1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* |
3 | * lm70.c |
4 | * |
5 | * The LM70 is a temperature sensor chip from National Semiconductor (NS). |
6 | * Copyright (C) 2006 Kaiwan N Billimoria <kaiwan@designergraphix.com> |
7 | * |
8 | * The LM70 communicates with a host processor via an SPI/Microwire Bus |
9 | * interface. The complete datasheet is available at National's website |
10 | * here: |
11 | * http://www.national.com/pf/LM/LM70.html |
12 | */ |
13 | |
14 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
15 | |
16 | #include <linux/init.h> |
17 | #include <linux/module.h> |
18 | #include <linux/kernel.h> |
19 | #include <linux/device.h> |
20 | #include <linux/err.h> |
21 | #include <linux/sysfs.h> |
22 | #include <linux/hwmon.h> |
23 | #include <linux/mutex.h> |
24 | #include <linux/mod_devicetable.h> |
25 | #include <linux/of.h> |
26 | #include <linux/property.h> |
27 | #include <linux/spi/spi.h> |
28 | #include <linux/slab.h> |
29 | |
30 | #define DRVNAME "lm70" |
31 | |
32 | #define LM70_CHIP_LM70 0 /* original NS LM70 */ |
33 | #define LM70_CHIP_TMP121 1 /* TI TMP121/TMP123 */ |
34 | #define LM70_CHIP_LM71 2 /* NS LM71 */ |
35 | #define LM70_CHIP_LM74 3 /* NS LM74 */ |
36 | #define LM70_CHIP_TMP122 4 /* TI TMP122/TMP124 */ |
37 | #define LM70_CHIP_TMP125 5 /* TI TMP125 */ |
38 | |
39 | struct lm70 { |
40 | struct spi_device *spi; |
41 | struct mutex lock; |
42 | unsigned int chip; |
43 | }; |
44 | |
45 | /* sysfs hook function */ |
46 | static ssize_t temp1_input_show(struct device *dev, |
47 | struct device_attribute *attr, char *buf) |
48 | { |
49 | struct lm70 *p_lm70 = dev_get_drvdata(dev); |
50 | struct spi_device *spi = p_lm70->spi; |
51 | int status, val = 0; |
52 | u8 rxbuf[2]; |
53 | s16 raw = 0; |
54 | |
55 | if (mutex_lock_interruptible(&p_lm70->lock)) |
56 | 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, n_tx: 0, rxbuf: &rxbuf[0], n_rx: 2); |
63 | if (status < 0) { |
64 | dev_warn(dev, "spi_write_then_read failed with status %d\n" , |
65 | status); |
66 | goto out; |
67 | } |
68 | raw = (rxbuf[0] << 8) + rxbuf[1]; |
69 | dev_dbg(dev, "rxbuf[0] : 0x%02x rxbuf[1] : 0x%02x raw=0x%04x\n" , |
70 | rxbuf[0], rxbuf[1], raw); |
71 | |
72 | /* |
73 | * LM70: |
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 | * LM74 and TMP121/TMP122/TMP123/TMP124: |
85 | * 13 bits of 2's complement data, discard LSB 3 bits, |
86 | * resolution 0.0625 degrees celsius. |
87 | * |
88 | * LM71: |
89 | * 14 bits of 2's complement data, discard LSB 2 bits, |
90 | * resolution 0.0312 degrees celsius. |
91 | * |
92 | * TMP125: |
93 | * MSB/D15 is a leading zero. D14 is the sign-bit. This is |
94 | * followed by 9 temperature bits (D13..D5) in 2's complement |
95 | * data format with a resolution of 0.25 degrees celsius per unit. |
96 | * LSB 5 bits (D4..D0) share the same value as D5 and get discarded. |
97 | */ |
98 | switch (p_lm70->chip) { |
99 | case LM70_CHIP_LM70: |
100 | val = ((int)raw / 32) * 250; |
101 | break; |
102 | |
103 | case LM70_CHIP_TMP121: |
104 | case LM70_CHIP_TMP122: |
105 | case LM70_CHIP_LM74: |
106 | val = ((int)raw / 8) * 625 / 10; |
107 | break; |
108 | |
109 | case LM70_CHIP_LM71: |
110 | val = ((int)raw / 4) * 3125 / 100; |
