linux/drivers/hwmon/adcxx.c
José Miguel Gonçalves 5748150eab drivers/hwmon/adcxx.c: fix for single-channel ADCs
While testing an ADC121S021 in an embedded board with a S3C2142 SoC (ARM
core), I have found that the 'adcxx' driver does not handle correctly
single channel ADCs from this chip family.  For single channel chips you
must only issue one read transfer for correct measurement.

Signed-off-by: Jose Miguel Goncalves <jose.goncalves@inov.pt>
Cc: Marc Pignat <marc.pignat@hevs.ch>
Cc: Anton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-03-06 11:26:45 -08:00

266 lines
6.8 KiB
C

/*
* adcxx.c
*
* The adcxx4s is an AD converter family from National Semiconductor (NS).
*
* Copyright (c) 2008 Marc Pignat <marc.pignat@hevs.ch>
*
* The adcxx4s communicates with a host processor via an SPI/Microwire Bus
* interface. This driver supports the whole family of devices with name
* ADC<bb><c>S<sss>, where
* * bb is the resolution in number of bits (8, 10, 12)
* * c is the number of channels (1, 2, 4, 8)
* * sss is the maximum conversion speed (021 for 200 kSPS, 051 for 500 kSPS
* and 101 for 1 MSPS)
*
* Complete datasheets are available at National's website here:
* http://www.national.com/ds/DC/ADC<bb><c>S<sss>.pdf
*
* Handling of 8, 10 and 12 bits converters are the same, the
* unavailable bits are 0 :)
*
* 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/hwmon-sysfs.h>
#include <linux/mutex.h>
#include <linux/mod_devicetable.h>
#include <linux/spi/spi.h>
#define DRVNAME "adcxx"
struct adcxx {
struct device *hwmon_dev;
struct mutex lock;
u32 channels;
u32 reference; /* in millivolts */
};
/* sysfs hook function */
static ssize_t adcxx_read(struct device *dev,
struct device_attribute *devattr, char *buf)
{
struct spi_device *spi = to_spi_device(dev);
struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
struct adcxx *adc = dev_get_drvdata(&spi->dev);
u8 tx_buf[2];
u8 rx_buf[2];
int status;
u32 value;
if (mutex_lock_interruptible(&adc->lock))
return -ERESTARTSYS;
if (adc->channels == 1) {
status = spi_read(spi, rx_buf, sizeof(rx_buf));
} else {
tx_buf[0] = attr->index << 3; /* other bits are don't care */
status = spi_write_then_read(spi, tx_buf, sizeof(tx_buf),
rx_buf, sizeof(rx_buf));
}
if (status < 0) {
dev_warn(dev, "SPI synch. transfer failed with status %d\n",
status);
goto out;
}
value = (rx_buf[0] << 8) + rx_buf[1];
dev_dbg(dev, "raw value = 0x%x\n", value);
value = value * adc->reference >> 12;
status = sprintf(buf, "%d\n", value);
out:
mutex_unlock(&adc->lock);
return status;
}
static ssize_t adcxx_show_min(struct device *dev,
struct device_attribute *devattr, char *buf)
{
/* The minimum reference is 0 for this chip family */
return sprintf(buf, "0\n");
}
static ssize_t adcxx_show_max(struct device *dev,
struct device_attribute *devattr, char *buf)
{
struct spi_device *spi = to_spi_device(dev);
struct adcxx *adc = dev_get_drvdata(&spi->dev);
u32 reference;
if (mutex_lock_interruptible(&adc->lock))
return -ERESTARTSYS;
reference = adc->reference;
mutex_unlock(&adc->lock);
return sprintf(buf, "%d\n", reference);
}
static ssize_t adcxx_set_max(struct device *dev,
struct device_attribute *devattr, const char *buf, size_t count)
{
struct spi_device *spi = to_spi_device(dev);
