usbvision-i2c.c revision f2242ee5474f46d87a45cd4e214b5c3aa02ff293 
1/*
2 * I2C_ALGO_USB.C
3 *  i2c algorithm for USB-I2C Bridges
4 *
5 * Copyright (c) 1999-2005 Joerg Heckenbach <joerg@heckenbach-aw.de>
6 *                         Dwaine Garden <dwainegarden@rogers.com>
7 *
8 * This module is part of usbvision driver project.
9 * Updates to driver completed by Dwaine P. Garden
10 *
11 * This program is free software; you can redistribute it and/or modify
12 * it under the terms of the GNU General Public License as published by
13 * the Free Software Foundation; either version 2 of the License, or
14 * (at your option) any later version.
15 *
16 * This program is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
19 * GNU General Public License for more details.
20 *
21 * You should have received a copy of the GNU General Public License
22 * along with this program; if not, write to the Free Software
23 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
24 */
25
26
27#include <linux/kernel.h>
28#include <linux/module.h>
29#include <linux/delay.h>
30#include <linux/slab.h>
31#include <linux/version.h>
32	#include <linux/utsname.h>
33#include <linux/init.h>
34#include <asm/uaccess.h>
35#include <linux/ioport.h>
36#include <linux/errno.h>
37#include <linux/sched.h>
38#include <linux/usb.h>
39#include <linux/i2c.h>
40#include "usbvision-i2c.h"
41
42static int debug_i2c_usb = 0;
43
44#if defined(module_param)                               // Showing parameters under SYSFS
45module_param (debug_i2c_usb, int, 0444);			// debug_i2c_usb mode of the device driver
46#else
47MODULE_PARM(debug_i2c_usb, "i");				// debug_i2c_usb mode of the device driver
48#endif
49
50
51static inline int try_write_address(struct i2c_adapter *i2c_adap,
52				    unsigned char addr, int retries)
53{
54	struct i2c_algo_usb_data *adap = i2c_adap->algo_data;
55	void *data;
56	int i, ret = -1;
57	char buf[4];
58
59	data = i2c_get_adapdata(i2c_adap);
60	buf[0] = 0x00;
61	for (i = 0; i <= retries; i++) {
62		ret = (adap->outb(data, addr, buf, 1));
63		if (ret == 1)
64			break;	/* success! */
65		udelay(5 /*adap->udelay */ );
66		if (i == retries)	/* no success */
67			break;
68		udelay(adap->udelay);
69	}
70	if (debug_i2c_usb) {
71		if (i) {
72			info("%s: Needed %d retries for address %#2x", __FUNCTION__, i, addr);
73			info("%s: Maybe there's no device at this address", __FUNCTION__);
74		}
75	}
76	return ret;
77}
78
79static inline int try_read_address(struct i2c_adapter *i2c_adap,
80				   unsigned char addr, int retries)
81{
82	struct i2c_algo_usb_data *adap = i2c_adap->algo_data;
83	void *data;
84	int i, ret = -1;
85	char buf[4];
86
87	data = i2c_get_adapdata(i2c_adap);
88	for (i = 0; i <= retries; i++) {
89		ret = (adap->inb(data, addr, buf, 1));
90		if (ret == 1)
91			break;	/* success! */
92		udelay(5 /*adap->udelay */ );
93		if (i == retries)	/* no success */
94			break;
95		udelay(adap->udelay);
96	}
97	if (debug_i2c_usb) {
98		if (i) {
99			info("%s: Needed %d retries for address %#2x", __FUNCTION__, i, addr);
100			info("%s: Maybe there's no device at this address", __FUNCTION__);
101		}
102	}
103	return ret;
104}
105
106static inline int usb_find_address(struct i2c_adapter *i2c_adap,
107				   struct i2c_msg *msg, int retries,
108				   unsigned char *add)
109{
110	unsigned short flags = msg->flags;
111
112	unsigned char addr;
113	int ret;
114	if ((flags & I2C_M_TEN)) {
115		/* a ten bit address */
116		addr = 0xf0 | ((msg->addr >> 7) & 0x03);
117		/* try extended address code... */
