1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *  Nano River Technologies viperboard i2c master driver
4  *
5  *  (C) 2012 by Lemonage GmbH
6  *  Author: Lars Poeschel <poeschel@lemonage.de>
7  *  All rights reserved.
8  */
9 
10 #include <linux/kernel.h>
11 #include <linux/errno.h>
12 #include <linux/module.h>
13 #include <linux/slab.h>
14 #include <linux/types.h>
15 #include <linux/mutex.h>
16 #include <linux/platform_device.h>
17 
18 #include <linux/usb.h>
19 #include <linux/i2c.h>
20 
21 #include <linux/mfd/viperboard.h>
22 
23 struct vprbrd_i2c {
24 	struct i2c_adapter i2c;
25 	u8 bus_freq_param;
26 };
27 
28 /* i2c bus frequency module parameter */
29 static u8 i2c_bus_param;
30 static unsigned int i2c_bus_freq = 100;
31 module_param(i2c_bus_freq, int, 0);
32 MODULE_PARM_DESC(i2c_bus_freq,
33 	"i2c bus frequency in khz (default is 100) valid values: 10, 100, 200, 400, 1000, 3000, 6000");
34 
35 static int vprbrd_i2c_status(struct i2c_adapter *i2c,
36 	struct vprbrd_i2c_status *status, bool prev_error)
37 {
38 	u16 bytes_xfer;
39 	int ret;
40 	struct vprbrd *vb = (struct vprbrd *)i2c->algo_data;
41 
42 	/* check for protocol error */
43 	bytes_xfer = sizeof(struct vprbrd_i2c_status);
44 
45 	ret = usb_control_msg(vb->usb_dev, usb_rcvctrlpipe(vb->usb_dev, 0),
46 		VPRBRD_USB_REQUEST_I2C, VPRBRD_USB_TYPE_IN, 0x0000, 0x0000,
47 		status, bytes_xfer, VPRBRD_USB_TIMEOUT_MS);
48 
49 	if (ret != bytes_xfer)
50 		prev_error = true;
51 
52 	if (prev_error) {
53 		dev_err(&i2c->dev, "failure in usb communication\n");
54 		return -EREMOTEIO;
55 	}
56 
57 	dev_dbg(&i2c->dev, "  status = %d\n", status->status);
58 	if (status->status != 0x00) {
59 		dev_err(&i2c->dev, "failure: i2c protocol error\n");
60 		return -EPROTO;
61 	}
62 	return 0;
63 }
64 
65 static int vprbrd_i2c_receive(struct usb_device *usb_dev,
66 	struct vprbrd_i2c_read_msg *rmsg, int bytes_xfer)
67 {
68 	int ret, bytes_actual;
69 	int error = 0;
70 
71 	/* send the read request */
72 	ret = usb_bulk_msg(usb_dev,
73 		usb_sndbulkpipe(usb_dev, VPRBRD_EP_OUT), rmsg,
74 		sizeof(struct vprbrd_i2c_read_hdr), &bytes_actual,
75 		VPRBRD_USB_TIMEOUT_MS);
76 
77 	if ((ret < 0)
78 		|| (bytes_actual != sizeof(struct vprbrd_i2c_read_hdr))) {
79 		dev_err(&usb_dev->dev, "failure transmitting usb\n");
80 		error = -EREMOTEIO;
81 	}
82 
83 	/* read the actual data */
84 	ret = usb_bulk_msg(usb_dev,
85 		usb_rcvbulkpipe(usb_dev, VPRBRD_EP_IN), rmsg,
86 		bytes_xfer, &bytes_actual, VPRBRD_USB_TIMEOUT_MS);
87 
88 	if ((ret < 0) || (bytes_xfer != bytes_actual)) {
89 		dev_err(&usb_dev->dev, "failure receiving usb\n");
90 		error = -EREMOTEIO;
91 	}
92 	return error;
93 }
94 
95 static int vprbrd_i2c_addr(struct usb_device *usb_dev,
