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
38 struct lm70 {
39 struct spi_device *spi;
40 struct mutex lock;
41 unsigned int chip;
42 };
43
44 /* sysfs hook function */
temp1_input_show(struct device * dev,struct device_attribute * attr,char * buf)45 static ssize_t temp1_input_show(struct device *dev,
46 struct device_attribute *attr, char *buf)
47 {
48 struct lm70 *p_lm70 = dev_get_drvdata(dev);
49 struct spi_device *spi = p_lm70->spi;
50 int status, val = 0;
51 u8 rxbuf[2];
52 s16 raw = 0;
53
54 if (mutex_lock_interruptible(&p_lm70->lock))
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 dev_warn(dev, "spi_write_then_read failed with status %d\n",
64 status);
65 goto out;
66 }
67 raw = (rxbuf[0] << 8) + rxbuf[1];
68 dev_dbg(dev, "rxbuf[0] : 0x%02x rxbuf[1] : 0x%02x raw=0x%04x\n",
69 rxbuf[0], rxbuf[1], raw);
70
71 /*
72 * LM70:
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 * LM74 and TMP121/TMP122/TMP123/TMP124:
84 * 13 bits of 2's complement data, discard LSB 3 bits,
85 * resolution 0.0625 degrees celsius.
86 *
87 * LM71:
88 * 14 bits of 2's complement data, discard LSB 2 bits,
89 * resolution 0.0312 degrees celsius.
90 */
91 switch (p_lm70->chip) {
92 case LM70_CHIP_LM70:
93 val = ((int)raw / 32) * 250;
94 break;
95
96 case LM70_CHIP_TMP121:
97 case LM70_CHIP_TMP122:
98 case LM70_CHIP_LM74:
99 val = ((int)raw / 8) * 625 / 10;
100 break;
101
102 case LM70_CHIP_LM71:
103 val = ((int)raw / 4) * 3125 / 100;
104 break;
105 }
106
107 status = sprintf(buf, "%d\n", val); /* millidegrees Celsius */
108 out:
109 mutex_unlock(&p_lm70->lock);
110 return status;
111 }
112
113 static DEVICE_ATTR_RO(temp1_input);
114
115 static struct attribute *lm70_attrs[] = {
116 &dev_attr_temp1_input.attr,
117 NULL
118 };
119
120 ATTRIBUTE_GROUPS(lm70);
121
122 /*----------------------------------------------------------------------*/
123
124 #ifdef CONFIG_OF
125 static const struct of_device_id lm70_of_ids[] = {
126 {
127 .compatible = "ti,lm70",
128 .data = (void *) LM70_CHIP_LM70,
129 },
130 {
131 .compatible = "ti,tmp121",
132 .data = (void *) LM70_CHIP_TMP121,
133 },
134 {
135 .compatible = "ti,tmp122",
136 .data = (void *) LM70_CHIP_TMP122,
137 },
138 {
139 .compatible = "ti,lm71",
140 .data = (void *) LM70_CHIP_LM71,
141 },
142 {
143 .compatible = "ti,lm74",
144 .data = (void *) LM70_CHIP_LM74,
145 },
146 {},
147 };
148 MODULE_DEVICE_TABLE(of, lm70_of_ids);
149 #endif
150
lm70_probe(struct spi_device * spi)151 static int lm70_probe(struct spi_device *spi)
152 {
153 struct device *hwmon_dev;
154 struct lm70 *p_lm70;
155 int chip;
156
157 if (dev_fwnode(&spi->dev))
158 chip = (int)(uintptr_t)device_get_match_data(&spi->dev);
159 else
160 chip = spi_get_device_id(spi)->driver_data;
161
162
163 /* signaling is SPI_MODE_0 */
164 if (spi->mode & (SPI_CPOL | SPI_CPHA))
165 return -EINVAL;
166
167 /* NOTE: we assume 8-bit words, and convert to 16 bits manually */
168
169 p_lm70 = devm_kzalloc(&spi->dev, sizeof(*p_lm70), GFP_KERNEL);
170 if (!p_lm70)
171 return -ENOMEM;
172
173 mutex_init(&p_lm70->lock);
174 p_lm70->chip = chip;
175 p_lm70->spi = spi;
176
177 hwmon_dev = devm_hwmon_device_register_with_groups(&spi->dev,
178 spi->modalias,
179 p_lm70, lm70_groups);
180 return PTR_ERR_OR_ZERO(hwmon_dev);
181 }
182
183 static const struct spi_device_id lm70_ids[] = {
184 { "lm70", LM70_CHIP_LM70 },
185 { "tmp121", LM70_CHIP_TMP121 },
186 { "tmp122", LM70_CHIP_TMP122 },
187 { "lm71", LM70_CHIP_LM71 },
188 { "lm74", LM70_CHIP_LM74 },
189 { },
190 };
191 MODULE_DEVICE_TABLE(spi, lm70_ids);
192
193 static struct spi_driver lm70_driver = {
194 .driver = {
195 .name = "lm70",
196 .of_match_table = of_match_ptr(lm70_of_ids),
197 },
198 .id_table = lm70_ids,
199 .probe = lm70_probe,
200 };
201
202 module_spi_driver(lm70_driver);
203
204 MODULE_AUTHOR("Kaiwan N Billimoria");
205 MODULE_DESCRIPTION("NS LM70 and compatibles Linux driver");
206 MODULE_LICENSE("GPL");
207