aboutsummaryrefslogtreecommitdiff
path: root/drivers/hwmon/lm70.c
blob: 583f883a4cfe61eb2bcaa9530a4c146eb8d23045 (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
/*
 * lm70.c
 *
 * The LM70 is a temperature sensor chip from National Semiconductor (NS).
 * Copyright (C) 2006 Kaiwan N Billimoria <kaiwan@designergraphix.com>
 *
 * The LM70 communicates with a host processor via an SPI/Microwire Bus
 * interface. The complete datasheet is available at National's website
 * here:
 * http://www.national.com/pf/LM/LM70.html
 *
 * 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.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/sysfs.h>
#include <linux/hwmon.h>
#include <linux/mutex.h>
#include <linux/mod_devicetable.h>
#include <linux/spi/spi.h>
#include <linux/slab.h>
#include <linux/of_device.h>


#define DRVNAME		"lm70"

#define LM70_CHIP_LM70		0	/* original NS LM70 */
#define LM70_CHIP_TMP121	1	/* TI TMP121/TMP123 */
#define LM70_CHIP_LM71		2	/* NS LM71 */
#define LM70_CHIP_LM74		3	/* NS LM74 */

struct lm70 {
	struct spi_device *spi;
	struct mutex lock;
	unsigned int chip;
};

/* sysfs hook function */
static ssize_t lm70_sense_temp(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	struct lm70 *p_lm70 = dev_get_drvdata(dev);
	struct spi_device *spi = p_lm70->spi;
	int status, val = 0;
	u8 rxbuf[2];
	s16 raw = 0;

	if (mutex_lock_interruptible(&p_lm70->lock))
		return -ERESTARTSYS;

	/*
	 * spi_read() requires a DMA-safe buffer; so we use
	 * spi_write_then_read(), transmitting 0 bytes.
	 */
	status = spi_write_then_read(spi, NULL, 0, &rxbuf[0], 2);
	if (status < 0) {
		pr_warn("spi_write_then_read failed with status %d\n", status);
		goto out;
	}
	raw = (rxbuf[0] << 8) + rxbuf[1];
	dev_dbg(dev, "rxbuf[0] : 0x%02x rxbuf[1] : 0x%02x raw=0x%04x\n",
		rxbuf[0], rxbuf[1], raw);

	/*
	 * LM70:
	 * The "raw" temperature read into rxbuf[] is a 16-bit signed 2's
	 * complement value. Only the MSB 11 bits (1 sign + 10 temperature
	 * bits) are meaningful; the LSB 5 bits are to be discarded.
	 * See the datasheet.
	 *
	 * Further, each bit represents 0.25 degrees Celsius; so, multiply
	 * by 0.25. Also multiply by 1000 to represent in millidegrees
	 * Celsius.
	 * So it's equivalent to multiplying by 0.25 * 1000 = 250.
	 *
	 * LM74 and TMP121/TMP123:
	 * 13 bits of 2's complement data, discard LSB 3 bits,
	 * resolution 0.0625 degrees celsius.
	 *
	 * LM71:
	 * 14 bits of 2's complement data, discard LSB 2 bits,
	 * resolution 0.0312 degrees celsius.
	 */
	switch (p_lm70->chip) {
	case LM70_CHIP_LM70:
		val = ((int)raw / 32) * 250;
		break;

	case LM70_CHIP_TMP121:
	case LM70_CHIP_LM74:
		val = ((int)raw / 8) * 625 / 10;
		break;

	case LM70_CHIP_LM71:
		val = ((int)raw / 4) * 3125 / 100;
		break;
	}

	status = sprintf(buf, "%d\n", val); /* millidegrees Celsius */
out:
	mutex_unlock(&p_lm70->lock);
	return status;
}

static DEVICE_ATTR(temp1_input, S_IRUGO, lm70_sense_temp, NULL);

static struct attribute *lm70_attrs[] = {
	&dev_attr_temp1_input.attr,
	NULL
};

ATTRIBUTE_GROUPS(lm70);

/*----------------------------------------------------------------------*/

#ifdef CONFIG_OF
static const struct of_device_id lm70_of_ids[] = {
	{
		.compatible = "ti,lm70",
		.data = (void *) LM70_CHIP_LM70,
	},
	{
		.compatible = "ti,tmp121",
		.data = (void *) LM70_CHIP_TMP121,
	},
	{
		.compatible = "ti,lm71",
		.data = (void *) LM70_CHIP_LM71,
	},
	{
		.compatible = "ti,lm74",
		.data = (void *) LM70_CHIP_LM74,
	},
	{},
};
MODULE_DEVICE_TABLE(of, lm70_of_ids);
#endif

static int lm70_probe(struct spi_device *spi)
{
	const struct of_device_id *match;
	struct device *hwmon_dev;
	struct lm70 *p_lm70;
	int chip;

	match = of_match_device(lm70_of_ids, &spi->dev);
	if (match)
		chip = (int)(uintptr_t)match->data;
	else
		chip = spi_get_device_id(spi)->driver_data;

	/* signaling is SPI_MODE_0 */
	if (spi->mode & (SPI_CPOL | SPI_CPHA))
		return -EINVAL;

	/* NOTE:  we assume 8-bit words, and convert to 16 bits manually */

	p_lm70 = devm_kzalloc(&spi->dev, sizeof(*p_lm70), GFP_KERNEL);
	if (!p_lm70)
		return -ENOMEM;

	mutex_init(&p_lm70->lock);
	p_lm70->chip = chip;
	p_lm70->spi = spi;

	hwmon_dev = devm_hwmon_device_register_with_groups(&spi->dev,
							   spi->modalias,
							   p_lm70, lm70_groups);
	return PTR_ERR_OR_ZERO(hwmon_dev);
}

static const struct spi_device_id lm70_ids[] = {
	{ "lm70",   LM70_CHIP_LM70 },
	{ "tmp121", LM70_CHIP_TMP121 },
	{ "lm71",   LM70_CHIP_LM71 },
	{ "lm74",   LM70_CHIP_LM74 },
	{ },
};
MODULE_DEVICE_TABLE(spi, lm70_ids);

static struct spi_driver lm70_driver = {
	.driver = {
		.name	= "lm70",
		.of_match_table	= of_match_ptr(lm70_of_ids),
	},
	.id_table = lm70_ids,
	.probe	= lm70_probe,
};

module_spi_driver(lm70_driver);

MODULE_AUTHOR("Kaiwan N Billimoria");
MODULE_DESCRIPTION("NS LM70 and compatibles Linux driver");
MODULE_LICENSE("GPL");