aboutsummaryrefslogtreecommitdiff
path: root/drivers/i2c/busses/i2c-tiny-usb.c
blob: f07307ff360d6ee4dec28765c5d3cdd0067c7e48 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
/*
 * driver for the i2c-tiny-usb adapter - 1.0
 * http://www.harbaum.org/till/i2c_tiny_usb
 *
 * Copyright (C) 2006-2007 Till Harbaum (Till@Harbaum.org)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation, version 2.
 *
 */

#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/types.h>

/* include interfaces to usb layer */
#include <linux/usb.h>

/* include interface to i2c layer */
#include <linux/i2c.h>

/* commands via USB, must match command ids in the firmware */
#define CMD_ECHO		0
#define CMD_GET_FUNC		1
#define CMD_SET_DELAY		2
#define CMD_GET_STATUS		3

#define CMD_I2C_IO		4
#define CMD_I2C_IO_BEGIN	(1<<0)
#define CMD_I2C_IO_END		(1<<1)

/* i2c bit delay, default is 10us -> 100kHz max
   (in practice, due to additional delays in the i2c bitbanging
   code this results in a i2c clock of about 50kHz) */
static unsigned short delay = 10;
module_param(delay, ushort, 0);
MODULE_PARM_DESC(delay, "bit delay in microseconds "
		 "(default is 10us for 100kHz max)");

static int usb_read(struct i2c_adapter *adapter, int cmd,
		    int value, int index, void *data, int len);

static int usb_write(struct i2c_adapter *adapter, int cmd,
		     int value, int index, void *data, int len);

/* ----- begin of i2c layer ---------------------------------------------- */

#define STATUS_IDLE		0
#define STATUS_ADDRESS_ACK	1
#define STATUS_ADDRESS_NAK	2

static int usb_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, int num)
{
	unsigned char status;
	struct i2c_msg *pmsg;
	int i;

	dev_dbg(&adapter->dev, "master xfer %d messages:\n", num);

	for (i = 0 ; i < num ; i++) {
		int cmd = CMD_I2C_IO;

		if (i == 0)
			cmd |= CMD_I2C_IO_BEGIN;

		if (i == num-1)
			cmd |= CMD_I2C_IO_END;

		pmsg = &msgs[i];

		dev_dbg(&adapter->dev,
			"  %d: %s (flags %d) %d bytes to 0x%02x\n",
			i, pmsg->flags & I2C_M_RD ? "read" : "write",
			pmsg->flags, pmsg->len, pmsg->addr);

		/* and directly send the message */
		if (pmsg->flags & I2C_M_RD) {
			/* read data */
			if (usb_read(adapter, cmd,
				     pmsg->flags, pmsg->addr,
				     pmsg->buf, pmsg->len) != pmsg->len) {
				dev_err(&adapter->dev,
					"failure reading data\n");
				return -EREMOTEIO;
			}
		} else {
			/* write data */
			if (usb_write(adapter, cmd,
				      pmsg->flags, pmsg->addr,
				      pmsg->buf, pmsg->len) != pmsg->len) {
				dev_err(&adapter->dev,
					"failure writing data\n");
				return -EREMOTEIO;
			}
		}

		/* read status */
		if (usb_read(adapter, CMD_GET_STATUS, 0, 0, &status, 1) != 1) {
			dev_err(&adapter->dev, "failure reading status\n");
			return -EREMOTEIO;
		}

		dev_dbg(&adapter->dev, "  status = %d\n", status);
		if (status == STATUS_ADDRESS_NAK)
			return -EREMOTEIO;
	}

	return i;
}

static u32 usb_func(struct i2c_adapter *adapter)
{
	__le32 func;

	/* get functionality from adapter */
	if (usb_read(adapter, CMD_GET_FUNC, 0, 0, &func, sizeof(func)) !=
	    sizeof(func)) {
		dev_err(&adapter->dev, "failure reading functionality\n");
		return 0;
	}

	return le32_to_cpu(func);
}

/* This is the actual algorithm we define */
static const struct i2c_algorithm usb_algorithm = {
	.master_xfer	= usb_xfer,
	.functionality	= usb_func,
};

/* ----- end of i2c layer ------------------------------------------------ */

/* ----- begin of usb layer ---------------------------------------------- */

/*
 * Initially the usb i2c interface uses a vid/pid pair donated by
 * Future Technology Devices International Ltd., later a pair was
 * bought from EZPrototypes
 */
static const struct usb_device_id i2c_tiny_usb_table[] = {
	{ USB_DEVICE(0x0403, 0xc631) },   /* FTDI */
	{ USB_DEVICE(0x1c40, 0x0534) },   /* EZPrototypes */
	{ }                               /* Terminating entry */
};

