227 lines
7.0 KiB
C
227 lines
7.0 KiB
C
/*
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* ads7828.c - driver for TI ADS7828 8-channel A/D converter and compatibles
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* (C) 2007 EADS Astrium
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*
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* This driver is based on the lm75 and other lm_sensors/hwmon drivers
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*
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* Written by Steve Hardy <shardy@redhat.com>
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*
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* ADS7830 support, by Guillaume Roguez <guillaume.roguez@savoirfairelinux.com>
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*
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* For further information, see the Documentation/hwmon/ads7828 file.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include <linux/err.h>
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#include <linux/hwmon.h>
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#include <linux/hwmon-sysfs.h>
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#include <linux/i2c.h>
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#include <linux/init.h>
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#include <linux/jiffies.h>
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#include <linux/module.h>
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#include <linux/mutex.h>
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#include <linux/platform_data/ads7828.h>
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#include <linux/slab.h>
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/* The ADS7828 registers */
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#define ADS7828_NCH 8 /* 8 channels supported */
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#define ADS7828_CMD_SD_SE 0x80 /* Single ended inputs */
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#define ADS7828_CMD_PD1 0x04 /* Internal vref OFF && A/D ON */
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#define ADS7828_CMD_PD3 0x0C /* Internal vref ON && A/D ON */
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#define ADS7828_INT_VREF_MV 2500 /* Internal vref is 2.5V, 2500mV */
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#define ADS7828_EXT_VREF_MV_MIN 50 /* External vref min value 0.05V */
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#define ADS7828_EXT_VREF_MV_MAX 5250 /* External vref max value 5.25V */
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/* List of supported devices */
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enum ads7828_chips { ads7828, ads7830 };
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/* Client specific data */
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struct ads7828_data {
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struct device *hwmon_dev;
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struct mutex update_lock; /* Mutex protecting updates */
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unsigned long last_updated; /* Last updated time (in jiffies) */
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u16 adc_input[ADS7828_NCH]; /* ADS7828_NCH samples */
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bool valid; /* Validity flag */
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bool diff_input; /* Differential input */
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bool ext_vref; /* External voltage reference */
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unsigned int vref_mv; /* voltage reference value */
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u8 cmd_byte; /* Command byte without channel bits */
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unsigned int lsb_resol; /* Resolution of the ADC sample LSB */
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s32 (*read_channel)(const struct i2c_client *client, u8 command);
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};
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/* Command byte C2,C1,C0 - see datasheet */
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static inline u8 ads7828_cmd_byte(u8 cmd, int ch)
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{
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return cmd | (((ch >> 1) | (ch & 0x01) << 2) << 4);
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}
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/* Update data for the device (all 8 channels) */
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static struct ads7828_data *ads7828_update_device(struct device *dev)
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{
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struct i2c_client *client = to_i2c_client(dev);
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struct ads7828_data *data = i2c_get_clientdata(client);
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mutex_lock(&data->update_lock);
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if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
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|| !data->valid) {
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unsigned int ch;
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dev_dbg(&client->dev, "Starting ads7828 update\n");
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for (ch = 0; ch < ADS7828_NCH; ch++) {
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u8 cmd = ads7828_cmd_byte(data->cmd_byte, ch);
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data->adc_input[ch] = data->read_channel(client, cmd);
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}
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data->last_updated = jiffies;
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data->valid = true;
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}
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mutex_unlock(&data->update_lock);
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return data;
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}
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/* sysfs callback function */
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static ssize_t ads7828_show_in(struct device *dev, struct device_attribute *da,
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char *buf)
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{
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struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
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struct ads7828_data *data = ads7828_update_device(dev);
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unsigned int value = DIV_ROUND_CLOSEST(data->adc_input[attr->index] *
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data->lsb_resol, 1000);
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return sprintf(buf, "%d\n", value);
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}
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static SENSOR_DEVICE_ATTR(in0_input, S_IRUGO, ads7828_show_in, NULL, 0);
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static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, ads7828_show_in, NULL, 1);
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static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, ads7828_show_in, NULL, 2);
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static SENSOR_DEVICE_ATTR(in3_input, S_IRUGO, ads7828_show_in, NULL, 3);
