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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * ltc2485.c - Driver for Linear Technology LTC2485 ADC4 *5 * Copyright (C) 2016 Alison Schofield <amsfield22@gmail.com>6 *7 * Datasheet: http://cds.linear.com/docs/en/datasheet/2485fd.pdf8 */9 10#include <linux/delay.h>11#include <linux/i2c.h>12#include <linux/module.h>13 14#include <linux/iio/iio.h>15#include <linux/iio/sysfs.h>16 17/* Power-on configuration: rejects both 50/60Hz, operates at 1x speed */18#define LTC2485_CONFIG_DEFAULT 019 20struct ltc2485_data {21 struct i2c_client *client;22 ktime_t time_prev; /* last conversion */23};24 25static void ltc2485_wait_conv(struct ltc2485_data *data)26{27 const unsigned int conv_time = 147; /* conversion time ms */28 unsigned int time_elapsed;29 30 /* delay if conversion time not passed since last read or write */31 time_elapsed = ktime_ms_delta(ktime_get(), data->time_prev);32 33 if (time_elapsed < conv_time)34 msleep(conv_time - time_elapsed);35}36 37static int ltc2485_read(struct ltc2485_data *data, int *val)38{39 struct i2c_client *client = data->client;40 __be32 buf = 0;41 int ret;42 43 ltc2485_wait_conv(data);44 45 ret = i2c_master_recv(client, (char *)&buf, 4);46 if (ret < 0) {47 dev_err(&client->dev, "i2c_master_recv failed\n");48 return ret;49 }50 data->time_prev = ktime_get();51 *val = sign_extend32(be32_to_cpu(buf) >> 6, 24);52 53 return ret;54}55 56static int ltc2485_read_raw(struct iio_dev *indio_dev,57 struct iio_chan_spec const *chan,58 int *val, int *val2, long mask)59{60 struct ltc2485_data *data = iio_priv(indio_dev);61 int ret;62 63 if (mask == IIO_CHAN_INFO_RAW) {64 ret = ltc2485_read(data, val);65 if (ret < 0)66 return ret;67 68 return IIO_VAL_INT;69 70 } else if (mask == IIO_CHAN_INFO_SCALE) {71 *val = 5000; /* on board vref millivolts */72 *val2 = 25; /* 25 (24 + sign) data bits */73 return IIO_VAL_FRACTIONAL_LOG2;74 75 } else {76 return -EINVAL;77 }78}79 80static const struct iio_chan_spec ltc2485_channel[] = {81 {82 .type = IIO_VOLTAGE,83 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),84 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE)85 },86};87 88static const struct iio_info ltc2485_info = {89 .read_raw = ltc2485_read_raw,90};91 92static int ltc2485_probe(struct i2c_client *client)93{94 const struct i2c_device_id *id = i2c_client_get_device_id(client);95 struct iio_dev *indio_dev;96 struct ltc2485_data *data;97 int ret;98 99 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |100 I2C_FUNC_SMBUS_WRITE_BYTE))101 return -EOPNOTSUPP;102 103 indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));104 if (!indio_dev)105 return -ENOMEM;106 107 data = iio_priv(indio_dev);108 i2c_set_clientdata(client, indio_dev);109 data->client = client;110 111 indio_dev->name = id->name;112 indio_dev->info = <c2485_info;113 indio_dev->modes = INDIO_DIRECT_MODE;114 indio_dev->channels = ltc2485_channel;115 indio_dev->num_channels = ARRAY_SIZE(ltc2485_channel);116 117 ret = i2c_smbus_write_byte(data->client, LTC2485_CONFIG_DEFAULT);118 if (ret < 0)119 return ret;120 121 data->time_prev = ktime_get();122 123 return devm_iio_device_register(&client->dev, indio_dev);124}125 126static const struct i2c_device_id ltc2485_id[] = {127 { "ltc2485" },128 { }129};130MODULE_DEVICE_TABLE(i2c, ltc2485_id);131 132static struct i2c_driver ltc2485_driver = {133 .driver = {134 .name = "ltc2485",135 },136 .probe = ltc2485_probe,137 .id_table = ltc2485_id,138};139module_i2c_driver(ltc2485_driver);140 141MODULE_AUTHOR("Alison Schofield <amsfield22@gmail.com>");142MODULE_DESCRIPTION("Linear Technology LTC2485 ADC driver");143MODULE_LICENSE("GPL v2");144