1/*
2 * Driver for the Diolan u2c-12 USB-I2C adapter
3 *
4 * Copyright (c) 2010-2011 Ericsson AB
5 *
6 * Derived from:
7 *  i2c-tiny-usb.c
8 *  Copyright (C) 2006-2007 Till Harbaum (Till@Harbaum.org)
9 *
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License as
12 * published by the Free Software Foundation, version 2.
13 */
14
15#include <linux/kernel.h>
16#include <linux/errno.h>
17#include <linux/module.h>
18#include <linux/types.h>
19#include <linux/slab.h>
20#include <linux/usb.h>
21#include <linux/i2c.h>
22
23#define DRIVER_NAME		"i2c-diolan-u2c"
24
25#define USB_VENDOR_ID_DIOLAN		0x0abf
26#define USB_DEVICE_ID_DIOLAN_U2C	0x3370
27
28
29/* commands via USB, must match command ids in the firmware */
30#define CMD_I2C_READ		0x01
31#define CMD_I2C_WRITE		0x02
32#define CMD_I2C_SCAN		0x03	/* Returns list of detected devices */
33#define CMD_I2C_RELEASE_SDA	0x04
34#define CMD_I2C_RELEASE_SCL	0x05
35#define CMD_I2C_DROP_SDA	0x06
36#define CMD_I2C_DROP_SCL	0x07
37#define CMD_I2C_READ_SDA	0x08
38#define CMD_I2C_READ_SCL	0x09
39#define CMD_GET_FW_VERSION	0x0a
40#define CMD_GET_SERIAL		0x0b
41#define CMD_I2C_START		0x0c
42#define CMD_I2C_STOP		0x0d
43#define CMD_I2C_REPEATED_START	0x0e
44#define CMD_I2C_PUT_BYTE	0x0f
45#define CMD_I2C_GET_BYTE	0x10
46#define CMD_I2C_PUT_ACK		0x11
47#define CMD_I2C_GET_ACK		0x12
48#define CMD_I2C_PUT_BYTE_ACK	0x13
49#define CMD_I2C_GET_BYTE_ACK	0x14
50#define CMD_I2C_SET_SPEED	0x1b
51#define CMD_I2C_GET_SPEED	0x1c
52#define CMD_I2C_SET_CLK_SYNC	0x24
53#define CMD_I2C_GET_CLK_SYNC	0x25
54#define CMD_I2C_SET_CLK_SYNC_TO	0x26
55#define CMD_I2C_GET_CLK_SYNC_TO	0x27
56
57#define RESP_OK			0x00
58#define RESP_FAILED		0x01
59#define RESP_BAD_MEMADDR	0x04
60#define RESP_DATA_ERR		0x05
61#define RESP_NOT_IMPLEMENTED	0x06
62#define RESP_NACK		0x07
63#define RESP_TIMEOUT		0x09
64
65#define U2C_I2C_SPEED_FAST	0	/* 400 kHz */
66#define U2C_I2C_SPEED_STD	1	/* 100 kHz */
67#define U2C_I2C_SPEED_2KHZ	242	/* 2 kHz, minimum speed */
68#define U2C_I2C_SPEED(f)	((DIV_ROUND_UP(1000000, (f)) - 10) / 2 + 1)
69
70#define U2C_I2C_FREQ_FAST	400000
71#define U2C_I2C_FREQ_STD	100000
72#define U2C_I2C_FREQ(s)		(1000000 / (2 * (s - 1) + 10))
73
74#define DIOLAN_USB_TIMEOUT	100	/* in ms */
75#define DIOLAN_SYNC_TIMEOUT	20	/* in ms */
76
77#define DIOLAN_OUTBUF_LEN	128
78#define DIOLAN_FLUSH_LEN	(DIOLAN_OUTBUF_LEN - 4)
79#define DIOLAN_INBUF_LEN	256	/* Maximum supported receive length */
80
81/* Structure to hold all of our device specific stuff */
82struct i2c_diolan_u2c {
83	u8 obuffer[DIOLAN_OUTBUF_LEN];	/* output buffer */
84	u8 ibuffer[DIOLAN_INBUF_LEN];	/* input buffer */
85	int ep_in, ep_out;              /* Endpoints    */
86	struct usb_device *usb_dev;	/* the usb device for this device */
87	struct usb_interface *interface;/* the interface for this device */
88	struct i2c_adapter adapter;	/* i2c related things */
89	int olen;			/* Output buffer length */
