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/string_choices.h>
14 #include <linux/types.h>
15
16 /* include interfaces to usb layer */
17 #include <linux/usb.h>
18
19 /* include interface to i2c layer */
20 #include <linux/i2c.h>
21
22 /* commands via USB, must match command ids in the firmware */
23 #define CMD_ECHO 0
24 #define CMD_GET_FUNC 1
25 #define CMD_SET_DELAY 2
26 #define CMD_GET_STATUS 3
27
28 #define CMD_I2C_IO 4
29 #define CMD_I2C_IO_BEGIN (1<<0)
30 #define CMD_I2C_IO_END (1<<1)
31
32 /* i2c bit delay, default is 10us -> 100kHz max
33 (in practice, due to additional delays in the i2c bitbanging
34 code this results in a i2c clock of about 50kHz) */
35 static unsigned short delay = 10;
36 module_param(delay, ushort, 0);
37 MODULE_PARM_DESC(delay, "bit delay in microseconds "
38 "(default is 10us for 100kHz max)");
39
40 static int usb_read(struct i2c_adapter *adapter, int cmd,
41 int value, int index, void *data, int len);
42
43 static int usb_write(struct i2c_adapter *adapter, int cmd,
44 int value, int index, void *data, int len);
45
46 /* ----- begin of i2c layer ---------------------------------------------- */
47
48 #define STATUS_IDLE 0
49 #define STATUS_ADDRESS_ACK 1
50 #define STATUS_ADDRESS_NAK 2
51
usb_xfer(struct i2c_adapter * adapter,struct i2c_msg * msgs,int num)52 static int usb_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, int num)
53 {
54 unsigned char *pstatus;
55 struct i2c_msg *pmsg;
56 int i, ret;
57
58 pstatus = kmalloc(sizeof(*pstatus), GFP_KERNEL);
59 if (!pstatus)
60 return -ENOMEM;
61
62 for (i = 0 ; i < num ; i++) {
63 int cmd = CMD_I2C_IO;
64
65 if (i == 0)
66 cmd |= CMD_I2C_IO_BEGIN;
67
68 if (i == num-1)
69 cmd |= CMD_I2C_IO_END;
70
71 pmsg = &msgs[i];
72
73 dev_dbg(&adapter->dev,
74 " %d: %s (flags %d) %d bytes to 0x%02x\n",
75 i, str_read_write(pmsg->flags & I2C_M_RD),
76 pmsg->flags, pmsg->len, pmsg->addr);
77
78 /* and directly send the message */
79 if (pmsg->flags & I2C_M_RD) {
80 /* read data */
81 if (usb_read(adapter, cmd,
82 pmsg->flags, pmsg->addr,
83 pmsg->buf, pmsg->len) != pmsg->len) {
84 dev_err(&adapter->dev,
85 "failure reading data\n");
86 ret = -EIO;
87 goto out;
88 }
89 } else {
90 /* write data */
91 if (usb_write(adapter, cmd,
92 pmsg->flags, pmsg->addr,
93 pmsg->buf, pmsg->len) != pmsg->len) {
94 dev_err(&adapter->dev,
95 "failure writing data\n");
96 ret = -EIO;
97 goto out;
98 }
99 }
100
101 /* read status */
102 if (usb_read(adapter, CMD_GET_STATUS, 0, 0, pstatus, 1) != 1) {
103 dev_err(&adapter->dev, "failure reading status\n");
104 ret = -EIO;
105 goto out;
106 }
107
108 dev_dbg(&adapter->dev, " status = %d\n", *pstatus);
109 if (*pstatus == STATUS_ADDRESS_NAK) {
110 ret = -ENXIO;
111 goto out;
112 }
113 }
114
115 ret = i;
116 out:
117 kfree(pstatus);
118 return ret;
119 }
120
usb_func(struct i2c_adapter * adapter)121 static u32 usb_func(struct i2c_adapter *adapter)
122 {
123 __le32 *pfunc;
124 u32 ret;
125
126 pfunc = kmalloc(sizeof(*pfunc), GFP_KERNEL);
127
128 /* get functionality from adapter */
129 if (!pfunc || usb_read(adapter, CMD_GET_FUNC, 0, 0, pfunc,
