1/* ------------------------------------------------------------------------ *
2 * i2c-parport-light.c I2C bus over parallel port                           *
3 * ------------------------------------------------------------------------ *
4   Copyright (C) 2003-2010 Jean Delvare <jdelvare@suse.de>
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
23#include <linux/kernel.h>
24#include <linux/module.h>
25#include <linux/init.h>
26#include <linux/delay.h>
27#include <linux/platform_device.h>
28#include <linux/ioport.h>
29#include <linux/i2c.h>
30#include <linux/i2c-algo-bit.h>
31#include <linux/i2c-smbus.h>
32#include <linux/io.h>
33#include "i2c-parport.h"
34
35#define DEFAULT_BASE 0x378
36#define DRVNAME "i2c-parport-light"
37
38static struct platform_device *pdev;
39
40static u16 base;
41module_param(base, ushort, 0);
42MODULE_PARM_DESC(base, "Base I/O address");
43
44static int irq;
45module_param(irq, int, 0);
46MODULE_PARM_DESC(irq, "IRQ (optional)");
47
48/* ----- Low-level parallel port access ----------------------------------- */
49
50static inline void port_write(unsigned char p, unsigned char d)
51{
52	outb(d, base+p);
53}
54
55static inline unsigned char port_read(unsigned char p)
56{
57	return inb(base+p);
58}
59
60/* ----- Unified line operation functions --------------------------------- */
61
62static inline void line_set(int state, const struct lineop *op)
63{
64	u8 oldval = port_read(op->port);
65
66	/* Touch only the bit(s) needed */
67	if ((op->inverted && !state) || (!op->inverted && state))
68		port_write(op->port, oldval | op->val);
69	else
70		port_write(op->port, oldval & ~op->val);
71}
72
73static inline int line_get(const struct lineop *op)
74{
75	u8 oldval = port_read(op->port);
76
77	return ((op->inverted && (oldval & op->val) != op->val)
78	    || (!op->inverted && (oldval & op->val) == op->val));
79}
80
81/* ----- I2C algorithm call-back functions and structures ----------------- */
82
83static void parport_setscl(void *data, int state)
84{
85	line_set(state, &adapter_parm[type].setscl);
86}
87
88static void parport_setsda(void *data, int state)
89{
90	line_set(state, &adapter_parm[type].setsda);
91}
92
93static int parport_getscl(void *data)
94{
95	return line_get(&adapter_parm[type].getscl);
96}
97
98static int parport_getsda(void *data)
99{
100	return line_get(&adapter_parm[type].getsda);
101}
102
103/* Encapsulate the functions above in the correct structure
104   Note that getscl will be set to NULL by the attaching code for adapters
105   that cannot read SCL back */
106static struct i2c_algo_bit_data parport_algo_data = {
107	.setsda		= parport_setsda,
108	.setscl		= parport_setscl,
109	.getsda		= parport_getsda,
110	.getscl		= parport_getscl,
111	.udelay		= 50,
112	.timeout	= HZ,
113};
114
115/* ----- Driver registration ---------------------------------------------- */
116
117static struct i2c_adapter parport_adapter = {
118	.owner		= THIS_MODULE,
119	.class		= I2C_CLASS_HWMON,
120	.algo_data	= &parport_algo_data,
121	.name		= "Parallel port adapter (light)",
122};
123
124/* SMBus alert support */
125static struct i2c_smbus_alert_setup alert_data = {
126	.alert_edge_triggered	= 1,
127};
128static struct i2c_client *ara;
129static struct lineop parport_ctrl_irq = {
130	.val		= (1 << 4),
131	.port		= PORT_CTRL,
132};
133
134static int i2c_parport_probe(struct platform_device *pdev)
135{
