summaryrefslogtreecommitdiffstats
path: root/drivers/hwmon/ads7828.c
blob: 3827ce4be071e01c30fe2c032b033cf8909b389b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
/*
	ads7828.c - lm_sensors driver for ads7828 12-bit 8-channel ADC
	(C) 2007 EADS Astrium

	This driver is based on the lm75 and other lm_sensors/hwmon drivers

	Written by Steve Hardy <steve@linuxrealtime.co.uk>

	Datasheet available at: http://focus.ti.com/lit/ds/symlink/ads7828.pdf

	This program is free software; you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation; either version 2 of the License, or
	(at your option) any later version.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	See the
	GNU General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with this program; if not, write to the Free Software
	Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/jiffies.h>
#include <linux/i2c.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/err.h>
#include <linux/mutex.h>

/* The ADS7828 registers */
#define ADS7828_NCH 8 /* 8 channels of 12-bit A-D supported */
#define ADS7828_CMD_SD_SE 0x80 /* Single ended inputs */
#define ADS7828_CMD_SD_DIFF 0x00 /* Differential inputs */
#define ADS7828_CMD_PD0 0x0 /* Power Down between A-D conversions */
#define ADS7828_CMD_PD1 0x04 /* Internal ref OFF && A-D ON */
#define ADS7828_CMD_PD2 0x08 /* Internal ref ON && A-D OFF */
#define ADS7828_CMD_PD3 0x0C /* Internal ref ON && A-D ON */
#define ADS7828_INT_VREF_MV 2500 /* Internal vref is 2.5V, 2500mV */

/* Addresses to scan */
static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b,
	I2C_CLIENT_END };

/* Insmod parameters */
I2C_CLIENT_INSMOD_1(ads7828);

/* Other module parameters */
static int se_input = 1; /* Default is SE, 0 == diff */
static int int_vref = 1; /* Default is internal ref ON */
static int vref_mv = ADS7828_INT_VREF_MV; /* set if vref != 2.5V */
module_param(se_input, bool, S_IRUGO);
module_param(int_vref, bool, S_IRUGO);
module_param(vref_mv, int, S_IRUGO);

/* Global Variables */
static u8 ads7828_cmd_byte; /* cmd byte without channel bits */
static unsigned int ads7828_lsb_resol; /* resolution of the ADC sample lsb */

/* Each client has this additional data */
struct ads7828_data {
	struct device *hwmon_dev;
	struct mutex update_lock; /* mutex protect updates */
	char valid; /* !=0 if following fields are valid */
	unsigned long last_updated; /* In jiffies */
	u16 adc_input[ADS7828_NCH]; /* ADS7828_NCH 12-bit samples */
};

/* Function declaration - necessary due to function dependencies */
static int ads7828_detect(struct i2c_client *client,
			  struct i2c_board_info *info);
static int ads7828_probe(struct i2c_client *client,
			 const struct i2c_device_id *id);

/* The ADS7828 returns the 12-bit sample in two bytes,
	these are read as a word then byte-swapped */
static u16 ads7828_read_value(struct i2c_client *client, u8 reg)
{
	return swab16(i2c_smbus_read_word_data(client, reg));
}

static inline u8 channel_cmd_byte(int ch)
{
	/* cmd byte C2,C1,C0 - see datasheet */
	u8 cmd = (((ch>>1) | (ch&0x01)<<2)<<4);
	cmd |= ads7828_cmd_byte;
	return cmd;
}

/* Update data for the device (all 8 channels) */
static struct ads7828_data *ads7828_update_device(struct device *dev)
{
	struct i2c_client *client = to_i2c_client(dev);
	struct ads7828_data *data = i2c_get_clientdata(client);

	mutex_lock(&data->update_lock);

	if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
			|| !data->valid) {
		unsigned int ch;
		dev_dbg(&client->dev, "Starting ads7828 update\n");

		for (ch = 0; ch < ADS7828_NCH; ch++) {
			u8 cmd = channel_cmd_byte(ch);
			data->adc_input[ch] = ads7828_read_value(client, cmd);
		}
		data->last_updated = jiffies;
		data->valid = 1;
	}

	mutex_unlock(&data->update_lock);

	return data;
}

/* sysfs callback function */
static ssize_t show_in(struct device *dev, struct device_attribute *da,
	char *buf)
{
	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
	struct ads7828_data *data = ads7828_update_device(dev);
	/* Print value (in mV as specified in sysfs-interface documentation) */
	return sprintf(buf, "%d\n", (data->adc_input[attr->index] *
		ads7828_lsb_resol)/1000);
}

