1/*
2 * ads7828.c - driver for TI ADS7828 8-channel A/D converter and compatibles
3 * (C) 2007 EADS Astrium
4 *
5 * This driver is based on the lm75 and other lm_sensors/hwmon drivers
6 *
7 * Written by Steve Hardy <shardy@redhat.com>
8 *
9 * ADS7830 support, by Guillaume Roguez <guillaume.roguez@savoirfairelinux.com>
10 *
11 * For further information, see the Documentation/hwmon/ads7828 file.
12 *
13 * This program is free software; you can redistribute it and/or modify
14 * it under the terms of the GNU General Public License as published by
15 * the Free Software Foundation; either version 2 of the License, or
16 * (at your option) any later version.
17 *
18 * This program is distributed in the hope that it will be useful,
19 * but WITHOUT ANY WARRANTY; without even the implied warranty of
20 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
21 * GNU General Public License for more details.
22 *
23 * You should have received a copy of the GNU General Public License
24 * along with this program; if not, write to the Free Software
25 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
26 */
27
28#include <linux/err.h>
29#include <linux/hwmon.h>
30#include <linux/hwmon-sysfs.h>
31#include <linux/i2c.h>
32#include <linux/init.h>
33#include <linux/module.h>
34#include <linux/of_device.h>
35#include <linux/platform_data/ads7828.h>
36#include <linux/regmap.h>
37#include <linux/slab.h>
38#include <linux/regulator/consumer.h>
39
40/* The ADS7828 registers */
41#define ADS7828_CMD_SD_SE 0x80 /* Single ended inputs */
42#define ADS7828_CMD_PD1 0x04 /* Internal vref OFF && A/D ON */
43#define ADS7828_CMD_PD3 0x0C /* Internal vref ON && A/D ON */
44#define ADS7828_INT_VREF_MV 2500 /* Internal vref is 2.5V, 2500mV */
45#define ADS7828_EXT_VREF_MV_MIN 50 /* External vref min value 0.05V */
46#define ADS7828_EXT_VREF_MV_MAX 5250 /* External vref max value 5.25V */
47
48/* List of supported devices */
49enum ads7828_chips { ads7828, ads7830 };
50
51/* Client specific data */
52struct ads7828_data {
53 struct regmap *regmap;
54 u8 cmd_byte; /* Command byte without channel bits */
55 unsigned int lsb_resol; /* Resolution of the ADC sample LSB */
56};
57
58/* Command byte C2,C1,C0 - see datasheet */
59static inline u8 ads7828_cmd_byte(u8 cmd, int ch)
60{
61 return cmd | (((ch >> 1) | (ch & 0x01) << 2) << 4);
62}
63
64/* sysfs callback function */
65static ssize_t ads7828_in_show(struct device *dev,
66 struct device_attribute *da, char *buf)
67{
68 struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
69 struct ads7828_data *data = dev_get_drvdata(dev);
70 u8 cmd = ads7828_cmd_byte(data->cmd_byte, attr->index);
71 unsigned int regval;
72 int err;
73
74 err = regmap_read(data->regmap, cmd, &regval);
75 if (err < 0)
76 return err;
77
78 return sprintf(buf, "%d\n",
79 DIV_ROUND_CLOSEST(regval * data->lsb_resol, 1000));
80}
81
82static SENSOR_DEVICE_ATTR_RO(in0_input, ads7828_in, 0);
83static SENSOR_DEVICE_ATTR_RO(in1_input, ads7828_in, 1);
84static SENSOR_DEVICE_ATTR_RO(in2_input, ads7828_in, 2);
85static SENSOR_DEVICE_ATTR_RO(in3_input, ads7828_in, 3);
86static SENSOR_DEVICE_ATTR_RO(in4_input, ads7828_in, 4);
87static SENSOR_DEVICE_ATTR_RO(in5_input, ads7828_in, 5);
88static SENSOR_DEVICE_ATTR_RO(in6_input, ads7828_in, 6);
89static SENSOR_DEVICE_ATTR_RO(in7_input, ads7828_in, 7);
90
91static struct attribute *ads7828_attrs[] = {
92 &sensor_dev_attr_in0_input.dev_attr.attr,
93 &sensor_dev_attr_in1_input.dev_attr.attr,
94 &sensor_dev_attr_in2_input.dev_attr.attr,
95 &sensor_dev_attr_in3_input.dev_attr.attr,
96 &sensor_dev_attr_in4_input.dev_attr.attr,
97 &sensor_dev_attr_in5_input.dev_attr.attr,
98 &sensor_dev_attr_in6_input.dev_attr.attr,
