1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * driver for the i2c-tiny-usb adapter - 1.0
4 * http://www.harbaum.org/till/i2c_tiny_usb
5 *
6 * Copyright (C) 2006-2007 Till Harbaum (Till@Harbaum.org)
7 */
8
9 #include <linux/kernel.h>
10 #include <linux/errno.h>
11 #include <linux/module.h>
12 #include <linux/slab.h>
13 #include <linux/types.h>
14
15 /* include interfaces to usb layer */
16 #include <linux/usb.h>
17
18 /* include interface to i2c layer */
19 #include <linux/i2c.h>
20
21 /* commands via USB, must match command ids in the firmware */
22 #define CMD_ECHO 0
23 #define CMD_GET_FUNC 1
24 #define CMD_SET_DELAY 2
25 #define CMD_GET_STATUS 3
26
27 #define CMD_I2C_IO 4
28 #define CMD_I2C_IO_BEGIN (1<<0)
29 #define CMD_I2C_IO_END (1<<1)
30
31 /* i2c bit delay, default is 10us -> 100kHz max
32 (in practice, due to additional delays in the i2c bitbanging
33 code this results in a i2c clock of about 50kHz) */
34 static unsigned short delay = 10;
35 module_param(delay, ushort, 0);
36 MODULE_PARM_DESC(delay, "bit delay in microseconds "
37 "(default is 10us for 100kHz max)");
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
usb_xfer(struct i2c_adapter * adapter,struct i2c_msg * msgs,int num)51 static int usb_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, int num)
52 {
53 unsigned char *pstatus;
54 struct i2c_msg *pmsg;
55 int i, ret;
56
57 dev_dbg(&adapter->dev, "master xfer %d messages:\n", num);
58
59 pstatus = kmalloc(sizeof(*pstatus), GFP_KERNEL);
60 if (!pstatus)
61 return -ENOMEM;
62
63 for (i = 0 ; i < num ; i++) {
64 int cmd = CMD_I2C_IO;
65
66 if (i == 0)
67 cmd |= CMD_I2C_IO_BEGIN;
68
69 if (i == num-1)
70 cmd |= CMD_I2C_IO_END;
71
72 pmsg = &msgs[i];
73
74 dev_dbg(&adapter->dev,
75 " %d: %s (flags %d) %d bytes to 0x%02x\n",
76 i, pmsg->flags & I2C_M_RD ? "read" : "write",
77 pmsg->flags, pmsg->len, pmsg->addr);
78
79 /* and directly send the message */
80 if (pmsg->flags & I2C_M_RD) {
81 /* read data */
82 if (usb_read(adapter, cmd,
83 pmsg->flags, pmsg->addr,
84 pmsg->buf, pmsg->len) != pmsg->len) {
85 dev_err(&adapter->dev,
86 "failure reading data\n");
87 ret = -EIO;
88 goto out;
89 }
90 } else {
91 /* write data */
92 if (usb_write(adapter, cmd,
93 pmsg->flags, pmsg->addr,
94 pmsg->buf, pmsg->len) != pmsg->len) {
95 dev_err(&adapter->dev,
96 "failure writing data\n");
97 ret = -EIO;
98 goto out;
99 }
100 }
101
102 /* read status */
103 if (usb_read(adapter, CMD_GET_STATUS, 0, 0, pstatus, 1) != 1) {
104 dev_err(&adapter->dev, "failure reading status\n");
105 ret = -EIO;
106 goto out;
107 }
108
109 dev_dbg(&adapter->dev, " status = %d\n", *pstatus);
110 if (*pstatus == STATUS_ADDRESS_NAK) {
111 ret = -ENXIO;
112 goto out;
113 }
114 }
115
116 ret = i;
117 out:
118 kfree(pstatus);
119 return ret;
120 }
121
usb_func(struct i2c_adapter * adapter)122 static u32 usb_func(struct i2c_adapter *adapter)
123 {
124 __le32 *pfunc;
125 u32 ret;
126
127 pfunc = kmalloc(sizeof(*pfunc), GFP_KERNEL);
128
129 /* get functionality from adapter */
130 if (!pfunc || usb_read(adapter, CMD_GET_FUNC, 0, 0, pfunc,
131 sizeof(*pfunc)) != sizeof(*pfunc)) {
132 dev_err(&adapter->dev, "failure reading functionality\n");
133 ret = 0;
134 goto out;
135 }
136
137 ret = le32_to_cpup(pfunc);
138 out:
139 kfree(pfunc);
140 return ret;
141 }
142
143 /* This is the actual algorithm we define */
144 static const struct i2c_algorithm usb_algorithm = {
145 .master_xfer = usb_xfer,
146 .functionality = usb_func,
147 };
148
149 /* ----- end of i2c layer ------------------------------------------------ */
150
151 /* ----- begin of usb layer ---------------------------------------------- */
152
153 /*
154 * Initially the usb i2c interface uses a vid/pid pair donated by
155 * Future Technology Devices International Ltd., later a pair was
156 * bought from EZPrototypes
157 */
158 static const struct usb_device_id i2c_tiny_usb_table[] = {
159 { USB_DEVICE(0x0403, 0xc631) }, /* FTDI */
160 { USB_DEVICE(0x1c40, 0x0534) }, /* EZPrototypes */
161 { } /* Terminating entry */
162 };
163
164 MODULE_DEVICE_TABLE(usb, i2c_tiny_usb_table);
165
166 /* Structure to hold all of our device specific stuff */
167 struct i2c_tiny_usb {
168 struct usb_device *usb_dev; /* the usb device for this device */
169 struct usb_interface *interface; /* the interface for this device */
