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#include <linux/of_device.h>
41
42
43#define DRVNAME "lm70"
44
45#define LM70_CHIP_LM70 0 /* original NS LM70 */
46#define LM70_CHIP_TMP121 1 /* TI TMP121/TMP123 */
47#define LM70_CHIP_LM71 2 /* NS LM71 */
48#define LM70_CHIP_LM74 3 /* NS LM74 */
49#define LM70_CHIP_TMP122 4 /* TI TMP122/TMP124 */
50
51struct lm70 {
52 struct spi_device *spi;
53 struct mutex lock;
54 unsigned int chip;
55};
56
57/* sysfs hook function */
58static ssize_t temp1_input_show(struct device *dev,
59 struct device_attribute *attr, char *buf)
60{
61 struct lm70 *p_lm70 = dev_get_drvdata(dev);
62 struct spi_device *spi = p_lm70->spi;
63 int status, val = 0;
64 u8 rxbuf[2];
65 s16 raw = 0;
66
67 if (mutex_lock_interruptible(&p_lm70->lock))
68 return -ERESTARTSYS;
69
70 /*
71 * spi_read() requires a DMA-safe buffer; so we use
72 * spi_write_then_read(), transmitting 0 bytes.
73 */
74 status = spi_write_then_read(spi, NULL, 0, &rxbuf[0], 2);
75 if (status < 0) {
76 dev_warn(dev, "spi_write_then_read failed with status %d\n",
77 status);
78 goto out;
79 }
80 raw = (rxbuf[0] << 8) + rxbuf[1];
81 dev_dbg(dev, "rxbuf[0] : 0x%02x rxbuf[1] : 0x%02x raw=0x%04x\n",
82 rxbuf[0], rxbuf[1], raw);
83
84 /*
85 * LM70:
86 * The "raw" temperature read into rxbuf[] is a 16-bit signed 2's
87 * complement value. Only the MSB 11 bits (1 sign + 10 temperature
88 * bits) are meaningful; the LSB 5 bits are to be discarded.
89 * See the datasheet.
90 *
91 * Further, each bit represents 0.25 degrees Celsius; so, multiply
92 * by 0.25. Also multiply by 1000 to represent in millidegrees
93 * Celsius.
94 * So it's equivalent to multiplying by 0.25 * 1000 = 250.
95 *
96 * LM74 and TMP121/TMP122/TMP123/TMP124:
97 * 13 bits of 2's complement data, discard LSB 3 bits,
98 * resolution 0.0625 degrees celsius.
99 *
100 * LM71:
101 * 14 bits of 2's complement data, discard LSB 2 bits,
102 * resolution 0.0312 degrees celsius.
103 */
104 switch (p_lm70->chip) {
105 case LM70_CHIP_LM70:
106 val = ((int)raw / 32) * 250;
107 break;
108
109 case LM70_CHIP_TMP121:
110 case LM70_CHIP_TMP122:
111 case LM70_CHIP_LM74:
112 val = ((int)raw / 8) * 625 / 10;
113 break;
114
115 case LM70_CHIP_LM71:
116 val = ((int)raw / 4) * 3125 / 100;
117 break;
118 }
119
120 status = sprintf(buf, "%d\n", val); /* millidegrees Celsius */
121out:
122 mutex_unlock(&p_lm70->lock);
123 return status;
124}
125
126static DEVICE_ATTR_RO(temp1_input);
127
128static struct attribute *lm70_attrs[] = {
129 &dev_attr_temp1_input.attr,
130 NULL
131};
132
133ATTRIBUTE_GROUPS(lm70);
134
135/*----------------------------------------------------------------------*/
136
137#ifdef CONFIG_OF
138static const struct of_device_id lm70_of_ids[] = {
139 {
140 .compatible = "ti,lm70",
141 .data = (void *) LM70_CHIP_LM70,
142 },
143 {
144 .compatible = "ti,tmp121",
145 .data = (void *) LM70_CHIP_TMP121,
146 },
147 {
148 .compatible = "ti,tmp122",
149 .data = (void *) LM70_CHIP_TMP122,
150 },
151 {
152 .compatible = "ti,lm71",
153 .data = (void *) LM70_CHIP_LM71,
154 },
155 {
156 .compatible = "ti,lm74",
157 .data = (void *) LM70_CHIP_LM74,
158 },
159 {},
160};
161MODULE_DEVICE_TABLE(of, lm70_of_ids);
162#endif
163
164static int lm70_probe(struct spi_device *spi)
165{
166 const struct of_device_id *match;
167 struct device *hwmon_dev;
168 struct lm70 *p_lm70;
169 int chip;
170
171 match = of_match_device(lm70_of_ids, &spi->dev);
172 if (match)
173 chip = (int)(uintptr_t)match->data;
174 else
175 chip = spi_get_device_id(spi)->driver_data;
176
177 /* signaling is SPI_MODE_0 */
178 if (spi->mode & (SPI_CPOL | SPI_CPHA))
179 return -EINVAL;
180
181 /* NOTE: we assume 8-bit words, and convert to 16 bits manually */
182
183 p_lm70 = devm_kzalloc(&spi->dev, sizeof(*p_lm70), GFP_KERNEL);
184 if (!p_lm70)
185 return -ENOMEM;
186
187 mutex_init(&p_lm70->lock);
188 p_lm70->chip = chip;
189 p_lm70->spi = spi;
190
191 hwmon_dev = devm_hwmon_device_register_with_groups(&spi->dev,
192 spi->modalias,
193 p_lm70, lm70_groups);
194 return PTR_ERR_OR_ZERO(hwmon_dev);
195}
196
197static const struct spi_device_id lm70_ids[] = {
198 { "lm70", LM70_CHIP_LM70 },
199 { "tmp121", LM70_CHIP_TMP121 },
200 { "tmp122", LM70_CHIP_TMP122 },
201 { "lm71", LM70_CHIP_LM71 },
202 { "lm74", LM70_CHIP_LM74 },
203 { },
204};
205MODULE_DEVICE_TABLE(spi, lm70_ids);
206
207static struct spi_driver lm70_driver = {
208 .driver = {
209 .name = "lm70",
210 .of_match_table = of_match_ptr(lm70_of_ids),
211 },
212 .id_table = lm70_ids,
213 .probe = lm70_probe,
214};
215
216module_spi_driver(lm70_driver);
217
218MODULE_AUTHOR("Kaiwan N Billimoria");
219MODULE_DESCRIPTION("NS LM70 and compatibles Linux driver");
220MODULE_LICENSE("GPL");
221