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
17 /* include interfaces to usb layer */
18 #include <linux/usb.h>
19
20 /* include interface to i2c layer */
21 #include <linux/i2c.h>
22
23 /* commands via USB, must match command ids in the firmware */
24 #define CMD_ECHO 0
25 #define CMD_GET_FUNC 1
26 #define CMD_SET_DELAY 2
27 #define CMD_GET_STATUS 3
28
29 #define CMD_I2C_IO 4
30 #define CMD_I2C_IO_BEGIN (1<<0)
31 #define CMD_I2C_IO_END (1<<1)
32
33 /* i2c bit delay, default is 10us -> 100kHz */
34 static int delay = 10;
35 module_param(delay, int, 0);
36 MODULE_PARM_DESC(delay, "bit delay in microseconds, "
37 "e.g. 10 for 100kHz (default is 100kHz)");
38
39 static int usb_read(struct i2c_adapter *adapter, int cmd,
40 int value, int index, void *data, int len);
41
42 static int usb_write(struct i2c_adapter *adapter, int cmd,
43 int value, int index, void *data, int len);
44
45 /* ----- begin of i2c layer ---------------------------------------------- */
46
47 #define STATUS_IDLE 0
48 #define STATUS_ADDRESS_ACK 1
49 #define STATUS_ADDRESS_NAK 2
50
51 static int usb_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, int num)
52 {
53 unsigned char status;
54 struct i2c_msg *pmsg;
55 int i;
56
57 dev_dbg(&adapter->dev, "master xfer %d messages:\n", num);
58
59 for (i = 0 ; i < num ; i++) {
60 int cmd = CMD_I2C_IO;
61
62 if (i == 0)
63 cmd |= CMD_I2C_IO_BEGIN;
64
65 if (i == num-1)
66 cmd |= CMD_I2C_IO_END;
67
68 pmsg = &msgs[i];
69
70 dev_dbg(&adapter->dev,
71 " %d: %s (flags %d) %d bytes to 0x%02x\n",
72 i, pmsg->flags & I2C_M_RD ? "read" : "write",
73 pmsg->flags, pmsg->len, pmsg->addr);
74
75 /* and directly send the message */
76 if (pmsg->flags & I2C_M_RD) {
77 /* read data */
78 if (usb_read(adapter, cmd,
79 pmsg->flags, pmsg->addr,
80 pmsg->buf, pmsg->len) != pmsg->len) {
81 dev_err(&adapter->dev,
82 "failure reading data\n");
83 return -EREMOTEIO;
84 }
85 } else {
86 /* write data */
87 if (usb_write(adapter, cmd,
88 pmsg->flags, pmsg->addr,
89 pmsg->buf, pmsg->len) != pmsg->len) {
90 dev_err(&adapter->dev,
91 "failure writing data\n");
92 return -EREMOTEIO;
93 }
94 }
95
96 /* read status */
97 if (usb_read(adapter, CMD_GET_STATUS, 0, 0, &status, 1) != 1) {
98 dev_err(&adapter->dev, "failure reading status\n");
99 return -EREMOTEIO;
100 }
101
102 dev_dbg(&adapter->dev, " status = %d\n", status);
103 if (status == STATUS_ADDRESS_NAK)
104 return -EREMOTEIO;
105 }
106
107 return i;
108 }
109
110 static u32 usb_func(struct i2c_adapter *adapter)
111 {
112 u32 func;
113
114 /* get functionality from adapter */
115 if (usb_read(adapter, CMD_GET_FUNC, 0, 0, &func, sizeof(func)) !=
116 sizeof(func)) {
117 dev_err(&adapter->dev, "failure reading functionality\n");
118 return 0;
119 }
120
121 return func;
122 }
123
124 /* This is the actual algorithm we define */
125 static const struct i2c_algorithm usb_algorithm = {
126 .master_xfer = usb_xfer,
127 .functionality = usb_func,
128 };
129
130 /* ----- end of i2c layer ------------------------------------------------ */
131
132 /* ----- begin of usb layer ---------------------------------------------- */
133
134 /*
135 * Initially the usb i2c interface uses a vid/pid pair donated by
136 * Future Technology Devices International Ltd., later a pair was
137 * bought from EZPrototypes
138 */
139 static struct usb_device_id i2c_tiny_usb_table [] = {
140 { USB_DEVICE(0x0403, 0xc631) }, /* FTDI */
141 { USB_DEVICE(0x1c40, 0x0534) }, /* EZPrototypes */
142 { } /* Terminating entry */
143 };
144
145 MODULE_DEVICE_TABLE(usb, i2c_tiny_usb_table);
146
147 /* Structure to hold all of our device specific stuff */
148 struct i2c_tiny_usb {
149 struct usb_device *usb_dev; /* the usb device for this device */
150 struct usb_interface *interface; /* the interface for this device */
151 struct i2c_adapter adapter; /* i2c related things */
152 };
153
154 static int usb_read(struct i2c_adapter *adapter, int cmd,
