1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Driver for the Diolan u2c-12 USB-I2C adapter
4 *
5 * Copyright (c) 2010-2011 Ericsson AB
6 *
7 * Derived from:
8 *  i2c-tiny-usb.c
9 *  Copyright (C) 2006-2007 Till Harbaum (Till@Harbaum.org)
10 */
11
12#include <linux/kernel.h>
13#include <linux/errno.h>
14#include <linux/module.h>
15#include <linux/types.h>
16#include <linux/slab.h>
17#include <linux/usb.h>
18#include <linux/i2c.h>
19
20#define DRIVER_NAME		"i2c-diolan-u2c"
21
22#define USB_VENDOR_ID_DIOLAN		0x0abf
23#define USB_DEVICE_ID_DIOLAN_U2C	0x3370
24
25
26/* commands via USB, must match command ids in the firmware */
27#define CMD_I2C_READ		0x01
28#define CMD_I2C_WRITE		0x02
29#define CMD_I2C_SCAN		0x03	/* Returns list of detected devices */
30#define CMD_I2C_RELEASE_SDA	0x04
31#define CMD_I2C_RELEASE_SCL	0x05
32#define CMD_I2C_DROP_SDA	0x06
33#define CMD_I2C_DROP_SCL	0x07
34#define CMD_I2C_READ_SDA	0x08
35#define CMD_I2C_READ_SCL	0x09
36#define CMD_GET_FW_VERSION	0x0a
37#define CMD_GET_SERIAL		0x0b
38#define CMD_I2C_START		0x0c
39#define CMD_I2C_STOP		0x0d
40#define CMD_I2C_REPEATED_START	0x0e
41#define CMD_I2C_PUT_BYTE	0x0f
42#define CMD_I2C_GET_BYTE	0x10
43#define CMD_I2C_PUT_ACK		0x11
44#define CMD_I2C_GET_ACK		0x12
45#define CMD_I2C_PUT_BYTE_ACK	0x13
46#define CMD_I2C_GET_BYTE_ACK	0x14
47#define CMD_I2C_SET_SPEED	0x1b
48#define CMD_I2C_GET_SPEED	0x1c
49#define CMD_I2C_SET_CLK_SYNC	0x24
50#define CMD_I2C_GET_CLK_SYNC	0x25
51#define CMD_I2C_SET_CLK_SYNC_TO	0x26
52#define CMD_I2C_GET_CLK_SYNC_TO	0x27
53
54#define RESP_OK			0x00
55#define RESP_FAILED		0x01
56#define RESP_BAD_MEMADDR	0x04
57#define RESP_DATA_ERR		0x05
58#define RESP_NOT_IMPLEMENTED	0x06
59#define RESP_NACK		0x07
60#define RESP_TIMEOUT		0x09
61
62#define U2C_I2C_SPEED_FAST	0	/* 400 kHz */
63#define U2C_I2C_SPEED_STD	1	/* 100 kHz */
64#define U2C_I2C_SPEED_2KHZ	242	/* 2 kHz, minimum speed */
65#define U2C_I2C_SPEED(f)	((DIV_ROUND_UP(1000000, (f)) - 10) / 2 + 1)
66
67#define U2C_I2C_FREQ(s)		(1000000 / (2 * (s - 1) + 10))
68
69#define DIOLAN_USB_TIMEOUT	100	/* in ms */
70#define DIOLAN_SYNC_TIMEOUT	20	/* in ms */
71
72#define DIOLAN_OUTBUF_LEN	128
73#define DIOLAN_FLUSH_LEN	(DIOLAN_OUTBUF_LEN - 4)
74#define DIOLAN_INBUF_LEN	256	/* Maximum supported receive length */
75
76/* Structure to hold all of our device specific stuff */
77struct i2c_diolan_u2c {
78	u8 obuffer[DIOLAN_OUTBUF_LEN];	/* output buffer */
79	u8 ibuffer[DIOLAN_INBUF_LEN];	/* input buffer */
80	int ep_in, ep_out;              /* Endpoints    */
81	struct usb_device *usb_dev;	/* the usb device for this device */
82	struct usb_interface *interface;/* the interface for this device */
83	struct i2c_adapter adapter;	/* i2c related things */
84	int olen;			/* Output buffer length */
85	int ocount;			/* Number of enqueued messages */
86};
