1/*
2 * driver for the i2c-tiny-usb adapter - 1.0
3 * http://www.harbaum.org/till/i2c_tiny_usb
4 *
5 * Copyright (C) 2006-2007 Till Harbaum (Till@Harbaum.org)
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License as
9 * published by the Free Software Foundation, version 2.
10 *
11 */
12
13#include <linux/kernel.h>
14#include <linux/errno.h>
15#include <linux/module.h>
16#include <linux/slab.h>
17#include <linux/types.h>
18
19/* include interfaces to usb layer */
20#include <linux/usb.h>
21
22/* include interface to i2c layer */
23#include <linux/i2c.h>
24
25/* commands via USB, must match command ids in the firmware */
26#define CMD_ECHO		0
27#define CMD_GET_FUNC		1
28#define CMD_SET_DELAY		2
29#define CMD_GET_STATUS		3
30
31#define CMD_I2C_IO		4
32#define CMD_I2C_IO_BEGIN	(1<<0)
33#define CMD_I2C_IO_END		(1<<1)
34
35/* i2c bit delay, default is 10us -> 100kHz max
36   (in practice, due to additional delays in the i2c bitbanging
37   code this results in a i2c clock of about 50kHz) */
38static unsigned short delay = 10;
39module_param(delay, ushort, 0);
40MODULE_PARM_DESC(delay, "bit delay in microseconds "
41		 "(default is 10us for 100kHz max)");
42
43static int usb_read(struct i2c_adapter *adapter, int cmd,
44		    int value, int index, void *data, int len);
45
46static int usb_write(struct i2c_adapter *adapter, int cmd,
47		     int value, int index, void *data, int len);
48
49/* ----- begin of i2c layer ---------------------------------------------- */
50
51#define STATUS_IDLE		0
52#define STATUS_ADDRESS_ACK	1
53#define STATUS_ADDRESS_NAK	2
54
55static int usb_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, int num)
56{
57	unsigned char *pstatus;
58	struct i2c_msg *pmsg;
59	int i, ret;
60
61	dev_dbg(&adapter->dev, "master xfer %d messages:\n", num);
62
63	pstatus = kmalloc(sizeof(*pstatus), GFP_KERNEL);
64	if (!pstatus)
65		return -ENOMEM;
66
67	for (i = 0 ; i < num ; i++) {
68		int cmd = CMD_I2C_IO;
69
70		if (i == 0)
71			cmd |= CMD_I2C_IO_BEGIN;
72
73		if (i == num-1)
74			cmd |= CMD_I2C_IO_END;
75
76		pmsg = &msgs[i];
77
78		dev_dbg(&adapter->dev,
79			"  %d: %s (flags %d) %d bytes to 0x%02x\n",
80			i, pmsg->flags & I2C_M_RD ? "read" : "write",
81			pmsg->flags, pmsg->len, pmsg->addr);
82
83		/* and directly send the message */
84		if (pmsg->flags & I2C_M_RD) {
85			/* read data */
86			if (usb_read(adapter, cmd,
87				     pmsg->flags, pmsg->addr,
88				     pmsg->buf, pmsg->len) != pmsg->len) {
89				dev_err(&adapter->dev,
90					"failure reading data\n");
91				ret = -EREMOTEIO;
92				goto out;
93			}
94		} else {
95			/* write data */
96			if (usb_write(adapter, cmd,
97				      pmsg->flags, pmsg->addr,
98				      pmsg->buf, pmsg->len) != pmsg->len) {
99				dev_err(&adapter->dev,
100					"failure writing data\n");
101				ret = -EREMOTEIO;
102				goto out;
103			}
104		}
105
106		/* read status */
107		if (usb_read(adapter, CMD_GET_STATUS, 0, 0, pstatus, 1) != 1) {
108			dev_err(&adapter->dev, "failure reading status\n");
109			ret = -EREMOTEIO;
110			goto out;
111		}
112
113		dev_dbg(&adapter->dev, "  status = %d\n", *pstatus);
114		if (*pstatus == STATUS_ADDRESS_NAK) {
115			ret = -EREMOTEIO;
116			goto out;
117		}
118	}
119
120	ret = i;
121out:
122	kfree(pstatus);
123	return ret;
124}
125
126static u32 usb_func(struct i2c_adapter *adapter)
127{
128	__le32 *pfunc;
129	u32 ret;
130
131	pfunc = kmalloc(sizeof(*pfunc), GFP_KERNEL);
132
133	/* get functionality from adapter */
134	if (!pfunc || usb_read(adapter, CMD_GET_FUNC, 0, 0, pfunc,
135			       sizeof(*pfunc)) != sizeof(*pfunc)) {
136		dev_err(&adapter->dev, "failure reading functionality\n");
137		ret = 0;
138		goto out;
139	}
140
141	ret = le32_to_cpup(pfunc);
142out:
143	kfree(pfunc);
144	return ret;
145}
146
147/* This is the actual algorithm we define */
148static const struct i2c_algorithm usb_algorithm = {
149	.master_xfer	= usb_xfer,
150	.functionality	= usb_func,
151};
152
153/* ----- end of i2c layer ------------------------------------------------ */
154
155/* ----- begin of usb layer ---------------------------------------------- */
156
157/*
158 * Initially the usb i2c interface uses a vid/pid pair donated by
159 * Future Technology Devices International Ltd., later a pair was
