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Kaiwan N Billimoriae1a8e912006-06-12 22:00:05 +02001/*
2 * lm70.c
3 *
4 * The LM70 is a temperature sensor chip from National Semiconductor (NS).
5 * Copyright (C) 2006 Kaiwan N Billimoria <kaiwan@designergraphix.com>
6 *
7 * The LM70 communicates with a host processor via an SPI/Microwire Bus
8 * interface. The complete datasheet is available at National's website
9 * here:
10 * http://www.national.com/pf/LM/LM70.html
11 *
12 * This program is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU General Public License as published by
14 * the Free Software Foundation; either version 2 of the License, or
15 * (at your option) any later version.
16 *
17 * This program is distributed in the hope that it will be useful,
18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 * GNU General Public License for more details.
21 *
22 * You should have received a copy of the GNU General Public License
23 * along with this program; if not, write to the Free Software
24 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
25 */
26
27#include <linux/init.h>
28#include <linux/module.h>
29#include <linux/kernel.h>
30#include <linux/device.h>
31#include <linux/err.h>
32#include <linux/sysfs.h>
33#include <linux/hwmon.h>
Matthias Kaehlcke4bfe6602007-10-24 14:59:09 +020034#include <linux/mutex.h>
Kaiwan N Billimoriae1a8e912006-06-12 22:00:05 +020035#include <linux/spi/spi.h>
Matthias Kaehlcke4bfe6602007-10-24 14:59:09 +020036
Kaiwan N Billimoriae1a8e912006-06-12 22:00:05 +020037
38#define DRVNAME "lm70"
39
40struct lm70 {
Tony Jones1beeffe2007-08-20 13:46:20 -070041 struct device *hwmon_dev;
Matthias Kaehlcke4bfe6602007-10-24 14:59:09 +020042 struct mutex lock;
Kaiwan N Billimoriae1a8e912006-06-12 22:00:05 +020043};
44
45/* sysfs hook function */
46static ssize_t lm70_sense_temp(struct device *dev,
47 struct device_attribute *attr, char *buf)
48{
49 struct spi_device *spi = to_spi_device(dev);
50 int status, val;
51 u8 rxbuf[2];
52 s16 raw=0;
53 struct lm70 *p_lm70 = dev_get_drvdata(&spi->dev);
54
Matthias Kaehlcke4bfe6602007-10-24 14:59:09 +020055 if (mutex_lock_interruptible(&p_lm70->lock))
Kaiwan N Billimoriae1a8e912006-06-12 22:00:05 +020056 return -ERESTARTSYS;
57
58 /*
59 * spi_read() requires a DMA-safe buffer; so we use
60 * spi_write_then_read(), transmitting 0 bytes.
61 */
62 status = spi_write_then_read(spi, NULL, 0, &rxbuf[0], 2);
63 if (status < 0) {
64 printk(KERN_WARNING
65 "spi_write_then_read failed with status %d\n", status);
66 goto out;
67 }
68 dev_dbg(dev, "rxbuf[1] : 0x%x rxbuf[0] : 0x%x\n", rxbuf[1], rxbuf[0]);
69
70 raw = (rxbuf[1] << 8) + rxbuf[0];
71 dev_dbg(dev, "raw=0x%x\n", raw);
72
73 /*
74 * The "raw" temperature read into rxbuf[] is a 16-bit signed 2's
75 * complement value. Only the MSB 11 bits (1 sign + 10 temperature
76 * bits) are meaningful; the LSB 5 bits are to be discarded.
77 * See the datasheet.
78 *
79 * Further, each bit represents 0.25 degrees Celsius; so, multiply
80 * by 0.25. Also multiply by 1000 to represent in millidegrees
81 * Celsius.
82 * So it's equivalent to multiplying by 0.25 * 1000 = 250.