87
88static uint frequency = I2C_MAX_STANDARD_MODE_FREQ;	/* I2C clock frequency in Hz */
89
90module_param(frequency, uint, S_IRUGO | S_IWUSR);
91MODULE_PARM_DESC(frequency, "I2C clock frequency in hertz");
92
93/* usb layer */
94
95/* Send command to device, and get response. */
96static int diolan_usb_transfer(struct i2c_diolan_u2c *dev)
97{
98	int ret = 0;
99	int actual;
100	int i;
101
102	if (!dev->olen || !dev->ocount)
103		return -EINVAL;
104
105	ret = usb_bulk_msg(dev->usb_dev,
106			   usb_sndbulkpipe(dev->usb_dev, dev->ep_out),
107			   dev->obuffer, dev->olen, &actual,
108			   DIOLAN_USB_TIMEOUT);
109	if (!ret) {
110		for (i = 0; i < dev->ocount; i++) {
111			int tmpret;
112
113			tmpret = usb_bulk_msg(dev->usb_dev,
114					      usb_rcvbulkpipe(dev->usb_dev,
115							      dev->ep_in),
116					      dev->ibuffer,
117					      sizeof(dev->ibuffer), &actual,
118					      DIOLAN_USB_TIMEOUT);
119			/*
120			 * Stop command processing if a previous command
121			 * returned an error.
122			 * Note that we still need to retrieve all messages.
123			 */
124			if (ret < 0)
125				continue;
126			ret = tmpret;
127			if (ret == 0 && actual > 0) {
128				switch (dev->ibuffer[actual - 1]) {
129				case RESP_NACK:
130					/*
131					 * Return ENXIO if NACK was received as
132					 * response to the address phase,
133					 * EIO otherwise
134					 */
135					ret = i == 1 ? -ENXIO : -EIO;
136					break;
137				case RESP_TIMEOUT:
138					ret = -ETIMEDOUT;
139					break;
140				case RESP_OK:
141					/* strip off return code */
142					ret = actual - 1;
143					break;
144				default:
145					ret = -EIO;
146					break;
147				}
148			}
149		}
150	}
151	dev->olen = 0;
152	dev->ocount = 0;
153	return ret;
154}
155
156static int diolan_write_cmd(struct i2c_diolan_u2c *dev, bool flush)
157{
158	if (flush || dev->olen >= DIOLAN_FLUSH_LEN)
159		return diolan_usb_transfer(dev);
160	return 0;
161}
162
163/* Send command (no data) */
164static int diolan_usb_cmd(struct i2c_diolan_u2c *dev, u8 command, bool flush)
165{
166	dev->obuffer[dev->olen++] = command;
167	dev->ocount++;
168	return diolan_write_cmd(dev, flush);
169}
170
171/* Send command with one byte of data */
172static int diolan_usb_cmd_data(struct i2c_diolan_u2c *dev, u8 command, u8 data,
173			       bool flush)
174{
175	dev->obuffer[dev->olen++] = command;
176	dev->obuffer[dev->olen++] = data;
177	dev->ocount++;
178	return diolan_write_cmd(dev, flush);
179}
180
181/* Send command with two bytes of data */
182static int diolan_usb_cmd_data2(struct i2c_diolan_u2c *dev, u8 command, u8 d1,
183				u8 d2, bool flush)
184{
185	dev->obuffer[dev->olen++] = command;
186	dev->obuffer[dev->olen++] = d1;
187	dev->obuffer[dev->olen++] = d2;
188	dev->ocount++;
189	return diolan_write_cmd(dev, flush);
190}
191
192/*
193 * Flush input queue.
