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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * ads7828.c - driver for TI ADS7828 8-channel A/D converter and compatibles
4 * (C) 2007 EADS Astrium
5 *
6 * This driver is based on the lm75 and other lm_sensors/hwmon drivers
7 *
8 * Written by Steve Hardy <[email protected]>
9 *
10 * ADS7830 support, by Guillaume Roguez <[email protected]>
11 *
12 * For further information, see the Documentation/hwmon/ads7828.rst file.
13 */
14
15#include <linux/err.h>
16#include <linux/hwmon.h>
17#include <linux/hwmon-sysfs.h>
18#include <linux/i2c.h>
19#include <linux/init.h>
20#include <linux/module.h>
21#include <linux/of.h>
22#include <linux/platform_data/ads7828.h>
23#include <linux/regmap.h>
24#include <linux/slab.h>
25#include <linux/regulator/consumer.h>
26
27/* The ADS7828 registers */
28#define ADS7828_CMD_SD_SE 0x80 /* Single ended inputs */
29#define ADS7828_CMD_PD1 0x04 /* Internal vref OFF && A/D ON */
30#define ADS7828_CMD_PD3 0x0C /* Internal vref ON && A/D ON */
31#define ADS7828_INT_VREF_MV 2500 /* Internal vref is 2.5V, 2500mV */
32#define ADS7828_EXT_VREF_MV_MIN 50 /* External vref min value 0.05V */
33#define ADS7828_EXT_VREF_MV_MAX 5250 /* External vref max value 5.25V */
34
35/* List of supported devices */
36enum ads7828_chips { ads7828, ads7830 };
37
38/* Client specific data */
39struct ads7828_data {
40 struct regmap *regmap;
41 u8 cmd_byte; /* Command byte without channel bits */
42 unsigned int lsb_resol; /* Resolution of the ADC sample LSB */
43};
44
45/* Command byte C2,C1,C0 - see datasheet */
46static inline u8 ads7828_cmd_byte(u8 cmd, int ch)
47{
48 return cmd | (((ch >> 1) | (ch & 0x01) << 2) << 4);
49}
50
51/* sysfs callback function */
52static ssize_t ads7828_in_show(struct device *dev,
53 struct device_attribute *da, char *buf)
54{
55 struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
56 struct ads7828_data *data = dev_get_drvdata(dev);
57 u8 cmd = ads7828_cmd_byte(data->cmd_byte, attr->index);
58 unsigned int regval;
59 int err;
60
61 err = regmap_read(data->regmap, cmd, &regval);
62 if (err < 0)
63 return err;
64
65 return sysfs_emit(buf, "%d\n",
66 DIV_ROUND_CLOSEST(regval * data->lsb_resol, 1000));
67}
68
69static SENSOR_DEVICE_ATTR_RO(in0_input, ads7828_in, 0);
70static SENSOR_DEVICE_ATTR_RO(in1_input, ads7828_in, 1);
71static SENSOR_DEVICE_ATTR_RO(in2_input, ads7828_in, 2);
72static SENSOR_DEVICE_ATTR_RO(in3_input, ads7828_in, 3);
73static SENSOR_DEVICE_ATTR_RO(in4_input, ads7828_in, 4);
74static SENSOR_DEVICE_ATTR_RO(in5_input, ads7828_in, 5);
75static SENSOR_DEVICE_ATTR_RO(in6_input, ads7828_in, 6);
76static SENSOR_DEVICE_ATTR_RO(in7_input, ads7828_in, 7);
77
78static struct attribute *ads7828_attrs[] = {
79 &sensor_dev_attr_in0_input.dev_attr.attr,
80 &sensor_dev_attr_in1_input.dev_attr.attr,
81 &sensor_dev_attr_in2_input.dev_attr.attr,
82 &sensor_dev_attr_in3_input.dev_attr.attr,
83 &sensor_dev_attr_in4_input.dev_attr.attr,
84 &sensor_dev_attr_in5_input.dev_attr.attr,
85 &sensor_dev_attr_in6_input.dev_attr.attr,
86 &sensor_dev_attr_in7_input.dev_attr.attr,
87 NULL
88};
89
90ATTRIBUTE_GROUPS(ads7828);
91
92static const struct regmap_config ads2828_regmap_config = {
93 .reg_bits = 8,
94 .val_bits = 16,
95};
96
97static const struct regmap_config ads2830_regmap_config = {
98 .reg_bits = 8,
99 .val_bits = 8,