99 &sensor_dev_attr_in7_input.dev_attr.attr,
100 NULL
101};
102
103ATTRIBUTE_GROUPS(ads7828);
104
105static const struct regmap_config ads2828_regmap_config = {
106 .reg_bits = 8,
107 .val_bits = 16,
108};
109
110static const struct regmap_config ads2830_regmap_config = {
111 .reg_bits = 8,
112 .val_bits = 8,
113};
114
115static int ads7828_probe(struct i2c_client *client,
116 const struct i2c_device_id *id)
117{
118 struct device *dev = &client->dev;
119 struct ads7828_platform_data *pdata = dev_get_platdata(dev);
120 struct ads7828_data *data;
121 struct device *hwmon_dev;
122 unsigned int vref_mv = ADS7828_INT_VREF_MV;
123 unsigned int vref_uv;
124 bool diff_input = false;
125 bool ext_vref = false;
126 unsigned int regval;
127 enum ads7828_chips chip;
128 struct regulator *reg;
129
130 data = devm_kzalloc(dev, sizeof(struct ads7828_data), GFP_KERNEL);
131 if (!data)
132 return -ENOMEM;
133
134 if (pdata) {
135 diff_input = pdata->diff_input;
136 ext_vref = pdata->ext_vref;
137 if (ext_vref && pdata->vref_mv)
138 vref_mv = pdata->vref_mv;
139 } else if (dev->of_node) {
140 diff_input = of_property_read_bool(dev->of_node,
141 "ti,differential-input");
142 reg = devm_regulator_get_optional(dev, "vref");
143 if (!IS_ERR(reg)) {
144 vref_uv = regulator_get_voltage(reg);
145 vref_mv = DIV_ROUND_CLOSEST(vref_uv, 1000);
146 if (vref_mv < ADS7828_EXT_VREF_MV_MIN ||
147 vref_mv > ADS7828_EXT_VREF_MV_MAX)
148 return -EINVAL;
149 ext_vref = true;
150 }
151 }
152
153 if (client->dev.of_node)
154 chip = (enum ads7828_chips)
155 of_device_get_match_data(&client->dev);
156 else
157 chip = id->driver_data;
158
159 /* Bound Vref with min/max values */
160 vref_mv = clamp_val(vref_mv, ADS7828_EXT_VREF_MV_MIN,
161 ADS7828_EXT_VREF_MV_MAX);
162
163 /* ADS7828 uses 12-bit samples, while ADS7830 is 8-bit */
164 if (chip == ads7828) {
165 data->lsb_resol = DIV_ROUND_CLOSEST(vref_mv * 1000, 4096);
166 data->regmap = devm_regmap_init_i2c(client,
167 &ads2828_regmap_config);
168 } else {
169 data->lsb_resol = DIV_ROUND_CLOSEST(vref_mv * 1000, 256);
170 data->regmap = devm_regmap_init_i2c(client,
171 &ads2830_regmap_config);
172 }
173
174 if (IS_ERR(data->regmap))
175 return PTR_ERR(data->regmap);
176
177 data->cmd_byte = ext_vref ? ADS7828_CMD_PD1 : ADS7828_CMD_PD3;
178 if (!diff_input)
179 data->cmd_byte |= ADS7828_CMD_SD_SE;
180
181 /*
182 * Datasheet specifies internal reference voltage is disabled by
183 * default. The internal reference voltage needs to be enabled and
184 * voltage needs to settle before getting valid ADC data. So perform a
185 * dummy read to enable the internal reference voltage.
186 */
187 if (!ext_vref)
188 regmap_read(data->regmap, data->cmd_byte, &regval);
189
190 hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
191 data,
192 ads7828_groups);
193 return PTR_ERR_OR_ZERO(hwmon_dev);
194}
195
196static const struct i2c_device_id ads7828_device_ids[] = {
197 { "ads7828", ads7828 },
198 { "ads7830", ads7830 },
199 { }
200};
201MODULE_DEVICE_TABLE(i2c, ads7828_device_ids);
202
203static const struct of_device_id ads7828_of_match[] = {
204 {
205 .compatible = "ti,ads7828",
206 .data = (void *)ads7828
207 },
208 {
209 .compatible = "ti,ads7830",
210 .data = (void *)ads7830
211 },
212 { },
213};
214MODULE_DEVICE_TABLE(of, ads7828_of_match);
215
216static struct i2c_driver ads7828_driver = {
217 .driver = {
218 .name = "ads7828",
219 .of_match_table = of_match_ptr(ads7828_of_match),
220 },
221
222 .id_table = ads7828_device_ids,
223 .probe = ads7828_probe,
224};
225
226module_i2c_driver(ads7828_driver);
227
228MODULE_LICENSE("GPL");
229MODULE_AUTHOR("Steve Hardy <shardy@redhat.com>");
230MODULE_DESCRIPTION("Driver for TI ADS7828 A/D converter and compatibles");
231