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		.name	= DRVNAME,
187	},
188	.probe		= i2c_parport_probe,
189	.remove		= i2c_parport_remove,
190};
191
192static int __init i2c_parport_device_add(u16 address)
193{
194	int err;
195
196	pdev = platform_device_alloc(DRVNAME, -1);
197	if (!pdev) {
198		err = -ENOMEM;
199		printk(KERN_ERR DRVNAME ": Device allocation failed\n");
200		goto exit;
201	}
202
203	err = platform_device_add(pdev);
204	if (err) {
205		printk(KERN_ERR DRVNAME ": Device addition failed (%d)\n",
206		       err);
207		goto exit_device_put;
208	}
209
210	return 0;
211
212exit_device_put:
213	platform_device_put(pdev);
214exit:
215	return err;
216}
217
218static int __init i2c_parport_init(void)
219{
220	int err;
221
222	if (type < 0) {
223		printk(KERN_ERR DRVNAME ": adapter type unspecified\n");
224		return -ENODEV;
225	}
226
227	if (type >= ARRAY_SIZE(adapter_parm)) {
228		printk(KERN_ERR DRVNAME ": invalid type (%d)\n", type);
229		return -ENODEV;
230	}
231
232	if (base == 0) {
233		pr_info(DRVNAME ": using default base 0x%x\n", DEFAULT_BASE);
234		base = DEFAULT_BASE;
235	}
236
237	if (!request_region(base, 3, DRVNAME))
238		return -EBUSY;
239
240	if (irq != 0)
241		pr_info(DRVNAME ": using irq %d\n", irq);
242
243	if (!adapter_parm[type].getscl.val)
244		parport_algo_data.getscl = NULL;
245
246	/* Sets global pdev as a side effect */
247	err = i2c_parport_device_add(base);
248	if (err)
249		goto exit_release;
250
251	err = platform_driver_register(&i2c_parport_driver);
252	if (err)
253		goto exit_device;
254
255	return 0;
256
257exit_device:
258	platform_device_unregister(pdev);
259exit_release:
260	release_region(base, 3);
261	return err;
262}
263
264static void __exit i2c_parport_exit(void)
265{
266	platform_driver_unregister(&i2c_parport_driver);
267	platform_device_unregister(pdev);
268	release_region(base, 3);
269}
270
271MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>");
272MODULE_DESCRIPTION("I2C bus over parallel port (light)");
273MODULE_LICENSE("GPL");
274
275module_init(i2c_parport_init);
276module_exit(i2c_parport_exit);
277