#define in_reg(offset)\
static SENSOR_DEVICE_ATTR(in##offset##_input, S_IRUGO, show_in,\
	NULL, offset)

in_reg(0);
in_reg(1);
in_reg(2);
in_reg(3);
in_reg(4);
in_reg(5);
in_reg(6);
in_reg(7);

static struct attribute *ads7828_attributes[] = {
	&sensor_dev_attr_in0_input.dev_attr.attr,
	&sensor_dev_attr_in1_input.dev_attr.attr,
	&sensor_dev_attr_in2_input.dev_attr.attr,
	&sensor_dev_attr_in3_input.dev_attr.attr,
	&sensor_dev_attr_in4_input.dev_attr.attr,
	&sensor_dev_attr_in5_input.dev_attr.attr,
	&sensor_dev_attr_in6_input.dev_attr.attr,
	&sensor_dev_attr_in7_input.dev_attr.attr,
	NULL
};

static const struct attribute_group ads7828_group = {
	.attrs = ads7828_attributes,
};

static int ads7828_remove(struct i2c_client *client)
{
	struct ads7828_data *data = i2c_get_clientdata(client);
	hwmon_device_unregister(data->hwmon_dev);
	sysfs_remove_group(&client->dev.kobj, &ads7828_group);
	kfree(i2c_get_clientdata(client));
	return 0;
}

static const struct i2c_device_id ads7828_id[] = {
	{ "ads7828", ads7828 },
	{ }
};
MODULE_DEVICE_TABLE(i2c, ads7828_id);

/* This is the driver that will be inserted */
static struct i2c_driver ads7828_driver = {
	.class = I2C_CLASS_HWMON,
	.driver = {
		.name = "ads7828",
	},
	.probe = ads7828_probe,
	.remove = ads7828_remove,
	.id_table = ads7828_id,
	.detect = ads7828_detect,
	.address_list = normal_i2c,
};

/* Return 0 if detection is successful, -ENODEV otherwise */
static int ads7828_detect(struct i2c_client *client,
			  struct i2c_board_info *info)
{
	struct i2c_adapter *adapter = client->adapter;
	int ch;

	/* Check we have a valid client */
	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_WORD_DATA))
		return -ENODEV;

	/* Now, we do the remaining detection. There is no identification
	dedicated register so attempt to sanity check using knowledge of
	the chip
	- Read from the 8 channel addresses
	- Check the top 4 bits of each result are not set (12 data bits)
	*/
	for (ch = 0; ch < ADS7828_NCH; ch++) {
		u16 in_data;
		u8 cmd = channel_cmd_byte(ch);
		in_data = ads7828_read_value(client, cmd);
		if (in_data & 0xF000) {
			pr_debug("%s : Doesn't look like an ads7828 device\n",
				 __func__);
			return -ENODEV;
		}
	}

	strlcpy(info->type, "ads7828", I2C_NAME_SIZE);

	return 0;
}

static int ads7828_probe(struct i2c_client *client,
			 const struct i2c_device_id *id)
{
	struct ads7828_data *data;
	int err;

	data = kzalloc(sizeof(struct ads7828_data), GFP_KERNEL);
	if (!data) {
		err = -ENOMEM;
		goto exit;
	}

	i2c_set_clientdata(client, data);
	mutex_init(&data->update_lock);

	/* Register sysfs hooks */
	err = sysfs_create_group(&client->dev.kobj, &ads7828_group);
	if (err)
		goto exit_free;

	data->hwmon_dev = hwmon_device_register(&client->dev);
	if (IS_ERR(data->hwmon_dev)) {
		err = PTR_ERR(data->hwmon_dev);
		goto exit_remove;
	}

	return 0;

exit_remove:
	sysfs_remove_group(&client->dev.kobj, &ads7828_group);
exit_free:
	kfree(data);
exit:
	return err;
}

static int __init sensors_ads7828_init(void)
{
	/* Initialize the command byte according to module parameters */
	ads7828_cmd_byte = se_input ?
		ADS7828_CMD_SD_SE : ADS7828_CMD_SD_DIFF;
	ads7828_cmd_byte |= int_vref ?
		ADS7828_CMD_PD3 : ADS7828_CMD_PD1;

	/* Calculate the LSB resolution */
	ads7828_lsb_resol = (vref_mv*1000)/4096;

	return i2c_add_driver(&ads7828_driver);
}

static void __exit sensors_ads7828_exit(void)
{
	i2c_del_driver(&ads7828_driver);
}

MODULE_AUTHOR("Steve Hardy <steve@linuxrealtime.co.uk>");
MODULE_DESCRIPTION("ADS7828 driver");
MODULE_LICENSE("GPL");

module_init(sensors_ads7828_init);
module_exit(sensors_ads7828_exit);
OpenPOWER on IntegriCloud