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   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/kernel.h>
 28#include <linux/module.h>
 29#include <linux/init.h>
 30#include <linux/delay.h>
 31#include <linux/platform_device.h>
 32#include <linux/ioport.h>
 33#include <linux/i2c.h>
 34#include <linux/i2c-algo-bit.h>
 35#include <linux/i2c-smbus.h>
 36#include <linux/io.h>
 37#include "i2c-parport.h"
 38
 39#define DEFAULT_BASE 0x378
 40#define DRVNAME "i2c-parport-light"
 41
 42static struct platform_device *pdev;
 43
 44static u16 base;
 45module_param(base, ushort, 0);
 46MODULE_PARM_DESC(base, "Base I/O address");
 47
 48static int irq;
 49module_param(irq, int, 0);
 50MODULE_PARM_DESC(irq, "IRQ (optional)");
 51
 52/* ----- Low-level parallel port access ----------------------------------- */
 53
 54static inline void port_write(unsigned char p, unsigned char d)
 55{
 56	outb(d, base+p);
 57}
 58
 59static inline unsigned char port_read(unsigned char p)
 60{
 61	return inb(base+p);
 62}
 63
 64/* ----- Unified line operation functions --------------------------------- */
 65
 66static inline void line_set(int state, const struct lineop *op)
 67{
 68	u8 oldval = port_read(op->port);
 69
 70	/* Touch only the bit(s) needed */
 71	if ((op->inverted && !state) || (!op->inverted && state))
 72		port_write(op->port, oldval | op->val);
 73	else
 74		port_write(op->port, oldval & ~op->val);
 75}
 76
 77static inline int line_get(const struct lineop *op)
 78{
 79	u8 oldval = port_read(op->port);
 80
 81	return ((op->inverted && (oldval & op->val) != op->val)
 82	    || (!op->inverted && (oldval & op->val) == op->val));
 83}
 84
 85/* ----- I2C algorithm call-back functions and structures ----------------- */
 86
 87static void parport_setscl(void *data, int state)
 88{
 89	line_set(state, &adapter_parm[type].setscl);
 90}
 91
 92static void parport_setsda(void *data, int state)
 93{
 94	line_set(state, &adapter_parm[type].setsda);
 95}
 96
 97static int parport_getscl(void *data)
 98{
 99	return line_get(&adapter_parm[type].getscl);
100}
101
102static int parport_getsda(void *data)
103{
104	return line_get(&adapter_parm[type].getsda);
105}
106
107/* Encapsulate the functions above in the correct structure
108   Note that getscl will be set to NULL by the attaching code for adapters
109   that cannot read SCL back */
110static struct i2c_algo_bit_data parport_algo_data = {
111	.setsda		= parport_setsda,
112	.setscl		= parport_setscl,
113	.getsda		= parport_getsda,
114	.getscl		= parport_getscl,
115	.udelay		= 50,
116	.timeout	= HZ,
117};
118
119/* ----- Driver registration ---------------------------------------------- */
120
121static struct i2c_adapter parport_adapter = {
122	.owner		= THIS_MODULE,
123	.class		= I2C_CLASS_HWMON,
124	.algo_data	= &parport_algo_data,
125	.name		= "Parallel port adapter (light)",
126};
127
128/* SMBus alert support */
129static struct i2c_smbus_alert_setup alert_data = {
130	.alert_edge_triggered	= 1,
131};
132static struct i2c_client *ara;
133static struct lineop parport_ctrl_irq = {
134	.val		= (1 << 4),
135	.port		= PORT_CTRL,
136};
137
138static int i2c_parport_probe(struct platform_device *pdev)
139{
140	int err;
141
142	/* Reset hardware to a sane state (SCL and SDA high) */
143	parport_setsda(NULL, 1);
