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1/*
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 <shardy@redhat.com>
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 */
47static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b,
48 I2C_CLIENT_END };
49
50/* Module parameters */
51static bool se_input = 1; /* Default is SE, 0 == diff */
52static bool int_vref = 1; /* Default is internal ref ON */
53static int vref_mv = ADS7828_INT_VREF_MV; /* set if vref != 2.5V */
54module_param(se_input, bool, S_IRUGO);
55module_param(int_vref, bool, S_IRUGO);
56module_param(vref_mv, int, S_IRUGO);
57
58/* Global Variables */
59static u8 ads7828_cmd_byte; /* cmd byte without channel bits */
60static unsigned int ads7828_lsb_resol; /* resolution of the ADC sample lsb */
61
62/* Each client has this additional data */
63struct ads7828_data {
64 struct device *hwmon_dev;
65 struct mutex update_lock; /* mutex protect updates */
66 char valid; /* !=0 if following fields are valid */
67 unsigned long last_updated; /* In jiffies */
68 u16 adc_input[ADS7828_NCH]; /* ADS7828_NCH 12-bit samples */
69};
70
71/* Function declaration - necessary due to function dependencies */
72static int ads7828_detect(struct i2c_client *client,
73 struct i2c_board_info *info);
74static int ads7828_probe(struct i2c_client *client,
75 const struct i2c_device_id *id);
76
77static inline u8 channel_cmd_byte(int ch)
78{
79 /* cmd byte C2,C1,C0 - see datasheet */
80 u8 cmd = (((ch>>1) | (ch&0x01)<<2)<<4);
81 cmd |= ads7828_cmd_byte;
82 return cmd;
83}
84
85/* Update data for the device (all 8 channels) */
86static struct ads7828_data *ads7828_update_device(struct device *dev)
87{
88 struct i2c_client *client = to_i2c_client(dev);
89 struct ads7828_data *data = i2c_get_clientdata(client);
90
91 mutex_lock(&data->update_lock);
92
93 if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
94 || !data->valid) {
95 unsigned int ch;
96 dev_dbg(&client->dev, "Starting ads7828 update\n");
97
98 for (ch = 0; ch < ADS7828_NCH; ch++) {
99 u8 cmd = channel_cmd_byte(ch);
100 data->adc_input[ch] =
101 i2c_smbus_read_word_swapped(client, cmd);
102 }
103 data->last_updated = jiffies;
104 data->valid = 1;
105 }
106
107 mutex_unlock(&data->update_lock);
108
109 return data;
110}
111
112/* sysfs callback function */
113static ssize_t show_in(struct device *dev, struct device_attribute *da,
114 char *buf)
115{
116 struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
117 struct ads7828_data *data = ads7828_update_device(dev);
118 /* Print value (in mV as specified in sysfs-interface documentation) */
119 return sprintf(buf, "%d\n", (data->adc_input[attr->index] *
120 ads7828_lsb_resol)/1000);
121}
122
123#define in_reg(offset)\
124static SENSOR_DEVICE_ATTR(in##offset##_input, S_IRUGO, show_in,\
125 NULL, offset)
126
127in_reg(0);
128in_reg(1);
129in_reg(2);
130in_reg(3);
131in_reg(4);
132in_reg(5);
133in_reg(6);
134in_reg(7);
135
136static struct attribute *ads7828_attributes[] = {
137 &sensor_dev_attr_in0_input.dev_attr.attr,
138 &sensor_dev_attr_in1_input.dev_attr.attr,
139 &sensor_dev_attr_in2_input.dev_attr.attr,
140 &sensor_dev_attr_in3_input.dev_attr.attr,
141 &sensor_dev_attr_in4_input.dev_attr.attr,
142 &sensor_dev_attr_in5_input.dev_attr.attr,
143 &sensor_dev_attr_in6_input.dev_attr.attr,
144 &sensor_dev_attr_in7_input.dev_attr.attr,
145 NULL
146};