96 	struct vprbrd_i2c_addr_msg *amsg)
97 {
98 	int ret, bytes_actual;
99 
100 	ret = usb_bulk_msg(usb_dev,
101 		usb_sndbulkpipe(usb_dev, VPRBRD_EP_OUT), amsg,
102 		sizeof(struct vprbrd_i2c_addr_msg), &bytes_actual,
103 		VPRBRD_USB_TIMEOUT_MS);
104 
105 	if ((ret < 0) ||
106 			(sizeof(struct vprbrd_i2c_addr_msg) != bytes_actual)) {
107 		dev_err(&usb_dev->dev, "failure transmitting usb\n");
108 		return -EREMOTEIO;
109 	}
110 	return 0;
111 }
112 
113 static int vprbrd_i2c_read(struct vprbrd *vb, struct i2c_msg *msg)
114 {
115 	int ret;
116 	u16 remain_len, len1, len2, start = 0x0000;
117 	struct vprbrd_i2c_read_msg *rmsg =
118 		(struct vprbrd_i2c_read_msg *)vb->buf;
119 
120 	remain_len = msg->len;
121 	rmsg->header.cmd = VPRBRD_I2C_CMD_READ;
122 	while (remain_len > 0) {
123 		rmsg->header.addr = cpu_to_le16(start + 0x4000);
124 		if (remain_len <= 255) {
125 			len1 = remain_len;
126 			len2 = 0x00;
127 			rmsg->header.len0 = remain_len;
128 			rmsg->header.len1 = 0x00;
129 			rmsg->header.len2 = 0x00;
130 			rmsg->header.len3 = 0x00;
131 			rmsg->header.len4 = 0x00;
132 			rmsg->header.len5 = 0x00;
133 			remain_len = 0;
134 		} else if (remain_len <= 510) {
135 			len1 = remain_len;
136 			len2 = 0x00;
137 			rmsg->header.len0 = remain_len - 255;
138 			rmsg->header.len1 = 0xff;
139 			rmsg->header.len2 = 0x00;
140 			rmsg->header.len3 = 0x00;
141 			rmsg->header.len4 = 0x00;
142 			rmsg->header.len5 = 0x00;
143 			remain_len = 0;
144 		} else if (remain_len <= 512) {
145 			len1 = remain_len;
146 			len2 = 0x00;
147 			rmsg->header.len0 = remain_len - 510;
148 			rmsg->header.len1 = 0xff;
149 			rmsg->header.len2 = 0xff;
150 			rmsg->header.len3 = 0x00;
151 			rmsg->header.len4 = 0x00;
152 			rmsg->header.len5 = 0x00;
153 			remain_len = 0;
154 		} else if (remain_len <= 767) {
155 			len1 = 512;
156 			len2 = remain_len - 512;
157 			rmsg->header.len0 = 0x02;
158 			rmsg->header.len1 = 0xff;
159 			rmsg->header.len2 = 0xff;
160 			rmsg->header.len3 = remain_len - 512;
161 			rmsg->header.len4 = 0x00;
162 			rmsg->header.len5 = 0x00;
163 			remain_len = 0;
164 		} else if (remain_len <= 1022) {
165 			len1 = 512;
166 			len2 = remain_len - 512;
167 			rmsg->header.len0 = 0x02;
168 			rmsg->header.len1 = 0xff;
169 			rmsg->header.len2 = 0xff;
170 			rmsg->header.len3 = remain_len - 767;
171 			rmsg->header.len4 = 0xff;
172 			rmsg->header.len5 = 0x00;
173 			remain_len = 0;
174 		} else if (remain_len <= 1024) {
175 			len1 = 512;
176 			len2 = remain_len - 512;
177 			rmsg->header.len0 = 0x02;
178 			rmsg->header.len1 = 0xff;
179 			rmsg->header.len2 = 0xff;
180 			rmsg->header.len3 = remain_len - 1022;