111 | break; |
112 | |
113 | case LM70_CHIP_TMP125: |
114 | val = (sign_extend32(value: raw, index: 14) / 32) * 250; |
115 | break; |
116 | } |
117 | |
118 | status = sprintf(buf, fmt: "%d\n" , val); /* millidegrees Celsius */ |
119 | out: |
120 | mutex_unlock(lock: &p_lm70->lock); |
121 | return status; |
122 | } |
123 | |
124 | static DEVICE_ATTR_RO(temp1_input); |
125 | |
126 | static struct attribute *lm70_attrs[] = { |
127 | &dev_attr_temp1_input.attr, |
128 | NULL |
129 | }; |
130 | |
131 | ATTRIBUTE_GROUPS(lm70); |
132 | |
133 | /*----------------------------------------------------------------------*/ |
134 | |
135 | #ifdef CONFIG_OF |
136 | static const struct of_device_id lm70_of_ids[] = { |
137 | { |
138 | .compatible = "ti,lm70" , |
139 | .data = (void *) LM70_CHIP_LM70, |
140 | }, |
141 | { |
142 | .compatible = "ti,tmp121" , |
143 | .data = (void *) LM70_CHIP_TMP121, |
144 | }, |
145 | { |
146 | .compatible = "ti,tmp122" , |
147 | .data = (void *) LM70_CHIP_TMP122, |
148 | }, |
149 | { |
150 | .compatible = "ti,tmp125" , |
151 | .data = (void *) LM70_CHIP_TMP125, |
152 | }, |
153 | { |
154 | .compatible = "ti,lm71" , |
155 | .data = (void *) LM70_CHIP_LM71, |
156 | }, |
157 | { |
158 | .compatible = "ti,lm74" , |
159 | .data = (void *) LM70_CHIP_LM74, |
160 | }, |
161 | {}, |
162 | }; |
163 | MODULE_DEVICE_TABLE(of, lm70_of_ids); |
164 | #endif |
165 | |
166 | static int lm70_probe(struct spi_device *spi) |
167 | { |
168 | struct device *hwmon_dev; |
169 | struct lm70 *p_lm70; |
170 | int chip; |
171 | |
172 | if (dev_fwnode(&spi->dev)) |
173 | chip = (int)(uintptr_t)device_get_match_data(dev: &spi->dev); |
174 | else |
175 | chip = spi_get_device_id(sdev: spi)->driver_data; |
176 | |
177 | |
178 | /* signaling is SPI_MODE_0 */ |
179 | if ((spi->mode & SPI_MODE_X_MASK) != SPI_MODE_0) |
180 | return -EINVAL; |
181 | |
182 | /* NOTE: we assume 8-bit words, and convert to 16 bits manually */ |
183 | |
184 | p_lm70 = devm_kzalloc(dev: &spi->dev, size: sizeof(*p_lm70), GFP_KERNEL); |
185 | if (!p_lm70) |
186 | return -ENOMEM; |
187 | |
188 | mutex_init(&p_lm70->lock); |
189 | p_lm70->chip = chip; |
190 | p_lm70->spi = spi; |
191 | |
192 | hwmon_dev = devm_hwmon_device_register_with_groups(dev: &spi->dev, |
193 | name: spi->modalias, |
194 | drvdata: p_lm70, groups: lm70_groups); |
195 | return PTR_ERR_OR_ZERO(ptr: hwmon_dev); |
196 | } |
197 | |
198 | static const struct spi_device_id lm70_ids[] = { |
199 | { "lm70" , LM70_CHIP_LM70 }, |
200 | { "tmp121" , LM70_CHIP_TMP121 }, |
201 | { "tmp122" , LM70_CHIP_TMP122 }, |
202 | { "tmp125" , LM70_CHIP_TMP125 }, |
203 | { "lm71" , LM70_CHIP_LM71 }, |
204 | { "lm74" , LM70_CHIP_LM74 }, |
205 | { }, |
206 | }; |
207 | MODULE_DEVICE_TABLE(spi, lm70_ids); |
208 | |
209 | static struct spi_driver lm70_driver = { |
210 | .driver = { |
211 | .name = "lm70" , |
212 | .of_match_table = of_match_ptr(lm70_of_ids), |
213 | }, |
214 | .id_table = lm70_ids, |
215 | .probe = lm70_probe, |
216 | }; |
217 | |
218 | module_spi_driver(lm70_driver); |
219 | |
220 | MODULE_AUTHOR("Kaiwan N Billimoria" ); |
221 | MODULE_DESCRIPTION("NS LM70 and compatibles Linux driver" ); |
222 | MODULE_LICENSE("GPL" ); |
223 | |