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) */
34static unsigned short delay = 10;
35module_param(delay, ushort, 0);
36MODULE_PARM_DESC(delay, "bit delay in microseconds "
37 "(default is 10us for 100kHz max)");
38
39static int usb_read(struct i2c_adapter *adapter, int cmd,
40 int value, int index, void *data, int len);
41
42static 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
51static 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(size: 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 value: pmsg->flags, index: pmsg->addr,
84 data: pmsg->buf, len: 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 value: pmsg->flags, index: pmsg->addr,
94 data: pmsg->buf, len: 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, value: 0, index: 0, data: pstatus, len: 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;
117out:
118 kfree(objp: pstatus);
119 return ret;
120}
121
122static u32 usb_func(struct i2c_adapter *adapter)
123{
124 __le32 *pfunc;
125 u32 ret;
126
127 pfunc = kmalloc(size: sizeof(*pfunc), GFP_KERNEL);
128
129 /* get functionality from adapter */
130 if (!pfunc || usb_read(adapter, CMD_GET_FUNC, value: 0, index: 0, data: pfunc,
131 len: 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(p: pfunc);
138out:
139 kfree(objp: pfunc);
140 return ret;
141}
142
143/* This is the actual algorithm we define */
144static 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 */
158static 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
164MODULE_DEVICE_TABLE(usb, i2c_tiny_usb_table);
165
166/* Structure to hold all of our device specific stuff */
167struct 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
173static 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(size: len, GFP_KERNEL);
178 int ret;
179
180 if (!dmadata)
181 return -ENOMEM;
182
183 /* do control transfer */
184 ret = usb_control_msg(dev: dev->usb_dev, usb_rcvctrlpipe(dev->usb_dev, 0),
185 request: cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE |
186 USB_DIR_IN, value, index, data: dmadata, size: len, timeout: 2000);
187
188 memcpy(data, dmadata, len);
189 kfree(objp: dmadata);
190 return ret;
191}
192
193static 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(p: data, size: len, GFP_KERNEL);
198 int ret;
199
200 if (!dmadata)
201 return -ENOMEM;
202
203 /* do control transfer */
204 ret = usb_control_msg(dev: dev->usb_dev, usb_sndctrlpipe(dev->usb_dev, 0),
205 request: cmd, USB_TYPE_VENDOR | USB_RECIP_INTERFACE,
206 value, index, data: dmadata, size: len, timeout: 2000);
207
208 kfree(objp: dmadata);
209 return ret;
210}
211
212static void i2c_tiny_usb_free(struct i2c_tiny_usb *dev)
213{
214 usb_put_dev(dev: dev->usb_dev);
215 kfree(objp: dev);
216}
217
218static 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 if (interface->intf_assoc &&
226 interface->intf_assoc->bFunctionClass != USB_CLASS_VENDOR_SPEC)
227 return -ENODEV;
228
229 dev_dbg(&interface->dev, "probing usb device\n");
230
231 /* allocate memory for our device state and initialize it */
232 dev = kzalloc(size: sizeof(*dev), GFP_KERNEL);
233 if (!dev)
234 goto error;
235
236 dev->usb_dev = usb_get_dev(interface_to_usbdev(interface));
237 dev->interface = interface;
238
239 /* save our data pointer in this interface device */
240 usb_set_intfdata(intf: interface, data: dev);
241
242 version = le16_to_cpu(dev->usb_dev->descriptor.bcdDevice);
243 dev_info(&interface->dev,
244 "version %x.%02x found at bus %03d address %03d\n",
245 version >> 8, version & 0xff,
246 dev->usb_dev->bus->busnum, dev->usb_dev->devnum);
247
248 /* setup i2c adapter description */
249 dev->adapter.owner = THIS_MODULE;
250 dev->adapter.class = I2C_CLASS_HWMON;
251 dev->adapter.algo = &usb_algorithm;
252 dev->adapter.algo_data = dev;
253 snprintf(buf: dev->adapter.name, size: sizeof(dev->adapter.name),
254 fmt: "i2c-tiny-usb at bus %03d device %03d",
255 dev->usb_dev->bus->busnum, dev->usb_dev->devnum);
256
257 if (usb_write(adapter: &dev->adapter, CMD_SET_DELAY, value: delay, index: 0, NULL, len: 0) != 0) {
258 dev_err(&dev->adapter.dev,
259 "failure setting delay to %dus\n", delay);
260 retval = -EIO;
261 goto error;
262 }
263
264 dev->adapter.dev.parent = &dev->interface->dev;
265
266 /* and finally attach to i2c layer */
267 i2c_add_adapter(adap: &dev->adapter);
268
269 /* inform user about successful attachment to i2c layer */
270 dev_info(&dev->adapter.dev, "connected i2c-tiny-usb device\n");
271
272 return 0;
273
274 error:
275 if (dev)
276 i2c_tiny_usb_free(dev);
277
278 return retval;
279}
280
281static void i2c_tiny_usb_disconnect(struct usb_interface *interface)
282{
283 struct i2c_tiny_usb *dev = usb_get_intfdata(intf: interface);
284
285 i2c_del_adapter(adap: &dev->adapter);
286 usb_set_intfdata(intf: interface, NULL);
287 i2c_tiny_usb_free(dev);
288
289 dev_dbg(&interface->dev, "disconnected\n");
290}
291
292static struct usb_driver i2c_tiny_usb_driver = {
293 .name = "i2c-tiny-usb",
294 .probe = i2c_tiny_usb_probe,
295 .disconnect = i2c_tiny_usb_disconnect,
296 .id_table = i2c_tiny_usb_table,
297};
298
299module_usb_driver(i2c_tiny_usb_driver);
300
301/* ----- end of usb layer ------------------------------------------------ */
302
303MODULE_AUTHOR("Till Harbaum <Till@Harbaum.org>");
304MODULE_DESCRIPTION("i2c-tiny-usb driver v1.0");
305MODULE_LICENSE("GPL");
306

source code of linux/drivers/i2c/busses/i2c-tiny-usb.c