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// SPDX-License-Identifier: GPL-2.0-only
/*
* ltc2497.c - Driver for Analog Devices/Linear Technology LTC2497 ADC
*
* Copyright (C) 2017 Analog Devices Inc.
*
* Datasheet: http://cds.linear.com/docs/en/datasheet/2497fd.pdf
*/
#include <linux/i2c.h>
#include <linux/iio/iio.h>
#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.
*/
union {
__be32 d32;
u8 d8[3];
} data __aligned(IIO_DMA_MINALIGN);
};
static int ltc2497_result_and_measure(struct ltc2497core_driverdata *ddata,
u8 address, int *val)
{
struct ltc2497_driverdata *st =
container_of(ddata, struct ltc2497_driverdata, common_ddata);
int ret;
if (val) {
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;
}
/*
* 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
* transfer, so if the address didn't change since the last call
* everything is fine and we can return early.
* If not (which should only happen when some sort of bulk
* conversion is implemented) we have to program the new
* address. Note that this probably fails as the conversion that
* was triggered above is like not complete yet and the two
* operations have to be done in a single transfer.
*/
if (ddata->addr_prev == address)
return 0;
}
ret = i2c_smbus_write_byte(st->client,
LTC2497_ENABLE | address);
if (ret)
dev_err(&st->client->dev, "i2c transfer failed: %pe\n",
ERR_PTR(ret));
return ret;
}
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))
return -EOPNOTSUPP;
indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
if (!indio_dev)
return -ENOMEM;
st = iio_priv(indio_dev);
i2c_set_clientdata(client, indio_dev);
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);
}
static void ltc2497_remove(struct i2c_client *client)
{
struct iio_dev *indio_dev = i2c_get_clientdata(client);
ltc2497core_remove(indio_dev);
}
static const struct ltc2497_chip_info ltc2497_info[] = {
[TYPE_LTC2497] = {
.resolution = 16,
.name = NULL,
},
[TYPE_LTC2499] = {
.resolution = 24,
.name = "ltc2499",
},
};
static const struct i2c_device_id ltc2497_id[] = {
{ "ltc2497", (kernel_ulong_t)<c2497_info[TYPE_LTC2497] },
{ "ltc2499", (kernel_ulong_t)<c2497_info[TYPE_LTC2499] },
{ }
};
MODULE_DEVICE_TABLE(i2c, ltc2497_id);
static const struct of_device_id ltc2497_of_match[] = {
{ .compatible = "lltc,ltc2497", .data = <c2497_info[TYPE_LTC2497] },
{ .compatible = "lltc,ltc2499", .data = <c2497_info[TYPE_LTC2499] },
{},
};
MODULE_DEVICE_TABLE(of, ltc2497_of_match);
static struct i2c_driver ltc2497_driver = {
.driver = {
.name = "ltc2497",
.of_match_table = ltc2497_of_match,
},
.probe = ltc2497_probe,
.remove = ltc2497_remove,
.id_table = ltc2497_id,
};
module_i2c_driver(ltc2497_driver);
MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
MODULE_DESCRIPTION("Linear Technology LTC2497 ADC driver");
MODULE_LICENSE("GPL v2");
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