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Steve Hardy5812f922008-01-22 23:00:02 +00001/*
2 ads7828.c - lm_sensors driver for ads7828 12-bit 8-channel ADC
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 <steve@linuxrealtime.co.uk>
8
9 Datasheet available at: http://focus.ti.com/lit/ds/symlink/ads7828.pdf
10
11 This program is free software; you can redistribute it and/or modify
12 it under the terms of the GNU General Public License as published by
13 the Free Software Foundation; either version 2 of the License, or
14 (at your option) any later version.
15
16 This program is distributed in the hope that it will be useful,
17 but WITHOUT ANY WARRANTY; without even the implied warranty of
18 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 GNU General Public License for more details.
20
21 You should have received a copy of the GNU General Public License
22 along with this program; if not, write to the Free Software
23 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
24*/
25
26#include <linux/module.h>
27#include <linux/init.h>
28#include <linux/slab.h>
29#include <linux/jiffies.h>
30#include <linux/i2c.h>
31#include <linux/hwmon.h>
32#include <linux/hwmon-sysfs.h>
33#include <linux/err.h>
34#include <linux/mutex.h>
35
36/* The ADS7828 registers */
37#define ADS7828_NCH 8 /* 8 channels of 12-bit A-D supported */
38#define ADS7828_CMD_SD_SE 0x80 /* Single ended inputs */
39#define ADS7828_CMD_SD_DIFF 0x00 /* Differential inputs */
40#define ADS7828_CMD_PD0 0x0 /* Power Down between A-D conversions */
41#define ADS7828_CMD_PD1 0x04 /* Internal ref OFF && A-D ON */
42#define ADS7828_CMD_PD2 0x08 /* Internal ref ON && A-D OFF */
43#define ADS7828_CMD_PD3 0x0C /* Internal ref ON && A-D ON */
44#define ADS7828_INT_VREF_MV 2500 /* Internal vref is 2.5V, 2500mV */
45
46/* Addresses to scan */
Mark M. Hoffman25e9c862008-02-17 22:28:03 -050047static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b,
Steve Hardy5812f922008-01-22 23:00:02 +000048 I2C_CLIENT_END };
49
50/* Insmod parameters */
51I2C_CLIENT_INSMOD_1(ads7828);
52
53/* Other module parameters */
54static int se_input = 1; /* Default is SE, 0 == diff */
55static int int_vref = 1; /* Default is internal ref ON */
56static int vref_mv = ADS7828_INT_VREF_MV; /* set if vref != 2.5V */
57module_param(se_input, bool, S_IRUGO);
58module_param(int_vref, bool, S_IRUGO);
59module_param(vref_mv, int, S_IRUGO);
60
61/* Global Variables */
62static u8 ads7828_cmd_byte; /* cmd byte without channel bits */
63static unsigned int ads7828_lsb_resol; /* resolution of the ADC sample lsb */
64
65/* Each client has this additional data */
66struct ads7828_data {
Steve Hardy5812f922008-01-22 23:00:02 +000067 struct device *hwmon_dev;
68 struct mutex update_lock; /* mutex protect updates */
69 char valid; /* !=0 if following fields are valid */
70 unsigned long last_updated; /* In jiffies */
71 u16 adc_input[ADS7828_NCH]; /* ADS7828_NCH 12-bit samples */
72};
73
74/* Function declaration - necessary due to function dependencies */
Jean Delvare7347cb32008-07-16 19:30:10 +020075static int ads7828_detect(struct i2c_client *client, int kind,
76 struct i2c_board_info *info);
77static int ads7828_probe(struct i2c_client *client,
78 const struct i2c_device_id *id);
Steve Hardy5812f922008-01-22 23:00:02 +000079
80/* The ADS7828 returns the 12-bit sample in two bytes,
81 these are read as a word then byte-swapped */