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static SENSOR_DEVICE_ATTR(in4_input, S_IRUGO, ads7828_show_in, NULL, 4);
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static SENSOR_DEVICE_ATTR(in5_input, S_IRUGO, ads7828_show_in, NULL, 5);
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static SENSOR_DEVICE_ATTR(in6_input, S_IRUGO, ads7828_show_in, NULL, 6);
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static SENSOR_DEVICE_ATTR(in7_input, S_IRUGO, ads7828_show_in, NULL, 7);
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static struct attribute *ads7828_attributes[] = {
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&sensor_dev_attr_in0_input.dev_attr.attr,
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&sensor_dev_attr_in1_input.dev_attr.attr,
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&sensor_dev_attr_in2_input.dev_attr.attr,
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&sensor_dev_attr_in3_input.dev_attr.attr,
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&sensor_dev_attr_in4_input.dev_attr.attr,
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&sensor_dev_attr_in5_input.dev_attr.attr,
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&sensor_dev_attr_in6_input.dev_attr.attr,
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&sensor_dev_attr_in7_input.dev_attr.attr,
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NULL
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};
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static const struct attribute_group ads7828_group = {
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.attrs = ads7828_attributes,
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};
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static int ads7828_remove(struct i2c_client *client)
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{
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struct ads7828_data *data = i2c_get_clientdata(client);
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hwmon_device_unregister(data->hwmon_dev);
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sysfs_remove_group(&client->dev.kobj, &ads7828_group);
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return 0;
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}
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static int ads7828_probe(struct i2c_client *client,
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const struct i2c_device_id *id)
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{
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struct ads7828_platform_data *pdata = client->dev.platform_data;
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struct ads7828_data *data;
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int err;
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data = devm_kzalloc(&client->dev, sizeof(struct ads7828_data),
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GFP_KERNEL);
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if (!data)
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return -ENOMEM;
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if (pdata) {
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data->diff_input = pdata->diff_input;
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data->ext_vref = pdata->ext_vref;
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if (data->ext_vref)
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data->vref_mv = pdata->vref_mv;
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}
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/* Bound Vref with min/max values if it was provided */
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if (data->vref_mv)
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data->vref_mv = clamp_val(data->vref_mv,
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ADS7828_EXT_VREF_MV_MIN,
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ADS7828_EXT_VREF_MV_MAX);
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else
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data->vref_mv = ADS7828_INT_VREF_MV;
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/* ADS7828 uses 12-bit samples, while ADS7830 is 8-bit */
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if (id->driver_data == ads7828) {
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data->lsb_resol = DIV_ROUND_CLOSEST(data->vref_mv * 1000, 4096);
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data->read_channel = i2c_smbus_read_word_swapped;
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} else {
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data->lsb_resol = DIV_ROUND_CLOSEST(data->vref_mv * 1000, 256);
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data->read_channel = i2c_smbus_read_byte_data;
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}
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data->cmd_byte = data->ext_vref ? ADS7828_CMD_PD1 : ADS7828_CMD_PD3;
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if (!data->diff_input)
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data->cmd_byte |= ADS7828_CMD_SD_SE;
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i2c_set_clientdata(client, data);
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mutex_init(&data->update_lock);
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err = sysfs_create_group(&client->dev.kobj, &ads7828_group);
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if (err)
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return err;
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data->hwmon_dev = hwmon_device_register(&client->dev);
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if (IS_ERR(data->hwmon_dev)) {
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err = PTR_ERR(data->hwmon_dev);
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goto error;
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}
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return 0;
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error:
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sysfs_remove_group(&client->dev.kobj, &ads7828_group);
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return err;
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}
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static const struct i2c_device_id ads7828_device_ids[] = {
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{ "ads7828", ads7828 },
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{ "ads7830", ads7830 },
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{ }
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};
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MODULE_DEVICE_TABLE(i2c, ads7828_device_ids);
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static struct i2c_driver ads7828_driver = {
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.driver = {
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.name = "ads7828",
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},
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.id_table = ads7828_device_ids,
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.probe = ads7828_probe,
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.remove = ads7828_remove,
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};
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module_i2c_driver(ads7828_driver);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Steve Hardy <shardy@redhat.com>");
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MODULE_DESCRIPTION("Driver for TI ADS7828 A/D converter and compatibles");
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