/drivers/hwmon/lm70.c

  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/spi/spi.h>
 26#include <linux/slab.h>
 27#include <linux/of_device.h>
 28
 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
 38struct lm70 {
 39	struct spi_device *spi;
 40	struct mutex lock;
 41	unsigned int chip;
 42};
 43
 44/* sysfs hook function */
 45static 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 */
108out:
109	mutex_unlock(&p_lm70->lock);
110	return status;
111}
112
113static DEVICE_ATTR_RO(temp1_input);
114
115static struct attribute *lm70_attrs[] = {
116	&dev_attr_temp1_input.attr,
117	NULL
118};
119
120ATTRIBUTE_GROUPS(lm70);
121
122/*----------------------------------------------------------------------*/
123
124#ifdef CONFIG_OF
125static 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};
148MODULE_DEVICE_TABLE(of, lm70_of_ids);
149#endif
150
151static int lm70_probe(struct spi_device *spi)
152{
153	const struct of_device_id *match;
154	struct device *hwmon_dev;
155	struct lm70 *p_lm70;
156	int chip;
157
158	match = of_match_device(lm70_of_ids, &spi->dev);
159	if (match)
160		chip = (int)(uintptr_t)match->data;
161	else
162		chip = spi_get_device_id(spi)->driver_data;
163
164	/* signaling is SPI_MODE_0 */
165	if (spi->mode & (SPI_CPOL | SPI_CPHA))
166		return -EINVAL;
167
168	/* NOTE:  we assume 8-bit words, and convert to 16 bits manually */
169
170	p_lm70 = devm_kzalloc(&spi->dev, sizeof(*p_lm70), GFP_KERNEL);
171	if (!p_lm70)
172		return -ENOMEM;
173
174	mutex_init(&p_lm70->lock);
175	p_lm70->chip = chip;
176	p_lm70->spi = spi;
177
178	hwmon_dev = devm_hwmon_device_register_with_groups(&spi->dev,
179							   spi->modalias,
180							   p_lm70, lm70_groups);
181	return PTR_ERR_OR_ZERO(hwmon_dev);
182}
183
184static const struct spi_device_id lm70_ids[] = {
185	{ "lm70",   LM70_CHIP_LM70 },
186	{ "tmp121", LM70_CHIP_TMP121 },
187	{ "tmp122", LM70_CHIP_TMP122 },
188	{ "lm71",   LM70_CHIP_LM71 },
189	{ "lm74",   LM70_CHIP_LM74 },
190	{ },
191};
192MODULE_DEVICE_TABLE(spi, lm70_ids);
193
194static struct spi_driver lm70_driver = {
195	.driver = {
196		.name	= "lm70",
197		.of_match_table	= of_match_ptr(lm70_of_ids),
198	},
199	.id_table = lm70_ids,
200	.probe	= lm70_probe,
201};
202
203module_spi_driver(lm70_driver);
204
205MODULE_AUTHOR("Kaiwan N Billimoria");
206MODULE_DESCRIPTION("NS LM70 and compatibles Linux driver");
207MODULE_LICENSE("GPL");