82static u16 ads7828_read_value(struct i2c_client *client, u8 reg)
83{
84 return swab16(i2c_smbus_read_word_data(client, reg));
85}
86
87static inline u8 channel_cmd_byte(int ch)
88{
89 /* cmd byte C2,C1,C0 - see datasheet */
90 u8 cmd = (((ch>>1) | (ch&0x01)<<2)<<4);
91 cmd |= ads7828_cmd_byte;
92 return cmd;
93}
94
95/* Update data for the device (all 8 channels) */
96static struct ads7828_data *ads7828_update_device(struct device *dev)
97{
98 struct i2c_client *client = to_i2c_client(dev);
99 struct ads7828_data *data = i2c_get_clientdata(client);
100
101 mutex_lock(&data->update_lock);
102
103 if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
104 || !data->valid) {
105 unsigned int ch;
106 dev_dbg(&client->dev, "Starting ads7828 update\n");
107
108 for (ch = 0; ch < ADS7828_NCH; ch++) {
109 u8 cmd = channel_cmd_byte(ch);
110 data->adc_input[ch] = ads7828_read_value(client, cmd);
111 }
112 data->last_updated = jiffies;
113 data->valid = 1;
114 }
115
116 mutex_unlock(&data->update_lock);
117
118 return data;
119}
120
121/* sysfs callback function */
122static ssize_t show_in(struct device *dev, struct device_attribute *da,
123 char *buf)
124{
125 struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
126 struct ads7828_data *data = ads7828_update_device(dev);
127 /* Print value (in mV as specified in sysfs-interface documentation) */
128 return sprintf(buf, "%d\n", (data->adc_input[attr->index] *
129 ads7828_lsb_resol)/1000);
130}
131
132#define in_reg(offset)\
133static SENSOR_DEVICE_ATTR(in##offset##_input, S_IRUGO, show_in,\
134 NULL, offset)
135
136in_reg(0);
137in_reg(1);
138in_reg(2);
139in_reg(3);
140in_reg(4);
141in_reg(5);
142in_reg(6);
143in_reg(7);
144
145static struct attribute *ads7828_attributes[] = {
146 &sensor_dev_attr_in0_input.dev_attr.attr,
147 &sensor_dev_attr_in1_input.dev_attr.attr,
148 &sensor_dev_attr_in2_input.dev_attr.attr,
149 &sensor_dev_attr_in3_input.dev_attr.attr,
150 &sensor_dev_attr_in4_input.dev_attr.attr,
151 &sensor_dev_attr_in5_input.dev_attr.attr,
152 &sensor_dev_attr_in6_input.dev_attr.attr,
153 &sensor_dev_attr_in7_input.dev_attr.attr,
154 NULL
155};
156
157static const struct attribute_group ads7828_group = {
158 .attrs = ads7828_attributes,
159};
160
Jean Delvare7347cb32008-07-16 19:30:10 +0200161static int ads7828_remove(struct i2c_client *client)
Steve Hardy5812f922008-01-22 23:00:02 +0000162{
163 struct ads7828_data *data = i2c_get_clientdata(client);
164 hwmon_device_unregister(data->hwmon_dev);
165 sysfs_remove_group(&client->dev.kobj, &ads7828_group);
Steve Hardy5812f922008-01-22 23:00:02 +0000166 kfree(i2c_get_clientdata(client));
167 return 0;
168}
169
Jean Delvare7347cb32008-07-16 19:30:10 +0200170static const struct i2c_device_id ads7828_id[] = {
171 { "ads7828", ads7828 },
172 { }
173};
174MODULE_DEVICE_TABLE(i2c, ads7828_id);
175
Steve Hardy5812f922008-01-22 23:00:02 +0000176/* This is the driver that will be inserted */
177static struct i2c_driver ads7828_driver = {
Jean Delvare7347cb32008-07-16 19:30:10 +0200178 .class = I2C_CLASS_HWMON,
Steve Hardy5812f922008-01-22 23:00:02 +0000179 .driver = {
180 .name = "ads7828",
181 },
Jean Delvare7347cb32008-07-16 19:30:10 +0200182 .probe = ads7828_probe,
183 .remove = ads7828_remove,
184 .id_table = ads7828_id,
185 .detect = ads7828_detect,
186 .address_data = &addr_data,
Steve Hardy5812f922008-01-22 23:00:02 +0000187};
188
Jean Delvare7347cb32008-07-16 19:30:10 +0200189/* Return 0 if detection is successful, -ENODEV otherwise */
