android_kernel_xiaomi_sm8350/drivers/hwmon/lm70.c
David Brownell c06e677aed SPI: add 3wire mode flag
Add a new spi->mode bit: SPI_3WIRE, for chips where the SI and SO signals
are shared (and which are thus only half duplex).  Update the LM70 driver
to require support for that hardware mode from the controller.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-17 10:23:04 -07:00

170 lines
4.5 KiB
C

/*
* 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.
*/
#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;
/* signaling is SPI_MODE_0 on a 3-wire link (shared SI/SO) */
if ((spi->mode & (SPI_CPOL|SPI_CPHA)) || !(spi->mode & SPI_3WIRE))
return -EINVAL;
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 __devexit 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");