1 /*
2  * tpl0102.c - Support for Texas Instruments digital potentiometers
3  *
4  * Copyright (C) 2016 Matt Ranostay <mranostay@gmail.com>
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License as published by
8  * the Free Software Foundation; either version 2 of the License, or
9  * (at your option) any later version.
10  *
11  * This program is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14  * GNU General Public License for more details.
15  *
16  * TODO: enable/disable hi-z output control
17  */
18 
19 #include <linux/module.h>
20 #include <linux/i2c.h>
21 #include <linux/regmap.h>
22 #include <linux/iio/iio.h>
23 
24 struct tpl0102_cfg {
25 	int wipers;
26 	int max_pos;
27 	int kohms;
28 };
29 
30 enum tpl0102_type {
31 	CAT5140_503,
32 	CAT5140_104,
33 	TPL0102_104,
34 	TPL0401_103,
35 };
36 
37 static const struct tpl0102_cfg tpl0102_cfg[] = {
38 	/* on-semiconductor parts */
39 	[CAT5140_503] = { .wipers = 1, .max_pos = 256, .kohms = 50, },
40 	[CAT5140_104] = { .wipers = 1, .max_pos = 256, .kohms = 100, },
41 	/* ti parts */
42 	[TPL0102_104] = { .wipers = 2, .max_pos = 256, .kohms = 100 },
43 	[TPL0401_103] = { .wipers = 1, .max_pos = 128, .kohms = 10, },
44 };
45 
46 struct tpl0102_data {
47 	struct regmap *regmap;
48 	unsigned long devid;
49 };
50 
51 static const struct regmap_config tpl0102_regmap_config = {
52 	.reg_bits = 8,
53 	.val_bits = 8,
54 };
55 
56 #define TPL0102_CHANNEL(ch) {					\
57 	.type = IIO_RESISTANCE,					\
58 	.indexed = 1,						\
59 	.output = 1,						\
60 	.channel = (ch),					\
61 	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
62 	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
63 }
64 
65 static const struct iio_chan_spec tpl0102_channels[] = {
66 	TPL0102_CHANNEL(0),
67 	TPL0102_CHANNEL(1),
68 };
69 
70 static int tpl0102_read_raw(struct iio_dev *indio_dev,
71 			    struct iio_chan_spec const *chan,
72 			    int *val, int *val2, long mask)
73 {
74 	struct tpl0102_data *data = iio_priv(indio_dev);
75 
76 	switch (mask) {
77 	case IIO_CHAN_INFO_RAW: {
78 		int ret = regmap_read(data->regmap, chan->channel, val);
79 
80 		return ret ? ret : IIO_VAL_INT;
81 	}
82 	case IIO_CHAN_INFO_SCALE:
83 		*val = 1000 * tpl0102_cfg[data->devid].kohms;
84 		*val2 = tpl0102_cfg[data->devid].max_pos;
85 		return IIO_VAL_FRACTIONAL;
86 	}
87 
88 	return -EINVAL;
89 }
90 
91 static int tpl0102_write_raw(struct iio_dev *indio_dev,
92 			     struct iio_chan_spec const *chan,
93 			     int val, int val2, long mask)
94 {
95 	struct tpl0102_data *data = iio_priv(indio_dev);
96 
97 	if (mask != IIO_CHAN_INFO_RAW)
98 		return -EINVAL;
99 
100 	if (val >= tpl0102_cfg[data->devid].max_pos || val < 0)
101 		return -EINVAL;
102 
103 	return regmap_write(data->regmap, chan->channel, val);
104 }
105 
106 static const struct iio_info tpl0102_info = {
107 	.read_raw = tpl0102_read_raw,
108 	.write_raw = tpl0102_write_raw,
109 	.driver_module = THIS_MODULE,
110 };
111 
112 static int tpl0102_probe(struct i2c_client *client,
113 			 const struct i2c_device_id *id)
114 {
115 	struct device *dev = &client->dev;
116 	struct tpl0102_data *data;
117 	struct iio_dev *indio_dev;
118 
119 	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
120 	if (!indio_dev)
121 		return -ENOMEM;
122 	data = iio_priv(indio_dev);
123 	i2c_set_clientdata(client, indio_dev);
124 
125 	data->devid = id->driver_data;
126 	data->regmap = devm_regmap_init_i2c(client, &tpl0102_regmap_config);
127 	if (IS_ERR(data->regmap)) {
128 		dev_err(dev, "regmap initialization failed\n");
129 		return PTR_ERR(data->regmap);
130 	}
131 
132 	indio_dev->dev.parent = dev;
133 	indio_dev->info = &tpl0102_info;
134 	indio_dev->channels = tpl0102_channels;
135 	indio_dev->num_channels = tpl0102_cfg[data->devid].wipers;
136 	indio_dev->name = client->name;
137 
138 	return devm_iio_device_register(dev, indio_dev);
139 }
140 
141 static const struct i2c_device_id tpl0102_id[] = {
142 	{ "cat5140-503", CAT5140_503 },
143 	{ "cat5140-104", CAT5140_104 },
144 	{ "tpl0102-104", TPL0102_104 },
145 	{ "tpl0401-103", TPL0401_103 },
146 	{}
147 };
148 MODULE_DEVICE_TABLE(i2c, tpl0102_id);
149 
150 static struct i2c_driver tpl0102_driver = {
151 	.driver = {
152 		.name = "tpl0102",
153 	},
154 	.probe = tpl0102_probe,
155 	.id_table = tpl0102_id,
156 };
157 
158 module_i2c_driver(tpl0102_driver);
159 
160 MODULE_AUTHOR("Matt Ranostay <mranostay@gmail.com>");
161 MODULE_DESCRIPTION("TPL0102 digital potentiometer");
162 MODULE_LICENSE("GPL");
163