MODULE_DEVICE_TABLE(usb, i2c_tiny_usb_table);

/* Structure to hold all of our device specific stuff */
struct i2c_tiny_usb {
	struct usb_device *usb_dev; /* the usb device for this device */
	struct usb_interface *interface; /* the interface for this device */
	struct i2c_adapter adapter; /* i2c related things */
};

static int usb_read(struct i2c_adapter *adapter, int cmd,
		    int value, int index, void *data, int len)
{
	struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data;

	/* do control transfer */
	return usb_control_msg(dev->usb_dev, usb_rcvctrlpipe(dev->usb_dev, 0),
			       cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE |
			       USB_DIR_IN, value, index, data, len, 2000);
}

static int usb_write(struct i2c_adapter *adapter, int cmd,
		     int value, int index, void *data, int len)
{
	struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data;

	/* do control transfer */
	return usb_control_msg(dev->usb_dev, usb_sndctrlpipe(dev->usb_dev, 0),
			       cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE,
			       value, index, data, len, 2000);
}

static void i2c_tiny_usb_free(struct i2c_tiny_usb *dev)
{
	usb_put_dev(dev->usb_dev);
	kfree(dev);
}

static int i2c_tiny_usb_probe(struct usb_interface *interface,
			      const struct usb_device_id *id)
{
	struct i2c_tiny_usb *dev;
	int retval = -ENOMEM;
	u16 version;

	dev_dbg(&interface->dev, "probing usb device\n");

	/* allocate memory for our device state and initialize it */
	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
	if (dev == NULL) {
		dev_err(&interface->dev, "Out of memory\n");
		goto error;
	}

	dev->usb_dev = usb_get_dev(interface_to_usbdev(interface));
	dev->interface = interface;

	/* save our data pointer in this interface device */
	usb_set_intfdata(interface, dev);

	version = le16_to_cpu(dev->usb_dev->descriptor.bcdDevice);
	dev_info(&interface->dev,
		 "version %x.%02x found at bus %03d address %03d\n",
		 version >> 8, version & 0xff,
		 dev->usb_dev->bus->busnum, dev->usb_dev->devnum);

	/* setup i2c adapter description */
	dev->adapter.owner = THIS_MODULE;
	dev->adapter.class = I2C_CLASS_HWMON;
	dev->adapter.algo = &usb_algorithm;
	dev->adapter.algo_data = dev;
	snprintf(dev->adapter.name, sizeof(dev->adapter.name),
		 "i2c-tiny-usb at bus %03d device %03d",
		 dev->usb_dev->bus->busnum, dev->usb_dev->devnum);

	if (usb_write(&dev->adapter, CMD_SET_DELAY, delay, 0, NULL, 0) != 0) {
		dev_err(&dev->adapter.dev,
			"failure setting delay to %dus\n", delay);
		retval = -EIO;
		goto error;
	}

	dev->adapter.dev.parent = &dev->interface->dev;

	/* and finally attach to i2c layer */
	i2c_add_adapter(&dev->adapter);

	/* inform user about successful attachment to i2c layer */
	dev_info(&dev->adapter.dev, "connected i2c-tiny-usb device\n");

	return 0;

 error:
	if (dev)
		i2c_tiny_usb_free(dev);

	return retval;
}

static void i2c_tiny_usb_disconnect(struct usb_interface *interface)
{
	struct i2c_tiny_usb *dev = usb_get_intfdata(interface);

	i2c_del_adapter(&dev->adapter);
	usb_set_intfdata(interface, NULL);
	i2c_tiny_usb_free(dev);

	dev_dbg(&interface->dev, "disconnected\n");
}

static struct usb_driver i2c_tiny_usb_driver = {
	.name		= "i2c-tiny-usb",
	.probe		= i2c_tiny_usb_probe,
	.disconnect	= i2c_tiny_usb_disconnect,
	.id_table	= i2c_tiny_usb_table,
};

module_usb_driver(i2c_tiny_usb_driver);

/* ----- end of usb layer ------------------------------------------------ */

MODULE_AUTHOR("Till Harbaum <Till@Harbaum.org>");
MODULE_DESCRIPTION("i2c-tiny-usb driver v1.0");
MODULE_LICENSE("GPL");