181 			rmsg->header.len4 = 0xff;
182 			rmsg->header.len5 = 0xff;
183 			remain_len = 0;
184 		} else {
185 			len1 = 512;
186 			len2 = 512;
187 			rmsg->header.len0 = 0x02;
188 			rmsg->header.len1 = 0xff;
189 			rmsg->header.len2 = 0xff;
190 			rmsg->header.len3 = 0x02;
191 			rmsg->header.len4 = 0xff;
192 			rmsg->header.len5 = 0xff;
193 			remain_len -= 1024;
194 			start += 1024;
195 		}
196 		rmsg->header.tf1 = cpu_to_le16(len1);
197 		rmsg->header.tf2 = cpu_to_le16(len2);
198 
199 		/* first read transfer */
200 		ret = vprbrd_i2c_receive(vb->usb_dev, rmsg, len1);
201 		if (ret < 0)
202 			return ret;
203 		/* copy the received data */
204 		memcpy(msg->buf + start, rmsg, len1);
205 
206 		/* second read transfer if neccessary */
207 		if (len2 > 0) {
208 			ret = vprbrd_i2c_receive(vb->usb_dev, rmsg, len2);
209 			if (ret < 0)
210 				return ret;
211 			/* copy the received data */
212 			memcpy(msg->buf + start + 512, rmsg, len2);
213 		}
214 	}
215 	return 0;
216 }
217 
218 static int vprbrd_i2c_write(struct vprbrd *vb, struct i2c_msg *msg)
219 {
220 	int ret, bytes_actual;
221 	u16 remain_len, bytes_xfer,
222 		start = 0x0000;
223 	struct vprbrd_i2c_write_msg *wmsg =
224 		(struct vprbrd_i2c_write_msg *)vb->buf;
225 
226 	remain_len = msg->len;
227 	wmsg->header.cmd = VPRBRD_I2C_CMD_WRITE;
228 	wmsg->header.last = 0x00;
229 	wmsg->header.chan = 0x00;
230 	wmsg->header.spi = 0x0000;
231 	while (remain_len > 0) {
232 		wmsg->header.addr = cpu_to_le16(start + 0x4000);
233 		if (remain_len > 503) {
234 			wmsg->header.len1 = 0xff;
235 			wmsg->header.len2 = 0xf8;
236 			remain_len -= 503;
237 			bytes_xfer = 503 + sizeof(struct vprbrd_i2c_write_hdr);
238 			start += 503;
239 		} else if (remain_len > 255) {
240 			wmsg->header.len1 = 0xff;
241 			wmsg->header.len2 = (remain_len - 255);
242 			bytes_xfer = remain_len +
243 				sizeof(struct vprbrd_i2c_write_hdr);
244 			remain_len = 0;
245 		} else {
246 			wmsg->header.len1 = remain_len;
247 			wmsg->header.len2 = 0x00;
248 			bytes_xfer = remain_len +
249 				sizeof(struct vprbrd_i2c_write_hdr);
250 			remain_len = 0;
251 		}
252 		memcpy(wmsg->data, msg->buf + start,
253 			bytes_xfer - sizeof(struct vprbrd_i2c_write_hdr));
254 
255 		ret = usb_bulk_msg(vb->usb_dev,
256 			usb_sndbulkpipe(vb->usb_dev,
257 			VPRBRD_EP_OUT), wmsg,
258 			bytes_xfer, &bytes_actual, VPRBRD_USB_TIMEOUT_MS);
259 		if ((ret < 0) || (bytes_xfer != bytes_actual))
260 			return -EREMOTEIO;
261 	}
262 	return 0;
263 }
264 
265 static int vprbrd_i2c_xfer(struct i2c_adapter *i2c, struct i2c_msg *msgs,
266 		int num)
267 {
268 	struct i2c_msg *pmsg;
269 	int i, ret,
270 		error = 0;
271 	struct vprbrd *vb = (struct vprbrd *)i2c->algo_data;