90	int ocount;			/* Number of enqueued messages */
91};
92
93static uint frequency = U2C_I2C_FREQ_STD;	/* I2C clock frequency in Hz */
94
95module_param(frequency, uint, S_IRUGO | S_IWUSR);
96MODULE_PARM_DESC(frequency, "I2C clock frequency in hertz");
97
98/* usb layer */
99
100/* Send command to device, and get response. */
101static int diolan_usb_transfer(struct i2c_diolan_u2c *dev)
102{
103	int ret = 0;
104	int actual;
105	int i;
106
107	if (!dev->olen || !dev->ocount)
108		return -EINVAL;
109
110	ret = usb_bulk_msg(dev->usb_dev,
111			   usb_sndbulkpipe(dev->usb_dev, dev->ep_out),
112			   dev->obuffer, dev->olen, &actual,
113			   DIOLAN_USB_TIMEOUT);
114	if (!ret) {
115		for (i = 0; i < dev->ocount; i++) {
116			int tmpret;
117
118			tmpret = usb_bulk_msg(dev->usb_dev,
119					      usb_rcvbulkpipe(dev->usb_dev,
120							      dev->ep_in),
121					      dev->ibuffer,
122					      sizeof(dev->ibuffer), &actual,
123					      DIOLAN_USB_TIMEOUT);
124			/*
125			 * Stop command processing if a previous command
126			 * returned an error.
127			 * Note that we still need to retrieve all messages.
128			 */
129			if (ret < 0)
130				continue;
131			ret = tmpret;
132			if (ret == 0 && actual > 0) {
133				switch (dev->ibuffer[actual - 1]) {
134				case RESP_NACK:
135					/*
136					 * Return ENXIO if NACK was received as
137					 * response to the address phase,
138					 * EIO otherwise
139					 */
140					ret = i == 1 ? -ENXIO : -EIO;
141					break;
142				case RESP_TIMEOUT:
143					ret = -ETIMEDOUT;
144					break;
145				case RESP_OK:
146					/* strip off return code */
147					ret = actual - 1;
148					break;
149				default:
150					ret = -EIO;
151					break;
152				}
153			}
154		}
155	}
156	dev->olen = 0;
157	dev->ocount = 0;
158	return ret;
159}
160
161static int diolan_write_cmd(struct i2c_diolan_u2c *dev, bool flush)
162{
163	if (flush || dev->olen >= DIOLAN_FLUSH_LEN)
164		return diolan_usb_transfer(dev);
165	return 0;
166}
167
168/* Send command (no data) */
169static int diolan_usb_cmd(struct i2c_diolan_u2c *dev, u8 command, bool flush)
170{
171	dev->obuffer[dev->olen++] = command;
172	dev->ocount++;
173	return diolan_write_cmd(dev, flush);
174}
175
176/* Send command with one byte of data */
177static int diolan_usb_cmd_data(struct i2c_diolan_u2c *dev, u8 command, u8 data,
178			       bool flush)
179{
180	dev->obuffer[dev->olen++] = command;
181	dev->obuffer[dev->olen++] = data;
182	dev->ocount++;
183	return diolan_write_cmd(dev, flush);
184}
185
186/* Send command with two bytes of data */
187static int diolan_usb_cmd_data2(struct i2c_diolan_u2c *dev, u8 command, u8 d1,
188				u8 d2, bool flush)
189{
190	dev->obuffer[dev->olen++] = command;
191	dev->obuffer[dev->olen++] = d1;
192	dev->obuffer[dev->olen++] = d2;
193	dev->ocount++;
194	return diolan_write_cmd(dev, flush);
195}
196
197/*
198 * Flush input queue.