160 * bought from EZPrototypes
161 */
162static const struct usb_device_id i2c_tiny_usb_table[] = {
163	{ USB_DEVICE(0x0403, 0xc631) },   /* FTDI */
164	{ USB_DEVICE(0x1c40, 0x0534) },   /* EZPrototypes */
165	{ }                               /* Terminating entry */
166};
167
168MODULE_DEVICE_TABLE(usb, i2c_tiny_usb_table);
169
170/* Structure to hold all of our device specific stuff */
171struct i2c_tiny_usb {
172	struct usb_device *usb_dev; /* the usb device for this device */
173	struct usb_interface *interface; /* the interface for this device */
174	struct i2c_adapter adapter; /* i2c related things */
175};
176
177static int usb_read(struct i2c_adapter *adapter, int cmd,
178		    int value, int index, void *data, int len)
179{
180	struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data;
181
182	/* do control transfer */
183	return usb_control_msg(dev->usb_dev, usb_rcvctrlpipe(dev->usb_dev, 0),
184			       cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE |
185			       USB_DIR_IN, value, index, data, len, 2000);
186}
187
188static int usb_write(struct i2c_adapter *adapter, int cmd,
189		     int value, int index, void *data, int len)
190{
191	struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data;
192
193	/* do control transfer */
194	return usb_control_msg(dev->usb_dev, usb_sndctrlpipe(dev->usb_dev, 0),
195			       cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE,
196			       value, index, data, len, 2000);
197}
198
199static void i2c_tiny_usb_free(struct i2c_tiny_usb *dev)
200{
201	usb_put_dev(dev->usb_dev);
202	kfree(dev);
203}
204
205static int i2c_tiny_usb_probe(struct usb_interface *interface,
206			      const struct usb_device_id *id)
207{
208	struct i2c_tiny_usb *dev;
209	int retval = -ENOMEM;
210	u16 version;
211
212	dev_dbg(&interface->dev, "probing usb device\n");
213
214	/* allocate memory for our device state and initialize it */
215	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
216	if (dev == NULL) {
217		dev_err(&interface->dev, "Out of memory\n");
218		goto error;
219	}
220
221	dev->usb_dev = usb_get_dev(interface_to_usbdev(interface));
222	dev->interface = interface;
223
224	/* save our data pointer in this interface device */
225	usb_set_intfdata(interface, dev);
226
227	version = le16_to_cpu(dev->usb_dev->descriptor.bcdDevice);
228	dev_info(&interface->dev,
229		 "version %x.%02x found at bus %03d address %03d\n",
230		 version >> 8, version & 0xff,
231		 dev->usb_dev->bus->busnum, dev->usb_dev->devnum);
232
233	/* setup i2c adapter description */
234	dev->adapter.owner = THIS_MODULE;
235	dev->adapter.class = I2C_CLASS_HWMON;
236	dev->adapter.algo = &usb_algorithm;
237	dev->adapter.algo_data = dev;
238	snprintf(dev->adapter.name, sizeof(dev->adapter.name),
239		 "i2c-tiny-usb at bus %03d device %03d",
240		 dev->usb_dev->bus->busnum, dev->usb_dev->devnum);
241
242	if (usb_write(&dev->adapter, CMD_SET_DELAY, delay, 0, NULL, 0) != 0) {
243		dev_err(&dev->adapter.dev,
244			"failure setting delay to %dus\n", delay);
245		retval = -EIO;
246		goto error;
247	}
248
249	dev->adapter.dev.parent = &dev->interface->dev;
250
251	/* and finally attach to i2c layer */
252	i2c_add_adapter(&dev->adapter);
253
254	/* inform user about successful attachment to i2c layer */
255	dev_info(&dev->adapter.dev, "connected i2c-tiny-usb device\n");
256
257	return 0;
258
259 error:
260	if (dev)
261		i2c_tiny_usb_free(dev);
262
263	return retval;
264}
265
266static void i2c_tiny_usb_disconnect(struct usb_interface *interface)
267{
268	struct i2c_tiny_usb *dev = usb_get_intfdata(interface);
269
270	i2c_del_adapter(&dev->adapter);
271	usb_set_intfdata(interface, NULL);
272	i2c_tiny_usb_free(dev);
273
274	dev_dbg(&interface->dev, "disconnected\n");
275}
276
277static struct usb_driver i2c_tiny_usb_driver = {
278	.name		= "i2c-tiny-usb",
279	.probe		= i2c_tiny_usb_probe,
280	.disconnect	= i2c_tiny_usb_disconnect,
281	.id_table	= i2c_tiny_usb_table,
282};
283
284module_usb_driver(i2c_tiny_usb_driver);
285
286/* ----- end of usb layer ------------------------------------------------ */
287
288MODULE_AUTHOR("Till Harbaum <Till@Harbaum.org>");
289MODULE_DESCRIPTION("i2c-tiny-usb driver v1.0");
290MODULE_LICENSE("GPL");
291