130 sizeof(*pfunc)) != sizeof(*pfunc)) {
131 dev_err(&adapter->dev, "failure reading functionality\n");
132 ret = 0;
133 goto out;
134 }
135
136 ret = le32_to_cpup(pfunc);
137 out:
138 kfree(pfunc);
139 return ret;
140 }
141
142 /* prevent invalid 0-length usb_control_msg */
143 static const struct i2c_adapter_quirks usb_quirks = {
144 .flags = I2C_AQ_NO_ZERO_LEN_READ,
145 };
146
147 /* This is the actual algorithm we define */
148 static const struct i2c_algorithm usb_algorithm = {
149 .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 if (interface->intf_assoc &&
230 interface->intf_assoc->bFunctionClass != USB_CLASS_VENDOR_SPEC)
231 return -ENODEV;
232
233 dev_dbg(&interface->dev, "probing usb device\n");
234
235 /* allocate memory for our device state and initialize it */
236 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
237 if (!dev)
238 goto error;
239
240 dev->usb_dev = usb_get_dev(interface_to_usbdev(interface));
241 dev->interface = interface;
242
243 /* save our data pointer in this interface device */
244 usb_set_intfdata(interface, dev);
245
246 version = le16_to_cpu(dev->usb_dev->descriptor.bcdDevice);
247 dev_info(&interface->dev,
248 "version %x.%02x found at bus %03d address %03d\n",
249 version >> 8, version & 0xff,
250 dev->usb_dev->bus->busnum, dev->usb_dev->devnum);
251
252 /* setup i2c adapter description */
253 dev->adapter.owner = THIS_MODULE;
254 dev->adapter.class = I2C_CLASS_HWMON;
255 dev->adapter.quirks = &usb_quirks;
256 dev->adapter.algo = &usb_algorithm;
257 dev->adapter.algo_data = dev;
258 snprintf(dev->adapter.name, sizeof(dev->adapter.name),
259 "i2c-tiny-usb at bus %03d device %03d",
260 dev->usb_dev->bus->busnum, dev->usb_dev->devnum);
261
262 if (usb_write(&dev->adapter, CMD_SET_DELAY, delay, 0, NULL, 0) != 0) {
263 dev_err(&dev->adapter.dev,
264 "failure setting delay to %dus\n", delay);
265 retval = -EIO;
266 goto error;
267 }
268
269 dev->adapter.dev.parent = &dev->interface->dev;
270
271 /* and finally attach to i2c layer */
272 i2c_add_adapter(&dev->adapter);
273
274 /* inform user about successful attachment to i2c layer */
275 dev_info(&dev->adapter.dev, "connected i2c-tiny-usb device\n");
276
277 return 0;
278
279 error:
280 if (dev)
281 i2c_tiny_usb_free(dev);
282
283 return retval;
284 }
285
i2c_tiny_usb_disconnect(struct usb_interface * interface)286 static void i2c_tiny_usb_disconnect(struct usb_interface *interface)
287 {
288 struct i2c_tiny_usb *dev = usb_get_intfdata(interface);
289
290 i2c_del_adapter(&dev->adapter);
291 usb_set_intfdata(interface, NULL);
292 i2c_tiny_usb_free(dev);
293
294 dev_dbg(&interface->dev, "disconnected\n");
295 }
296
297 static struct usb_driver i2c_tiny_usb_driver = {
298 .name = "i2c-tiny-usb",
299 .probe = i2c_tiny_usb_probe,
300 .disconnect = i2c_tiny_usb_disconnect,
301 .id_table = i2c_tiny_usb_table,
302 };
303
304 module_usb_driver(i2c_tiny_usb_driver);
305
306 /* ----- end of usb layer ------------------------------------------------ */
307
308 MODULE_AUTHOR("Till Harbaum <Till@Harbaum.org>");
309 MODULE_DESCRIPTION("i2c-tiny-usb driver v1.0");
310 MODULE_LICENSE("GPL");
311