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