aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/i2c/busses/i2c-parport-light.c
blob: 322c5691e38eb72072c8135f8036dd35e991d958 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
/* ------------------------------------------------------------------------ *
 * i2c-parport-light.c I2C bus over parallel port                           *
 * ------------------------------------------------------------------------ *
   Copyright (C) 2003-2007 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/platform_device.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
#define DRVNAME "i2c-parport-light"

static struct platform_device *pdev;

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,
}; 

/* ----- Driver registration ---------------------------------------------- */

static struct i2c_adapter parport_adapter = {
	.owner		= THIS_MODULE,
	.class		= I2C_CLASS_HWMON,
	.algo_data	= &parport_algo_data,
	.name		= "Parallel port adapter (light)",
};

static int __devinit i2c_parport_probe(struct platform_device *pdev)
{
	int err;

	/* 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);

	parport_adapter.dev.parent = &pdev->dev;
	err = i2c_bit_add_bus(&parport_adapter);
	if (err)
		dev_err(&pdev->dev, "Unable to register with I2C\n");
	return err;
}

static int __devexit i2c_parport_remove(struct platform_device *pdev)
{
	i2c_del_adapter(&parport_adapter);

	/* Un-init if needed (power off...) */
	if (adapter_parm[type].init.val)
		line_set(0, &adapter_parm[type].init);

	return 0;
}

static struct platform_driver i2c_parport_driver = {
	.driver = {
		.owner	= THIS_MODULE,
		.name	= DRVNAME,
	},
	.probe		= i2c_parport_probe,
	.remove		= __devexit_p(i2c_parport_remove),
};

static int __init i2c_parport_device_add(u16 address)
{
	int err;

	pdev = platform_device_alloc(DRVNAME, -1);
	if (!pdev) {
		err = -ENOMEM;
		printk(KERN_ERR DRVNAME ": Device allocation failed\n");
		goto exit;
	}

	err = platform_device_add(pdev);
	if (err) {
		printk(KERN_ERR DRVNAME ": Device addition failed (%d)\n",
		       err);
		goto exit_device_put;
	}

	return 0;

exit_device_put:
	platform_device_put(pdev);
exit:
	return err;
}

static int __init i2c_parport_init(void)
{
	int err;

	if (type < 0) {
		printk(KERN_ERR DRVNAME ": adapter type unspecified\n");
		return -ENODEV;
	}

	if (type >= ARRAY_SIZE(adapter_parm)) {
		printk(KERN_ERR DRVNAME ": invalid type (%d)\n", type);
		return -ENODEV;
	}

	if (base == 0) {
		pr_info(DRVNAME ": using default base 0x%x\n", DEFAULT_BASE);
		base = DEFAULT_BASE;
	}

	if (!request_region(base, 3, DRVNAME))
		return -EBUSY;

        if (!adapter_parm[type].getscl.val)
		parport_algo_data.getscl = NULL;

	/* Sets global pdev as a side effect */
	err = i2c_parport_device_add(base);
	if (err)
		goto exit_release;

	err = platform_driver_register(&i2c_parport_driver);
	if (err)
		goto exit_device;

	return 0;

exit_device:
	platform_device_unregister(pdev);
exit_release:
	release_region(base, 3);
	return err;
}

static void __exit i2c_parport_exit(void)
{
	platform_driver_unregister(&i2c_parport_driver);
	platform_device_unregister(pdev);
	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);

Privacy Policy