199 * If we don't do this at startup and the controller has queued up
200 * messages which were not retrieved, it will stop responding
201 * at some point.
202 */
203static void diolan_flush_input(struct i2c_diolan_u2c *dev)
204{
205	int i;
206
207	for (i = 0; i < 10; i++) {
208		int actual = 0;
209		int ret;
210
211		ret = usb_bulk_msg(dev->usb_dev,
212				   usb_rcvbulkpipe(dev->usb_dev, dev->ep_in),
213				   dev->ibuffer, sizeof(dev->ibuffer), &actual,
214				   DIOLAN_USB_TIMEOUT);
215		if (ret < 0 || actual == 0)
216			break;
217	}
218	if (i == 10)
219		dev_err(&dev->interface->dev, "Failed to flush input buffer\n");
220}
221
222static int diolan_i2c_start(struct i2c_diolan_u2c *dev)
223{
224	return diolan_usb_cmd(dev, CMD_I2C_START, false);
225}
226
227static int diolan_i2c_repeated_start(struct i2c_diolan_u2c *dev)
228{
229	return diolan_usb_cmd(dev, CMD_I2C_REPEATED_START, false);
230}
231
232static int diolan_i2c_stop(struct i2c_diolan_u2c *dev)
233{
234	return diolan_usb_cmd(dev, CMD_I2C_STOP, true);
235}
236
237static int diolan_i2c_get_byte_ack(struct i2c_diolan_u2c *dev, bool ack,
238				   u8 *byte)
239{
240	int ret;
241
242	ret = diolan_usb_cmd_data(dev, CMD_I2C_GET_BYTE_ACK, ack, true);
243	if (ret > 0)
244		*byte = dev->ibuffer[0];
245	else if (ret == 0)
246		ret = -EIO;
247
248	return ret;
249}
250
251static int diolan_i2c_put_byte_ack(struct i2c_diolan_u2c *dev, u8 byte)
252{
253	return diolan_usb_cmd_data(dev, CMD_I2C_PUT_BYTE_ACK, byte, false);
254}
255
256static int diolan_set_speed(struct i2c_diolan_u2c *dev, u8 speed)
257{
258	return diolan_usb_cmd_data(dev, CMD_I2C_SET_SPEED, speed, true);
259}
260
261/* Enable or disable clock synchronization (stretching) */
262static int diolan_set_clock_synch(struct i2c_diolan_u2c *dev, bool enable)
263{
264	return diolan_usb_cmd_data(dev, CMD_I2C_SET_CLK_SYNC, enable, true);
265}
266
267/* Set clock synchronization timeout in ms */
268static int diolan_set_clock_synch_timeout(struct i2c_diolan_u2c *dev, int ms)
269{
270	int to_val = ms * 10;
271
272	return diolan_usb_cmd_data2(dev, CMD_I2C_SET_CLK_SYNC_TO,
273				    to_val & 0xff, (to_val >> 8) & 0xff, true);
274}
275
276static void diolan_fw_version(struct i2c_diolan_u2c *dev)
277{
278	int ret;
279
280	ret = diolan_usb_cmd(dev, CMD_GET_FW_VERSION, true);
281	if (ret >= 2)
282		dev_info(&dev->interface->dev,
283			 "Diolan U2C firmware version %u.%u\n",
284			 (unsigned int)dev->ibuffer[0],
285			 (unsigned int)dev->ibuffer[1]);
286}
287
288static void diolan_get_serial(struct i2c_diolan_u2c *dev)
289{
290	int ret;
291	u32 serial;
292
293	ret = diolan_usb_cmd(dev, CMD_GET_SERIAL, true);
294	if (ret >= 4) {
295		serial = le32_to_cpu(*(u32 *)dev->ibuffer);
296		dev_info(&dev->interface->dev,
297			 "Diolan U2C serial number %u\n", serial);
298	}
299}
300
301static int diolan_init(struct i2c_diolan_u2c *dev)