100};
101
102static int ads7828_probe(struct i2c_client *client)
103{
104 struct device *dev = &client->dev;
105 struct ads7828_platform_data *pdata = dev_get_platdata(dev);
106 struct ads7828_data *data;
107 struct device *hwmon_dev;
108 unsigned int vref_mv = ADS7828_INT_VREF_MV;
109 int vref_uv;
110 bool diff_input = false;
111 bool ext_vref = false;
112 unsigned int regval;
113 enum ads7828_chips chip;
114
115 data = devm_kzalloc(dev, sizeof(struct ads7828_data), GFP_KERNEL);
116 if (!data)
117 return -ENOMEM;
118
119 if (pdata) {
120 diff_input = pdata->diff_input;
121 ext_vref = pdata->ext_vref;
122 if (ext_vref && pdata->vref_mv)
123 vref_mv = pdata->vref_mv;
124 } else if (dev->of_node) {
125 diff_input = of_property_read_bool(dev->of_node,
126 "ti,differential-input");
127 vref_uv = devm_regulator_get_enable_read_voltage(dev, "vref");
128 if (vref_uv < 0) {
129 if (vref_uv != -ENODEV)
130 return vref_uv;
131 } else {
132 vref_mv = DIV_ROUND_CLOSEST(vref_uv, 1000);
133 if (vref_mv < ADS7828_EXT_VREF_MV_MIN ||
134 vref_mv > ADS7828_EXT_VREF_MV_MAX)
135 return -EINVAL;
136 ext_vref = true;
137 }
138 }
139
140 chip = (uintptr_t)i2c_get_match_data(client);
141
142 /* Bound Vref with min/max values */
143 vref_mv = clamp_val(vref_mv, ADS7828_EXT_VREF_MV_MIN,
144 ADS7828_EXT_VREF_MV_MAX);
145
146 /* ADS7828 uses 12-bit samples, while ADS7830 is 8-bit */
147 if (chip == ads7828) {
148 data->lsb_resol = DIV_ROUND_CLOSEST(vref_mv * 1000, 4096);
149 data->regmap = devm_regmap_init_i2c(client,
150 &ads2828_regmap_config);
151 } else {
152 data->lsb_resol = DIV_ROUND_CLOSEST(vref_mv * 1000, 256);
153 data->regmap = devm_regmap_init_i2c(client,
154 &ads2830_regmap_config);
155 }
156
157 if (IS_ERR(data->regmap))
158 return PTR_ERR(data->regmap);
159
160 data->cmd_byte = ext_vref ? ADS7828_CMD_PD1 : ADS7828_CMD_PD3;
161 if (!diff_input)
162 data->cmd_byte |= ADS7828_CMD_SD_SE;
163
164 /*
165 * Datasheet specifies internal reference voltage is disabled by
166 * default. The internal reference voltage needs to be enabled and
167 * voltage needs to settle before getting valid ADC data. So perform a
168 * dummy read to enable the internal reference voltage.
169 */
170 if (!ext_vref)
171 regmap_read(data->regmap, data->cmd_byte, &regval);
172
173 hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
174 data,
175 ads7828_groups);
176 return PTR_ERR_OR_ZERO(hwmon_dev);
177}
178
179static const struct i2c_device_id ads7828_device_ids[] = {
180 { .name = "ads7828", .driver_data = ads7828 },
181 { .name = "ads7830", .driver_data = ads7830 },
182 { }
183};
184MODULE_DEVICE_TABLE(i2c, ads7828_device_ids);
185
186static const struct of_device_id __maybe_unused ads7828_of_match[] = {
187 {
188 .compatible = "ti,ads7828",
189 .data = (void *)ads7828
190 },
191 {
192 .compatible = "ti,ads7830",
193 .data = (void *)ads7830
194 },
195 { },
196};
197MODULE_DEVICE_TABLE(of, ads7828_of_match);
198
199static struct i2c_driver ads7828_driver = {
200 .driver = {
201 .name = "ads7828",
202 .of_match_table = of_match_ptr(ads7828_of_match),
203 },
204
205 .id_table = ads7828_device_ids,
206 .probe = ads7828_probe,
207};
208
209module_i2c_driver(ads7828_driver);
210
211MODULE_LICENSE("GPL");
212MODULE_AUTHOR("Steve Hardy <[email protected]>");
213MODULE_DESCRIPTION("Driver for TI ADS7828 A/D converter and compatibles");