268 lines
7.2 KiB
C
268 lines
7.2 KiB
C
/* ------------------------------------------------------------------------ *
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* i2c-parport.c I2C bus over parallel port *
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* ------------------------------------------------------------------------ *
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Copyright (C) 2003-2004 Jean Delvare <khali@linux-fr.org>
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Based on older i2c-philips-par.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/parport.h>
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#include <linux/i2c.h>
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#include <linux/i2c-algo-bit.h>
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#include "i2c-parport.h"
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/* ----- Device list ------------------------------------------------------ */
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struct i2c_par {
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struct pardevice *pdev;
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struct i2c_adapter adapter;
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struct i2c_algo_bit_data algo_data;
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struct i2c_par *next;
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};
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static struct i2c_par *adapter_list;
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/* ----- Low-level parallel port access ----------------------------------- */
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static void port_write_data(struct parport *p, unsigned char d)
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{
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parport_write_data(p, d);
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}
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static void port_write_control(struct parport *p, unsigned char d)
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{
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parport_write_control(p, d);
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}
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static unsigned char port_read_data(struct parport *p)
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{
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return parport_read_data(p);
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}
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static unsigned char port_read_status(struct parport *p)
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{
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return parport_read_status(p);
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}
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static unsigned char port_read_control(struct parport *p)
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{
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return parport_read_control(p);
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}
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static void (*port_write[])(struct parport *, unsigned char) = {
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port_write_data,
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NULL,
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port_write_control,
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};
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static unsigned char (*port_read[])(struct parport *) = {
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port_read_data,
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port_read_status,
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port_read_control,
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};
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/* ----- Unified line operation functions --------------------------------- */
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static inline void line_set(struct parport *data, int state,
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const struct lineop *op)
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{
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u8 oldval = port_read[op->port](data);
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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](data, oldval | op->val);
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else
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port_write[op->port](data, oldval & ~op->val);
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}
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static inline int line_get(struct parport *data,
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const struct lineop *op)
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{
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u8 oldval = port_read[op->port](data);
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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((struct parport *) data, 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((struct parport *) data, 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((struct parport *) data, &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((struct parport *) data, &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 this is only a template, from which the real structures are
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copied. The attaching code will set getscl to NULL for adapters that
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cannot read SCL back, and will also make the data field point to
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the parallel port structure. */
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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 = 60,
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.mdelay = 60,
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.timeout = HZ,
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};
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/* ----- I2c and parallel port call-back functions and structures --------- */
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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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.name = "Parallel port adapter",
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};
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static void i2c_parport_attach (struct parport *port)
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{
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struct i2c_par *adapter;
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adapter = kzalloc(sizeof(struct i2c_par), GFP_KERNEL);
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if (adapter == NULL) {
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printk(KERN_ERR "i2c-parport: Failed to kzalloc\n");
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return;
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}
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pr_debug("i2c-parport: attaching to %s\n", port->name);
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adapter->pdev = parport_register_device(port, "i2c-parport",
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NULL, NULL, NULL, PARPORT_FLAG_EXCL, NULL);
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if (!adapter->pdev) {
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printk(KERN_ERR "i2c-parport: Unable to register with parport\n");
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goto ERROR0;
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}
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/* Fill the rest of the structure */
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adapter->adapter = parport_adapter;
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adapter->algo_data = parport_algo_data;
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if (!adapter_parm[type].getscl.val)
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adapter->algo_data.getscl = NULL;
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adapter->algo_data.data = port;
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adapter->adapter.algo_data = &adapter->algo_data;
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if (parport_claim_or_block(adapter->pdev) < 0) {
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printk(KERN_ERR "i2c-parport: Could not claim parallel port\n");
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goto ERROR1;
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}
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/* Reset hardware to a sane state (SCL and SDA high) */
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parport_setsda(port, 1);
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parport_setscl(port, 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(port, 1, &adapter_parm[type].init);
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parport_release(adapter->pdev);
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if (i2c_bit_add_bus(&adapter->adapter) < 0) {
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printk(KERN_ERR "i2c-parport: Unable to register with I2C\n");
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goto ERROR1;
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}
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/* Add the new adapter to the list */
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adapter->next = adapter_list;
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adapter_list = adapter;
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return;
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ERROR1:
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parport_unregister_device(adapter->pdev);
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ERROR0:
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kfree(adapter);
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}
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static void i2c_parport_detach (struct parport *port)
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{
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struct i2c_par *adapter, *prev;
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/* Walk the list */
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for (prev = NULL, adapter = adapter_list; adapter;
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prev = adapter, adapter = adapter->next) {
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if (adapter->pdev->port == port) {
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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(port, 0, &adapter_parm[type].init);
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i2c_bit_del_bus(&adapter->adapter);
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parport_unregister_device(adapter->pdev);
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if (prev)
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prev->next = adapter->next;
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else
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adapter_list = adapter->next;
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kfree(adapter);
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return;
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}
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}
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}
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static struct parport_driver i2c_parport_driver = {
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.name = "i2c-parport",
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.attach = i2c_parport_attach,
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.detach = i2c_parport_detach,
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};
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/* ----- Module loading, unloading and information ------------------------ */
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static int __init i2c_parport_init(void)
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{
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if (type < 0) {
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printk(KERN_WARNING "i2c-parport: 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_WARNING "i2c-parport: invalid type (%d)\n", type);
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return -ENODEV;
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}
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return parport_register_driver(&i2c_parport_driver);
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}
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static void __exit i2c_parport_exit(void)
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{
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parport_unregister_driver(&i2c_parport_driver);
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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");
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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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