272 	struct vprbrd_i2c_addr_msg *amsg =
273 		(struct vprbrd_i2c_addr_msg *)vb->buf;
274 	struct vprbrd_i2c_status *smsg = (struct vprbrd_i2c_status *)vb->buf;
275 
276 	dev_dbg(&i2c->dev, "master xfer %d messages:\n", num);
277 
278 	for (i = 0 ; i < num ; i++) {
279 		pmsg = &msgs[i];
280 
281 		dev_dbg(&i2c->dev,
282 			"  %d: %s (flags %d) %d bytes to 0x%02x\n",
283 			i, pmsg->flags & I2C_M_RD ? "read" : "write",
284 			pmsg->flags, pmsg->len, pmsg->addr);
285 
286 		mutex_lock(&vb->lock);
287 		/* directly send the message */
288 		if (pmsg->flags & I2C_M_RD) {
289 			/* read data */
290 			amsg->cmd = VPRBRD_I2C_CMD_ADDR;
291 			amsg->unknown2 = 0x00;
292 			amsg->unknown3 = 0x00;
293 			amsg->addr = pmsg->addr;
294 			amsg->unknown1 = 0x01;
295 			amsg->len = cpu_to_le16(pmsg->len);
296 			/* send the addr and len, we're interested to board */
297 			ret = vprbrd_i2c_addr(vb->usb_dev, amsg);
298 			if (ret < 0)
299 				error = ret;
300 
301 			ret = vprbrd_i2c_read(vb, pmsg);
302 			if (ret < 0)
303 				error = ret;
304 
305 			ret = vprbrd_i2c_status(i2c, smsg, error);
306 			if (ret < 0)
307 				error = ret;
308 			/* in case of protocol error, return the error */
309 			if (error < 0)
310 				goto error;
311 		} else {
312 			/* write data */
313 			ret = vprbrd_i2c_write(vb, pmsg);
314 
315 			amsg->cmd = VPRBRD_I2C_CMD_ADDR;
316 			amsg->unknown2 = 0x00;
317 			amsg->unknown3 = 0x00;
318 			amsg->addr = pmsg->addr;
319 			amsg->unknown1 = 0x00;
320 			amsg->len = cpu_to_le16(pmsg->len);
321 			/* send the addr, the data goes to to board */
322 			ret = vprbrd_i2c_addr(vb->usb_dev, amsg);
323 			if (ret < 0)
324 				error = ret;
325 
326 			ret = vprbrd_i2c_status(i2c, smsg, error);
327 			if (ret < 0)
328 				error = ret;
329 
330 			if (error < 0)
331 				goto error;
332 		}
333 		mutex_unlock(&vb->lock);
334 	}
335 	return num;
336 error:
337 	mutex_unlock(&vb->lock);
338 	return error;
339 }
340 
341 static u32 vprbrd_i2c_func(struct i2c_adapter *i2c)
342 {
343 	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
344 }
345 
346 /* This is the actual algorithm we define */
347 static const struct i2c_algorithm vprbrd_algorithm = {
348 	.master_xfer	= vprbrd_i2c_xfer,
349 	.functionality	= vprbrd_i2c_func,
350 };
351 
352 static const struct i2c_adapter_quirks vprbrd_quirks = {
353 	.max_read_len = 2048,
354 	.max_write_len = 2048,
355 };
356 
357 static int vprbrd_i2c_probe(struct platform_device *pdev)
358 {
359 	struct vprbrd *vb = dev_get_drvdata(pdev->dev.parent);
360 	struct vprbrd_i2c *vb_i2c;
361 	int ret;
362 	int pipe;
363 
364 	vb_i2c = devm_kzalloc(&pdev->dev, sizeof(*vb_i2c), GFP_KERNEL);
365 	if (vb_i2c == NULL)
