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(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;
117out:
118	kfree(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(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);
138out:
139	kfree(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(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
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(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
212static void i2c_tiny_usb_free(struct i2c_tiny_usb *dev)
213{
214	usb_put_dev(dev->usb_dev);
215	kfree(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(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(interface, 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(dev->adapter.name, sizeof(dev->adapter.name),
254		 "i2c-tiny-usb at bus %03d device %03d",
255		 dev->usb_dev->bus->busnum, dev->usb_dev->devnum);
256
257	if (usb_write(&dev->adapter, CMD_SET_DELAY, delay, 0, NULL, 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(&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(interface);
284
285	i2c_del_adapter(&dev->adapter);
286	usb_set_intfdata(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