Thomas Gleixner | 3e5580c | 2019-05-29 07:12:27 -0700 | [diff] [blame] | 1 | // SPDX-License-Identifier: GPL-2.0-only |
Mike Looijmans | 1d3eacb | 2017-07-03 08:25:57 +0200 | [diff] [blame] | 2 | /* |
| 3 | * Driver for Linear Technology LTC2471 and LTC2473 voltage monitors |
| 4 | * The LTC2473 is identical to the 2471, but reports a differential signal. |
| 5 | * |
| 6 | * Copyright (C) 2017 Topic Embedded Products |
| 7 | * Author: Mike Looijmans <mike.looijmans@topic.nl> |
Mike Looijmans | 1d3eacb | 2017-07-03 08:25:57 +0200 | [diff] [blame] | 8 | */ |
| 9 | |
| 10 | #include <linux/err.h> |
| 11 | #include <linux/i2c.h> |
| 12 | #include <linux/kernel.h> |
| 13 | #include <linux/module.h> |
| 14 | #include <linux/iio/iio.h> |
| 15 | #include <linux/iio/sysfs.h> |
| 16 | |
| 17 | enum ltc2471_chips { |
| 18 | ltc2471, |
| 19 | ltc2473, |
| 20 | }; |
| 21 | |
| 22 | struct ltc2471_data { |
| 23 | struct i2c_client *client; |
| 24 | }; |
| 25 | |
| 26 | /* Reference voltage is 1.25V */ |
| 27 | #define LTC2471_VREF 1250 |
| 28 | |
| 29 | /* Read two bytes from the I2C bus to obtain the ADC result */ |
| 30 | static int ltc2471_get_value(struct i2c_client *client) |
| 31 | { |
| 32 | int ret; |
| 33 | __be16 buf; |
| 34 | |
| 35 | ret = i2c_master_recv(client, (char *)&buf, sizeof(buf)); |
| 36 | if (ret < 0) |
| 37 | return ret; |
| 38 | if (ret != sizeof(buf)) |
| 39 | return -EIO; |
| 40 | |
| 41 | /* MSB first */ |
| 42 | return be16_to_cpu(buf); |
| 43 | } |
| 44 | |
| 45 | static int ltc2471_read_raw(struct iio_dev *indio_dev, |
| 46 | struct iio_chan_spec const *chan, |
| 47 | int *val, int *val2, long info) |
| 48 | { |
| 49 | struct ltc2471_data *data = iio_priv(indio_dev); |
| 50 | int ret; |
| 51 | |
| 52 | switch (info) { |
| 53 | case IIO_CHAN_INFO_RAW: |
| 54 | ret = ltc2471_get_value(data->client); |
| 55 | if (ret < 0) |
| 56 | return ret; |
| 57 | *val = ret; |
| 58 | return IIO_VAL_INT; |
| 59 | |
| 60 | case IIO_CHAN_INFO_SCALE: |
| 61 | if (chan->differential) |
| 62 | /* Output ranges from -VREF to +VREF */ |
| 63 | *val = 2 * LTC2471_VREF; |
| 64 | else |
| 65 | /* Output ranges from 0 to VREF */ |
| 66 | *val = LTC2471_VREF; |
| 67 | *val2 = 16; /* 16 data bits */ |
| 68 | return IIO_VAL_FRACTIONAL_LOG2; |
| 69 | |
| 70 | case IIO_CHAN_INFO_OFFSET: |
| 71 | /* Only differential chip has this property */ |
| 72 | *val = -LTC2471_VREF; |
| 73 | return IIO_VAL_INT; |
| 74 | |
| 75 | default: |
| 76 | return -EINVAL; |
| 77 | } |
| 78 | } |
| 79 | |
| 80 | static const struct iio_chan_spec ltc2471_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 | |
| 88 | static const struct iio_chan_spec ltc2473_channel[] = { |
| 89 | { |
| 90 | .type = IIO_VOLTAGE, |
| 91 | .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), |
| 92 | .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) | |
| 93 | BIT(IIO_CHAN_INFO_OFFSET), |
| 94 | .differential = 1, |
| 95 | }, |
| 96 | }; |
| 97 | |
| 98 | static const struct iio_info ltc2471_info = { |
| 99 | .read_raw = ltc2471_read_raw, |
Mike Looijmans | 1d3eacb | 2017-07-03 08:25:57 +0200 | [diff] [blame] | 100 | }; |
| 101 | |
| 102 | static int ltc2471_i2c_probe(struct i2c_client *client, |
| 103 | const struct i2c_device_id *id) |
| 104 | { |
| 105 | struct iio_dev *indio_dev; |
| 106 | struct ltc2471_data *data; |
| 107 | int ret; |
| 108 | |
| 109 | if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) |
| 110 | return -EOPNOTSUPP; |
| 111 | |
| 112 | indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data)); |
| 113 | if (!indio_dev) |
| 114 | return -ENOMEM; |
| 115 | |
| 116 | data = iio_priv(indio_dev); |
| 117 | data->client = client; |
| 118 | |
Mike Looijmans | 1d3eacb | 2017-07-03 08:25:57 +0200 | [diff] [blame] | 119 | indio_dev->name = id->name; |
| 120 | indio_dev->info = <c2471_info; |
| 121 | indio_dev->modes = INDIO_DIRECT_MODE; |
| 122 | if (id->driver_data == ltc2473) |
| 123 | indio_dev->channels = ltc2473_channel; |
| 124 | else |
| 125 | indio_dev->channels = ltc2471_channel; |
| 126 | indio_dev->num_channels = 1; |
| 127 | |
| 128 | /* Trigger once to start conversion and check if chip is there */ |
| 129 | ret = ltc2471_get_value(client); |
| 130 | if (ret < 0) { |
| 131 | dev_err(&client->dev, "Cannot read from device.\n"); |
| 132 | return ret; |
| 133 | } |
| 134 | |
| 135 | return devm_iio_device_register(&client->dev, indio_dev); |
| 136 | } |
| 137 | |
| 138 | static const struct i2c_device_id ltc2471_i2c_id[] = { |
| 139 | { "ltc2471", ltc2471 }, |
| 140 | { "ltc2473", ltc2473 }, |
| 141 | {} |
| 142 | }; |
| 143 | MODULE_DEVICE_TABLE(i2c, ltc2471_i2c_id); |
| 144 | |
| 145 | static struct i2c_driver ltc2471_i2c_driver = { |
| 146 | .driver = { |
| 147 | .name = "ltc2471", |
| 148 | }, |
| 149 | .probe = ltc2471_i2c_probe, |
| 150 | .id_table = ltc2471_i2c_id, |
| 151 | }; |
| 152 | |
| 153 | module_i2c_driver(ltc2471_i2c_driver); |
| 154 | |
| 155 | MODULE_DESCRIPTION("LTC2471/LTC2473 ADC driver"); |
| 156 | MODULE_AUTHOR("Topic Embedded Products"); |
| 157 | MODULE_LICENSE("GPL v2"); |