194 * If we don't do this at startup and the controller has queued up
195 * messages which were not retrieved, it will stop responding
196 * at some point.
197 */
198static void diolan_flush_input(struct i2c_diolan_u2c *dev)
199{
200	int i;
201
202	for (i = 0; i < 10; i++) {
203		int actual = 0;
204		int ret;
205
206		ret = usb_bulk_msg(dev->usb_dev,
207				   usb_rcvbulkpipe(dev->usb_dev, dev->ep_in),
208				   dev->ibuffer, sizeof(dev->ibuffer), &actual,
209				   DIOLAN_USB_TIMEOUT);
210		if (ret < 0 || actual == 0)
211			break;
212	}
213	if (i == 10)
214		dev_err(&dev->interface->dev, "Failed to flush input buffer\n");
215}
216
217static int diolan_i2c_start(struct i2c_diolan_u2c *dev)
218{
219	return diolan_usb_cmd(dev, CMD_I2C_START, false);
220}
221
222static int diolan_i2c_repeated_start(struct i2c_diolan_u2c *dev)
223{
224	return diolan_usb_cmd(dev, CMD_I2C_REPEATED_START, false);
225}
226
227static int diolan_i2c_stop(struct i2c_diolan_u2c *dev)
228{
229	return diolan_usb_cmd(dev, CMD_I2C_STOP, true);
230}
231
232static int diolan_i2c_get_byte_ack(struct i2c_diolan_u2c *dev, bool ack,
233				   u8 *byte)
234{
235	int ret;
236
237	ret = diolan_usb_cmd_data(dev, CMD_I2C_GET_BYTE_ACK, ack, true);
238	if (ret > 0)
239		*byte = dev->ibuffer[0];
240	else if (ret == 0)
241		ret = -EIO;
242
243	return ret;
244}
245
246static int diolan_i2c_put_byte_ack(struct i2c_diolan_u2c *dev, u8 byte)
247{
248	return diolan_usb_cmd_data(dev, CMD_I2C_PUT_BYTE_ACK, byte, false);
249}
250
251static int diolan_set_speed(struct i2c_diolan_u2c *dev, u8 speed)
252{
253	return diolan_usb_cmd_data(dev, CMD_I2C_SET_SPEED, speed, true);
254}
255
256/* Enable or disable clock synchronization (stretching) */
257static int diolan_set_clock_synch(struct i2c_diolan_u2c *dev, bool enable)
258{
259	return diolan_usb_cmd_data(dev, CMD_I2C_SET_CLK_SYNC, enable, true);
260}
261
262/* Set clock synchronization timeout in ms */
263static int diolan_set_clock_synch_timeout(struct i2c_diolan_u2c *dev, int ms)
264{
265	int to_val = ms * 10;
266
267	return diolan_usb_cmd_data2(dev, CMD_I2C_SET_CLK_SYNC_TO,
268				    to_val & 0xff, (to_val >> 8) & 0xff, true);
269}
270
271static void diolan_fw_version(struct i2c_diolan_u2c *dev)
272{
273	int ret;
274
275	ret = diolan_usb_cmd(dev, CMD_GET_FW_VERSION, true);
276	if (ret >= 2)
277		dev_info(&dev->interface->dev,
278			 "Diolan U2C firmware version %u.%u\n",
279			 (unsigned int)dev->ibuffer[0],
280			 (unsigned int)dev->ibuffer[1]);
281}
282
283static void diolan_get_serial(struct i2c_diolan_u2c *dev)
284{
285	int ret;
286	u32 serial;
287
288	ret = diolan_usb_cmd(dev, CMD_GET_SERIAL, true);
289	if (ret >= 4) {
290		serial = le32_to_cpu(*(u32 *)dev->ibuffer);
291		dev_info(&dev->interface->dev,
292			 "Diolan U2C serial number %u\n", serial);
293	}
294}
295
296static int diolan_init(struct i2c_diolan_u2c *dev)