147
148static const struct attribute_group ads7828_group = {
149 .attrs = ads7828_attributes,
150};
151
152static int ads7828_remove(struct i2c_client *client)
153{
154 struct ads7828_data *data = i2c_get_clientdata(client);
155 hwmon_device_unregister(data->hwmon_dev);
156 sysfs_remove_group(&client->dev.kobj, &ads7828_group);
157 kfree(i2c_get_clientdata(client));
158 return 0;
159}
160
161static const struct i2c_device_id ads7828_id[] = {
162 { "ads7828", 0 },
163 { }
164};
165MODULE_DEVICE_TABLE(i2c, ads7828_id);
166
167/* This is the driver that will be inserted */
168static struct i2c_driver ads7828_driver = {
169 .class = I2C_CLASS_HWMON,
170 .driver = {
171 .name = "ads7828",
172 },
173 .probe = ads7828_probe,
174 .remove = ads7828_remove,
175 .id_table = ads7828_id,
176 .detect = ads7828_detect,
177 .address_list = normal_i2c,
178};
179
180/* Return 0 if detection is successful, -ENODEV otherwise */
181static int ads7828_detect(struct i2c_client *client,
182 struct i2c_board_info *info)
183{
184 struct i2c_adapter *adapter = client->adapter;
185 int ch;
186
187 /* Check we have a valid client */
188 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_WORD_DATA))
189 return -ENODEV;
190
191 /*
192 * Now, we do the remaining detection. There is no identification
193 * dedicated register so attempt to sanity check using knowledge of
194 * the chip
195 * - Read from the 8 channel addresses
196 * - Check the top 4 bits of each result are not set (12 data bits)
197 */
198 for (ch = 0; ch < ADS7828_NCH; ch++) {
199 u16 in_data;
200 u8 cmd = channel_cmd_byte(ch);
201 in_data = i2c_smbus_read_word_swapped(client, cmd);
202 if (in_data & 0xF000) {
203 pr_debug("%s : Doesn't look like an ads7828 device\n",
204 __func__);
205 return -ENODEV;
206 }
207 }
208
209 strlcpy(info->type, "ads7828", I2C_NAME_SIZE);
210
211 return 0;
212}
213
214static int ads7828_probe(struct i2c_client *client,
215 const struct i2c_device_id *id)
216{
217 struct ads7828_data *data;
218 int err;
219
220 data = kzalloc(sizeof(struct ads7828_data), GFP_KERNEL);
221 if (!data) {
222 err = -ENOMEM;
223 goto exit;
224 }
225
226 i2c_set_clientdata(client, data);
227 mutex_init(&data->update_lock);
228
229 /* Register sysfs hooks */
230 err = sysfs_create_group(&client->dev.kobj, &ads7828_group);
231 if (err)
232 goto exit_free;
233
234 data->hwmon_dev = hwmon_device_register(&client->dev);
235 if (IS_ERR(data->hwmon_dev)) {
236 err = PTR_ERR(data->hwmon_dev);
237 goto exit_remove;
238 }
239
240 return 0;
241
242exit_remove:
243 sysfs_remove_group(&client->dev.kobj, &ads7828_group);
244exit_free:
245 kfree(data);
246exit:
247 return err;
248}
249
250static int __init sensors_ads7828_init(void)
251{
252 /* Initialize the command byte according to module parameters */
253 ads7828_cmd_byte = se_input ?
254 ADS7828_CMD_SD_SE : ADS7828_CMD_SD_DIFF;
255 ads7828_cmd_byte |= int_vref ?
256 ADS7828_CMD_PD3 : ADS7828_CMD_PD1;
257
258 /* Calculate the LSB resolution */
259 ads7828_lsb_resol = (vref_mv*1000)/4096;
260
261 return i2c_add_driver(&ads7828_driver);
262}
263
264static void __exit sensors_ads7828_exit(void)
265{
266 i2c_del_driver(&ads7828_driver);
267}
268
269MODULE_AUTHOR("Steve Hardy <shardy@redhat.com>");
270MODULE_DESCRIPTION("ADS7828 driver");
271MODULE_LICENSE("GPL");
272
273module_init(sensors_ads7828_init);
274module_exit(sensors_ads7828_exit);