190static int ads7828_detect(struct i2c_client *client, int kind,
191 struct i2c_board_info *info)
Steve Hardy5812f922008-01-22 23:00:02 +0000192{
Jean Delvare7347cb32008-07-16 19:30:10 +0200193 struct i2c_adapter *adapter = client->adapter;
Steve Hardy5812f922008-01-22 23:00:02 +0000194
195 /* Check we have a valid client */
196 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_WORD_DATA))
Jean Delvare7347cb32008-07-16 19:30:10 +0200197 return -ENODEV;
Steve Hardy5812f922008-01-22 23:00:02 +0000198
199 /* Now, we do the remaining detection. There is no identification
200 dedicated register so attempt to sanity check using knowledge of
201 the chip
202 - Read from the 8 channel addresses
203 - Check the top 4 bits of each result are not set (12 data bits)
204 */
205 if (kind < 0) {
206 int ch;
207 for (ch = 0; ch < ADS7828_NCH; ch++) {
208 u16 in_data;
209 u8 cmd = channel_cmd_byte(ch);
210 in_data = ads7828_read_value(client, cmd);
211 if (in_data & 0xF000) {
212 printk(KERN_DEBUG
213 "%s : Doesn't look like an ads7828 device\n",
Harvey Harrison145980a2008-04-30 00:54:57 -0700214 __func__);
Jean Delvare7347cb32008-07-16 19:30:10 +0200215 return -ENODEV;
Steve Hardy5812f922008-01-22 23:00:02 +0000216 }
217 }
218 }
Jean Delvare7347cb32008-07-16 19:30:10 +0200219 strlcpy(info->type, "ads7828", I2C_NAME_SIZE);
Steve Hardy5812f922008-01-22 23:00:02 +0000220
Jean Delvare7347cb32008-07-16 19:30:10 +0200221 return 0;
222}
Steve Hardy5812f922008-01-22 23:00:02 +0000223
Jean Delvare7347cb32008-07-16 19:30:10 +0200224static int ads7828_probe(struct i2c_client *client,
225 const struct i2c_device_id *id)
226{
227 struct ads7828_data *data;
228 int err;
Steve Hardy5812f922008-01-22 23:00:02 +0000229
Jean Delvare7347cb32008-07-16 19:30:10 +0200230 data = kzalloc(sizeof(struct ads7828_data), GFP_KERNEL);
231 if (!data) {
232 err = -ENOMEM;
233 goto exit;
234 }
Steve Hardy5812f922008-01-22 23:00:02 +0000235
Jean Delvare7347cb32008-07-16 19:30:10 +0200236 i2c_set_clientdata(client, data);
Steve Hardy5812f922008-01-22 23:00:02 +0000237 mutex_init(&data->update_lock);
238
Steve Hardy5812f922008-01-22 23:00:02 +0000239 /* Register sysfs hooks */
240 err = sysfs_create_group(&client->dev.kobj, &ads7828_group);
241 if (err)
Jean Delvare7347cb32008-07-16 19:30:10 +0200242 goto exit_free;
Steve Hardy5812f922008-01-22 23:00:02 +0000243
244 data->hwmon_dev = hwmon_device_register(&client->dev);
245 if (IS_ERR(data->hwmon_dev)) {
246 err = PTR_ERR(data->hwmon_dev);
247 goto exit_remove;
248 }
249
250 return 0;
251
252exit_remove:
253 sysfs_remove_group(&client->dev.kobj, &ads7828_group);
Steve Hardy5812f922008-01-22 23:00:02 +0000254exit_free:
255 kfree(data);
256exit:
257 return err;
258}
259
260static int __init sensors_ads7828_init(void)
261{
262 /* Initialize the command byte according to module parameters */
263 ads7828_cmd_byte = se_input ?
264 ADS7828_CMD_SD_SE : ADS7828_CMD_SD_DIFF;
265 ads7828_cmd_byte |= int_vref ?
266 ADS7828_CMD_PD3 : ADS7828_CMD_PD1;
267
268 /* Calculate the LSB resolution */
269 ads7828_lsb_resol = (vref_mv*1000)/4096;
270
271 return i2c_add_driver(&ads7828_driver);
272}
273
274static void __exit sensors_ads7828_exit(void)
275{
276 i2c_del_driver(&ads7828_driver);
277}
278
279MODULE_AUTHOR("Steve Hardy <steve@linuxrealtime.co.uk>");
280MODULE_DESCRIPTION("ADS7828 driver");
281MODULE_LICENSE("GPL");
282
283module_init(sensors_ads7828_init);
284module_exit(sensors_ads7828_exit);