/* ------------------------------------------------------------------------ *
* i2c-parport.c I2C bus over parallel port *
* ------------------------------------------------------------------------ *
Copyright (C) 2003-2004 Jean Delvare <khali@linux-fr.org>
Based on older i2c-velleman.c driver
Copyright (C) 1995-2000 Simon G. Vogl
With some changes from:
Frodo Looijaard <frodol@dds.nl>
Kyösti Mälkki <kmalkki@cc.hut.fi>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
* ------------------------------------------------------------------------ */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/ioport.h>
#include <linux/i2c.h>
#include <linux/i2c-algo-bit.h>
#include <asm/io.h>
#include "i2c-parport.h"
#define DEFAULT_BASE 0x378
static u16 base;
module_param(base, ushort, 0);
MODULE_PARM_DESC(base, "Base I/O address");
/* ----- Low-level parallel port access ----------------------------------- */
static inline void port_write(unsigned char p, unsigned char d)
{
outb(d, base+p);
}
static inline unsigned char port_read(unsigned char p)
{
return inb(base+p);
}
/* ----- Unified line operation functions --------------------------------- */
static inline void line_set(int state, const struct lineop *op)
{
u8 oldval = port_read(op->port);
/* Touch only the bit(s) needed */
if ((op->inverted && !state) || (!op->inverted && state))
port_write(op->port, oldval | op->val);
else
port_write(op->port, oldval & ~op->val);
}
static inline int line_get(const struct lineop *op)
{
u8 oldval = port_read(op->port);
return ((op->inverted && (oldval & op->val) != op->val)
|| (!op->inverted && (oldval & op->val) == op->val));
}
/* ----- I2C algorithm call-back functions and structures ----------------- */
static void parport_setscl(void *data, int state)
{
line_set(state, &adapter_parm[type].setscl);
}
static void parport_setsda(void *data, int state)
{
line_set(state, &adapter_parm[type].setsda);
}
static int parport_getscl(void *data)
{
return line_get(&adapter_parm[type].getscl);
}
static int parport_getsda(void *data)
{
return line_get(&adapter_parm[type].getsda);
}
/* Encapsulate the functions above in the correct structure
Note that getscl will be set to NULL by the attaching code for adapters
that cannot read SCL back */
static struct i2c_algo_bit_data parport_algo_data = {
.setsda = parport_setsda,
.setscl = parport_setscl,
.getsda = parport_getsda,
.getscl = parport_getscl,
.udelay = 50,
.timeout = HZ,
};
/* ----- I2c structure ---------------------------------------------------- */
static struct i2c_adapter parport_adapter = {
.owner = THIS_MODULE,
.class = I2C_CLASS_HWMON,
.id = I2C_HW_B_LP,
.algo_data = &parport_algo_data,
.name = "Parallel port adapter (light)",
};
/* ----- Module loading, unloading and information ------------------------ */
static int __init i2c_parport_init(void)
{
if (type < 0) {
printk(KERN_WARNING "i2c-parport: adapter type unspecified\n");
return -ENODEV;
}
if (type >= ARRAY_SIZE(adapter_parm)) {
printk(KERN_WARNING "i2c-parport: invalid type (%d)\n", type);
return -ENODEV;
}
if (base == 0) {
printk(KERN_INFO "i2c-parport: using default base 0x%x\n", DEFAULT_BASE);
base = DEFAULT_BASE;
}
if (!request_region(base, 3, "i2c-parport"))
return -ENODEV;
if (!adapter_parm[type].getscl.val)
parport_algo_data.getscl = NULL;
/* Reset hardware to a sane state (SCL and SDA high) */
parport_setsda(NULL, 1);
parport_setscl(NULL, 1);
/* Other init if needed (power on...) */
if (adapter_parm[type].init.val)
line_set(1, &adapter_parm[type].init);
if (i2c_bit_add_bus(&parport_adapter) < 0) {
printk(KERN_ERR "i2c-parport: Unable to register with I2C\n");
release_region(base, 3);
return -ENODEV;
}
return 0;
}
static void __exit i2c_parport_exit(void)
{
/* Un-init if needed (power off...) */
if (adapter_parm[type].init.val)
line_set(0, &adapter_parm[type].init);
i2c_bit_del_bus(&parport_adapter);
release_region(base, 3);
}
MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>");
MODULE_DESCRIPTION("I2C bus over parallel port (light)");
MODULE_LICENSE("GPL");
module_init(i2c_parport_init);
module_exit(i2c_parport_exit);