297{
298	int speed, ret;
299
300	if (frequency >= 2 * I2C_MAX_STANDARD_MODE_FREQ) {
301		speed = U2C_I2C_SPEED_FAST;
302		frequency = I2C_MAX_FAST_MODE_FREQ;
303	} else if (frequency >= I2C_MAX_STANDARD_MODE_FREQ || frequency == 0) {
304		speed = U2C_I2C_SPEED_STD;
305		frequency = I2C_MAX_STANDARD_MODE_FREQ;
306	} else {
307		speed = U2C_I2C_SPEED(frequency);
308		if (speed > U2C_I2C_SPEED_2KHZ)
309			speed = U2C_I2C_SPEED_2KHZ;
310		frequency = U2C_I2C_FREQ(speed);
311	}
312
313	dev_info(&dev->interface->dev,
314		 "Diolan U2C at USB bus %03d address %03d speed %d Hz\n",
315		 dev->usb_dev->bus->busnum, dev->usb_dev->devnum, frequency);
316
317	diolan_flush_input(dev);
318	diolan_fw_version(dev);
319	diolan_get_serial(dev);
320
321	/* Set I2C speed */
322	ret = diolan_set_speed(dev, speed);
323	if (ret < 0)
324		return ret;
325
326	/* Configure I2C clock synchronization */
327	ret = diolan_set_clock_synch(dev, speed != U2C_I2C_SPEED_FAST);
328	if (ret < 0)
329		return ret;
330
331	if (speed != U2C_I2C_SPEED_FAST)
332		ret = diolan_set_clock_synch_timeout(dev, DIOLAN_SYNC_TIMEOUT);
333
334	return ret;
335}
336
337/* i2c layer */
338
339static int diolan_usb_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs,
340			   int num)
341{
342	struct i2c_diolan_u2c *dev = i2c_get_adapdata(adapter);
343	struct i2c_msg *pmsg;
344	int i, j;
345	int ret, sret;
346
347	ret = diolan_i2c_start(dev);
348	if (ret < 0)
349		return ret;
350
351	for (i = 0; i < num; i++) {
352		pmsg = &msgs[i];
353		if (i) {
354			ret = diolan_i2c_repeated_start(dev);
355			if (ret < 0)
356				goto abort;
357		}
358		ret = diolan_i2c_put_byte_ack(dev,
359					      i2c_8bit_addr_from_msg(pmsg));
360		if (ret < 0)
361			goto abort;
362		if (pmsg->flags & I2C_M_RD) {
363			for (j = 0; j < pmsg->len; j++) {
364				u8 byte;
365				bool ack = j < pmsg->len - 1;
366
367				/*
368				 * Don't send NACK if this is the first byte
369				 * of a SMBUS_BLOCK message.
370				 */
371				if (j == 0 && (pmsg->flags & I2C_M_RECV_LEN))
372					ack = true;
373
374				ret = diolan_i2c_get_byte_ack(dev, ack, &byte);
375				if (ret < 0)
376					goto abort;
377				/*
378				 * Adjust count if first received byte is length
379				 */
380				if (j == 0 && (pmsg->flags & I2C_M_RECV_LEN)) {
381					if (byte == 0
382					    || byte > I2C_SMBUS_BLOCK_MAX) {
383						ret = -EPROTO;
384						goto abort;
385					}
386					pmsg->len += byte;
387				}
388				pmsg->buf[j] = byte;
389			}
390		} else {
391			for (j = 0; j < pmsg->len; j++) {
392				ret = diolan_i2c_put_byte_ack(dev,
393							      pmsg->buf[j]);
394				if (ret < 0)
395					goto abort;
396			}
397		}
398	}
399	ret = num;
400abort:
401	sret = diolan_i2c_stop(dev);
402	if (sret < 0 && ret >= 0)
403		ret = sret;
404	return ret;
405}
406
407/*
408 * Return list of supported functionality.