118		ret = try_write_address(i2c_adap, addr, retries);
119		if (ret != 1) {
120			err("died at extended address code, while writing");
121			return -EREMOTEIO;
122		}
123		add[0] = addr;
124		if (flags & I2C_M_RD) {
125			/* okay, now switch into reading mode */
126			addr |= 0x01;
127			ret = try_read_address(i2c_adap, addr, retries);
128			if (ret != 1) {
129				err("died at extended address code, while reading");
130				return -EREMOTEIO;
131			}
132		}
133
134	} else {		/* normal 7bit address  */
135		addr = (msg->addr << 1);
136		if (flags & I2C_M_RD)
137			addr |= 1;
138		if (flags & I2C_M_REV_DIR_ADDR)
139			addr ^= 1;
140
141		add[0] = addr;
142		if (flags & I2C_M_RD)
143			ret = try_read_address(i2c_adap, addr, retries);
144		else
145			ret = try_write_address(i2c_adap, addr, retries);
146
147		if (ret != 1) {
148			return -EREMOTEIO;
149		}
150	}
151	return 0;
152}
153
154static int
155usb_xfer(struct i2c_adapter *i2c_adap, struct i2c_msg msgs[], int num)
156{
157	struct i2c_msg *pmsg;
158	struct i2c_algo_usb_data *adap = i2c_adap->algo_data;
159	void *data;
160	int i, ret;
161	unsigned char addr;
162
163	data = i2c_get_adapdata(i2c_adap);
164
165	for (i = 0; i < num; i++) {
166		pmsg = &msgs[i];
167		ret = usb_find_address(i2c_adap, pmsg, i2c_adap->retries, &addr);
168		if (ret != 0) {
169			if (debug_i2c_usb) {
170				info("%s: got NAK from device, message #%d\n", __FUNCTION__, i);
171			}
172			return (ret < 0) ? ret : -EREMOTEIO;
173		}
174
175		if (pmsg->flags & I2C_M_RD) {
176			/* read bytes into buffer */
177			ret = (adap->inb(data, addr, pmsg->buf, pmsg->len));
178			if (ret < pmsg->len) {
179				return (ret < 0) ? ret : -EREMOTEIO;
180			}
181		} else {
182			/* write bytes from buffer */
183			ret = (adap->outb(data, addr, pmsg->buf, pmsg->len));
184			if (ret < pmsg->len) {
185				return (ret < 0) ? ret : -EREMOTEIO;
186			}
187		}
188	}
189	return num;
190}
191
192static int algo_control(struct i2c_adapter *adapter, unsigned int cmd, unsigned long arg)
193{
194	return 0;
195}
196
197static u32 usb_func(struct i2c_adapter *adap)
198{
199	return I2C_FUNC_SMBUS_EMUL | I2C_FUNC_10BIT_ADDR | I2C_FUNC_PROTOCOL_MANGLING;
200}
201
202
203/* -----exported algorithm data: -------------------------------------	*/
204
205static struct i2c_algorithm i2c_usb_algo = {
206	.master_xfer   = usb_xfer,
207	.smbus_xfer    = NULL,
208	.algo_control  = algo_control,
209	.functionality = usb_func,
210};
211
212
213/*
214 * registering functions to load algorithms at runtime
215 */
216int usbvision_i2c_usb_add_bus(struct i2c_adapter *adap)
217{
218	/* register new adapter to i2c module... */
219
220	adap->algo = &i2c_usb_algo;
221
222	adap->timeout = 100;	/* default values, should       */
223	adap->retries = 3;	/* be replaced by defines       */
224
225#ifdef MODULE
226	#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 4, 21)
227		MOD_INC_USE_COUNT;
228	#endif
229#endif
230
231	i2c_add_adapter(adap);
232
233	if (debug_i2c_usb) {
234		info("i2c bus for %s registered", adap->name);
235	}
236
237	return 0;
238}
239
240
241int usbvision_i2c_usb_del_bus(struct i2c_adapter *adap)
242{
243
244	i2c_del_adapter(adap);
245
246	if (debug_i2c_usb) {
247		info("i2c bus for %s unregistered", adap->name);
248	}
249#ifdef MODULE
250	#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 4, 21)
251		MOD_DEC_USE_COUNT;
252	#endif
253#endif
254
255	return 0;
256}
257
258EXPORT_SYMBOL(usbvision_i2c_usb_add_bus);
259EXPORT_SYMBOL(usbvision_i2c_usb_del_bus);
260