/*
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 <steve@linuxrealtime.co.uk>
Datasheet available at: http://focus.ti.com/lit/ds/symlink/ads7828.pdf
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/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/jiffies.h>
#include <linux/i2c.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/err.h>
#include <linux/mutex.h>
/* The ADS7828 registers */
#define ADS7828_NCH 8 /* 8 channels of 12-bit A-D supported */
#define ADS7828_CMD_SD_SE 0x80 /* Single ended inputs */
#define ADS7828_CMD_SD_DIFF 0x00 /* Differential inputs */
#define ADS7828_CMD_PD0 0x0 /* Power Down between A-D conversions */
#define ADS7828_CMD_PD1 0x04 /* Internal ref OFF && A-D ON */
#define ADS7828_CMD_PD2 0x08 /* Internal ref ON && A-D OFF */
#define ADS7828_CMD_PD3 0x0C /* Internal ref ON && A-D ON */
#define ADS7828_INT_VREF_MV 2500 /* Internal vref is 2.5V, 2500mV */
/* Addresses to scan */
static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b,
I2C_CLIENT_END };
/* Module parameters */
static int se_input = 1; /* Default is SE, 0 == diff */
static int int_vref = 1; /* Default is internal ref ON */
static int vref_mv = ADS7828_INT_VREF_MV; /* set if vref != 2.5V */
module_param(se_input, bool, S_IRUGO);
module_param(int_vref, bool, S_IRUGO);
module_param(vref_mv, int, S_IRUGO);
/* Global Variables */
static u8 ads7828_cmd_byte; /* cmd byte without channel bits */
static unsigned int ads7828_lsb_resol; /* resolution of the ADC sample lsb */
/* Each client has this additional data */
struct ads7828_data {
struct device *hwmon_dev;
struct mutex update_lock; /* mutex protect updates */
char valid; /* !=0 if following fields are valid */
unsigned long last_updated; /* In jiffies */
u16 adc_input[ADS7828_NCH]; /* ADS7828_NCH 12-bit samples */
};
/* Function declaration - necessary due to function dependencies */
static int ads7828_detect(struct i2c_client *client,
struct i2c_board_info *info);
static int ads7828_probe(struct i2c_client *client,
const struct i2c_device_id *id);
/* The ADS7828 returns the 12-bit sample in two bytes,
these are read as a word then byte-swapped */
static u16 ads7828_read_value(struct i2c_client *client, u8 reg)
{
return swab16(i2c_smbus_read_word_data(client, reg));
}
static inline u8 channel_cmd_byte(int ch)
{
/* cmd byte C2,C1,C0 - see datasheet */
u8 cmd = (((ch>>1) | (ch&0x01)<<2)<<4);
cmd |= ads7828_cmd_byte;
return cmd;
}
/* 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 = channel_cmd_byte(ch);
data->adc_input[ch] = ads7828_read_value(client, cmd);
}
data->last_updated = jiffies;
data->valid = 1;
}
mutex_unlock(&data->update_lock);
return data;
}
/* sysfs callback function */
static ssize_t 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);
/* Print value (in mV as specified in sysfs-interface documentation) */
return sprintf(buf, "%d\n", (data->adc_input[attr->index] *
ads7828_lsb_resol)/1000);
}
#define in_reg(offset)\
static SENSOR_DEVICE_ATTR(in##offset##_input, S_IRUGO, show_in,\
NULL, offset)
in_reg(0);
in_reg(1);
in_reg(2);
in_reg(3);
in_reg(4);
in_reg(5);
in_reg(6);
in_reg(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);
kfree(i2c_get_clientdata(client));
return 0;
}
static const struct i2c_device_id ads7828_id[] = {
{ "ads7828", 0 },
{ }
};
MODULE_DEVICE_TABLE(i2c, ads7828_id);
/* This is the driver that will be inserted */
static struct i2c_driver ads7828_driver = {
.class = I2C_CLASS_HWMON,
.driver = {
.name = "ads7828",
},
.probe = ads7828_probe,
.remove = ads7828_remove,
.id_table = ads7828_id,
.detect = ads7828_detect,
.address_list = normal_i2c,
};
/* Return 0 if detection is successful, -ENODEV otherwise */
static int ads7828_detect(struct i2c_client *client,
struct i2c_board_info *info)
{
struct i2c_adapter *adapter = client->adapter;
int ch;
/* Check we have a valid client */
if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_WORD_DATA))
return -ENODEV;
/* Now, we do the remaining detection. There is no identification
dedicated register so attempt to sanity check using knowledge of
the chip
- Read from the 8 channel addresses
- Check the top 4 bits of each result are not set (12 data bits)
*/
for (ch = 0; ch < ADS7828_NCH; ch++) {
u16 in_data;
u8 cmd = channel_cmd_byte(ch);
in_data = ads7828_read_value(client, cmd);
if (in_data & 0xF000) {
pr_debug("%s : Doesn't look like an ads7828 device\n",
__func__);
return -ENODEV;
}
}
strlcpy(info->type, "ads7828", I2C_NAME_SIZE);
return 0;
}
static int ads7828_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
struct ads7828_data *data;
int err;
data = kzalloc(sizeof(struct ads7828_data), GFP_KERNEL);
if (!data) {
err = -ENOMEM;
goto exit;
}
i2c_set_clientdata(client, data);
mutex_init(&data->update_lock);
/* Register sysfs hooks */
err = sysfs_create_group(&client->dev.kobj, &ads7828_group);
if (err)
goto exit_free;
data->hwmon_dev = hwmon_device_register(&client->dev);
if (IS_ERR(data->hwmon_dev)) {
err = PTR_ERR(data->hwmon_dev);
goto exit_remove;
}
return 0;
exit_remove:
sysfs_remove_group(&client->dev.kobj, &ads7828_group);
exit_free:
kfree(data);
exit:
return err;
}
static int __init sensors_ads7828_init(void)
{
/* Initialize the command byte according to module parameters */
ads7828_cmd_byte = se_input ?
ADS7828_CMD_SD_SE : ADS7828_CMD_SD_DIFF;
ads7828_cmd_byte |= int_vref ?
ADS7828_CMD_PD3 : ADS7828_CMD_PD1;
/* Calculate the LSB resolution */
ads7828_lsb_resol = (vref_mv*1000)/4096;
return i2c_add_driver(&ads7828_driver);
}
static void __exit sensors_ads7828_exit(void)
{
i2c_del_driver(&ads7828_driver);
}
MODULE_AUTHOR("Steve Hardy <steve@linuxrealtime.co.uk>");
MODULE_DESCRIPTION("ADS7828 driver");
MODULE_LICENSE("GPL");
module_init(sensors_ads7828_init);
module_exit(sensors_ads7828_exit);
