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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/* ------------------------------------------------------------------------ *
2 * i2c-parport.c I2C bus over parallel port *
3 * ------------------------------------------------------------------------ *
4 Copyright (C) 2003-2004 Jean Delvare <khali@linux-fr.org>
5
6 Based on older i2c-velleman.c driver
7 Copyright (C) 1995-2000 Simon G. Vogl
8 With some changes from:
9 Frodo Looijaard <frodol@dds.nl>
10 Kyösti Mälkki <kmalkki@cc.hut.fi>
11
12 This program is free software; you can redistribute it and/or modify
13 it under the terms of the GNU General Public License as published by
14 the Free Software Foundation; either version 2 of the License, or
15 (at your option) any later version.
16
17 This program is distributed in the hope that it will be useful,
18 but WITHOUT ANY WARRANTY; without even the implied warranty of
19 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 GNU General Public License for more details.
21
22 You should have received a copy of the GNU General Public License
23 along with this program; if not, write to the Free Software
24 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
25 * ------------------------------------------------------------------------ */
26
27#include <linux/config.h>
28#include <linux/kernel.h>
29#include <linux/module.h>
30#include <linux/init.h>
31#include <linux/ioport.h>
32#include <linux/i2c.h>
33#include <linux/i2c-algo-bit.h>
34#include <asm/io.h>
35#include "i2c-parport.h"
36
37#define DEFAULT_BASE 0x378
38
39static u16 base;
40module_param(base, ushort, 0);
41MODULE_PARM_DESC(base, "Base I/O address");
42
43/* ----- Low-level parallel port access ----------------------------------- */
44
45static inline void port_write(unsigned char p, unsigned char d)
46{
47 outb(d, base+p);
48}
49
50static inline unsigned char port_read(unsigned char p)
51{
52 return inb(base+p);
53}
54
55/* ----- Unified line operation functions --------------------------------- */
56
57static inline void line_set(int state, const struct lineop *op)
58{
59 u8 oldval = port_read(op->port);
60
61 /* Touch only the bit(s) needed */
62 if ((op->inverted && !state) || (!op->inverted && state))
63 port_write(op->port, oldval | op->val);
64 else
65 port_write(op->port, oldval & ~op->val);
66}
67
68static inline int line_get(const struct lineop *op)
69{
70 u8 oldval = port_read(op->port);
71
72 return ((op->inverted && (oldval & op->val) != op->val)
73 || (!op->inverted && (oldval & op->val) == op->val));
74}
75
76/* ----- I2C algorithm call-back functions and structures ----------------- */
77
78static void parport_setscl(void *data, int state)
79{
80 line_set(state, &adapter_parm[type].setscl);
81}
82
83static void parport_setsda(void *data, int state)
84{
85 line_set(state, &adapter_parm[type].setsda);
86}
87
88static int parport_getscl(void *data)
89{
90 return line_get(&adapter_parm[type].getscl);
91}
92
93static int parport_getsda(void *data)
94{
95 return line_get(&adapter_parm[type].getsda);
96}
97
98/* Encapsulate the functions above in the correct structure
99 Note that getscl will be set to NULL by the attaching code for adapters
100 that cannot read SCL back */
101static struct i2c_algo_bit_data parport_algo_data = {
102 .setsda = parport_setsda,
103 .setscl = parport_setscl,
104 .getsda = parport_getsda,
105 .getscl = parport_getscl,
106 .udelay = 50,
107 .mdelay = 50,
108 .timeout = HZ,
109};
110
111/* ----- I2c structure ---------------------------------------------------- */
112
113static struct i2c_adapter parport_adapter = {
114 .owner = THIS_MODULE,
115 .class = I2C_CLASS_HWMON,
116 .id = I2C_HW_B_LP,
117 .algo_data = &parport_algo_data,
118 .name = "Parallel port adapter (light)",
119};
120
121/* ----- Module loading, unloading and information ------------------------ */
122
123static int __init i2c_parport_init(void)
124{
125 int type_count;
126
127 type_count = sizeof(adapter_parm)/sizeof(struct adapter_parm);
128 if (type < 0 || type >= type_count) {
129 printk(KERN_WARNING "i2c-parport: invalid type (%d)\n", type);
130 type = 0;
131 }
132
133 if (base == 0) {
134 printk(KERN_INFO "i2c-parport: using default base 0x%x\n", DEFAULT_BASE);
135 base = DEFAULT_BASE;
136 }
137
138 if (!request_region(base, 3, "i2c-parport"))
139 return -ENODEV;
140
141 if (!adapter_parm[type].getscl.val)
142 parport_algo_data.getscl = NULL;
143
144 /* Reset hardware to a sane state (SCL and SDA high) */
145 parport_setsda(NULL, 1);
146 parport_setscl(NULL, 1);
147 /* Other init if needed (power on...) */
148 if (adapter_parm[type].init.val)
149 line_set(1, &adapter_parm[type].init);
150
151 if (i2c_bit_add_bus(&parport_adapter) < 0) {
152 printk(KERN_ERR "i2c-parport: Unable to register with I2C\n");
153 release_region(base, 3);
154 return -ENODEV;
155 }
156
157 return 0;
158}
159
160static void __exit i2c_parport_exit(void)
161{
162 /* Un-init if needed (power off...) */
163 if (adapter_parm[type].init.val)
164 line_set(0, &adapter_parm[type].init);
165
166 i2c_bit_del_bus(&parport_adapter);
167 release_region(base, 3);
168}
169
170MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>");
171MODULE_DESCRIPTION("I2C bus over parallel port (light)");
172MODULE_LICENSE("GPL");
173
174module_init(i2c_parport_init);
175module_exit(i2c_parport_exit);