177 строки
4.9 KiB
C
177 строки
4.9 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-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/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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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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.mdelay = 50,
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.timeout = HZ,
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};
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/* ----- I2c structure ---------------------------------------------------- */
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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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/* ----- 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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if (base == 0) {
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printk(KERN_INFO "i2c-parport: 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, "i2c-parport"))
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return -ENODEV;
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if (!adapter_parm[type].getscl.val)
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parport_algo_data.getscl = NULL;
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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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if (i2c_bit_add_bus(&parport_adapter) < 0) {
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printk(KERN_ERR "i2c-parport: Unable to register with I2C\n");
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release_region(base, 3);
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return -ENODEV;
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}
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return 0;
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}
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static void __exit i2c_parport_exit(void)
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{
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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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i2c_bit_del_bus(&parport_adapter);
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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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