[linux.git] / drivers / hwmon / lm70.c

/*
 * lm70.c
 *
 * The LM70 is a temperature sensor chip from National Semiconductor (NS).
 * Copyright (C) 2006 Kaiwan N Billimoria <[email protected]>
 *
 * The LM70 communicates with a host processor via an SPI/Microwire Bus
 * interface. The complete datasheet is available at National's website
 * here:
 * http://www.national.com/pf/LM/LM70.html
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/sysfs.h>
#include <linux/hwmon.h>
#include <linux/spi/spi.h>
#include <asm/semaphore.h>

#define DRVNAME		"lm70"

struct lm70 {
	struct class_device *cdev;
	struct semaphore sem;
};

/* sysfs hook function */
static ssize_t lm70_sense_temp(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	struct spi_device *spi = to_spi_device(dev);
	int status, val;
	u8 rxbuf[2];
	s16 raw=0;
	struct lm70 *p_lm70 = dev_get_drvdata(&spi->dev);

	if (down_interruptible(&p_lm70->sem))
		return -ERESTARTSYS;

	/*
	 * spi_read() requires a DMA-safe buffer; so we use
	 * spi_write_then_read(), transmitting 0 bytes.
	 */
	status = spi_write_then_read(spi, NULL, 0, &rxbuf[0], 2);
	if (status < 0) {
		printk(KERN_WARNING
		"spi_write_then_read failed with status %d\n", status);
		goto out;
	}
	dev_dbg(dev, "rxbuf[1] : 0x%x rxbuf[0] : 0x%x\n", rxbuf[1], rxbuf[0]);

	raw = (rxbuf[1] << 8) + rxbuf[0];
	dev_dbg(dev, "raw=0x%x\n", raw);

	/*
	 * The "raw" temperature read into rxbuf[] is a 16-bit signed 2's
	 * complement value. Only the MSB 11 bits (1 sign + 10 temperature
	 * bits) are meaningful; the LSB 5 bits are to be discarded.
	 * See the datasheet.
	 *
	 * Further, each bit represents 0.25 degrees Celsius; so, multiply
	 * by 0.25. Also multiply by 1000 to represent in millidegrees
	 * Celsius.
	 * So it's equivalent to multiplying by 0.25 * 1000 = 250.
	 */
	val = ((int)raw/32) * 250;
	status = sprintf(buf, "%+d\n", val); /* millidegrees Celsius */
out:
	up(&p_lm70->sem);
	return status;
}

static DEVICE_ATTR(temp1_input, S_IRUGO, lm70_sense_temp, NULL);

/*----------------------------------------------------------------------*/

static int __devinit lm70_probe(struct spi_device *spi)
{
	struct lm70 *p_lm70;
	int status;

	p_lm70 = kzalloc(sizeof *p_lm70, GFP_KERNEL);
	if (!p_lm70)
		return -ENOMEM;

	init_MUTEX(&p_lm70->sem);

	/* sysfs hook */
	p_lm70->cdev = hwmon_device_register(&spi->dev);
	if (IS_ERR(p_lm70->cdev)) {
		dev_dbg(&spi->dev, "hwmon_device_register failed.\n");
		status = PTR_ERR(p_lm70->cdev);
		goto out_dev_reg_failed;
	}
	dev_set_drvdata(&spi->dev, p_lm70);

	if ((status = device_create_file(&spi->dev, &dev_attr_temp1_input))) {
		dev_dbg(&spi->dev, "device_create_file failure.\n");
		goto out_dev_create_file_failed;
	}

	return 0;

out_dev_create_file_failed:
	hwmon_device_unregister(p_lm70->cdev);
out_dev_reg_failed:
	dev_set_drvdata(&spi->dev, NULL);
	kfree(p_lm70);
	return status;
}

static int __exit lm70_remove(struct spi_device *spi)
{
	struct lm70 *p_lm70 = dev_get_drvdata(&spi->dev);

	device_remove_file(&spi->dev, &dev_attr_temp1_input);
	hwmon_device_unregister(p_lm70->cdev);
	dev_set_drvdata(&spi->dev, NULL);
	kfree(p_lm70);

	return 0;
}

static struct spi_driver lm70_driver = {
	.driver = {
		.name	= "lm70",
		.owner	= THIS_MODULE,
	},
	.probe	= lm70_probe,
	.remove	= __devexit_p(lm70_remove),
};

static int __init init_lm70(void)
{
	return spi_register_driver(&lm70_driver);
}

static void __exit cleanup_lm70(void)
{
	spi_unregister_driver(&lm70_driver);
}

module_init(init_lm70);
module_exit(cleanup_lm70);

