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
39struct lm70 {
40	struct spi_device *spi;
41	struct mutex lock;
42	unsigned int chip;
43};
44
45/* sysfs hook function */
46static 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, 0, &rxbuf[0], 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(raw, 14) / 32) * 250;
115		break;
116	}
117
118	status = sprintf(buf, "%d\n", val); /* millidegrees Celsius */
119out:
120	mutex_unlock(&p_lm70->lock);
121	return status;
122}
123
124static DEVICE_ATTR_RO(temp1_input);
125
126static struct attribute *lm70_attrs[] = {
127	&dev_attr_temp1_input.attr,
128	NULL
129};
130
131ATTRIBUTE_GROUPS(lm70);
132
133/*----------------------------------------------------------------------*/
134
135#ifdef CONFIG_OF
136static 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};
163MODULE_DEVICE_TABLE(of, lm70_of_ids);
164#endif
165
166static 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(&spi->dev);
174	else
175		chip = spi_get_device_id(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(&spi->dev, 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(&spi->dev,
193							   spi->modalias,
194							   p_lm70, lm70_groups);
195	return PTR_ERR_OR_ZERO(hwmon_dev);
196}
197
198static 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};
207MODULE_DEVICE_TABLE(spi, lm70_ids);
208
209static 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
218module_spi_driver(lm70_driver);
219
220MODULE_AUTHOR("Kaiwan N Billimoria");
221MODULE_DESCRIPTION("NS LM70 and compatibles Linux driver");
222MODULE_LICENSE("GPL");
223