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/*
* ads7828.c - lm_sensors driver for ads7828 12-bit 8-channel ADC
* (C) 2007 EADS Astrium
*
* This driver is based on the lm75 and other lm_sensors/hwmon drivers
*
* Written by Steve Hardy <shardy@redhat.com>
*
* For further information, see the Documentation/hwmon/ads7828 file.
*
* 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/err.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/jiffies.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/platform_data/ads7828.h>
#include <linux/slab.h>
/* The ADS7828 registers */
#define ADS7828_NCH 8 /* 8 channels supported */
#define ADS7828_CMD_SD_SE 0x80 /* Single ended inputs */
#define ADS7828_CMD_PD1 0x04 /* Internal vref OFF && A/D ON */
#define ADS7828_CMD_PD3 0x0C /* Internal vref ON && A/D ON */
#define ADS7828_INT_VREF_MV 2500 /* Internal vref is 2.5V, 2500mV */
#define ADS7828_EXT_VREF_MV_MIN 50 /* External vref min value 0.05V */
#define ADS7828_EXT_VREF_MV_MAX 5250 /* External vref max value 5.25V */
/* Client specific data */
struct ads7828_data {
struct device *hwmon_dev;
struct mutex update_lock; /* Mutex protecting updates */
unsigned long last_updated; /* Last updated time (in jiffies) */
u16 adc_input[ADS7828_NCH]; /* ADS7828_NCH samples */
bool valid; /* Validity flag */
bool diff_input; /* Differential input */
bool ext_vref; /* External voltage reference */
unsigned int vref_mv; /* voltage reference value */
u8 cmd_byte; /* Command byte without channel bits */
unsigned int lsb_resol; /* Resolution of the ADC sample LSB */
};
/* Command byte C2,C1,C0 - see datasheet */
static inline u8 ads7828_cmd_byte(u8 cmd, int ch)
{
return cmd | (((ch >> 1) | (ch & 0x01) << 2) << 4);
}
/* Update data for the device (all 8 channels) */
static struct ads7828_data *ads7828_update_device(struct device *dev)
{
struct i2c_client *client = to_i2c_client(dev);
struct ads7828_data *data = i2c_get_clientdata(client);
mutex_lock(&data->update_lock);
if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
|| !data->valid) {
unsigned int ch;
dev_dbg(&client->dev, "Starting ads7828 update\n");
for (ch = 0; ch < ADS7828_NCH; ch++) {
u8 cmd = ads7828_cmd_byte(data->cmd_byte, ch);
data->adc_input[ch] =
i2c_smbus_read_word_swapped(client, cmd);
}
data->last_updated = jiffies;
data->valid = true;
}
mutex_unlock(&data->update_lock);
return data;
}
/* sysfs callback function */
static ssize_t ads7828_show_in(struct device *dev, struct device_attribute *da,
char *buf)
{
struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
struct ads7828_data *data = ads7828_update_device(dev);
unsigned int value = DIV_ROUND_CLOSEST(data->adc_input[attr->index] *
data->lsb_resol, 1000);
return sprintf(buf, "%d\n", value);
}
static SENSOR_DEVICE_ATTR(in0_input, S_IRUGO, ads7828_show_in, NULL, 0);
static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, ads7828_show_in, NULL, 1);
static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, ads7828_show_in, NULL, 2);
static SENSOR_DEVICE_ATTR(in3_input, S_IRUGO, ads7828_show_in, NULL, 3);
static SENSOR_DEVICE_ATTR(in4_input, S_IRUGO, ads7828_show_in, NULL, 4);
static SENSOR_DEVICE_ATTR(in5_input, S_IRUGO, ads7828_show_in, NULL, 5);
static SENSOR_DEVICE_ATTR(in6_input, S_IRUGO, ads7828_show_in, NULL, 6);
static SENSOR_DEVICE_ATTR(in7_input, S_IRUGO, ads7828_show_in, NULL, 7);
static struct attribute *ads7828_attributes[] = {
&sensor_dev_attr_in0_input.dev_attr.attr,
&sensor_dev_attr_in1_input.dev_attr.attr,
&sensor_dev_attr_in2_input.dev_attr.attr,
&sensor_dev_attr_in3_input.dev_attr.attr,
&sensor_dev_attr_in4_input.dev_attr.attr,
&sensor_dev_attr_in5_input.dev_attr.attr,
&sensor_dev_attr_in6_input.dev_attr.attr,
&sensor_dev_attr_in7_input.dev_attr.attr,
NULL
};
static const struct attribute_group ads7828_group = {
.attrs = ads7828_attributes,
};
static int ads7828_remove(struct i2c_client *client)
{
struct ads7828_data *data = i2c_get_clientdata(client);
hwmon_device_unregister(data->hwmon_dev);
sysfs_remove_group(&client->dev.kobj, &ads7828_group);
return 0;
}
static int ads7828_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
struct ads7828_platform_data *pdata = client->dev.platform_data;
struct ads7828_data *data;
int err;
data = devm_kzalloc(&client->dev, sizeof(struct ads7828_data),
GFP_KERNEL);
if (!data)
return -ENOMEM;
if (pdata) {
data->diff_input = pdata->diff_input;
data->ext_vref = pdata->ext_vref;
if (data->ext_vref)
data->vref_mv = pdata->vref_mv;
}
/* Bound Vref with min/max values if it was provided */
if (data->vref_mv)
data->vref_mv = SENSORS_LIMIT(data->vref_mv,
ADS7828_EXT_VREF_MV_MIN,
ADS7828_EXT_VREF_MV_MAX);
else
data->vref_mv = ADS7828_INT_VREF_MV;
data->lsb_resol = DIV_ROUND_CLOSEST(data->vref_mv * 1000, 4096);
data->cmd_byte = data->ext_vref ? ADS7828_CMD_PD1 : ADS7828_CMD_PD3;
if (!data->diff_input)
data->cmd_byte |= ADS7828_CMD_SD_SE;
i2c_set_clientdata(client, data);
mutex_init(&data->update_lock);
err = sysfs_create_group(&client->dev.kobj, &ads7828_group);
if (err)
return err;
data->hwmon_dev = hwmon_device_register(&client->dev);
if (IS_ERR(data->hwmon_dev)) {
err = PTR_ERR(data->hwmon_dev);
goto error;
}
return 0;
error:
sysfs_remove_group(&client->dev.kobj, &ads7828_group);
return err;
}
static const struct i2c_device_id ads7828_device_ids[] = {
{ "ads7828", 0 },
{ }
};
MODULE_DEVICE_TABLE(i2c, ads7828_device_ids);
static struct i2c_driver ads7828_driver = {
.driver = {
.name = "ads7828",
},
.id_table = ads7828_device_ids,
.probe = ads7828_probe,
.remove = ads7828_remove,
};
module_i2c_driver(ads7828_driver);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Steve Hardy <shardy@redhat.com>");
MODULE_DESCRIPTION("Driver for TI ADS7828 A/D converter");
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