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) */
38 static unsigned short delay = 10;
39 module_param(delay, ushort, 0);
40 MODULE_PARM_DESC(delay, "bit delay in microseconds "
41 "(default is 10us for 100kHz max)");
42
43 static int usb_read(struct i2c_adapter *adapter, int cmd,
44 int value, int index, void *data, int len);
45
46 static 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
usb_xfer(struct i2c_adapter * adapter,struct i2c_msg * msgs,int num)55 static 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;
121 out:
122 kfree(pstatus);
123 return ret;
124 }
125
usb_func(struct i2c_adapter * adapter)126 static 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);
142 out:
143 kfree(pfunc);
144 return ret;
145 }
146
147 /* This is the actual algorithm we define */
148 static 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 */
162 static 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
168 MODULE_DEVICE_TABLE(usb, i2c_tiny_usb_table);
169
170 /* Structure to hold all of our device specific stuff */
171 struct 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
usb_read(struct i2c_adapter * adapter,int cmd,int value,int index,void * data,int len)177 static 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 void *dmadata = kmalloc(len, GFP_KERNEL);
182 int ret;
183
184 if (!dmadata)
185 return -ENOMEM;
186
187 /* do control transfer */
188 ret = usb_control_msg(dev->usb_dev, usb_rcvctrlpipe(dev->usb_dev, 0),
189 cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE |
190 USB_DIR_IN, value, index, dmadata, len, 2000);
191
192 memcpy(data, dmadata, len);
193 kfree(dmadata);
194 return ret;
195 }
196
usb_write(struct i2c_adapter * adapter,int cmd,int value,int index,void * data,int len)197 static int usb_write(struct i2c_adapter *adapter, int cmd,
198 int value, int index, void *data, int len)
199 {
200 struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data;
201 void *dmadata = kmemdup(data, len, GFP_KERNEL);
202 int ret;
203
204 if (!dmadata)
205 return -ENOMEM;
206
207 /* do control transfer */
208 ret = usb_control_msg(dev->usb_dev, usb_sndctrlpipe(dev->usb_dev, 0),
209 cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE,
210 value, index, dmadata, len, 2000);
211
212 kfree(dmadata);
213 return ret;
214 }
215
i2c_tiny_usb_free(struct i2c_tiny_usb * dev)216 static void i2c_tiny_usb_free(struct i2c_tiny_usb *dev)
217 {
218 usb_put_dev(dev->usb_dev);
219 kfree(dev);
220 }
221
i2c_tiny_usb_probe(struct usb_interface * interface,const struct usb_device_id * id)222 static int i2c_tiny_usb_probe(struct usb_interface *interface,
223 const struct usb_device_id *id)
224 {
225 struct i2c_tiny_usb *dev;
226 int retval = -ENOMEM;
227 u16 version;
228
229 dev_dbg(&interface->dev, "probing usb device\n");
230
231 /* allocate memory for our device state and initialize it */
232 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
233 if (dev == NULL) {
234 dev_err(&interface->dev, "Out of memory\n");
235 goto error;
236 }
237
238 dev->usb_dev = usb_get_dev(interface_to_usbdev(interface));
239 dev->interface = interface;
240
241 /* save our data pointer in this interface device */
242 usb_set_intfdata(interface, dev);
243
244 version = le16_to_cpu(dev->usb_dev->descriptor.bcdDevice);
245 dev_info(&interface->dev,
246 "version %x.%02x found at bus %03d address %03d\n",
247 version >> 8, version & 0xff,
248 dev->usb_dev->bus->busnum, dev->usb_dev->devnum);
249
250 /* setup i2c adapter description */
251 dev->adapter.owner = THIS_MODULE;
252 dev->adapter.class = I2C_CLASS_HWMON;
253 dev->adapter.algo = &usb_algorithm;
254 dev->adapter.algo_data = dev;
255 snprintf(dev->adapter.name, sizeof(dev->adapter.name),
256 "i2c-tiny-usb at bus %03d device %03d",
257 dev->usb_dev->bus->busnum, dev->usb_dev->devnum);
258
259 if (usb_write(&dev->adapter, CMD_SET_DELAY, delay, 0, NULL, 0) != 0) {
260 dev_err(&dev->adapter.dev,
261 "failure setting delay to %dus\n", delay);
262 retval = -EIO;
263 goto error;
264 }
265
266 dev->adapter.dev.parent = &dev->interface->dev;
267
268 /* and finally attach to i2c layer */
269 i2c_add_adapter(&dev->adapter);
270
271 /* inform user about successful attachment to i2c layer */
272 dev_info(&dev->adapter.dev, "connected i2c-tiny-usb device\n");
273
274 return 0;
275
276 error:
277 if (dev)
278 i2c_tiny_usb_free(dev);
279
280 return retval;
281 }
282
i2c_tiny_usb_disconnect(struct usb_interface * interface)283 static void i2c_tiny_usb_disconnect(struct usb_interface *interface)
284 {
285 struct i2c_tiny_usb *dev = usb_get_intfdata(interface);
286
287 i2c_del_adapter(&dev->adapter);
288 usb_set_intfdata(interface, NULL);
289 i2c_tiny_usb_free(dev);
290
291 dev_dbg(&interface->dev, "disconnected\n");
292 }
293
294 static struct usb_driver i2c_tiny_usb_driver = {
295 .name = "i2c-tiny-usb",
296 .probe = i2c_tiny_usb_probe,
297 .disconnect = i2c_tiny_usb_disconnect,
298 .id_table = i2c_tiny_usb_table,
299 };
300
301 module_usb_driver(i2c_tiny_usb_driver);
302
303 /* ----- end of usb layer ------------------------------------------------ */
304
305 MODULE_AUTHOR("Till Harbaum <Till@Harbaum.org>");
306 MODULE_DESCRIPTION("i2c-tiny-usb driver v1.0");
307 MODULE_LICENSE("GPL");
308