144	parport_setscl(NULL, 1);
145	/* Other init if needed (power on...) */
146	if (adapter_parm[type].init.val) {
147		line_set(1, &adapter_parm[type].init);
148		/* Give powered devices some time to settle */
149		msleep(100);
150	}
151
152	parport_adapter.dev.parent = &pdev->dev;
153	err = i2c_bit_add_bus(&parport_adapter);
154	if (err) {
155		dev_err(&pdev->dev, "Unable to register with I2C\n");
156		return err;
157	}
158
159	/* Setup SMBus alert if supported */
160	if (adapter_parm[type].smbus_alert && irq) {
161		alert_data.irq = irq;
162		ara = i2c_setup_smbus_alert(&parport_adapter, &alert_data);
163		if (ara)
164			line_set(1, &parport_ctrl_irq);
165		else
166			dev_warn(&pdev->dev, "Failed to register ARA client\n");
167	}
168
169	return 0;
170}
171
172static int i2c_parport_remove(struct platform_device *pdev)
173{
174	if (ara) {
175		line_set(0, &parport_ctrl_irq);
176		i2c_unregister_device(ara);
177		ara = NULL;
178	}
179	i2c_del_adapter(&parport_adapter);
180
181	/* Un-init if needed (power off...) */
182	if (adapter_parm[type].init.val)
183		line_set(0, &adapter_parm[type].init);
184
185	return 0;
186}
187
188static struct platform_driver i2c_parport_driver = {
189	.driver = {
190		.owner	= THIS_MODULE,
191		.name	= DRVNAME,
192	},
193	.probe		= i2c_parport_probe,
194	.remove		= i2c_parport_remove,
195};
196
197static int __init i2c_parport_device_add(u16 address)
198{
199	int err;
200
201	pdev = platform_device_alloc(DRVNAME, -1);
202	if (!pdev) {
203		err = -ENOMEM;
204		printk(KERN_ERR DRVNAME ": Device allocation failed\n");
205		goto exit;
206	}
207
208	err = platform_device_add(pdev);
209	if (err) {
210		printk(KERN_ERR DRVNAME ": Device addition failed (%d)\n",
211		       err);
212		goto exit_device_put;
213	}
214
215	return 0;
216
217exit_device_put:
218	platform_device_put(pdev);
219exit:
220	return err;
221}
222
223static int __init i2c_parport_init(void)
224{
225	int err;
226
227	if (type < 0) {
228		printk(KERN_ERR DRVNAME ": adapter type unspecified\n");
229		return -ENODEV;
230	}
231
232	if (type >= ARRAY_SIZE(adapter_parm)) {
233		printk(KERN_ERR DRVNAME ": invalid type (%d)\n", type);
234		return -ENODEV;
235	}
236
237	if (base == 0) {
238		pr_info(DRVNAME ": using default base 0x%x\n", DEFAULT_BASE);
239		base = DEFAULT_BASE;
240	}
241
242	if (!request_region(base, 3, DRVNAME))
243		return -EBUSY;
244
245	if (irq != 0)
246		pr_info(DRVNAME ": using irq %d\n", irq);
247
248	if (!adapter_parm[type].getscl.val)
249		parport_algo_data.getscl = NULL;
250
251	/* Sets global pdev as a side effect */
252	err = i2c_parport_device_add(base);
253	if (err)
254		goto exit_release;
255
256	err = platform_driver_register(&i2c_parport_driver);
257	if (err)
258		goto exit_device;
259
260	return 0;
261
262exit_device:
263	platform_device_unregister(pdev);
264exit_release:
265	release_region(base, 3);
266	return err;
267}
268
269static void __exit i2c_parport_exit(void)
270{
271	platform_driver_unregister(&i2c_parport_driver);
272	platform_device_unregister(pdev);
273	release_region(base, 3);
274}
275
276MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>");
277MODULE_DESCRIPTION("I2C bus over parallel port (light)");
278MODULE_LICENSE("GPL");
279
280module_init(i2c_parport_init);
281module_exit(i2c_parport_exit);