1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * ltc2497.c - Driver for Analog Devices/Linear Technology LTC2497 ADC
4 *
5 * Copyright (C) 2017 Analog Devices Inc.
6 *
7 * Datasheet: http://cds.linear.com/docs/en/datasheet/2497fd.pdf
8 */
9
10 #include <linux/i2c.h>
11 #include <linux/iio/iio.h>
12 #include <linux/iio/driver.h>
13 #include <linux/module.h>
14 #include <linux/mod_devicetable.h>
15 #include <linux/property.h>
16
17 #include <linux/unaligned.h>
18
19 #include "ltc2497.h"
20
21 enum ltc2497_chip_type {
22 TYPE_LTC2497,
23 TYPE_LTC2499,
24 };
25
26 struct ltc2497_driverdata {
27 /* this must be the first member */
28 struct ltc2497core_driverdata common_ddata;
29 struct i2c_client *client;
30 u32 recv_size;
31 /*
32 * DMA (thus cache coherency maintenance) may require the
33 * transfer buffers to live in their own cache lines.
34 */
35 union {
36 __be32 d32;
37 u8 d8[3];
38 } data __aligned(IIO_DMA_MINALIGN);
39 };
40
ltc2497_result_and_measure(struct ltc2497core_driverdata * ddata,u8 address,int * val)41 static int ltc2497_result_and_measure(struct ltc2497core_driverdata *ddata,
42 u8 address, int *val)
43 {
44 struct ltc2497_driverdata *st =
45 container_of(ddata, struct ltc2497_driverdata, common_ddata);
46 int ret;
47
48 if (val) {
49 if (st->recv_size == 3)
50 ret = i2c_master_recv(st->client, (char *)&st->data.d8,
51 st->recv_size);
52 else
53 ret = i2c_master_recv(st->client, (char *)&st->data.d32,
54 st->recv_size);
55 if (ret < 0) {
56 dev_err(&st->client->dev, "i2c_master_recv failed\n");
57 return ret;
58 }
59
60 /*
61 * The data format is 16/24 bit 2s complement, but with an upper sign bit on the
62 * resolution + 1 position, which is set for positive values only. Given this
63 * bit's value, subtracting BIT(resolution + 1) from the ADC's result is
64 * equivalent to a sign extension.
65 */
66 if (st->recv_size == 3) {
67 *val = (get_unaligned_be24(st->data.d8) >> 6)
68 - BIT(ddata->chip_info->resolution + 1);
69 } else {
70 *val = (be32_to_cpu(st->data.d32) >> 6)
71 - BIT(ddata->chip_info->resolution + 1);
72 }
73
74 /*
75 * The part started a new conversion at the end of the above i2c
76 * transfer, so if the address didn't change since the last call
77 * everything is fine and we can return early.
78 * If not (which should only happen when some sort of bulk
79 * conversion is implemented) we have to program the new
80 * address. Note that this probably fails as the conversion that
81 * was triggered above is like not complete yet and the two
82 * operations have to be done in a single transfer.
83 */
84 if (ddata->addr_prev == address)
85 return 0;
86 }
87
88 ret = i2c_smbus_write_byte(st->client,
89 LTC2497_ENABLE | address);
90 if (ret)
91 dev_err(&st->client->dev, "i2c transfer failed: %pe\n",
92 ERR_PTR(ret));
93 return ret;
94 }
95
ltc2497_probe(struct i2c_client * client)96 static int ltc2497_probe(struct i2c_client *client)
97 {
98 const struct ltc2497_chip_info *chip_info;
99 struct iio_dev *indio_dev;
100 struct ltc2497_driverdata *st;
101 struct device *dev = &client->dev;
102 u32 resolution;
103
104 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
105 I2C_FUNC_SMBUS_WRITE_BYTE))
106 return -EOPNOTSUPP;
107
108 indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
109 if (!indio_dev)
110 return -ENOMEM;
111
112 st = iio_priv(indio_dev);
113 i2c_set_clientdata(client, indio_dev);
114 st->client = client;
115 st->common_ddata.result_and_measure = ltc2497_result_and_measure;
116
117 chip_info = i2c_get_match_data(client);
118 st->common_ddata.chip_info = chip_info;
119
120 resolution = chip_info->resolution;
121 st->recv_size = BITS_TO_BYTES(resolution) + 1;
122
123 return ltc2497core_probe(dev, indio_dev);
124 }
125
ltc2497_remove(struct i2c_client * client)126 static void ltc2497_remove(struct i2c_client *client)
127 {
128 struct iio_dev *indio_dev = i2c_get_clientdata(client);
129
130 ltc2497core_remove(indio_dev);
131 }
132
133 static const struct ltc2497_chip_info ltc2497_info[] = {
134 [TYPE_LTC2497] = {
135 .resolution = 16,
136 .name = NULL,
137 },
138 [TYPE_LTC2499] = {
139 .resolution = 24,
140 .name = "ltc2499",
141 },
142 };
143
144 static const struct i2c_device_id ltc2497_id[] = {
145 { "ltc2497", (kernel_ulong_t)<c2497_info[TYPE_LTC2497] },
146 { "ltc2499", (kernel_ulong_t)<c2497_info[TYPE_LTC2499] },
147 { }
148 };
149 MODULE_DEVICE_TABLE(i2c, ltc2497_id);
150
151 static const struct of_device_id ltc2497_of_match[] = {
152 { .compatible = "lltc,ltc2497", .data = <c2497_info[TYPE_LTC2497] },
153 { .compatible = "lltc,ltc2499", .data = <c2497_info[TYPE_LTC2499] },
154 { }
155 };
156 MODULE_DEVICE_TABLE(of, ltc2497_of_match);
157
158 static struct i2c_driver ltc2497_driver = {
159 .driver = {
160 .name = "ltc2497",
161 .of_match_table = ltc2497_of_match,
162 },
163 .probe = ltc2497_probe,
164 .remove = ltc2497_remove,
165 .id_table = ltc2497_id,
166 };
167 module_i2c_driver(ltc2497_driver);
168
169 MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
170 MODULE_DESCRIPTION("Linear Technology LTC2497 ADC driver");
171 MODULE_LICENSE("GPL v2");
172