/drivers/hwmon/lm70.c

  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#include <linux/init.h>
 28#include <linux/module.h>
 29#include <linux/kernel.h>
 30#include <linux/device.h>
 31#include <linux/err.h>
 32#include <linux/sysfs.h>
 33#include <linux/hwmon.h>
 34#include <linux/mutex.h>
 35#include <linux/mod_devicetable.h>
 36#include <linux/spi/spi.h>
 37#include <linux/slab.h>
 38
 39
 40#define DRVNAME		"lm70"
 41
 42#define LM70_CHIP_LM70		0	/* original NS LM70 */
 43#define LM70_CHIP_TMP121	1	/* TI TMP121/TMP123 */
 44
 45struct lm70 {
 46	struct device *hwmon_dev;
 47	struct mutex lock;
 48	unsigned int chip;
 49};
 50
 51/* sysfs hook function */
 52static ssize_t lm70_sense_temp(struct device *dev,
 53		struct device_attribute *attr, char *buf)
 54{
 55	struct spi_device *spi = to_spi_device(dev);
 56	int status, val = 0;
 57	u8 rxbuf[2];
 58	s16 raw=0;
 59	struct lm70 *p_lm70 = dev_get_drvdata(&spi->dev);
 60
 61	if (mutex_lock_interruptible(&p_lm70->lock))
 62		return -ERESTARTSYS;
 63
 64	/*
 65	 * spi_read() requires a DMA-safe buffer; so we use
 66	 * spi_write_then_read(), transmitting 0 bytes.
 67	 */
 68	status = spi_write_then_read(spi, NULL, 0, &rxbuf[0], 2);
 69	if (status < 0) {
 70		printk(KERN_WARNING
 71		"spi_write_then_read failed with status %d\n", status);
 72		goto out;
 73	}
 74	raw = (rxbuf[0] << 8) + rxbuf[1];
 75	dev_dbg(dev, "rxbuf[0] : 0x%02x rxbuf[1] : 0x%02x raw=0x%04x\n",
 76		rxbuf[0], rxbuf[1], raw);
 77
 78	/*
 79	 * LM70:
 80	 * The "raw" temperature read into rxbuf[] is a 16-bit signed 2's
 81	 * complement value. Only the MSB 11 bits (1 sign + 10 temperature
 82	 * bits) are meaningful; the LSB 5 bits are to be discarded.
 83	 * See the datasheet.
 84	 *
 85	 * Further, each bit represents 0.25 degrees Celsius; so, multiply
 86	 * by 0.25. Also multiply by 1000 to represent in millidegrees
 87	 * Celsius.
 88	 * So it's equivalent to multiplying by 0.25 * 1000 = 250.
 89	 *
 90	 * TMP121/TMP123:
 91	 * 13 bits of 2's complement data, discard LSB 3 bits,
 92	 * resolution 0.0625 degrees celsius.
