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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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
28
29 #include <linux/init.h>
30 #include <linux/module.h>
31 #include <linux/kernel.h>
32 #include <linux/device.h>
33 #include <linux/err.h>
34 #include <linux/sysfs.h>
35 #include <linux/hwmon.h>
36 #include <linux/mutex.h>
37 #include <linux/mod_devicetable.h>
38 #include <linux/spi/spi.h>
39 #include <linux/slab.h>
40
41
42 #define DRVNAME "lm70"
43
44 #define LM70_CHIP_LM70 0 /* original NS LM70 */
45 #define LM70_CHIP_TMP121 1 /* TI TMP121/TMP123 */
46 #define LM70_CHIP_LM71 2 /* NS LM71 */
47 #define LM70_CHIP_LM74 3 /* NS LM74 */
48
49 struct lm70 {
50 struct device *hwmon_dev;
51 struct mutex lock;
52 unsigned int chip;
53 };
54
55 /* sysfs hook function */
56 static ssize_t lm70_sense_temp(struct device *dev,
57 struct device_attribute *attr, char *buf)
58 {
59 struct spi_device *spi = to_spi_device(dev);
60 int status, val = 0;
61 u8 rxbuf[2];
62 s16 raw = 0;
63 struct lm70 *p_lm70 = spi_get_drvdata(spi);
64
65 if (mutex_lock_interruptible(&p_lm70->lock))
66 return -ERESTARTSYS;
67
68 /*
69 * spi_read() requires a DMA-safe buffer; so we use
70 * spi_write_then_read(), transmitting 0 bytes.
71 */
72 status = spi_write_then_read(spi, NULL, 0, &rxbuf[0], 2);
73 if (status < 0) {
74 pr_warn("spi_write_then_read failed with status %d\n", status);
75 goto out;
76 }
77 raw = (rxbuf[0] << 8) + rxbuf[1];
78 dev_dbg(dev, "rxbuf[0] : 0x%02x rxbuf[1] : 0x%02x raw=0x%04x\n",
79 rxbuf[0], rxbuf[1], raw);
80
81 /*
82 * LM70:
83 * The "raw" temperature read into rxbuf[] is a 16-bit signed 2's
84 * complement value. Only the MSB 11 bits (1 sign + 10 temperature
85 * bits) are meaningful; the LSB 5 bits are to be discarded.
86 * See the datasheet.
87 *
88 * Further, each bit represents 0.25 degrees Celsius; so, multiply
89 * by 0.25. Also multiply by 1000 to represent in millidegrees
90 * Celsius.
91 * So it's equivalent to multiplying by 0.25 * 1000 = 250.
92 *
93 * LM74 and TMP121/TMP123:
94 * 13 bits of 2's complement data, discard LSB 3 bits,
95 * resolution 0.0625 degrees celsius.
96 *
97 * LM71:
98 * 14 bits of 2's complement data, discard LSB 2 bits,
99 * resolution 0.0312 degrees celsius.
100 */
101 switch (p_lm70->chip) {
102 case LM70_CHIP_LM70:
103 val = ((int)raw / 32) * 250;
104 break;
105
106 case LM70_CHIP_TMP121:
107 case LM70_CHIP_LM74:
108 val = ((int)raw / 8) * 625 / 10;
109 break;
110
111 case LM70_CHIP_LM71:
112 val = ((int)raw / 4) * 3125 / 100;
113 break;
114 }
115
116 status = sprintf(buf, "%d\n", val); /* millidegrees Celsius */
117 out:
118 mutex_unlock(&p_lm70->lock);
119 return status;
120 }
121
122 static DEVICE_ATTR(temp1_input, S_IRUGO, lm70_sense_temp, NULL);
123
124 static ssize_t lm70_show_name(struct device *dev, struct device_attribute
125 *devattr, char *buf)
126 {
127 return sprintf(buf, "%s\n", to_spi_device(dev)->modalias);
128 }
129
130 static DEVICE_ATTR(name, S_IRUGO, lm70_show_name, NULL);
131
132 /*----------------------------------------------------------------------*/
133
134 static int lm70_probe(struct spi_device *spi)
135 {
136 int chip = spi_get_device_id(spi)->driver_data;
137 struct lm70 *p_lm70;
138 int status;
139
140 /* signaling is SPI_MODE_0 */
141 if (spi->mode & (SPI_CPOL | SPI_CPHA))
142 return -EINVAL;
143
144 /* NOTE: we assume 8-bit words, and convert to 16 bits manually */
145
146 p_lm70 = devm_kzalloc(&spi->dev, sizeof(*p_lm70), GFP_KERNEL);
147 if (!p_lm70)
148 return -ENOMEM;
149
150 mutex_init(&p_lm70->lock);
151 p_lm70->chip = chip;
152
153 spi_set_drvdata(spi, p_lm70);
154
155 status = device_create_file(&spi->dev, &dev_attr_temp1_input);
156 if (status)
157 goto out_dev_create_temp_file_failed;
158 status = device_create_file(&spi->dev, &dev_attr_name);
159 if (status)
160 goto out_dev_create_file_failed;
161
162 /* sysfs hook */
163 p_lm70->hwmon_dev = hwmon_device_register(&spi->dev);
164 if (IS_ERR(p_lm70->hwmon_dev)) {
165 dev_dbg(&spi->dev, "hwmon_device_register failed.\n");
166 status = PTR_ERR(p_lm70->hwmon_dev);
167 goto out_dev_reg_failed;
168 }
169
170 return 0;
171
172 out_dev_reg_failed:
173 device_remove_file(&spi->dev, &dev_attr_name);
174 out_dev_create_file_failed:
175 device_remove_file(&spi->dev, &dev_attr_temp1_input);
176 out_dev_create_temp_file_failed:
177 spi_set_drvdata(spi, NULL);
178 return status;
179 }
180
181 static int lm70_remove(struct spi_device *spi)
182 {
183 struct lm70 *p_lm70 = spi_get_drvdata(spi);
184
185 hwmon_device_unregister(p_lm70->hwmon_dev);
186 device_remove_file(&spi->dev, &dev_attr_temp1_input);
187 device_remove_file(&spi->dev, &dev_attr_name);
188 spi_set_drvdata(spi, NULL);
189
190 return 0;
191 }
192
193
194 static const struct spi_device_id lm70_ids[] = {
195 { "lm70", LM70_CHIP_LM70 },
196 { "tmp121", LM70_CHIP_TMP121 },
197 { "lm71", LM70_CHIP_LM71 },
198 { "lm74", LM70_CHIP_LM74 },
199 { },
200 };
201 MODULE_DEVICE_TABLE(spi, lm70_ids);
202
203 static struct spi_driver lm70_driver = {
204 .driver = {
205 .name = "lm70",
206 .owner = THIS_MODULE,
207 },
208 .id_table = lm70_ids,
209 .probe = lm70_probe,
210 .remove = lm70_remove,
211 };
212
213 module_spi_driver(lm70_driver);
214
215 MODULE_AUTHOR("Kaiwan N Billimoria");
216 MODULE_DESCRIPTION("NS LM70 and compatibles Linux driver");
217 MODULE_LICENSE("GPL");