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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"); |
218 |
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