83 */
84 val = ((int)raw/32) * 250;
Jean Delvare67f921d2007-08-17 17:31:35 +020085 status = sprintf(buf, "%d\n", val); /* millidegrees Celsius */
Kaiwan N Billimoriae1a8e912006-06-12 22:00:05 +020086out:
Matthias Kaehlcke4bfe6602007-10-24 14:59:09 +020087 mutex_unlock(&p_lm70->lock);
Kaiwan N Billimoriae1a8e912006-06-12 22:00:05 +020088 return status;
89}
90
91static DEVICE_ATTR(temp1_input, S_IRUGO, lm70_sense_temp, NULL);
92
Jean Delvare67f921d2007-08-17 17:31:35 +020093static ssize_t lm70_show_name(struct device *dev, struct device_attribute
94 *devattr, char *buf)
95{
96 return sprintf(buf, "lm70\n");
97}
98
99static DEVICE_ATTR(name, S_IRUGO, lm70_show_name, NULL);
100
Kaiwan N Billimoriae1a8e912006-06-12 22:00:05 +0200101/*----------------------------------------------------------------------*/
102
103static int __devinit lm70_probe(struct spi_device *spi)
104{
105 struct lm70 *p_lm70;
106 int status;
107
David Brownellc06e6772007-07-17 04:04:03 -0700108 /* signaling is SPI_MODE_0 on a 3-wire link (shared SI/SO) */
109 if ((spi->mode & (SPI_CPOL|SPI_CPHA)) || !(spi->mode & SPI_3WIRE))
110 return -EINVAL;
111
Kaiwan N Billimoriae1a8e912006-06-12 22:00:05 +0200112 p_lm70 = kzalloc(sizeof *p_lm70, GFP_KERNEL);
113 if (!p_lm70)
114 return -ENOMEM;
115
Matthias Kaehlcke4bfe6602007-10-24 14:59:09 +0200116 mutex_init(&p_lm70->lock);
Kaiwan N Billimoriae1a8e912006-06-12 22:00:05 +0200117
118 /* sysfs hook */
Tony Jones1beeffe2007-08-20 13:46:20 -0700119 p_lm70->hwmon_dev = hwmon_device_register(&spi->dev);
120 if (IS_ERR(p_lm70->hwmon_dev)) {
Kaiwan N Billimoriae1a8e912006-06-12 22:00:05 +0200121 dev_dbg(&spi->dev, "hwmon_device_register failed.\n");
Tony Jones1beeffe2007-08-20 13:46:20 -0700122 status = PTR_ERR(p_lm70->hwmon_dev);
Kaiwan N Billimoriae1a8e912006-06-12 22:00:05 +0200123 goto out_dev_reg_failed;
124 }
125 dev_set_drvdata(&spi->dev, p_lm70);
126
Jean Delvare67f921d2007-08-17 17:31:35 +0200127 if ((status = device_create_file(&spi->dev, &dev_attr_temp1_input))
128 || (status = device_create_file(&spi->dev, &dev_attr_name))) {
Kaiwan N Billimoriae1a8e912006-06-12 22:00:05 +0200129 dev_dbg(&spi->dev, "device_create_file failure.\n");
130 goto out_dev_create_file_failed;
131 }
132
133 return 0;
134
135out_dev_create_file_failed:
Jean Delvare67f921d2007-08-17 17:31:35 +0200136 device_remove_file(&spi->dev, &dev_attr_temp1_input);
Tony Jones1beeffe2007-08-20 13:46:20 -0700137 hwmon_device_unregister(p_lm70->hwmon_dev);
Kaiwan N Billimoriae1a8e912006-06-12 22:00:05 +0200138out_dev_reg_failed:
139 dev_set_drvdata(&spi->dev, NULL);
140 kfree(p_lm70);
141 return status;
142}
143
Ralf Baechle41be7222007-02-14 21:15:04 +0100144static int __devexit lm70_remove(struct spi_device *spi)
Kaiwan N Billimoriae1a8e912006-06-12 22:00:05 +0200145{
146 struct lm70 *p_lm70 = dev_get_drvdata(&spi->dev);
147
148 device_remove_file(&spi->dev, &dev_attr_temp1_input);
Jean Delvare67f921d2007-08-17 17:31:35 +0200149 device_remove_file(&spi->dev, &dev_attr_name);
Tony Jones1beeffe2007-08-20 13:46:20 -0700150 hwmon_device_unregister(p_lm70->hwmon_dev);
Kaiwan N Billimoriae1a8e912006-06-12 22:00:05 +0200151 dev_set_drvdata(&spi->dev, NULL);
152 kfree(p_lm70);
153
154 return 0;
155}
156
157static struct spi_driver lm70_driver = {
158 .driver = {
159 .name = "lm70",
160 .owner = THIS_MODULE,
161 },
162 .probe = lm70_probe,
163 .remove = __devexit_p(lm70_remove),
164};
165
166static int __init init_lm70(void)
167{
168 return spi_register_driver(&lm70_driver);
169}
170
171static void __exit cleanup_lm70(void)
172{
173 spi_unregister_driver(&lm70_driver);
174}
175
176module_init(init_lm70);
177module_exit(cleanup_lm70);
178
179MODULE_AUTHOR("Kaiwan N Billimoria");
180MODULE_DESCRIPTION("National Semiconductor LM70 Linux driver");
181MODULE_LICENSE("GPL");