302{
303	int speed, ret;
304
305	if (frequency >= 200000) {
306		speed = U2C_I2C_SPEED_FAST;
307		frequency = U2C_I2C_FREQ_FAST;
308	} else if (frequency >= 100000 || frequency == 0) {
309		speed = U2C_I2C_SPEED_STD;
310		frequency = U2C_I2C_FREQ_STD;
311	} else {
312		speed = U2C_I2C_SPEED(frequency);
313		if (speed > U2C_I2C_SPEED_2KHZ)
314			speed = U2C_I2C_SPEED_2KHZ;
315		frequency = U2C_I2C_FREQ(speed);
316	}
317
318	dev_info(&dev->interface->dev,
319		 "Diolan U2C at USB bus %03d address %03d speed %d Hz\n",
320		 dev->usb_dev->bus->busnum, dev->usb_dev->devnum, frequency);
321
322	diolan_flush_input(dev);
323	diolan_fw_version(dev);
324	diolan_get_serial(dev);
325
326	/* Set I2C speed */
327	ret = diolan_set_speed(dev, speed);
328	if (ret < 0)
329		return ret;
330
331	/* Configure I2C clock synchronization */
332	ret = diolan_set_clock_synch(dev, speed != U2C_I2C_SPEED_FAST);
333	if (ret < 0)
334		return ret;
335
336	if (speed != U2C_I2C_SPEED_FAST)
337		ret = diolan_set_clock_synch_timeout(dev, DIOLAN_SYNC_TIMEOUT);
338
339	return ret;
340}
341
342/* i2c layer */
343
344static int diolan_usb_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs,
345			   int num)
346{
347	struct i2c_diolan_u2c *dev = i2c_get_adapdata(adapter);
348	struct i2c_msg *pmsg;
349	int i, j;
350	int ret, sret;
351
352	ret = diolan_i2c_start(dev);
353	if (ret < 0)
354		return ret;
355
356	for (i = 0; i < num; i++) {
357		pmsg = &msgs[i];
358		if (i) {
359			ret = diolan_i2c_repeated_start(dev);
360			if (ret < 0)
361				goto abort;
362		}
363		if (pmsg->flags & I2C_M_RD) {
364			ret =
365			    diolan_i2c_put_byte_ack(dev, (pmsg->addr << 1) | 1);
366			if (ret < 0)
367				goto abort;
368			for (j = 0; j < pmsg->len; j++) {
369				u8 byte;
370				bool ack = j < pmsg->len - 1;
371
372				/*
373				 * Don't send NACK if this is the first byte
374				 * of a SMBUS_BLOCK message.
375				 */
376				if (j == 0 && (pmsg->flags & I2C_M_RECV_LEN))
377					ack = true;
378
379				ret = diolan_i2c_get_byte_ack(dev, ack, &byte);
380				if (ret < 0)
381					goto abort;
382				/*
383				 * Adjust count if first received byte is length
384				 */
385				if (j == 0 && (pmsg->flags & I2C_M_RECV_LEN)) {
386					if (byte == 0
387					    || byte > I2C_SMBUS_BLOCK_MAX) {
388						ret = -EPROTO;
389						goto abort;
390					}
391					pmsg->len += byte;
392				}
393				pmsg->buf[j] = byte;
394			}
395		} else {
396			ret = diolan_i2c_put_byte_ack(dev, pmsg->addr << 1);
397			if (ret < 0)
398				goto abort;
399			for (j = 0; j < pmsg->len; j++) {
400				ret = diolan_i2c_put_byte_ack(dev,
401							      pmsg->buf[j]);
402				if (ret < 0)
403					goto abort;
404			}
405		}
406	}
407	ret = num;
408abort:
409	sret = diolan_i2c_stop(dev);
410	if (sret < 0 && ret >= 0)
411		ret = sret;
412	return ret;
413}
414
415/*
416 * Return list of supported functionality.
