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 */
77 struct 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
88 static uint frequency = I2C_MAX_STANDARD_MODE_FREQ; /* I2C clock frequency in Hz */
89
90 module_param(frequency, uint, S_IRUGO | S_IWUSR);
91 MODULE_PARM_DESC(frequency, "I2C clock frequency in hertz");
92
93 /* usb layer */
94
95 /* Send command to device, and get response. */
diolan_usb_transfer(struct i2c_diolan_u2c * dev)96 static 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
diolan_write_cmd(struct i2c_diolan_u2c * dev,bool flush)156 static 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) */
diolan_usb_cmd(struct i2c_diolan_u2c * dev,u8 command,bool flush)164 static 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 */
diolan_usb_cmd_data(struct i2c_diolan_u2c * dev,u8 command,u8 data,bool flush)172 static 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 */
diolan_usb_cmd_data2(struct i2c_diolan_u2c * dev,u8 command,u8 d1,u8 d2,bool flush)182 static 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 */
diolan_flush_input(struct i2c_diolan_u2c * dev)198 static 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
diolan_i2c_start(struct i2c_diolan_u2c * dev)217 static int diolan_i2c_start(struct i2c_diolan_u2c *dev)
218 {
219 return diolan_usb_cmd(dev, CMD_I2C_START, false);
220 }
221
diolan_i2c_repeated_start(struct i2c_diolan_u2c * dev)222 static int diolan_i2c_repeated_start(struct i2c_diolan_u2c *dev)
223 {
224 return diolan_usb_cmd(dev, CMD_I2C_REPEATED_START, false);
225 }
226
diolan_i2c_stop(struct i2c_diolan_u2c * dev)227 static int diolan_i2c_stop(struct i2c_diolan_u2c *dev)
228 {
229 return diolan_usb_cmd(dev, CMD_I2C_STOP, true);
230 }
231
diolan_i2c_get_byte_ack(struct i2c_diolan_u2c * dev,bool ack,u8 * byte)232 static 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
diolan_i2c_put_byte_ack(struct i2c_diolan_u2c * dev,u8 byte)246 static 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
diolan_set_speed(struct i2c_diolan_u2c * dev,u8 speed)251 static 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) */
diolan_set_clock_synch(struct i2c_diolan_u2c * dev,bool enable)257 static 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 */
diolan_set_clock_synch_timeout(struct i2c_diolan_u2c * dev,int ms)263 static 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
diolan_fw_version(struct i2c_diolan_u2c * dev)271 static 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
diolan_get_serial(struct i2c_diolan_u2c * dev)283 static 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
diolan_init(struct i2c_diolan_u2c * dev)296 static 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
diolan_usb_xfer(struct i2c_adapter * adapter,struct i2c_msg * msgs,int num)339 static 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;
400 abort:
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 */
diolan_usb_func(struct i2c_adapter * a)410 static 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
416 static const struct i2c_algorithm diolan_usb_algorithm = {
417 .xfer = diolan_usb_xfer,
418 .functionality = diolan_usb_func,
419 };
420
421 /* device layer */
422
423 static const struct usb_device_id diolan_u2c_table[] = {
424 { USB_DEVICE(USB_VENDOR_ID_DIOLAN, USB_DEVICE_ID_DIOLAN_U2C) },
425 { }
426 };
427
428 MODULE_DEVICE_TABLE(usb, diolan_u2c_table);
429
diolan_u2c_free(struct i2c_diolan_u2c * dev)430 static void diolan_u2c_free(struct i2c_diolan_u2c *dev)
431 {
432 usb_put_dev(dev->usb_dev);
433 kfree(dev);
434 }
435
diolan_u2c_probe(struct usb_interface * interface,const struct usb_device_id * id)436 static 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
489 error_free:
490 usb_set_intfdata(interface, NULL);
491 diolan_u2c_free(dev);
492 error:
493 return ret;
494 }
495
diolan_u2c_disconnect(struct usb_interface * interface)496 static 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
507 static 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
514 module_usb_driver(diolan_u2c_driver);
515
516 MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>");
517 MODULE_DESCRIPTION(DRIVER_NAME " driver");
518 MODULE_LICENSE("GPL");
519