409 */
410static u32 diolan_usb_func(struct i2c_adapter *a)
411{
412	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
413	       I2C_FUNC_SMBUS_READ_BLOCK_DATA | I2C_FUNC_SMBUS_BLOCK_PROC_CALL;
414}
415
416static const struct i2c_algorithm diolan_usb_algorithm = {
417	.master_xfer = diolan_usb_xfer,
418	.functionality = diolan_usb_func,
419};
420
421/* device layer */
422
423static const struct usb_device_id diolan_u2c_table[] = {
424	{ USB_DEVICE(USB_VENDOR_ID_DIOLAN, USB_DEVICE_ID_DIOLAN_U2C) },
425	{ }
426};
427
428MODULE_DEVICE_TABLE(usb, diolan_u2c_table);
429
430static void diolan_u2c_free(struct i2c_diolan_u2c *dev)
431{
432	usb_put_dev(dev->usb_dev);
433	kfree(dev);
434}
435
436static int diolan_u2c_probe(struct usb_interface *interface,
437			    const struct usb_device_id *id)
438{
439	struct usb_host_interface *hostif = interface->cur_altsetting;
440	struct i2c_diolan_u2c *dev;
441	int ret;
442
443	if (hostif->desc.bInterfaceNumber != 0
444	    || hostif->desc.bNumEndpoints < 2)
445		return -ENODEV;
446
447	/* allocate memory for our device state and initialize it */
448	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
449	if (dev == NULL) {
450		ret = -ENOMEM;
451		goto error;
452	}
453	dev->ep_out = hostif->endpoint[0].desc.bEndpointAddress;
454	dev->ep_in = hostif->endpoint[1].desc.bEndpointAddress;
455
456	dev->usb_dev = usb_get_dev(interface_to_usbdev(interface));
457	dev->interface = interface;
458
459	/* save our data pointer in this interface device */
460	usb_set_intfdata(interface, dev);
461
462	/* setup i2c adapter description */
463	dev->adapter.owner = THIS_MODULE;
464	dev->adapter.class = I2C_CLASS_HWMON;
465	dev->adapter.algo = &diolan_usb_algorithm;
466	i2c_set_adapdata(&dev->adapter, dev);
467	snprintf(dev->adapter.name, sizeof(dev->adapter.name),
468		 DRIVER_NAME " at bus %03d device %03d",
469		 dev->usb_dev->bus->busnum, dev->usb_dev->devnum);
470
471	dev->adapter.dev.parent = &dev->interface->dev;
472
473	/* initialize diolan i2c interface */
474	ret = diolan_init(dev);
475	if (ret < 0) {
476		dev_err(&interface->dev, "failed to initialize adapter\n");
477		goto error_free;
478	}
479
480	/* and finally attach to i2c layer */
481	ret = i2c_add_adapter(&dev->adapter);
482	if (ret < 0)
483		goto error_free;
484
485	dev_dbg(&interface->dev, "connected " DRIVER_NAME "\n");
486
487	return 0;
488
489error_free:
490	usb_set_intfdata(interface, NULL);
491	diolan_u2c_free(dev);
492error:
493	return ret;
494}
495
496static void diolan_u2c_disconnect(struct usb_interface *interface)
497{
498	struct i2c_diolan_u2c *dev = usb_get_intfdata(interface);
499
500	i2c_del_adapter(&dev->adapter);
501	usb_set_intfdata(interface, NULL);
502	diolan_u2c_free(dev);
503
504	dev_dbg(&interface->dev, "disconnected\n");
505}
506
507static struct usb_driver diolan_u2c_driver = {
508	.name = DRIVER_NAME,
509	.probe = diolan_u2c_probe,
510	.disconnect = diolan_u2c_disconnect,
511	.id_table = diolan_u2c_table,
512};
513
514module_usb_driver(diolan_u2c_driver);
515
516MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>");
517MODULE_DESCRIPTION(DRIVER_NAME " driver");
518MODULE_LICENSE("GPL");
519