417 */
418static u32 diolan_usb_func(struct i2c_adapter *a)
419{
420	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
421	       I2C_FUNC_SMBUS_READ_BLOCK_DATA | I2C_FUNC_SMBUS_BLOCK_PROC_CALL;
422}
423
424static const struct i2c_algorithm diolan_usb_algorithm = {
425	.master_xfer = diolan_usb_xfer,
426	.functionality = diolan_usb_func,
427};
428
429/* device layer */
430
431static const struct usb_device_id diolan_u2c_table[] = {
432	{ USB_DEVICE(USB_VENDOR_ID_DIOLAN, USB_DEVICE_ID_DIOLAN_U2C) },
433	{ }
434};
435
436MODULE_DEVICE_TABLE(usb, diolan_u2c_table);
437
438static void diolan_u2c_free(struct i2c_diolan_u2c *dev)
439{
440	usb_put_dev(dev->usb_dev);
441	kfree(dev);
442}
443
444static int diolan_u2c_probe(struct usb_interface *interface,
445			    const struct usb_device_id *id)
446{
447	struct usb_host_interface *hostif = interface->cur_altsetting;
448	struct i2c_diolan_u2c *dev;
449	int ret;
450
451	if (hostif->desc.bInterfaceNumber != 0
452	    || hostif->desc.bNumEndpoints < 2)
453		return -ENODEV;
454
455	/* allocate memory for our device state and initialize it */
456	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
457	if (dev == NULL) {
458		ret = -ENOMEM;
459		goto error;
460	}
461	dev->ep_out = hostif->endpoint[0].desc.bEndpointAddress;
462	dev->ep_in = hostif->endpoint[1].desc.bEndpointAddress;
463
464	dev->usb_dev = usb_get_dev(interface_to_usbdev(interface));
465	dev->interface = interface;
466
467	/* save our data pointer in this interface device */
468	usb_set_intfdata(interface, dev);
469
470	/* setup i2c adapter description */
471	dev->adapter.owner = THIS_MODULE;
472	dev->adapter.class = I2C_CLASS_HWMON;
473	dev->adapter.algo = &diolan_usb_algorithm;
474	i2c_set_adapdata(&dev->adapter, dev);
475	snprintf(dev->adapter.name, sizeof(dev->adapter.name),
476		 DRIVER_NAME " at bus %03d device %03d",
477		 dev->usb_dev->bus->busnum, dev->usb_dev->devnum);
478
479	dev->adapter.dev.parent = &dev->interface->dev;
480
481	/* initialize diolan i2c interface */
482	ret = diolan_init(dev);
483	if (ret < 0) {
484		dev_err(&interface->dev, "failed to initialize adapter\n");
485		goto error_free;
486	}
487
488	/* and finally attach to i2c layer */
489	ret = i2c_add_adapter(&dev->adapter);
490	if (ret < 0) {
491		dev_err(&interface->dev, "failed to add I2C adapter\n");
492		goto error_free;
493	}
494
495	dev_dbg(&interface->dev, "connected " DRIVER_NAME "\n");
496
497	return 0;
498
499error_free:
500	usb_set_intfdata(interface, NULL);
501	diolan_u2c_free(dev);
502error:
503	return ret;
504}
505
506static void diolan_u2c_disconnect(struct usb_interface *interface)
507{
508	struct i2c_diolan_u2c *dev = usb_get_intfdata(interface);
509
510	i2c_del_adapter(&dev->adapter);
511	usb_set_intfdata(interface, NULL);
512	diolan_u2c_free(dev);
513
514	dev_dbg(&interface->dev, "disconnected\n");
515}
516
517static struct usb_driver diolan_u2c_driver = {
518	.name = DRIVER_NAME,
519	.probe = diolan_u2c_probe,
520	.disconnect = diolan_u2c_disconnect,
521	.id_table = diolan_u2c_table,
522};
523
524module_usb_driver(diolan_u2c_driver);
525
526MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>");
527MODULE_DESCRIPTION(DRIVER_NAME " driver");
528MODULE_LICENSE("GPL");
529