4 * The LM70 is a temperature sensor chip from National Semiconductor (NS).
5 * Copyright (C) 2006 Kaiwan N Billimoria <kaiwan@designergraphix.com>
7 * The LM70 communicates with a host processor via an SPI/Microwire Bus
8 * interface. The complete datasheet is available at National's website
10 * http://www.national.com/pf/LM/LM70.html
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.
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.
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.
27 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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>
43 #define DRVNAME "lm70"
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 */
51 struct spi_device *spi;
56 /* sysfs hook function */
57 static ssize_t temp1_input_show(struct device *dev,
58 struct device_attribute *attr, char *buf)
60 struct lm70 *p_lm70 = dev_get_drvdata(dev);
61 struct spi_device *spi = p_lm70->spi;
66 if (mutex_lock_interruptible(&p_lm70->lock))
70 * spi_read() requires a DMA-safe buffer; so we use
71 * spi_write_then_read(), transmitting 0 bytes.
73 status = spi_write_then_read(spi, NULL, 0, &rxbuf[0], 2);
75 dev_warn(dev, "spi_write_then_read failed with status %d\n",
79 raw = (rxbuf[0] << 8) + rxbuf[1];
80 dev_dbg(dev, "rxbuf[0] : 0x%02x rxbuf[1] : 0x%02x raw=0x%04x\n",
81 rxbuf[0], rxbuf[1], raw);
85 * The "raw" temperature read into rxbuf[] is a 16-bit signed 2's
86 * complement value. Only the MSB 11 bits (1 sign + 10 temperature
87 * bits) are meaningful; the LSB 5 bits are to be discarded.
90 * Further, each bit represents 0.25 degrees Celsius; so, multiply
91 * by 0.25. Also multiply by 1000 to represent in millidegrees
93 * So it's equivalent to multiplying by 0.25 * 1000 = 250.
95 * LM74 and TMP121/TMP123:
96 * 13 bits of 2's complement data, discard LSB 3 bits,
97 * resolution 0.0625 degrees celsius.
100 * 14 bits of 2's complement data, discard LSB 2 bits,
101 * resolution 0.0312 degrees celsius.
103 switch (p_lm70->chip) {
105 val = ((int)raw / 32) * 250;
108 case LM70_CHIP_TMP121:
110 val = ((int)raw / 8) * 625 / 10;
114 val = ((int)raw / 4) * 3125 / 100;
118 status = sprintf(buf, "%d\n", val); /* millidegrees Celsius */
120 mutex_unlock(&p_lm70->lock);
124 static DEVICE_ATTR_RO(temp1_input);
126 static struct attribute *lm70_attrs[] = {
127 &dev_attr_temp1_input.attr,
131 ATTRIBUTE_GROUPS(lm70);
133 /*----------------------------------------------------------------------*/
136 static const struct of_device_id lm70_of_ids[] = {
138 .compatible = "ti,lm70",
139 .data = (void *) LM70_CHIP_LM70,
142 .compatible = "ti,tmp121",
143 .data = (void *) LM70_CHIP_TMP121,
146 .compatible = "ti,lm71",
147 .data = (void *) LM70_CHIP_LM71,
150 .compatible = "ti,lm74",
151 .data = (void *) LM70_CHIP_LM74,
155 MODULE_DEVICE_TABLE(of, lm70_of_ids);
158 static int lm70_probe(struct spi_device *spi)
160 const struct of_device_id *match;
161 struct device *hwmon_dev;
165 match = of_match_device(lm70_of_ids, &spi->dev);
167 chip = (int)(uintptr_t)match->data;
169 chip = spi_get_device_id(spi)->driver_data;
171 /* signaling is SPI_MODE_0 */
172 if (spi->mode & (SPI_CPOL | SPI_CPHA))
175 /* NOTE: we assume 8-bit words, and convert to 16 bits manually */
177 p_lm70 = devm_kzalloc(&spi->dev, sizeof(*p_lm70), GFP_KERNEL);
181 mutex_init(&p_lm70->lock);
185 hwmon_dev = devm_hwmon_device_register_with_groups(&spi->dev,
187 p_lm70, lm70_groups);
188 return PTR_ERR_OR_ZERO(hwmon_dev);
191 static const struct spi_device_id lm70_ids[] = {
192 { "lm70", LM70_CHIP_LM70 },
193 { "tmp121", LM70_CHIP_TMP121 },
194 { "lm71", LM70_CHIP_LM71 },
195 { "lm74", LM70_CHIP_LM74 },
198 MODULE_DEVICE_TABLE(spi, lm70_ids);
200 static struct spi_driver lm70_driver = {
203 .of_match_table = of_match_ptr(lm70_of_ids),
205 .id_table = lm70_ids,
209 module_spi_driver(lm70_driver);
211 MODULE_AUTHOR("Kaiwan N Billimoria");
212 MODULE_DESCRIPTION("NS LM70 and compatibles Linux driver");
213 MODULE_LICENSE("GPL");