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/jiffies.h>
34 #include <linux/module.h>
35 #include <linux/mutex.h>
36 #include <linux/platform_data/ads7828.h>
37 #include <linux/slab.h>
38
39 /* The ADS7828 registers */
40 #define ADS7828_NCH 8 /* 8 channels supported */
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 */
49 enum ads7828_chips { ads7828, ads7830 };
50
51 /* Client specific data */
52 struct ads7828_data {
53 struct i2c_client *client;
54 struct mutex update_lock; /* Mutex protecting updates */
55 unsigned long last_updated; /* Last updated time (in jiffies) */
56 u16 adc_input[ADS7828_NCH]; /* ADS7828_NCH samples */
57 bool valid; /* Validity flag */
58 bool diff_input; /* Differential input */
59 bool ext_vref; /* External voltage reference */
60 unsigned int vref_mv; /* voltage reference value */
61 u8 cmd_byte; /* Command byte without channel bits */
62 unsigned int lsb_resol; /* Resolution of the ADC sample LSB */
63 s32 (*read_channel)(const struct i2c_client *client, u8 command);
64 };
65
66 /* Command byte C2,C1,C0 - see datasheet */
ads7828_cmd_byte(u8 cmd,int ch)67 static inline u8 ads7828_cmd_byte(u8 cmd, int ch)
68 {
69 return cmd | (((ch >> 1) | (ch & 0x01) << 2) << 4);
70 }
71
72 /* Update data for the device (all 8 channels) */
ads7828_update_device(struct device * dev)73 static struct ads7828_data *ads7828_update_device(struct device *dev)
74 {
75 struct ads7828_data *data = dev_get_drvdata(dev);
76 struct i2c_client *client = data->client;
77
78 mutex_lock(&data->update_lock);
79
80 if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
81 || !data->valid) {
82 unsigned int ch;
83 dev_dbg(&client->dev, "Starting ads7828 update\n");
84
85 for (ch = 0; ch < ADS7828_NCH; ch++) {
86 u8 cmd = ads7828_cmd_byte(data->cmd_byte, ch);
87 data->adc_input[ch] = data->read_channel(client, cmd);
88 }
89 data->last_updated = jiffies;
90 data->valid = true;
91 }
92
93 mutex_unlock(&data->update_lock);
94
95 return data;
96 }
97
98 /* sysfs callback function */
ads7828_show_in(struct device * dev,struct device_attribute * da,char * buf)99 static ssize_t ads7828_show_in(struct device *dev, struct device_attribute *da,
100 char *buf)
101 {
102 struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
103 struct ads7828_data *data = ads7828_update_device(dev);
104 unsigned int value = DIV_ROUND_CLOSEST(data->adc_input[attr->index] *
105 data->lsb_resol, 1000);
106
107 return sprintf(buf, "%d\n", value);
108 }
109
110 static SENSOR_DEVICE_ATTR(in0_input, S_IRUGO, ads7828_show_in, NULL, 0);
111 static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, ads7828_show_in, NULL, 1);
112 static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, ads7828_show_in, NULL, 2);
113 static SENSOR_DEVICE_ATTR(in3_input, S_IRUGO, ads7828_show_in, NULL, 3);
114 static SENSOR_DEVICE_ATTR(in4_input, S_IRUGO, ads7828_show_in, NULL, 4);
115 static SENSOR_DEVICE_ATTR(in5_input, S_IRUGO, ads7828_show_in, NULL, 5);
116 static SENSOR_DEVICE_ATTR(in6_input, S_IRUGO, ads7828_show_in, NULL, 6);
117 static SENSOR_DEVICE_ATTR(in7_input, S_IRUGO, ads7828_show_in, NULL, 7);
118
119 static struct attribute *ads7828_attrs[] = {
120 &sensor_dev_attr_in0_input.dev_attr.attr,
121 &sensor_dev_attr_in1_input.dev_attr.attr,
122 &sensor_dev_attr_in2_input.dev_attr.attr,
123 &sensor_dev_attr_in3_input.dev_attr.attr,
124 &sensor_dev_attr_in4_input.dev_attr.attr,
125 &sensor_dev_attr_in5_input.dev_attr.attr,
126 &sensor_dev_attr_in6_input.dev_attr.attr,
127 &sensor_dev_attr_in7_input.dev_attr.attr,
128 NULL
129 };
130
131 ATTRIBUTE_GROUPS(ads7828);
132
ads7828_probe(struct i2c_client * client,const struct i2c_device_id * id)133 static int ads7828_probe(struct i2c_client *client,
134 const struct i2c_device_id *id)
135 {
136 struct device *dev = &client->dev;
137 struct ads7828_platform_data *pdata = dev_get_platdata(dev);
138 struct ads7828_data *data;
139 struct device *hwmon_dev;
140
141 data = devm_kzalloc(dev, sizeof(struct ads7828_data), GFP_KERNEL);
142 if (!data)
143 return -ENOMEM;
144
145 if (pdata) {
146 data->diff_input = pdata->diff_input;
147 data->ext_vref = pdata->ext_vref;
148 if (data->ext_vref)
149 data->vref_mv = pdata->vref_mv;
150 }
151
152 /* Bound Vref with min/max values if it was provided */
153 if (data->vref_mv)
154 data->vref_mv = clamp_val(data->vref_mv,
155 ADS7828_EXT_VREF_MV_MIN,
156 ADS7828_EXT_VREF_MV_MAX);
157 else
158 data->vref_mv = ADS7828_INT_VREF_MV;
159
160 /* ADS7828 uses 12-bit samples, while ADS7830 is 8-bit */
161 if (id->driver_data == ads7828) {
162 data->lsb_resol = DIV_ROUND_CLOSEST(data->vref_mv * 1000, 4096);
163 data->read_channel = i2c_smbus_read_word_swapped;
164 } else {
165 data->lsb_resol = DIV_ROUND_CLOSEST(data->vref_mv * 1000, 256);
166 data->read_channel = i2c_smbus_read_byte_data;
167 }
168
169 data->cmd_byte = data->ext_vref ? ADS7828_CMD_PD1 : ADS7828_CMD_PD3;
170 if (!data->diff_input)
171 data->cmd_byte |= ADS7828_CMD_SD_SE;
172
173 data->client = client;
174 mutex_init(&data->update_lock);
175
176 hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
177 data,
178 ads7828_groups);
179 return PTR_ERR_OR_ZERO(hwmon_dev);
180 }
181
182 static const struct i2c_device_id ads7828_device_ids[] = {
183 { "ads7828", ads7828 },
184 { "ads7830", ads7830 },
185 { }
186 };
187 MODULE_DEVICE_TABLE(i2c, ads7828_device_ids);
188
189 static struct i2c_driver ads7828_driver = {
190 .driver = {
191 .name = "ads7828",
192 },
193
194 .id_table = ads7828_device_ids,
195 .probe = ads7828_probe,
196 };
197
198 module_i2c_driver(ads7828_driver);
199
200 MODULE_LICENSE("GPL");
201 MODULE_AUTHOR("Steve Hardy <shardy@redhat.com>");
202 MODULE_DESCRIPTION("Driver for TI ADS7828 A/D converter and compatibles");
203