summaryrefslogtreecommitdiffstats
path: root/drivers/hwmon/ads7871.c
blob: a79875986f911a62d4aeb8fd61a4081dff2d9356 (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
/*
 *  ads7871 - driver for TI ADS7871 A/D converter
 *
 *  Copyright (c) 2010 Paul Thomas <pthomas8589@gmail.com>
 *
 *  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.
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2 or
 *  later as publishhed by the Free Software Foundation.
 *
 *	You need to have something like this in struct spi_board_info
 *	{
 *		.modalias	= "ads7871",
 *		.max_speed_hz	= 2*1000*1000,
 *		.chip_select	= 0,
 *		.bus_num	= 1,
 *	},
 */

/*From figure 18 in the datasheet*/
/*Register addresses*/
#define REG_LS_BYTE	0 /*A/D Output Data, LS Byte*/
#define REG_MS_BYTE	1 /*A/D Output Data, MS Byte*/
#define REG_PGA_VALID	2 /*PGA Valid Register*/
#define REG_AD_CONTROL	3 /*A/D Control Register*/
#define REG_GAIN_MUX	4 /*Gain/Mux Register*/
#define REG_IO_STATE	5 /*Digital I/O State Register*/
#define REG_IO_CONTROL	6 /*Digital I/O Control Register*/
#define REG_OSC_CONTROL	7 /*Rev/Oscillator Control Register*/
#define REG_SER_CONTROL 24 /*Serial Interface Control Register*/
#define REG_ID		31 /*ID Register*/

/*
 * From figure 17 in the datasheet
 * These bits get ORed with the address to form
 * the instruction byte
 */
/*Instruction Bit masks*/
#define INST_MODE_bm	(1<<7)
#define INST_READ_bm	(1<<6)
#define INST_16BIT_bm	(1<<5)

/*From figure 18 in the datasheet*/
/*bit masks for Rev/Oscillator Control Register*/
#define MUX_CNV_bv	7
#define MUX_CNV_bm	(1<<MUX_CNV_bv)
#define MUX_M3_bm	(1<<3) /*M3 selects single ended*/
#define MUX_G_bv	4 /*allows for reg = (gain << MUX_G_bv) | ...*/

/*From figure 18 in the datasheet*/
/*bit masks for Rev/Oscillator Control Register*/
#define OSC_OSCR_bm	(1<<5)
#define OSC_OSCE_bm	(1<<4)
#define OSC_REFE_bm	(1<<3)
#define OSC_BUFE_bm	(1<<2)
#define OSC_R2V_bm	(1<<1)
#define OSC_RBG_bm	(1<<0)

#include <linux/module.h>
#include <linux/init.h>
#include <linux/spi/spi.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/err.h>
#include <linux/mutex.h>
#include <linux/delay.h>

#define DEVICE_NAME	"ads7871"

struct ads7871_data {
	struct device	*hwmon_dev;
	struct mutex	update_lock;
};

static int ads7871_read_reg8(struct spi_device *spi, int reg)
{
	int ret;
	reg = reg | INST_READ_bm;
	ret = spi_w8r8(spi, reg);
	return ret;
}

static int ads7871_read_reg16(struct spi_device *spi, int reg)
{
	int ret;
	reg = reg | INST_READ_bm | INST_16BIT_bm;
	ret = spi_w8r16(spi, reg);
	return ret;
}

static int ads7871_write_reg8(struct spi_device *spi, int reg, u8 val)
{
	u8 tmp[2] = {reg, val};
	return spi_write(spi, tmp, sizeof(tmp));
}

static ssize_t show_voltage(struct device *dev,
		struct device_attribute *da, char *buf)
{
	struct spi_device *spi = to_spi_device(dev);
	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
	int ret, val, i = 0;
	uint8_t channel, mux_cnv;

	channel = attr->index;
	/*
	 * TODO: add support for conversions
	 * other than single ended with a gain of 1
	 */
	/*MUX_M3_bm forces single ended*/
	/*This is also where the gain of the PGA would be set*/
	ads7871_write_reg8(spi, REG_GAIN_MUX,
		(MUX_CNV_bm | MUX_M3_bm | channel));

