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 /* prevent invalid 0-length usb_control_msg */
144 static const struct i2c_adapter_quirks usb_quirks = {
145 .flags = I2C_AQ_NO_ZERO_LEN_READ,
146 };
147
148 /* This is the actual algorithm we define */
149 static const struct i2c_algorithm usb_algorithm = {
150 .master_xfer = usb_xfer,
151 .functionality = usb_func,
152 };
153
154 /* ----- end of i2c layer ------------------------------------------------ */
155
156 /* ----- begin of usb layer ---------------------------------------------- */
157
158 /*
159 * Initially the usb i2c interface uses a vid/pid pair donated by
160 * Future Technology Devices International Ltd., later a pair was
161 * bought from EZPrototypes
162 */
163 static const struct usb_device_id i2c_tiny_usb_table[] = {
164 { USB_DEVICE(0x0403, 0xc631) }, /* FTDI */
165 { USB_DEVICE(0x1c40, 0x0534) }, /* EZPrototypes */
166 { } /* Terminating entry */
167 };
168
169 MODULE_DEVICE_TABLE(usb, i2c_tiny_usb_table);
170
171 /* Structure to hold all of our device specific stuff */
172 struct i2c_tiny_usb {
173 struct usb_device *usb_dev; /* the usb device for this device */
174 struct usb_interface *interface; /* the interface for this device */
175 struct i2c_adapter adapter; /* i2c related things */
176 };
177
usb_read(struct i2c_adapter * adapter,int cmd,int value,int index,void * data,int len)178 static int usb_read(struct i2c_adapter *adapter, int cmd,
179 int value, int index, void *data, int len)
180 {
181 struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data;
182 void *dmadata = kmalloc(len, GFP_KERNEL);
183 int ret;
184
185 if (!dmadata)
186 return -ENOMEM;
187
188 /* do control transfer */
189 ret = usb_control_msg(dev->usb_dev, usb_rcvctrlpipe(dev->usb_dev, 0),
190 cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE |
191 USB_DIR_IN, value, index, dmadata, len, 2000);
192
193 memcpy(data, dmadata, len);
194 kfree(dmadata);
195 return ret;
196 }
197
usb_write(struct i2c_adapter * adapter,int cmd,int value,int index,void * data,int len)198 static int usb_write(struct i2c_adapter *adapter, int cmd,
199 int value, int index, void *data, int len)
200 {
201 struct i2c_tiny_usb *dev = (struct i2c_tiny_usb *)adapter->algo_data;
202 void *dmadata = kmemdup(data, len, GFP_KERNEL);
203 int ret;
204
205 if (!dmadata)
206 return -ENOMEM;
207
208 /* do control transfer */
209 ret = usb_control_msg(dev->usb_dev, usb_sndctrlpipe(dev->usb_dev, 0),
210 cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE,
211 value, index, dmadata, len, 2000);
212
213 kfree(dmadata);
214 return ret;
215 }
216
i2c_tiny_usb_free(struct i2c_tiny_usb * dev)217 static void i2c_tiny_usb_free(struct i2c_tiny_usb *dev)
218 {
219 usb_put_dev(dev->usb_dev);
220 kfree(dev);
221 }
222
i2c_tiny_usb_probe(struct usb_interface * interface,const struct usb_device_id * id)223 static int i2c_tiny_usb_probe(struct usb_interface *interface,
224 const struct usb_device_id *id)
225 {
226 struct i2c_tiny_usb *dev;
227 int retval = -ENOMEM;
228 u16 version;
229
230 if (interface->intf_assoc &&
231 interface->intf_assoc->bFunctionClass != USB_CLASS_VENDOR_SPEC)
232 return -ENODEV;
233
234 dev_dbg(&interface->dev, "probing usb device\n");
235
236 /* allocate memory for our device state and initialize it */
237 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
238 if (!dev)
239 goto error;
240
241 dev->usb_dev = usb_get_dev(interface_to_usbdev(interface));
242 dev->interface = interface;
243
244 /* save our data pointer in this interface device */
245 usb_set_intfdata(interface, dev);
246
247 version = le16_to_cpu(dev->usb_dev->descriptor.bcdDevice);
248 dev_info(&interface->dev,
249 "version %x.%02x found at bus %03d address %03d\n",
250 version >> 8, version & 0xff,
251 dev->usb_dev->bus->busnum, dev->usb_dev->devnum);
252
253 /* setup i2c adapter description */
254 dev->adapter.owner = THIS_MODULE;
255 dev->adapter.class = I2C_CLASS_HWMON;
256 dev->adapter.quirks = &usb_quirks;
257 dev->adapter.algo = &usb_algorithm;
258 dev->adapter.algo_data = dev;
259 snprintf(dev->adapter.name, sizeof(dev->adapter.name),
260 "i2c-tiny-usb at bus %03d device %03d",
261 dev->usb_dev->bus->busnum, dev->usb_dev->devnum);
262
263 if (usb_write(&dev->adapter, CMD_SET_DELAY, delay, 0, NULL, 0) != 0) {
264 dev_err(&dev->adapter.dev,
265 "failure setting delay to %dus\n", delay);
266 retval = -EIO;
267 goto error;
268 }
269
270 dev->adapter.dev.parent = &dev->interface->dev;
271
272 /* and finally attach to i2c layer */
273 i2c_add_adapter(&dev->adapter);
274
275 /* inform user about successful attachment to i2c layer */
276 dev_info(&dev->adapter.dev, "connected i2c-tiny-usb device\n");
277
278 return 0;
279
280 error:
281 if (dev)
282 i2c_tiny_usb_free(dev);
283
284 return retval;
285 }
286
i2c_tiny_usb_disconnect(struct usb_interface * interface)287 static void i2c_tiny_usb_disconnect(struct usb_interface *interface)
288 {
289 struct i2c_tiny_usb *dev = usb_get_intfdata(interface);
290
291 i2c_del_adapter(&dev->adapter);
292 usb_set_intfdata(interface, NULL);
293 i2c_tiny_usb_free(dev);
294
295 dev_dbg(&interface->dev, "disconnected\n");
296 }
297
298 static struct usb_driver i2c_tiny_usb_driver = {
299 .name = "i2c-tiny-usb",
300 .probe = i2c_tiny_usb_probe,
301 .disconnect = i2c_tiny_usb_disconnect,
302 .id_table = i2c_tiny_usb_table,
303 };
304
305 module_usb_driver(i2c_tiny_usb_driver);
306
307 /* ----- end of usb layer ------------------------------------------------ */
308
309 MODULE_AUTHOR("Till Harbaum <Till@Harbaum.org>");
310 MODULE_DESCRIPTION("i2c-tiny-usb driver v1.0");
311 MODULE_LICENSE("GPL");
312