236 lines
6.2 KiB
C
236 lines
6.2 KiB
C
/*
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pcf8574.c - Part of lm_sensors, Linux kernel modules for hardware
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monitoring
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Copyright (c) 2000 Frodo Looijaard <frodol@dds.nl>,
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Philip Edelbrock <phil@netroedge.com>,
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Dan Eaton <dan.eaton@rocketlogix.com>
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Ported to Linux 2.6 by Aurelien Jarno <aurel32@debian.org> with
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the help of Jean Delvare <khali@linux-fr.org>
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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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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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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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/* A few notes about the PCF8574:
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* The PCF8574 is an 8-bit I/O expander for the I2C bus produced by
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Philips Semiconductors. It is designed to provide a byte I2C
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interface to up to 8 separate devices.
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* The PCF8574 appears as a very simple SMBus device which can be
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read from or written to with SMBUS byte read/write accesses.
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--Dan
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*/
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/slab.h>
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#include <linux/i2c.h>
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/* Addresses to scan */
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static const unsigned short normal_i2c[] = {
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0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,
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0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,
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I2C_CLIENT_END
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};
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/* Insmod parameters */
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I2C_CLIENT_INSMOD_2(pcf8574, pcf8574a);
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/* Each client has this additional data */
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struct pcf8574_data {
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struct i2c_client client;
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int write; /* Remember last written value */
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};
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static int pcf8574_attach_adapter(struct i2c_adapter *adapter);
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static int pcf8574_detect(struct i2c_adapter *adapter, int address, int kind);
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static int pcf8574_detach_client(struct i2c_client *client);
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static void pcf8574_init_client(struct i2c_client *client);
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/* This is the driver that will be inserted */
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static struct i2c_driver pcf8574_driver = {
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.driver = {
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.name = "pcf8574",
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},
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.id = I2C_DRIVERID_PCF8574,
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.attach_adapter = pcf8574_attach_adapter,
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.detach_client = pcf8574_detach_client,
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};
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/* following are the sysfs callback functions */
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static ssize_t show_read(struct device *dev, struct device_attribute *attr, char *buf)
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{
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struct i2c_client *client = to_i2c_client(dev);
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return sprintf(buf, "%u\n", i2c_smbus_read_byte(client));
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}
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static DEVICE_ATTR(read, S_IRUGO, show_read, NULL);
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static ssize_t show_write(struct device *dev, struct device_attribute *attr, char *buf)
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{
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struct pcf8574_data *data = i2c_get_clientdata(to_i2c_client(dev));
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if (data->write < 0)
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return data->write;
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return sprintf(buf, "%d\n", data->write);
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}
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static ssize_t set_write(struct device *dev, struct device_attribute *attr, const char *buf,
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size_t count)
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{
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struct i2c_client *client = to_i2c_client(dev);
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struct pcf8574_data *data = i2c_get_clientdata(client);
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unsigned long val = simple_strtoul(buf, NULL, 10);
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if (val > 0xff)
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return -EINVAL;
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data->write = val;
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i2c_smbus_write_byte(client, data->write);
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return count;
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}
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static DEVICE_ATTR(write, S_IWUSR | S_IRUGO, show_write, set_write);
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static struct attribute *pcf8574_attributes[] = {
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&dev_attr_read.attr,
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&dev_attr_write.attr,
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NULL
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};
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static const struct attribute_group pcf8574_attr_group = {
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.attrs = pcf8574_attributes,
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};
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/*
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* Real code
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*/
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static int pcf8574_attach_adapter(struct i2c_adapter *adapter)
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{
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return i2c_probe(adapter, &addr_data, pcf8574_detect);
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}
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/* This function is called by i2c_probe */
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static int pcf8574_detect(struct i2c_adapter *adapter, int address, int kind)
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{
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struct i2c_client *new_client;
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struct pcf8574_data *data;
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int err = 0;
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const char *client_name = "";
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if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE))
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goto exit;
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/* OK. For now, we presume we have a valid client. We now create the
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client structure, even though we cannot fill it completely yet. */
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if (!(data = kzalloc(sizeof(struct pcf8574_data), GFP_KERNEL))) {
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err = -ENOMEM;
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goto exit;
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}
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new_client = &data->client;
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i2c_set_clientdata(new_client, data);
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new_client->addr = address;
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new_client->adapter = adapter;
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new_client->driver = &pcf8574_driver;
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new_client->flags = 0;
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/* Now, we would do the remaining detection. But the PCF8574 is plainly
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impossible to detect! Stupid chip. */
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/* Determine the chip type */
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if (kind <= 0) {
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if (address >= 0x38 && address <= 0x3f)
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kind = pcf8574a;
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else
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kind = pcf8574;
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}
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if (kind == pcf8574a)
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client_name = "pcf8574a";
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else
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client_name = "pcf8574";
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/* Fill in the remaining client fields and put it into the global list */
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strlcpy(new_client->name, client_name, I2C_NAME_SIZE);
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/* Tell the I2C layer a new client has arrived */
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if ((err = i2c_attach_client(new_client)))
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goto exit_free;
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/* Initialize the PCF8574 chip */
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pcf8574_init_client(new_client);
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/* Register sysfs hooks */
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err = sysfs_create_group(&new_client->dev.kobj, &pcf8574_attr_group);
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if (err)
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goto exit_detach;
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return 0;
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exit_detach:
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i2c_detach_client(new_client);
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exit_free:
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kfree(data);
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exit:
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return err;
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}
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static int pcf8574_detach_client(struct i2c_client *client)
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{
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int err;
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sysfs_remove_group(&client->dev.kobj, &pcf8574_attr_group);
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if ((err = i2c_detach_client(client)))
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return err;
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kfree(i2c_get_clientdata(client));
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return 0;
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}
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/* Called when we have found a new PCF8574. */
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static void pcf8574_init_client(struct i2c_client *client)
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{
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struct pcf8574_data *data = i2c_get_clientdata(client);
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data->write = -EAGAIN;
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}
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static int __init pcf8574_init(void)
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{
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return i2c_add_driver(&pcf8574_driver);
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}
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static void __exit pcf8574_exit(void)
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{
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i2c_del_driver(&pcf8574_driver);
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}
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MODULE_AUTHOR
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("Frodo Looijaard <frodol@dds.nl>, "
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"Philip Edelbrock <phil@netroedge.com>, "
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"Dan Eaton <dan.eaton@rocketlogix.com> "
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"and Aurelien Jarno <aurelien@aurel32.net>");
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MODULE_DESCRIPTION("PCF8574 driver");
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MODULE_LICENSE("GPL");
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module_init(pcf8574_init);
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module_exit(pcf8574_exit);
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