	ret = ads7871_read_reg8(spi, REG_GAIN_MUX);
	mux_cnv = ((ret & MUX_CNV_bm)>>MUX_CNV_bv);
	/*
	 * on 400MHz arm9 platform the conversion
	 * is already done when we do this test
	 */
	while ((i < 2) && mux_cnv) {
		i++;
		ret = ads7871_read_reg8(spi, REG_GAIN_MUX);
		mux_cnv = ((ret & MUX_CNV_bm)>>MUX_CNV_bv);
		msleep_interruptible(1);
	}

	if (mux_cnv == 0) {
		val = ads7871_read_reg16(spi, REG_LS_BYTE);
		/*result in volts*10000 = (val/8192)*2.5*10000*/
		val = ((val>>2) * 25000) / 8192;
		return sprintf(buf, "%d\n", val);
	} else {
		return -1;
	}
}

static ssize_t ads7871_show_name(struct device *dev,
				 struct device_attribute *devattr, char *buf)
{
	return sprintf(buf, "%s\n", to_spi_device(dev)->modalias);
}

static SENSOR_DEVICE_ATTR(in0_input, S_IRUGO, show_voltage, NULL, 0);
static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, show_voltage, NULL, 1);
static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, show_voltage, NULL, 2);
static SENSOR_DEVICE_ATTR(in3_input, S_IRUGO, show_voltage, NULL, 3);
static SENSOR_DEVICE_ATTR(in4_input, S_IRUGO, show_voltage, NULL, 4);
static SENSOR_DEVICE_ATTR(in5_input, S_IRUGO, show_voltage, NULL, 5);
static SENSOR_DEVICE_ATTR(in6_input, S_IRUGO, show_voltage, NULL, 6);
static SENSOR_DEVICE_ATTR(in7_input, S_IRUGO, show_voltage, NULL, 7);

static DEVICE_ATTR(name, S_IRUGO, ads7871_show_name, NULL);

static struct attribute *ads7871_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,
	&dev_attr_name.attr,
	NULL
};

static const struct attribute_group ads7871_group = {
	.attrs = ads7871_attributes,
};

static int ads7871_probe(struct spi_device *spi)
{
	int ret, err;
	uint8_t val;
	struct ads7871_data *pdata;

	dev_dbg(&spi->dev, "probe\n");

	/* Configure the SPI bus */
	spi->mode = (SPI_MODE_0);
	spi->bits_per_word = 8;
	spi_setup(spi);

	ads7871_write_reg8(spi, REG_SER_CONTROL, 0);
	ads7871_write_reg8(spi, REG_AD_CONTROL, 0);

	val = (OSC_OSCR_bm | OSC_OSCE_bm | OSC_REFE_bm | OSC_BUFE_bm);
	ads7871_write_reg8(spi, REG_OSC_CONTROL, val);
	ret = ads7871_read_reg8(spi, REG_OSC_CONTROL);

	dev_dbg(&spi->dev, "REG_OSC_CONTROL write:%x, read:%x\n", val, ret);
	/*
	 * because there is no other error checking on an SPI bus
	 * we need to make sure we really have a chip
	 */
	if (val != ret)
		return -ENODEV;

	pdata = devm_kzalloc(&spi->dev, sizeof(struct ads7871_data),
			     GFP_KERNEL);
	if (!pdata)
		return -ENOMEM;

	err = sysfs_create_group(&spi->dev.kobj, &ads7871_group);
	if (err < 0)
		return err;

	spi_set_drvdata(spi, pdata);

	pdata->hwmon_dev = hwmon_device_register(&spi->dev);
	if (IS_ERR(pdata->hwmon_dev)) {
		err = PTR_ERR(pdata->hwmon_dev);
		goto error_remove;
	}

	return 0;

error_remove:
	sysfs_remove_group(&spi->dev.kobj, &ads7871_group);
	return err;
}

static int ads7871_remove(struct spi_device *spi)
{
	struct ads7871_data *pdata = spi_get_drvdata(spi);

	hwmon_device_unregister(pdata->hwmon_dev);
	sysfs_remove_group(&spi->dev.kobj, &ads7871_group);
	return 0;
}

static struct spi_driver ads7871_driver = {
	.driver = {
		.name = DEVICE_NAME,
		.owner = THIS_MODULE,
	},

	.probe = ads7871_probe,
	.remove = ads7871_remove,
};

module_spi_driver(ads7871_driver);

MODULE_AUTHOR("Paul Thomas <pthomas8589@gmail.com>");
MODULE_DESCRIPTION("TI ADS7871 A/D driver");
MODULE_LICENSE("GPL");
OpenPOWER on IntegriCloud