struct adcxx *adc = dev_get_drvdata(&spi->dev);
unsigned long value;
if (strict_strtoul(buf, 10, &value))
return -EINVAL;
if (mutex_lock_interruptible(&adc->lock))
return -ERESTARTSYS;
adc->reference = value;
mutex_unlock(&adc->lock);
return count;
}
static ssize_t adcxx_show_name(struct device *dev, struct device_attribute
*devattr, char *buf)
{
struct spi_device *spi = to_spi_device(dev);
struct adcxx *adc = dev_get_drvdata(&spi->dev);
return sprintf(buf, "adcxx%ds\n", adc->channels);
}
static struct sensor_device_attribute ad_input[] = {
SENSOR_ATTR(name, S_IRUGO, adcxx_show_name, NULL, 0),
SENSOR_ATTR(in_min, S_IRUGO, adcxx_show_min, NULL, 0),
SENSOR_ATTR(in_max, S_IWUSR | S_IRUGO, adcxx_show_max,
adcxx_set_max, 0),
SENSOR_ATTR(in0_input, S_IRUGO, adcxx_read, NULL, 0),
SENSOR_ATTR(in1_input, S_IRUGO, adcxx_read, NULL, 1),
SENSOR_ATTR(in2_input, S_IRUGO, adcxx_read, NULL, 2),
SENSOR_ATTR(in3_input, S_IRUGO, adcxx_read, NULL, 3),
SENSOR_ATTR(in4_input, S_IRUGO, adcxx_read, NULL, 4),
SENSOR_ATTR(in5_input, S_IRUGO, adcxx_read, NULL, 5),
SENSOR_ATTR(in6_input, S_IRUGO, adcxx_read, NULL, 6),
SENSOR_ATTR(in7_input, S_IRUGO, adcxx_read, NULL, 7),
};
/*----------------------------------------------------------------------*/
static int __devinit adcxx_probe(struct spi_device *spi)
{
int channels = spi_get_device_id(spi)->driver_data;
struct adcxx *adc;
int status;
int i;
adc = kzalloc(sizeof *adc, GFP_KERNEL);
if (!adc)
return -ENOMEM;
/* set a default value for the reference */
adc->reference = 3300;
adc->channels = channels;
mutex_init(&adc->lock);
mutex_lock(&adc->lock);
dev_set_drvdata(&spi->dev, adc);
for (i = 0; i < 3 + adc->channels; i++) {
status = device_create_file(&spi->dev, &ad_input[i].dev_attr);
if (status) {
dev_err(&spi->dev, "device_create_file failed.\n");
goto out_err;
}
}
adc->hwmon_dev = hwmon_device_register(&spi->dev);
if (IS_ERR(adc->hwmon_dev)) {
dev_err(&spi->dev, "hwmon_device_register failed.\n");
status = PTR_ERR(adc->hwmon_dev);
goto out_err;
}
mutex_unlock(&adc->lock);
return 0;
out_err:
for (i--; i >= 0; i--)
device_remove_file(&spi->dev, &ad_input[i].dev_attr);
dev_set_drvdata(&spi->dev, NULL);
mutex_unlock(&adc->lock);
kfree(adc);
return status;
}
static int __devexit adcxx_remove(struct spi_device *spi)
{
struct adcxx *adc = dev_get_drvdata(&spi->dev);
int i;
mutex_lock(&adc->lock);
hwmon_device_unregister(adc->hwmon_dev);
for (i = 0; i < 3 + adc->channels; i++)
device_remove_file(&spi->dev, &ad_input[i].dev_attr);
dev_set_drvdata(&spi->dev, NULL);
mutex_unlock(&adc->lock);
kfree(adc);
return 0;
}
static const struct spi_device_id adcxx_ids[] = {
{ "adcxx1s", 1 },
{ "adcxx2s", 2 },
{ "adcxx4s", 4 },
{ "adcxx8s", 8 },
{ },
};
MODULE_DEVICE_TABLE(spi, adcxx_ids);
static struct spi_driver adcxx_driver = {
.driver = {
.name = "adcxx",
.owner = THIS_MODULE,
},
.id_table = adcxx_ids,
.probe = adcxx_probe,
.remove = __devexit_p(adcxx_remove),
};
static int __init init_adcxx(void)
{
return spi_register_driver(&adcxx_driver);
}
static void __exit exit_adcxx(void)
{
spi_unregister_driver(&adcxx_driver);
}
module_init(init_adcxx);
module_exit(exit_adcxx);
MODULE_AUTHOR("Marc Pignat");
MODULE_DESCRIPTION("National Semiconductor adcxx8sxxx Linux driver");
MODULE_LICENSE("GPL");