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/*
* lm70.c
*
* The LM70 is a temperature sensor chip from National Semiconductor (NS).
* Copyright (C) 2006 Kaiwan N Billimoria <kaiwan@designergraphix.com>
*
* 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.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#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/mutex.h>
#include <linux/mod_devicetable.h>
#include <linux/spi/spi.h>
#include <linux/slab.h>
#define DRVNAME "lm70"
#define LM70_CHIP_LM70 0 /* original NS LM70 */
#define LM70_CHIP_TMP121 1 /* TI TMP121/TMP123 */
#define LM70_CHIP_LM71 2 /* NS LM71 */
#define LM70_CHIP_LM74 3 /* NS LM74 */
struct lm70 {
struct spi_device *spi;
struct mutex lock;
unsigned int chip;
};
/* sysfs hook function */
static ssize_t lm70_sense_temp(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct lm70 *p_lm70 = dev_get_drvdata(dev);
struct spi_device *spi = p_lm70->spi;
int status, val = 0;
u8 rxbuf[2];
s16 raw = 0;
if (mutex_lock_interruptible(&p_lm70->lock))
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) {
pr_warn("spi_write_then_read failed with status %d\n", status);
goto out;
}
raw = (rxbuf[0] << 8) + rxbuf[1];
dev_dbg(dev, "rxbuf[0] : 0x%02x rxbuf[1] : 0x%02x raw=0x%04x\n",
rxbuf[0], rxbuf[1], raw);
/*
* LM70:
* 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.
*
* LM74 and TMP121/TMP123:
* 13 bits of 2's complement data, discard LSB 3 bits,
* resolution 0.0625 degrees celsius.
*
* LM71:
* 14 bits of 2's complement data, discard LSB 2 bits,
* resolution 0.0312 degrees celsius.
*/
switch (p_lm70->chip) {
case LM70_CHIP_LM70:
val = ((int)raw / 32) * 250;
break;
case LM70_CHIP_TMP121:
case LM70_CHIP_LM74:
val = ((int)raw / 8) * 625 / 10;
break;
case LM70_CHIP_LM71:
val = ((int)raw / 4) * 3125 / 100;
break;
}
status = sprintf(buf, "%d\n", val); /* millidegrees Celsius */
out:
mutex_unlock(&p_lm70->lock);
return status;
}
static DEVICE_ATTR(temp1_input, S_IRUGO, lm70_sense_temp, NULL);
static struct attribute *lm70_attrs[] = {
&dev_attr_temp1_input.attr,
NULL
};
ATTRIBUTE_GROUPS(lm70);
/*----------------------------------------------------------------------*/
static int lm70_probe(struct spi_device *spi)
{
int chip = spi_get_device_id(spi)->driver_data;
struct device *hwmon_dev;
struct lm70 *p_lm70;
/* signaling is SPI_MODE_0 */
if (spi->mode & (SPI_CPOL | SPI_CPHA))
return -EINVAL;
/* NOTE: we assume 8-bit words, and convert to 16 bits manually */
p_lm70 = devm_kzalloc(&spi->dev, sizeof(*p_lm70), GFP_KERNEL);
if (!p_lm70)
return -ENOMEM;
mutex_init(&p_lm70->lock);
p_lm70->chip = chip;
p_lm70->spi = spi;
hwmon_dev = devm_hwmon_device_register_with_groups(&spi->dev,
spi->modalias,
p_lm70, lm70_groups);
return PTR_ERR_OR_ZERO(hwmon_dev);
}
static const struct spi_device_id lm70_ids[] = {
{ "lm70", LM70_CHIP_LM70 },
{ "tmp121", LM70_CHIP_TMP121 },
{ "lm71", LM70_CHIP_LM71 },
{ "lm74", LM70_CHIP_LM74 },
{ },
};
MODULE_DEVICE_TABLE(spi, lm70_ids);
static struct spi_driver lm70_driver = {
.driver = {
.name = "lm70",
.owner = THIS_MODULE,
},
.id_table = lm70_ids,
.probe = lm70_probe,
};
module_spi_driver(lm70_driver);
MODULE_AUTHOR("Kaiwan N Billimoria");
MODULE_DESCRIPTION("NS LM70 and compatibles Linux driver");
MODULE_LICENSE("GPL");
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