155 int value, int index, void *data, int len)
156 {
157 struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data;
158
159 /* do control transfer */
160 return usb_control_msg(dev->usb_dev, usb_rcvctrlpipe(dev->usb_dev, 0),
161 cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE |
162 USB_DIR_IN, value, index, data, len, 2000);
163 }
164
165 static int usb_write(struct i2c_adapter *adapter, int cmd,
166 int value, int index, void *data, int len)
167 {
168 struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data;
169
170 /* do control transfer */
171 return usb_control_msg(dev->usb_dev, usb_sndctrlpipe(dev->usb_dev, 0),
172 cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE,
173 value, index, data, len, 2000);
174 }
175
176 static void i2c_tiny_usb_free(struct i2c_tiny_usb *dev)
177 {
178 usb_put_dev(dev->usb_dev);
179 kfree(dev);
180 }
181
182 static int i2c_tiny_usb_probe(struct usb_interface *interface,
183 const struct usb_device_id *id)
184 {
185 struct i2c_tiny_usb *dev;
186 int retval = -ENOMEM;
187 u16 version;
188
189 dev_dbg(&interface->dev, "probing usb device\n");
190
191 /* allocate memory for our device state and initialize it */
192 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
193 if (dev == NULL) {
194 dev_err(&interface->dev, "Out of memory\n");
195 goto error;
196 }
197
198 dev->usb_dev = usb_get_dev(interface_to_usbdev(interface));
199 dev->interface = interface;
200
201 /* save our data pointer in this interface device */
202 usb_set_intfdata(interface, dev);
203
204 version = le16_to_cpu(dev->usb_dev->descriptor.bcdDevice);
205 dev_info(&interface->dev,
206 "version %x.%02x found at bus %03d address %03d\n",
207 version >> 8, version & 0xff,
208 dev->usb_dev->bus->busnum, dev->usb_dev->devnum);
209
210 /* setup i2c adapter description */
211 dev->adapter.owner = THIS_MODULE;
212 dev->adapter.class = I2C_CLASS_HWMON;
213 dev->adapter.algo = &usb_algorithm;
214 dev->adapter.algo_data = dev;
215 snprintf(dev->adapter.name, sizeof(dev->adapter.name),
216 "i2c-tiny-usb at bus %03d device %03d",
217 dev->usb_dev->bus->busnum, dev->usb_dev->devnum);
218
219 if (usb_write(&dev->adapter, CMD_SET_DELAY,
220 cpu_to_le16(delay), 0, NULL, 0) != 0) {
221 dev_err(&dev->adapter.dev,
222 "failure setting delay to %dus\n", delay);
223 retval = -EIO;
224 goto error;
225 }
226
227 dev->adapter.dev.parent = &dev->interface->dev;
228
229 /* and finally attach to i2c layer */
230 i2c_add_adapter(&dev->adapter);
231
232 /* inform user about successful attachment to i2c layer */
233 dev_info(&dev->adapter.dev, "connected i2c-tiny-usb device\n");
234
235 return 0;
236
237 error:
238 if (dev)
239 i2c_tiny_usb_free(dev);
240
241 return retval;
242 }
243
244 static void i2c_tiny_usb_disconnect(struct usb_interface *interface)
245 {
246 struct i2c_tiny_usb *dev = usb_get_intfdata(interface);
247
248 i2c_del_adapter(&dev->adapter);
249 usb_set_intfdata(interface, NULL);
250 i2c_tiny_usb_free(dev);
251
252 dev_dbg(&interface->dev, "disconnected\n");
253 }
254
255 static struct usb_driver i2c_tiny_usb_driver = {
256 .name = "i2c-tiny-usb",
257 .probe = i2c_tiny_usb_probe,
258 .disconnect = i2c_tiny_usb_disconnect,
259 .id_table = i2c_tiny_usb_table,
260 };
261
262 static int __init usb_i2c_tiny_usb_init(void)
263 {
264 /* register this driver with the USB subsystem */
265 return usb_register(&i2c_tiny_usb_driver);
266 }
267
268 static void __exit usb_i2c_tiny_usb_exit(void)
269 {
270 /* deregister this driver with the USB subsystem */
271 usb_deregister(&i2c_tiny_usb_driver);
272 }
273
274 module_init(usb_i2c_tiny_usb_init);
275 module_exit(usb_i2c_tiny_usb_exit);
276
277 /* ----- end of usb layer ------------------------------------------------ */
278
279 MODULE_AUTHOR("Till Harbaum <Till@Harbaum.org>");
280 MODULE_DESCRIPTION("i2c-tiny-usb driver v1.0");
281 MODULE_LICENSE("GPL");
282
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