136	int err;
137
138	/* Reset hardware to a sane state (SCL and SDA high) */
139	parport_setsda(NULL, 1);
140	parport_setscl(NULL, 1);
141	/* Other init if needed (power on...) */
142	if (adapter_parm[type].init.val) {
143		line_set(1, &adapter_parm[type].init);
144		/* Give powered devices some time to settle */
145		msleep(100);
146	}
147
148	parport_adapter.dev.parent = &pdev->dev;
149	err = i2c_bit_add_bus(&parport_adapter);
150	if (err) {
151		dev_err(&pdev->dev, "Unable to register with I2C\n");
152		return err;
153	}
154
155	/* Setup SMBus alert if supported */
156	if (adapter_parm[type].smbus_alert && irq) {
157		alert_data.irq = irq;
158		ara = i2c_setup_smbus_alert(&parport_adapter, &alert_data);
159		if (ara)
160			line_set(1, &parport_ctrl_irq);
161		else
162			dev_warn(&pdev->dev, "Failed to register ARA client\n");
163	}
164
165	return 0;
166}
167
168static int i2c_parport_remove(struct platform_device *pdev)
169{
170	if (ara) {
171		line_set(0, &parport_ctrl_irq);
172		i2c_unregister_device(ara);
173		ara = NULL;
174	}
175	i2c_del_adapter(&parport_adapter);
176
177	/* Un-init if needed (power off...) */
178	if (adapter_parm[type].init.val)
179		line_set(0, &adapter_parm[type].init);
180
181	return 0;
182}
183
184static struct platform_driver i2c_parport_driver = {
185	.driver = {
186		.owner	= THIS_MODULE,
187		.name	= DRVNAME,
188	},
189	.probe		= i2c_parport_probe,
190	.remove		= i2c_parport_remove,
191};
192
193static int __init i2c_parport_device_add(u16 address)
194{
195	int err;
196
197	pdev = platform_device_alloc(DRVNAME, -1);
198	if (!pdev) {
199		err = -ENOMEM;
200		printk(KERN_ERR DRVNAME ": Device allocation failed\n");
201		goto exit;
202	}
203
204	err = platform_device_add(pdev);
205	if (err) {
206		printk(KERN_ERR DRVNAME ": Device addition failed (%d)\n",
207		       err);
208		goto exit_device_put;
209	}
210
211	return 0;
212
213exit_device_put:
214	platform_device_put(pdev);
215exit:
216	return err;
217}
218
219static int __init i2c_parport_init(void)
220{
221	int err;
222
223	if (type < 0) {
224		printk(KERN_ERR DRVNAME ": adapter type unspecified\n");
225		return -ENODEV;
226	}
227
228	if (type >= ARRAY_SIZE(adapter_parm)) {
229		printk(KERN_ERR DRVNAME ": invalid type (%d)\n", type);
230		return -ENODEV;
231	}
232
233	if (base == 0) {
234		pr_info(DRVNAME ": using default base 0x%x\n", DEFAULT_BASE);
235		base = DEFAULT_BASE;
236	}
237
238	if (!request_region(base, 3, DRVNAME))
239		return -EBUSY;
240
241	if (irq != 0)
242		pr_info(DRVNAME ": using irq %d\n", irq);
243
244	if (!adapter_parm[type].getscl.val)
245		parport_algo_data.getscl = NULL;
246
247	/* Sets global pdev as a side effect */
248	err = i2c_parport_device_add(base);
249	if (err)
250		goto exit_release;
251
252	err = platform_driver_register(&i2c_parport_driver);
253	if (err)
254		goto exit_device;
255
256	return 0;
257
258exit_device:
259	platform_device_unregister(pdev);
260exit_release:
261	release_region(base, 3);
262	return err;
263}
264
265static void __exit i2c_parport_exit(void)
266{
267	platform_driver_unregister(&i2c_parport_driver);
268	platform_device_unregister(pdev);
269	release_region(base, 3);
270}
271
272MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>");
273MODULE_DESCRIPTION("I2C bus over parallel port (light)");
274MODULE_LICENSE("GPL");
275
276module_init(i2c_parport_init);
277module_exit(i2c_parport_exit);
278