170 struct i2c_adapter adapter; /* i2c related things */
171 };
172
usb_read(struct i2c_adapter * adapter,int cmd,int value,int index,void * data,int len)173 static int usb_read(struct i2c_adapter *adapter, int cmd,
174 int value, int index, void *data, int len)
175 {
176 struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data;
177 void *dmadata = kmalloc(len, GFP_KERNEL);
178 int ret;
179
180 if (!dmadata)
181 return -ENOMEM;
182
183 /* do control transfer */
184 ret = usb_control_msg(dev->usb_dev, usb_rcvctrlpipe(dev->usb_dev, 0),
185 cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE |
186 USB_DIR_IN, value, index, dmadata, len, 2000);
187
188 memcpy(data, dmadata, len);
189 kfree(dmadata);
190 return ret;
191 }
192
usb_write(struct i2c_adapter * adapter,int cmd,int value,int index,void * data,int len)193 static int usb_write(struct i2c_adapter *adapter, int cmd,
194 int value, int index, void *data, int len)
195 {
196 struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data;
197 void *dmadata = kmemdup(data, len, GFP_KERNEL);
198 int ret;
199
200 if (!dmadata)
201 return -ENOMEM;
202
203 /* do control transfer */
204 ret = usb_control_msg(dev->usb_dev, usb_sndctrlpipe(dev->usb_dev, 0),
205 cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE,
206 value, index, dmadata, len, 2000);
207
208 kfree(dmadata);
209 return ret;
210 }
211
i2c_tiny_usb_free(struct i2c_tiny_usb * dev)212 static void i2c_tiny_usb_free(struct i2c_tiny_usb *dev)
213 {
214 usb_put_dev(dev->usb_dev);
215 kfree(dev);
216 }
217
i2c_tiny_usb_probe(struct usb_interface * interface,const struct usb_device_id * id)218 static int i2c_tiny_usb_probe(struct usb_interface *interface,
219 const struct usb_device_id *id)
220 {
221 struct i2c_tiny_usb *dev;
222 int retval = -ENOMEM;
223 u16 version;
224
225 dev_dbg(&interface->dev, "probing usb device\n");
226
227 /* allocate memory for our device state and initialize it */
228 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
229 if (dev == NULL) {
230 dev_err(&interface->dev, "Out of memory\n");
231 goto error;
232 }
233
234 dev->usb_dev = usb_get_dev(interface_to_usbdev(interface));
235 dev->interface = interface;
236
237 /* save our data pointer in this interface device */
238 usb_set_intfdata(interface, dev);
239
240 version = le16_to_cpu(dev->usb_dev->descriptor.bcdDevice);
241 dev_info(&interface->dev,
242 "version %x.%02x found at bus %03d address %03d\n",
243 version >> 8, version & 0xff,
244 dev->usb_dev->bus->busnum, dev->usb_dev->devnum);
245
246 /* setup i2c adapter description */
247 dev->adapter.owner = THIS_MODULE;
248 dev->adapter.class = I2C_CLASS_HWMON;
249 dev->adapter.algo = &usb_algorithm;
250 dev->adapter.algo_data = dev;
251 snprintf(dev->adapter.name, sizeof(dev->adapter.name),
252 "i2c-tiny-usb at bus %03d device %03d",
253 dev->usb_dev->bus->busnum, dev->usb_dev->devnum);
254
255 if (usb_write(&dev->adapter, CMD_SET_DELAY, delay, 0, NULL, 0) != 0) {
256 dev_err(&dev->adapter.dev,
257 "failure setting delay to %dus\n", delay);
258 retval = -EIO;
259 goto error;
260 }
261
262 dev->adapter.dev.parent = &dev->interface->dev;
263
264 /* and finally attach to i2c layer */
265 i2c_add_adapter(&dev->adapter);
266
267 /* inform user about successful attachment to i2c layer */
268 dev_info(&dev->adapter.dev, "connected i2c-tiny-usb device\n");
269
270 return 0;
271
272 error:
273 if (dev)
274 i2c_tiny_usb_free(dev);
275
276 return retval;
277 }
278
i2c_tiny_usb_disconnect(struct usb_interface * interface)279 static void i2c_tiny_usb_disconnect(struct usb_interface *interface)
280 {
281 struct i2c_tiny_usb *dev = usb_get_intfdata(interface);
282
283 i2c_del_adapter(&dev->adapter);
284 usb_set_intfdata(interface, NULL);
285 i2c_tiny_usb_free(dev);
286
287 dev_dbg(&interface->dev, "disconnected\n");
288 }
289
290 static struct usb_driver i2c_tiny_usb_driver = {
291 .name = "i2c-tiny-usb",
292 .probe = i2c_tiny_usb_probe,
293 .disconnect = i2c_tiny_usb_disconnect,
294 .id_table = i2c_tiny_usb_table,
295 };
296
297 module_usb_driver(i2c_tiny_usb_driver);
298
299 /* ----- end of usb layer ------------------------------------------------ */
300
301 MODULE_AUTHOR("Till Harbaum <Till@Harbaum.org>");
302 MODULE_DESCRIPTION("i2c-tiny-usb driver v1.0");
303 MODULE_LICENSE("GPL");
304