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5812f928 SH |
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 <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 */ | |
25e9c86d | 47 | static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b, |
5812f928 SH |
48 | I2C_CLIENT_END }; |
49 | ||
50 | /* Insmod parameters */ | |
51 | I2C_CLIENT_INSMOD_1(ads7828); | |
52 | ||
53 | /* Other module parameters */ | |
54 | static int se_input = 1; /* Default is SE, 0 == diff */ | |
55 | static int int_vref = 1; /* Default is internal ref ON */ | |
56 | static int vref_mv = ADS7828_INT_VREF_MV; /* set if vref != 2.5V */ | |
57 | module_param(se_input, bool, S_IRUGO); | |
58 | module_param(int_vref, bool, S_IRUGO); | |
59 | module_param(vref_mv, int, S_IRUGO); | |
60 | ||
61 | /* Global Variables */ | |
62 | static u8 ads7828_cmd_byte; /* cmd byte without channel bits */ | |
63 | static unsigned int ads7828_lsb_resol; /* resolution of the ADC sample lsb */ | |
64 | ||
65 | /* Each client has this additional data */ | |
66 | struct ads7828_data { | |
5812f928 SH |
67 | 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 */ | |
7347cb38 JD |
75 | static int ads7828_detect(struct i2c_client *client, int kind, |
76 | struct i2c_board_info *info); | |
77 | static int ads7828_probe(struct i2c_client *client, | |
78 | const struct i2c_device_id *id); | |
5812f928 SH |
79 | |
80 | /* The ADS7828 returns the 12-bit sample in two bytes, | |
81 | these are read as a word then byte-swapped */ | |
82 | static u16 ads7828_read_value(struct i2c_client *client, u8 reg) | |
83 | { | |
84 | return swab16(i2c_smbus_read_word_data(client, reg)); | |
85 | } | |
86 | ||
87 | static 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) */ | |
96 | static 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 */ | |
122 | static 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)\ | |
133 | static SENSOR_DEVICE_ATTR(in##offset##_input, S_IRUGO, show_in,\ | |
134 | NULL, offset) | |
135 | ||
136 | in_reg(0); | |
137 | in_reg(1); | |
138 | in_reg(2); | |
139 | in_reg(3); | |
140 | in_reg(4); | |
141 | in_reg(5); | |
142 | in_reg(6); | |
143 | in_reg(7); | |
144 | ||
145 | static 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 | ||
157 | static const struct attribute_group ads7828_group = { | |
158 | .attrs = ads7828_attributes, | |
159 | }; | |
160 | ||
7347cb38 | 161 | static int ads7828_remove(struct i2c_client *client) |
5812f928 SH |
162 | { |
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); | |
5812f928 SH |
166 | kfree(i2c_get_clientdata(client)); |
167 | return 0; | |
168 | } | |
169 | ||
7347cb38 JD |
170 | static const struct i2c_device_id ads7828_id[] = { |
171 | { "ads7828", ads7828 }, | |
172 | { } | |
173 | }; | |
174 | MODULE_DEVICE_TABLE(i2c, ads7828_id); | |
175 | ||
5812f928 SH |
176 | /* This is the driver that will be inserted */ |
177 | static struct i2c_driver ads7828_driver = { | |
7347cb38 | 178 | .class = I2C_CLASS_HWMON, |
5812f928 SH |
179 | .driver = { |
180 | .name = "ads7828", | |
181 | }, | |
7347cb38 JD |
182 | .probe = ads7828_probe, |
183 | .remove = ads7828_remove, | |
184 | .id_table = ads7828_id, | |
185 | .detect = ads7828_detect, | |
186 | .address_data = &addr_data, | |
5812f928 SH |
187 | }; |
188 | ||
7347cb38 JD |
189 | /* Return 0 if detection is successful, -ENODEV otherwise */ |
190 | static int ads7828_detect(struct i2c_client *client, int kind, | |
191 | struct i2c_board_info *info) | |
5812f928 | 192 | { |
7347cb38 | 193 | struct i2c_adapter *adapter = client->adapter; |
5812f928 SH |
194 | |
195 | /* Check we have a valid client */ | |
196 | if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_WORD_DATA)) | |
7347cb38 | 197 | return -ENODEV; |
5812f928 SH |
198 | |
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", | |
145980a0 | 214 | __func__); |
7347cb38 | 215 | return -ENODEV; |
5812f928 SH |
216 | } |
217 | } | |
218 | } | |
7347cb38 | 219 | strlcpy(info->type, "ads7828", I2C_NAME_SIZE); |
5812f928 | 220 | |
7347cb38 JD |
221 | return 0; |
222 | } | |
5812f928 | 223 | |
7347cb38 JD |
224 | static int ads7828_probe(struct i2c_client *client, |
225 | const struct i2c_device_id *id) | |
226 | { | |
227 | struct ads7828_data *data; | |
228 | int err; | |
5812f928 | 229 | |
7347cb38 JD |
230 | data = kzalloc(sizeof(struct ads7828_data), GFP_KERNEL); |
231 | if (!data) { | |
232 | err = -ENOMEM; | |
233 | goto exit; | |
234 | } | |
5812f928 | 235 | |
7347cb38 | 236 | i2c_set_clientdata(client, data); |
5812f928 SH |
237 | mutex_init(&data->update_lock); |
238 | ||
5812f928 SH |
239 | /* Register sysfs hooks */ |
240 | err = sysfs_create_group(&client->dev.kobj, &ads7828_group); | |
241 | if (err) | |
7347cb38 | 242 | goto exit_free; |
5812f928 SH |
243 | |
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 | ||
252 | exit_remove: | |
253 | sysfs_remove_group(&client->dev.kobj, &ads7828_group); | |
5812f928 SH |
254 | exit_free: |
255 | kfree(data); | |
256 | exit: | |
257 | return err; | |
258 | } | |
259 | ||
260 | static 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 | ||
274 | static void __exit sensors_ads7828_exit(void) | |
275 | { | |
276 | i2c_del_driver(&ads7828_driver); | |
277 | } | |
278 | ||
279 | MODULE_AUTHOR("Steve Hardy <steve@linuxrealtime.co.uk>"); | |
280 | MODULE_DESCRIPTION("ADS7828 driver"); | |
281 | MODULE_LICENSE("GPL"); | |
282 | ||
283 | module_init(sensors_ads7828_init); | |
284 | module_exit(sensors_ads7828_exit); |