 93	 */
 94	switch (p_lm70->chip) {
 95	case LM70_CHIP_LM70:
 96		val = ((int)raw / 32) * 250;
 97		break;
 98
 99	case LM70_CHIP_TMP121:
100		val = ((int)raw / 8) * 625 / 10;
101		break;
102	}
103
104	status = sprintf(buf, "%d\n", val); /* millidegrees Celsius */
105out:
106	mutex_unlock(&p_lm70->lock);
107	return status;
108}
109
110static DEVICE_ATTR(temp1_input, S_IRUGO, lm70_sense_temp, NULL);
111
112static ssize_t lm70_show_name(struct device *dev, struct device_attribute
113			      *devattr, char *buf)
114{
115	struct lm70 *p_lm70 = dev_get_drvdata(dev);
116	int ret;
117
118	switch (p_lm70->chip) {
119	case LM70_CHIP_LM70:
120		ret = sprintf(buf, "lm70\n");
121		break;
122	case LM70_CHIP_TMP121:
123		ret = sprintf(buf, "tmp121\n");
124		break;
125	default:
126		ret = -EINVAL;
127	}
128	return ret;
129}
130
131static DEVICE_ATTR(name, S_IRUGO, lm70_show_name, NULL);
132
133/*----------------------------------------------------------------------*/
134
135static int __devinit lm70_probe(struct spi_device *spi)
136{
137	int chip = spi_get_device_id(spi)->driver_data;
138	struct lm70 *p_lm70;
139	int status;
140
141	/* signaling is SPI_MODE_0 for both LM70 and TMP121 */
142	if (spi->mode & (SPI_CPOL | SPI_CPHA))
143		return -EINVAL;
144
145	/* 3-wire link (shared SI/SO) for LM70 */
146	if (chip == LM70_CHIP_LM70 && !(spi->mode & SPI_3WIRE))
147		return -EINVAL;
148
149	/* NOTE:  we assume 8-bit words, and convert to 16 bits manually */
150
151	p_lm70 = kzalloc(sizeof *p_lm70, GFP_KERNEL);
152	if (!p_lm70)
153		return -ENOMEM;
154
155	mutex_init(&p_lm70->lock);
156	p_lm70->chip = chip;
157
158	/* sysfs hook */
159	p_lm70->hwmon_dev = hwmon_device_register(&spi->dev);
160	if (IS_ERR(p_lm70->hwmon_dev)) {
161		dev_dbg(&spi->dev, "hwmon_device_register failed.\n");
162		status = PTR_ERR(p_lm70->hwmon_dev);
163		goto out_dev_reg_failed;
164	}
165	dev_set_drvdata(&spi->dev, p_lm70);
166
167	if ((status = device_create_file(&spi->dev, &dev_attr_temp1_input))
168	 || (status = device_create_file(&spi->dev, &dev_attr_name))) {
169		dev_dbg(&spi->dev, "device_create_file failure.\n");
170		goto out_dev_create_file_failed;
171	}
172
173	return 0;
174
175out_dev_create_file_failed:
176	device_remove_file(&spi->dev, &dev_attr_temp1_input);
177	hwmon_device_unregister(p_lm70->hwmon_dev);
178out_dev_reg_failed:
179	dev_set_drvdata(&spi->dev, NULL);
180	kfree(p_lm70);
181	return status;
182}
183
184static int __devexit lm70_remove(struct spi_device *spi)
185{
186	struct lm70 *p_lm70 = dev_get_drvdata(&spi->dev);
187
188	device_remove_file(&spi->dev, &dev_attr_temp1_input);
189	device_remove_file(&spi->dev, &dev_attr_name);
190	hwmon_device_unregister(p_lm70->hwmon_dev);
191	dev_set_drvdata(&spi->dev, NULL);
192	kfree(p_lm70);
193
194	return 0;
195}
196
197
198static const struct spi_device_id lm70_ids[] = {
199	{ "lm70",   LM70_CHIP_LM70 },
200	{ "tmp121", LM70_CHIP_TMP121 },
201	{ },
202};
203MODULE_DEVICE_TABLE(spi, lm70_ids);
204
205static struct spi_driver lm70_driver = {
206	.driver = {
207		.name	= "lm70",
208		.owner	= THIS_MODULE,
209	},
210	.id_table = lm70_ids,
211	.probe	= lm70_probe,
212	.remove	= __devexit_p(lm70_remove),
213};
214
215static int __init init_lm70(void)
216{
217	return spi_register_driver(&lm70_driver);
218}
219
220static void __exit cleanup_lm70(void)
221{
222	spi_unregister_driver(&lm70_driver);
223}
224
225module_init(init_lm70);
226module_exit(cleanup_lm70);
227
228MODULE_AUTHOR("Kaiwan N Billimoria");
229MODULE_DESCRIPTION("NS LM70 / TI TMP121/TMP123 Linux driver");
230MODULE_LICENSE("GPL");