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1 | /* |
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> | |
34 | #include <linux/spi/spi.h> | |
35 | #include <asm/semaphore.h> | |
36 | ||
37 | #define DRVNAME "lm70" | |
38 | ||
39 | struct lm70 { | |
1beeffe4 | 40 | struct device *hwmon_dev; |
e1a8e913 KB |
41 | struct semaphore sem; |
42 | }; | |
43 | ||
44 | /* sysfs hook function */ | |
45 | static ssize_t lm70_sense_temp(struct device *dev, | |
46 | struct device_attribute *attr, char *buf) | |
47 | { | |
48 | struct spi_device *spi = to_spi_device(dev); | |
49 | int status, val; | |
50 | u8 rxbuf[2]; | |
51 | s16 raw=0; | |
52 | struct lm70 *p_lm70 = dev_get_drvdata(&spi->dev); | |
53 | ||
54 | if (down_interruptible(&p_lm70->sem)) | |
55 | return -ERESTARTSYS; | |
56 | ||
57 | /* | |
58 | * spi_read() requires a DMA-safe buffer; so we use | |
59 | * spi_write_then_read(), transmitting 0 bytes. | |
60 | */ | |
61 | status = spi_write_then_read(spi, NULL, 0, &rxbuf[0], 2); | |
62 | if (status < 0) { | |
63 | printk(KERN_WARNING | |
64 | "spi_write_then_read failed with status %d\n", status); | |
65 | goto out; | |
66 | } | |
67 | dev_dbg(dev, "rxbuf[1] : 0x%x rxbuf[0] : 0x%x\n", rxbuf[1], rxbuf[0]); | |
68 | ||
69 | raw = (rxbuf[1] << 8) + rxbuf[0]; | |
70 | dev_dbg(dev, "raw=0x%x\n", raw); | |
71 | ||
72 | /* | |
73 | * The "raw" temperature read into rxbuf[] is a 16-bit signed 2's | |
74 | * complement value. Only the MSB 11 bits (1 sign + 10 temperature | |
75 | * bits) are meaningful; the LSB 5 bits are to be discarded. | |
76 | * See the datasheet. | |
77 | * | |
78 | * Further, each bit represents 0.25 degrees Celsius; so, multiply | |
79 | * by 0.25. Also multiply by 1000 to represent in millidegrees | |
80 | * Celsius. | |
81 | * So it's equivalent to multiplying by 0.25 * 1000 = 250. | |
82 | */ | |
83 | val = ((int)raw/32) * 250; | |
67f921d1 | 84 | status = sprintf(buf, "%d\n", val); /* millidegrees Celsius */ |
e1a8e913 KB |
85 | out: |
86 | up(&p_lm70->sem); | |
87 | return status; | |
88 | } | |
89 | ||
90 | static DEVICE_ATTR(temp1_input, S_IRUGO, lm70_sense_temp, NULL); | |
91 | ||
67f921d1 JD |
92 | static ssize_t lm70_show_name(struct device *dev, struct device_attribute |
93 | *devattr, char *buf) | |
94 | { | |
95 | return sprintf(buf, "lm70\n"); | |
96 | } | |
97 | ||
98 | static DEVICE_ATTR(name, S_IRUGO, lm70_show_name, NULL); | |
99 | ||
e1a8e913 KB |
100 | /*----------------------------------------------------------------------*/ |
101 | ||
102 | static int __devinit lm70_probe(struct spi_device *spi) | |
103 | { | |
104 | struct lm70 *p_lm70; | |
105 | int status; | |
106 | ||
c06e677a DB |
107 | /* signaling is SPI_MODE_0 on a 3-wire link (shared SI/SO) */ |
108 | if ((spi->mode & (SPI_CPOL|SPI_CPHA)) || !(spi->mode & SPI_3WIRE)) | |
109 | return -EINVAL; | |
110 | ||
e1a8e913 KB |
111 | p_lm70 = kzalloc(sizeof *p_lm70, GFP_KERNEL); |
112 | if (!p_lm70) | |
113 | return -ENOMEM; | |
114 | ||
115 | init_MUTEX(&p_lm70->sem); | |
116 | ||
117 | /* sysfs hook */ | |
1beeffe4 TJ |
118 | p_lm70->hwmon_dev = hwmon_device_register(&spi->dev); |
119 | if (IS_ERR(p_lm70->hwmon_dev)) { | |
e1a8e913 | 120 | dev_dbg(&spi->dev, "hwmon_device_register failed.\n"); |
1beeffe4 | 121 | status = PTR_ERR(p_lm70->hwmon_dev); |
e1a8e913 KB |
122 | goto out_dev_reg_failed; |
123 | } | |
124 | dev_set_drvdata(&spi->dev, p_lm70); | |
125 | ||
67f921d1 JD |
126 | if ((status = device_create_file(&spi->dev, &dev_attr_temp1_input)) |
127 | || (status = device_create_file(&spi->dev, &dev_attr_name))) { | |
e1a8e913 KB |
128 | dev_dbg(&spi->dev, "device_create_file failure.\n"); |
129 | goto out_dev_create_file_failed; | |
130 | } | |
131 | ||
132 | return 0; | |
133 | ||
134 | out_dev_create_file_failed: | |
67f921d1 | 135 | device_remove_file(&spi->dev, &dev_attr_temp1_input); |
1beeffe4 | 136 | hwmon_device_unregister(p_lm70->hwmon_dev); |
e1a8e913 KB |
137 | out_dev_reg_failed: |
138 | dev_set_drvdata(&spi->dev, NULL); | |
139 | kfree(p_lm70); | |
140 | return status; | |
141 | } | |
142 | ||
41be722b | 143 | static int __devexit lm70_remove(struct spi_device *spi) |
e1a8e913 KB |
144 | { |
145 | struct lm70 *p_lm70 = dev_get_drvdata(&spi->dev); | |
146 | ||
147 | device_remove_file(&spi->dev, &dev_attr_temp1_input); | |
67f921d1 | 148 | device_remove_file(&spi->dev, &dev_attr_name); |
1beeffe4 | 149 | hwmon_device_unregister(p_lm70->hwmon_dev); |
e1a8e913 KB |
150 | dev_set_drvdata(&spi->dev, NULL); |
151 | kfree(p_lm70); | |
152 | ||
153 | return 0; | |
154 | } | |
155 | ||
156 | static struct spi_driver lm70_driver = { | |
157 | .driver = { | |
158 | .name = "lm70", | |
159 | .owner = THIS_MODULE, | |
160 | }, | |
161 | .probe = lm70_probe, | |
162 | .remove = __devexit_p(lm70_remove), | |
163 | }; | |
164 | ||
165 | static int __init init_lm70(void) | |
166 | { | |
167 | return spi_register_driver(&lm70_driver); | |
168 | } | |
169 | ||
170 | static void __exit cleanup_lm70(void) | |
171 | { | |
172 | spi_unregister_driver(&lm70_driver); | |
173 | } | |
174 | ||
175 | module_init(init_lm70); | |
176 | module_exit(cleanup_lm70); | |
177 | ||
178 | MODULE_AUTHOR("Kaiwan N Billimoria"); | |
179 | MODULE_DESCRIPTION("National Semiconductor LM70 Linux driver"); | |
180 | MODULE_LICENSE("GPL"); |