info ltc2496_info = {

	.resolution = 16,

};



static const struct of_device_id ltc2496_of_match[] = {

	{ .compatible = "lltc,ltc2496", },

	{ .compatible = "lltc,ltc2496", .data = &ltc2496_info, },

	{},

};

MODULE_DEVICE_TABLE(of, ltc2496_of_match);

drivers/iio/adc/ltc2497-core.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

drivers/iio/adc/ltc2497.c

+57 −5
Original line number Diff line number Diff line
@@ -12,18 +12,31 @@ 
#include <linux/iio/driver.h>

#include <linux/module.h>

#include <linux/mod_devicetable.h>

#include <linux/property.h>



#include <asm/unaligned.h>



#include "ltc2497.h"



enum ltc2497_chip_type {

	TYPE_LTC2497,

	TYPE_LTC2499,

};



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.

	 */

	__be32 buf __aligned(IIO_DMA_MINALIGN);

	union {

		__be32 d32;

		u8 d8[3];

	} data __aligned(IIO_DMA_MINALIGN);

};



static int ltc2497_result_and_measure(struct ltc2497core_driverdata *ddata,
@@ -34,13 +47,30 @@ static int ltc2497_result_and_measure(struct ltc2497core_driverdata *ddata, 
	int ret;



	if (val) {

		ret = i2c_master_recv(st->client, (char *)&st->buf, 3);

		if (st->recv_size == 3)

			ret = i2c_master_recv(st->client, (char *)&st->data.d8,

					      st->recv_size);

		else

			ret = i2c_master_recv(st->client, (char *)&st->data.d32,

					      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);

		/*

		 * The data format is 16/24 bit 2s complement, but with an upper sign bit on the

		 * resolution + 1 position, which is set for positive values only. Given this

		 * bit's value, subtracting BIT(resolution + 1) from the ADC's result is

		 * equivalent to a sign extension.

		 */

		if (st->recv_size == 3) {

			*val = (get_unaligned_be24(st->data.d8) >> st->sub_lsb)

				- BIT(ddata->chip_info->resolution + 1);

		} else {

			*val = (be32_to_cpu(st->data.d32) >> st->sub_lsb)

				- BIT(ddata->chip_info->resolution + 1);

		}



		/*

		 * The part started a new conversion at the end of the above i2c
@@ -67,9 +97,11 @@ static int ltc2497_result_and_measure(struct ltc2497core_driverdata *ddata, 
static int ltc2497_probe(struct i2c_client *client,

			 const struct i2c_device_id *id)

{

	const struct ltc2497_chip_info *chip_info;

	struct iio_dev *indio_dev;

	struct ltc2497_driverdata *st;

	struct device *dev = &client->dev;

	u32 resolution;



	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |

				     I2C_FUNC_SMBUS_WRITE_BYTE))
@@ -84,6 +116,15 @@ static int ltc2497_probe(struct i2c_client *client, 
	st->client = client;

	st->common_ddata.result_and_measure = ltc2497_result_and_measure;



	chip_info = device_get_match_data(dev);

	if (!chip_info)

		chip_info = (const struct ltc2497_chip_info *)id->driver_data;

	st->common_ddata.chip_info = chip_info;



	resolution = chip_info->resolution;

	st->sub_lsb = 31 - (resolution + 1);

	st->recv_size = BITS_TO_BYTES(resolution) + 1;



	return ltc2497core_probe(dev, indio_dev);

}
@@ -96,14 +137,25 @@ static int ltc2497_remove(struct i2c_client *client) 
	return 0;

}



static const struct ltc2497_chip_info ltc2497_info[] = {

	[TYPE_LTC2497] = {

		.resolution = 16,

	},

	[TYPE_LTC2499] = {

		.resolution = 24,

	},

};



static const struct i2c_device_id ltc2497_id[] = {

	{ "ltc2497", 0 },

	{ "ltc2497", (kernel_ulong_t)&ltc2497_info[TYPE_LTC2497] },

	{ "ltc2499", (kernel_ulong_t)&ltc2497_info[TYPE_LTC2499] },

	{ }

};

MODULE_DEVICE_TABLE(i2c, ltc2497_id);



static const struct of_device_id ltc2497_of_match[] = {

	{ .compatible = "lltc,ltc2497", },

	{ .compatible = "lltc,ltc2497", .data = &ltc2497_info[TYPE_LTC2497] },

	{ .compatible = "lltc,ltc2499", .data = &ltc2497_info[TYPE_LTC2499] },

	{},

};

MODULE_DEVICE_TABLE(of, ltc2497_of_match);

drivers/iio/adc/ltc2497.h

+5 −0
Original line number Diff line number Diff line
@@ -4,9 +4,14 @@ 
#define LTC2497_CONFIG_DEFAULT		LTC2497_ENABLE

#define LTC2497_CONVERSION_TIME_MS	150ULL



struct ltc2497_chip_info {

	u32 resolution;

};



struct ltc2497core_driverdata {

	struct regulator *ref;

	ktime_t	time_prev;

	const struct ltc2497_chip_info	*chip_info;

	u8 addr_prev;

	int (*result_and_measure)(struct ltc2497core_driverdata *ddata,

				  u8 address, int *val);