MODULE_AUTHOR("Kaiwan N Billimoria");
MODULE_DESCRIPTION("National Semiconductor LM70 Linux driver");
MODULE_LICENSE("GPL");
Commit	Line	Data
e1a8e913 KB	1	/*
	2	* lm70.c
	3	*
	4	* The LM70 is a temperature sensor chip from National Semiconductor (NS).
	5	* Copyright (C) 2006 Kaiwan N Billimoria <[email protected]>
	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/spi/spi.h>
	35	#include <asm/semaphore.h>
	36
	37	#define DRVNAME "lm70"
	38
	39	struct lm70 {
	40	struct class_device *cdev;
	41	struct semaphore sem;
	42	};
	43
	44	/* sysfs hook function */
	45	static ssize_t lm70_sense_temp(struct device *dev,
	46	struct device_attribute attr, char buf)
	47	{
	48	struct spi_device *spi = to_spi_device(dev);
	49	int status, val;
	50	u8 rxbuf[2];
	51	s16 raw=0;
	52	struct lm70 *p_lm70 = dev_get_drvdata(&spi->dev);
	53
	54	if (down_interruptible(&p_lm70->sem))
	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	printk(KERN_WARNING
	64	"spi_write_then_read failed with status %d\n", status);
65	goto out;
66	}
67	dev_dbg(dev, "rxbuf[1] : 0x%x rxbuf[0] : 0x%x\n", rxbuf[1], rxbuf[0]);
68
69	raw = (rxbuf[1] << 8) + rxbuf[0];
70	dev_dbg(dev, "raw=0x%x\n", raw);
71
72	/*
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	val = ((int)raw/32) * 250;
84	status = sprintf(buf, "%+d\n", val); /* millidegrees Celsius */
85	out:
86	up(&p_lm70->sem);
87	return status;
88	}
89
90	static DEVICE_ATTR(temp1_input, S_IRUGO, lm70_sense_temp, NULL);
91
92	/----------------------------------------------------------------------/
93
94	static int __devinit lm70_probe(struct spi_device *spi)
95	{
96	struct lm70 *p_lm70;
97	int status;
98
99	p_lm70 = kzalloc(sizeof *p_lm70, GFP_KERNEL);
100	if (!p_lm70)
101	return -ENOMEM;
102
103	init_MUTEX(&p_lm70->sem);
104
105	/* sysfs hook */
106	p_lm70->cdev = hwmon_device_register(&spi->dev);
107	if (IS_ERR(p_lm70->cdev)) {
108	dev_dbg(&spi->dev, "hwmon_device_register failed.\n");
109	status = PTR_ERR(p_lm70->cdev);
110	goto out_dev_reg_failed;
111	}
112	dev_set_drvdata(&spi->dev, p_lm70);
113
114	if ((status = device_create_file(&spi->dev, &dev_attr_temp1_input))) {
115	dev_dbg(&spi->dev, "device_create_file failure.\n");
116	goto out_dev_create_file_failed;
117	}
118
119	return 0;
120
121	out_dev_create_file_failed:
122	hwmon_device_unregister(p_lm70->cdev);
123	out_dev_reg_failed:
124	dev_set_drvdata(&spi->dev, NULL);
125	kfree(p_lm70);
126	return status;
127	}
128
129	static int __exit lm70_remove(struct spi_device *spi)
130	{
131	struct lm70 *p_lm70 = dev_get_drvdata(&spi->dev);
132
133	device_remove_file(&spi->dev, &dev_attr_temp1_input);
134	hwmon_device_unregister(p_lm70->cdev);
135	dev_set_drvdata(&spi->dev, NULL);
136	kfree(p_lm70);
137
138	return 0;
139	}
140
141	static struct spi_driver lm70_driver = {
142	.driver = {
143	.name = "lm70",
144	.owner = THIS_MODULE,
145	},
146	.probe = lm70_probe,
147	.remove = __devexit_p(lm70_remove),
148	};
149
150	static int __init init_lm70(void)
151	{
152	return spi_register_driver(&lm70_driver);
153	}
154
155	static void __exit cleanup_lm70(void)
156	{
157	spi_unregister_driver(&lm70_driver);
158	}
159
160	module_init(init_lm70);
161	module_exit(cleanup_lm70);
162
163	MODULE_AUTHOR("Kaiwan N Billimoria");
164	MODULE_DESCRIPTION("National Semiconductor LM70 Linux driver");
165	MODULE_LICENSE("GPL");