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 <shardy@redhat.com>
9 *
10 * ADS7830 support, by Guillaume Roguez <guillaume.roguez@savoirfairelinux.com>
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 */
36 enum ads7828_chips { ads7828, ads7830 };
37
38 /* Client specific data */
39 struct 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 */
ads7828_cmd_byte(u8 cmd,int ch)46 static 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 */
ads7828_in_show(struct device * dev,struct device_attribute * da,char * buf)52 static 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, ®val);
62 if (err < 0)
63 return err;
64
65 return sprintf(buf, "%d\n",
66 DIV_ROUND_CLOSEST(regval * data->lsb_resol, 1000));
67 }
68
69 static SENSOR_DEVICE_ATTR_RO(in0_input, ads7828_in, 0);
70 static SENSOR_DEVICE_ATTR_RO(in1_input, ads7828_in, 1);
71 static SENSOR_DEVICE_ATTR_RO(in2_input, ads7828_in, 2);
72 static SENSOR_DEVICE_ATTR_RO(in3_input, ads7828_in, 3);
73 static SENSOR_DEVICE_ATTR_RO(in4_input, ads7828_in, 4);
74 static SENSOR_DEVICE_ATTR_RO(in5_input, ads7828_in, 5);
75 static SENSOR_DEVICE_ATTR_RO(in6_input, ads7828_in, 6);
76 static SENSOR_DEVICE_ATTR_RO(in7_input, ads7828_in, 7);
77
78 static 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
90 ATTRIBUTE_GROUPS(ads7828);
91
92 static const struct regmap_config ads2828_regmap_config = {
93 .reg_bits = 8,
94 .val_bits = 16,
95 };
96
97 static const struct regmap_config ads2830_regmap_config = {
98 .reg_bits = 8,
99 .val_bits = 8,
100 };
101
102 static const struct i2c_device_id ads7828_device_ids[];
103
ads7828_probe(struct i2c_client * client)104 static int ads7828_probe(struct i2c_client *client)
105 {
106 struct device *dev = &client->dev;
107 struct ads7828_platform_data *pdata = dev_get_platdata(dev);
108 struct ads7828_data *data;
109 struct device *hwmon_dev;
110 unsigned int vref_mv = ADS7828_INT_VREF_MV;
111 unsigned int vref_uv;
112 bool diff_input = false;
113 bool ext_vref = false;
114 unsigned int regval;
115 enum ads7828_chips chip;
116 struct regulator *reg;
117
118 data = devm_kzalloc(dev, sizeof(struct ads7828_data), GFP_KERNEL);
119 if (!data)
120 return -ENOMEM;
121
122 if (pdata) {
123 diff_input = pdata->diff_input;
124 ext_vref = pdata->ext_vref;
125 if (ext_vref && pdata->vref_mv)
126 vref_mv = pdata->vref_mv;
127 } else if (dev->of_node) {
128 diff_input = of_property_read_bool(dev->of_node,
129 "ti,differential-input");
130 reg = devm_regulator_get_optional(dev, "vref");
131 if (!IS_ERR(reg)) {
132 vref_uv = regulator_get_voltage(reg);
133 vref_mv = DIV_ROUND_CLOSEST(vref_uv, 1000);
134 if (vref_mv < ADS7828_EXT_VREF_MV_MIN ||
135 vref_mv > ADS7828_EXT_VREF_MV_MAX)
136 return -EINVAL;
137 ext_vref = true;
138 }
139 }
140
141 if (client->dev.of_node)
142 chip = (uintptr_t)of_device_get_match_data(&client->dev);
143 else
144 chip = i2c_match_id(ads7828_device_ids, client)->driver_data;
145
146 /* Bound Vref with min/max values */
147 vref_mv = clamp_val(vref_mv, ADS7828_EXT_VREF_MV_MIN,
148 ADS7828_EXT_VREF_MV_MAX);
149
150 /* ADS7828 uses 12-bit samples, while ADS7830 is 8-bit */
151 if (chip == ads7828) {
152 data->lsb_resol = DIV_ROUND_CLOSEST(vref_mv * 1000, 4096);
153 data->regmap = devm_regmap_init_i2c(client,
154 &ads2828_regmap_config);
155 } else {
156 data->lsb_resol = DIV_ROUND_CLOSEST(vref_mv * 1000, 256);
157 data->regmap = devm_regmap_init_i2c(client,
158 &ads2830_regmap_config);
159 }
160
161 if (IS_ERR(data->regmap))
162 return PTR_ERR(data->regmap);
163
164 data->cmd_byte = ext_vref ? ADS7828_CMD_PD1 : ADS7828_CMD_PD3;
165 if (!diff_input)
166 data->cmd_byte |= ADS7828_CMD_SD_SE;
167
168 /*
169 * Datasheet specifies internal reference voltage is disabled by
170 * default. The internal reference voltage needs to be enabled and
171 * voltage needs to settle before getting valid ADC data. So perform a
172 * dummy read to enable the internal reference voltage.
173 */
174 if (!ext_vref)
175 regmap_read(data->regmap, data->cmd_byte, ®val);
176
177 hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
178 data,
179 ads7828_groups);
180 return PTR_ERR_OR_ZERO(hwmon_dev);
181 }
182
183 static const struct i2c_device_id ads7828_device_ids[] = {
184 { "ads7828", ads7828 },
185 { "ads7830", ads7830 },
186 { }
187 };
188 MODULE_DEVICE_TABLE(i2c, ads7828_device_ids);
189
190 static const struct of_device_id __maybe_unused ads7828_of_match[] = {
191 {
192 .compatible = "ti,ads7828",
193 .data = (void *)ads7828
194 },
195 {
196 .compatible = "ti,ads7830",
197 .data = (void *)ads7830
198 },
199 { },
200 };
201 MODULE_DEVICE_TABLE(of, ads7828_of_match);
202
203 static struct i2c_driver ads7828_driver = {
204 .driver = {
205 .name = "ads7828",
206 .of_match_table = of_match_ptr(ads7828_of_match),
207 },
208
209 .id_table = ads7828_device_ids,
210 .probe = ads7828_probe,
211 };
212
213 module_i2c_driver(ads7828_driver);
214
215 MODULE_LICENSE("GPL");
216 MODULE_AUTHOR("Steve Hardy <shardy@redhat.com>");
217 MODULE_DESCRIPTION("Driver for TI ADS7828 A/D converter and compatibles");
218