2 ads7828.c - lm_sensors driver for ads7828 12-bit 8-channel ADC
5 This driver is based on the lm75 and other lm_sensors/hwmon drivers
7 Written by Steve Hardy <shardy@redhat.com>
9 Datasheet available at: http://focus.ti.com/lit/ds/symlink/ads7828.pdf
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.
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.
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.
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>
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 */
46 /* Addresses to scan */
47 static const unsigned short normal_i2c
[] = { 0x48, 0x49, 0x4a, 0x4b,
50 /* Module parameters */
51 static int se_input
= 1; /* Default is SE, 0 == diff */
52 static int int_vref
= 1; /* Default is internal ref ON */
53 static int vref_mv
= ADS7828_INT_VREF_MV
; /* set if vref != 2.5V */
54 module_param(se_input
, bool, S_IRUGO
);
55 module_param(int_vref
, bool, S_IRUGO
);
56 module_param(vref_mv
, int, S_IRUGO
);
58 /* Global Variables */
59 static u8 ads7828_cmd_byte
; /* cmd byte without channel bits */
60 static unsigned int ads7828_lsb_resol
; /* resolution of the ADC sample lsb */
62 /* Each client has this additional 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 */
71 /* Function declaration - necessary due to function dependencies */
72 static int ads7828_detect(struct i2c_client
*client
,
73 struct i2c_board_info
*info
);
74 static int ads7828_probe(struct i2c_client
*client
,
75 const struct i2c_device_id
*id
);
77 static inline u8
channel_cmd_byte(int ch
)
79 /* cmd byte C2,C1,C0 - see datasheet */
80 u8 cmd
= (((ch
>>1) | (ch
&0x01)<<2)<<4);
81 cmd
|= ads7828_cmd_byte
;
85 /* Update data for the device (all 8 channels) */
86 static struct ads7828_data
*ads7828_update_device(struct device
*dev
)
88 struct i2c_client
*client
= to_i2c_client(dev
);
89 struct ads7828_data
*data
= i2c_get_clientdata(client
);
91 mutex_lock(&data
->update_lock
);
93 if (time_after(jiffies
, data
->last_updated
+ HZ
+ HZ
/ 2)
96 dev_dbg(&client
->dev
, "Starting ads7828 update\n");
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
);
103 data
->last_updated
= jiffies
;
107 mutex_unlock(&data
->update_lock
);
112 /* sysfs callback function */
113 static ssize_t
show_in(struct device
*dev
, struct device_attribute
*da
,
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);
123 #define in_reg(offset)\
124 static SENSOR_DEVICE_ATTR(in##offset##_input, S_IRUGO, show_in,\
136 static 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
,
148 static const struct attribute_group ads7828_group
= {
149 .attrs
= ads7828_attributes
,
152 static int ads7828_remove(struct i2c_client
*client
)
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
));
161 static const struct i2c_device_id ads7828_id
[] = {
165 MODULE_DEVICE_TABLE(i2c
, ads7828_id
);
167 /* This is the driver that will be inserted */
168 static struct i2c_driver ads7828_driver
= {
169 .class = I2C_CLASS_HWMON
,
173 .probe
= ads7828_probe
,
174 .remove
= ads7828_remove
,
175 .id_table
= ads7828_id
,
176 .detect
= ads7828_detect
,
177 .address_list
= normal_i2c
,
180 /* Return 0 if detection is successful, -ENODEV otherwise */
181 static int ads7828_detect(struct i2c_client
*client
,
182 struct i2c_board_info
*info
)
184 struct i2c_adapter
*adapter
= client
->adapter
;
187 /* Check we have a valid client */
188 if (!i2c_check_functionality(adapter
, I2C_FUNC_SMBUS_READ_WORD_DATA
))
191 /* Now, we do the remaining detection. There is no identification
192 dedicated register so attempt to sanity check using knowledge of
194 - Read from the 8 channel addresses
195 - Check the top 4 bits of each result are not set (12 data bits)
197 for (ch
= 0; ch
< ADS7828_NCH
; ch
++) {
199 u8 cmd
= channel_cmd_byte(ch
);
200 in_data
= i2c_smbus_read_word_swapped(client
, cmd
);
201 if (in_data
& 0xF000) {
202 pr_debug("%s : Doesn't look like an ads7828 device\n",
208 strlcpy(info
->type
, "ads7828", I2C_NAME_SIZE
);
213 static int ads7828_probe(struct i2c_client
*client
,
214 const struct i2c_device_id
*id
)
216 struct ads7828_data
*data
;
219 data
= kzalloc(sizeof(struct ads7828_data
), GFP_KERNEL
);
225 i2c_set_clientdata(client
, data
);
226 mutex_init(&data
->update_lock
);
228 /* Register sysfs hooks */
229 err
= sysfs_create_group(&client
->dev
.kobj
, &ads7828_group
);
233 data
->hwmon_dev
= hwmon_device_register(&client
->dev
);
234 if (IS_ERR(data
->hwmon_dev
)) {
235 err
= PTR_ERR(data
->hwmon_dev
);
242 sysfs_remove_group(&client
->dev
.kobj
, &ads7828_group
);
249 static int __init
sensors_ads7828_init(void)
251 /* Initialize the command byte according to module parameters */
252 ads7828_cmd_byte
= se_input
?
253 ADS7828_CMD_SD_SE
: ADS7828_CMD_SD_DIFF
;
254 ads7828_cmd_byte
|= int_vref
?
255 ADS7828_CMD_PD3
: ADS7828_CMD_PD1
;
257 /* Calculate the LSB resolution */
258 ads7828_lsb_resol
= (vref_mv
*1000)/4096;
260 return i2c_add_driver(&ads7828_driver
);
263 static void __exit
sensors_ads7828_exit(void)
265 i2c_del_driver(&ads7828_driver
);
268 MODULE_AUTHOR("Steve Hardy <shardy@redhat.com>");
269 MODULE_DESCRIPTION("ADS7828 driver");
270 MODULE_LICENSE("GPL");
272 module_init(sensors_ads7828_init
);
273 module_exit(sensors_ads7828_exit
);