9def255631
The i2c-parport-light driver isn't a real platform driver, so it should not instantiate platform devices with resources. The resource management system can't cope with colliding resources, and we are likely to create such a colliding resource. So, better just try to grab the I/O ports we need right at module initialization time, and bail out if we can't. It has the added benefit that the module will no longer load if it isn't going to work, which is definitely more user-friendly. Signed-off-by: Jean Delvare <khali@linux-fr.org>
242 lines
6 KiB
C
242 lines
6 KiB
C
/* ------------------------------------------------------------------------ *
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* i2c-parport-light.c I2C bus over parallel port *
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* ------------------------------------------------------------------------ *
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Copyright (C) 2003-2007 Jean Delvare <khali@linux-fr.org>
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Based on older i2c-velleman.c driver
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Copyright (C) 1995-2000 Simon G. Vogl
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With some changes from:
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Frodo Looijaard <frodol@dds.nl>
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Kyösti Mälkki <kmalkki@cc.hut.fi>
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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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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/platform_device.h>
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#include <linux/ioport.h>
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#include <linux/i2c.h>
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#include <linux/i2c-algo-bit.h>
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#include <asm/io.h>
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#include "i2c-parport.h"
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#define DEFAULT_BASE 0x378
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#define DRVNAME "i2c-parport-light"
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static struct platform_device *pdev;
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static u16 base;
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module_param(base, ushort, 0);
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MODULE_PARM_DESC(base, "Base I/O address");
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/* ----- Low-level parallel port access ----------------------------------- */
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static inline void port_write(unsigned char p, unsigned char d)
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{
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outb(d, base+p);
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}
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static inline unsigned char port_read(unsigned char p)
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{
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return inb(base+p);
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}
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/* ----- Unified line operation functions --------------------------------- */
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static inline void line_set(int state, const struct lineop *op)
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{
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u8 oldval = port_read(op->port);
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/* Touch only the bit(s) needed */
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if ((op->inverted && !state) || (!op->inverted && state))
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port_write(op->port, oldval | op->val);
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else
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port_write(op->port, oldval & ~op->val);
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}
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static inline int line_get(const struct lineop *op)
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{
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u8 oldval = port_read(op->port);
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return ((op->inverted && (oldval & op->val) != op->val)
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|| (!op->inverted && (oldval & op->val) == op->val));
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}
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/* ----- I2C algorithm call-back functions and structures ----------------- */
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static void parport_setscl(void *data, int state)
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{
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line_set(state, &adapter_parm[type].setscl);
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}
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static void parport_setsda(void *data, int state)
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{
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line_set(state, &adapter_parm[type].setsda);
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}
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static int parport_getscl(void *data)
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{
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return line_get(&adapter_parm[type].getscl);
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}
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static int parport_getsda(void *data)
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{
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return line_get(&adapter_parm[type].getsda);
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}
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/* Encapsulate the functions above in the correct structure
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Note that getscl will be set to NULL by the attaching code for adapters
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that cannot read SCL back */
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static struct i2c_algo_bit_data parport_algo_data = {
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.setsda = parport_setsda,
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.setscl = parport_setscl,
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.getsda = parport_getsda,
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.getscl = parport_getscl,
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.udelay = 50,
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.timeout = HZ,
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};
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/* ----- Driver registration ---------------------------------------------- */
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static struct i2c_adapter parport_adapter = {
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.owner = THIS_MODULE,
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.class = I2C_CLASS_HWMON,
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.id = I2C_HW_B_LP,
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.algo_data = &parport_algo_data,
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.name = "Parallel port adapter (light)",
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};
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static int __devinit i2c_parport_probe(struct platform_device *pdev)
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{
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int err;
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/* Reset hardware to a sane state (SCL and SDA high) */
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parport_setsda(NULL, 1);
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parport_setscl(NULL, 1);
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/* Other init if needed (power on...) */
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if (adapter_parm[type].init.val)
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line_set(1, &adapter_parm[type].init);
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parport_adapter.dev.parent = &pdev->dev;
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err = i2c_bit_add_bus(&parport_adapter);
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if (err)
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dev_err(&pdev->dev, "Unable to register with I2C\n");
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return err;
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}
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static int __devexit i2c_parport_remove(struct platform_device *pdev)
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{
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i2c_del_adapter(&parport_adapter);
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/* Un-init if needed (power off...) */
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if (adapter_parm[type].init.val)
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line_set(0, &adapter_parm[type].init);
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return 0;
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}
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static struct platform_driver i2c_parport_driver = {
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.driver = {
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.owner = THIS_MODULE,
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.name = DRVNAME,
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},
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.probe = i2c_parport_probe,
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.remove = __devexit_p(i2c_parport_remove),
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};
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static int __init i2c_parport_device_add(u16 address)
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{
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int err;
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pdev = platform_device_alloc(DRVNAME, -1);
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if (!pdev) {
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err = -ENOMEM;
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printk(KERN_ERR DRVNAME ": Device allocation failed\n");
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goto exit;
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}
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err = platform_device_add(pdev);
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if (err) {
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printk(KERN_ERR DRVNAME ": Device addition failed (%d)\n",
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err);
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goto exit_device_put;
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}
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return 0;
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exit_device_put:
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platform_device_put(pdev);
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exit:
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return err;
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}
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static int __init i2c_parport_init(void)
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{
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int err;
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if (type < 0) {
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printk(KERN_ERR DRVNAME ": adapter type unspecified\n");
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return -ENODEV;
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}
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if (type >= ARRAY_SIZE(adapter_parm)) {
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printk(KERN_ERR DRVNAME ": invalid type (%d)\n", type);
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return -ENODEV;
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}
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if (base == 0) {
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pr_info(DRVNAME ": using default base 0x%x\n", DEFAULT_BASE);
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base = DEFAULT_BASE;
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}
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if (!request_region(base, 3, DRVNAME))
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return -EBUSY;
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if (!adapter_parm[type].getscl.val)
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parport_algo_data.getscl = NULL;
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/* Sets global pdev as a side effect */
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err = i2c_parport_device_add(base);
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if (err)
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goto exit_release;
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err = platform_driver_register(&i2c_parport_driver);
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if (err)
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goto exit_device;
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return 0;
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exit_device:
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platform_device_unregister(pdev);
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exit_release:
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release_region(base, 3);
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return err;
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}
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static void __exit i2c_parport_exit(void)
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{
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platform_driver_unregister(&i2c_parport_driver);
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platform_device_unregister(pdev);
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release_region(base, 3);
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}
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MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>");
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MODULE_DESCRIPTION("I2C bus over parallel port (light)");
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MODULE_LICENSE("GPL");
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module_init(i2c_parport_init);
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module_exit(i2c_parport_exit);
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