366 		return -ENOMEM;
367 
368 	/* setup i2c adapter description */
369 	vb_i2c->i2c.owner = THIS_MODULE;
370 	vb_i2c->i2c.class = I2C_CLASS_HWMON;
371 	vb_i2c->i2c.algo = &vprbrd_algorithm;
372 	vb_i2c->i2c.quirks = &vprbrd_quirks;
373 	vb_i2c->i2c.algo_data = vb;
374 	/* save the param in usb capabable memory */
375 	vb_i2c->bus_freq_param = i2c_bus_param;
376 
377 	snprintf(vb_i2c->i2c.name, sizeof(vb_i2c->i2c.name),
378 		 "viperboard at bus %03d device %03d",
379 		 vb->usb_dev->bus->busnum, vb->usb_dev->devnum);
380 
381 	/* setting the bus frequency */
382 	if ((i2c_bus_param <= VPRBRD_I2C_FREQ_10KHZ)
383 		&& (i2c_bus_param >= VPRBRD_I2C_FREQ_6MHZ)) {
384 		pipe = usb_sndctrlpipe(vb->usb_dev, 0);
385 		ret = usb_control_msg(vb->usb_dev, pipe,
386 			VPRBRD_USB_REQUEST_I2C_FREQ, VPRBRD_USB_TYPE_OUT,
387 			0x0000, 0x0000, &vb_i2c->bus_freq_param, 1,
388 			VPRBRD_USB_TIMEOUT_MS);
389 		if (ret != 1) {
390 			dev_err(&pdev->dev, "failure setting i2c_bus_freq to %d\n",
391 				i2c_bus_freq);
392 			return -EIO;
393 		}
394 	} else {
395 		dev_err(&pdev->dev,
396 			"invalid i2c_bus_freq setting:%d\n", i2c_bus_freq);
397 		return -EIO;
398 	}
399 
400 	vb_i2c->i2c.dev.parent = &pdev->dev;
401 
402 	/* attach to i2c layer */
403 	i2c_add_adapter(&vb_i2c->i2c);
404 
405 	platform_set_drvdata(pdev, vb_i2c);
406 
407 	return 0;
408 }
409 
410 static void vprbrd_i2c_remove(struct platform_device *pdev)
411 {
412 	struct vprbrd_i2c *vb_i2c = platform_get_drvdata(pdev);
413 
414 	i2c_del_adapter(&vb_i2c->i2c);
415 }
416 
417 static struct platform_driver vprbrd_i2c_driver = {
418 	.driver.name	= "viperboard-i2c",
419 	.driver.owner	= THIS_MODULE,
420 	.probe		= vprbrd_i2c_probe,
421 	.remove_new	= vprbrd_i2c_remove,
422 };
423 
424 static int __init vprbrd_i2c_init(void)
425 {
426 	switch (i2c_bus_freq) {
427 	case 6000:
428 		i2c_bus_param = VPRBRD_I2C_FREQ_6MHZ;
429 		break;
430 	case 3000:
431 		i2c_bus_param = VPRBRD_I2C_FREQ_3MHZ;
432 		break;
433 	case 1000:
434 		i2c_bus_param = VPRBRD_I2C_FREQ_1MHZ;
435 		break;
436 	case 400:
437 		i2c_bus_param = VPRBRD_I2C_FREQ_400KHZ;
438 		break;
439 	case 200:
440 		i2c_bus_param = VPRBRD_I2C_FREQ_200KHZ;
441 		break;
442 	case 100:
443 		i2c_bus_param = VPRBRD_I2C_FREQ_100KHZ;
444 		break;
445 	case 10:
446 		i2c_bus_param = VPRBRD_I2C_FREQ_10KHZ;
447 		break;
448 	default:
449 		pr_warn("invalid i2c_bus_freq (%d)\n", i2c_bus_freq);
450 		i2c_bus_param = VPRBRD_I2C_FREQ_100KHZ;
451 	}
452 
453 	return platform_driver_register(&vprbrd_i2c_driver);
454 }
455 subsys_initcall(vprbrd_i2c_init);
456 
457 static void __exit vprbrd_i2c_exit(void)
458 {
459 	platform_driver_unregister(&vprbrd_i2c_driver);
460 }
461 module_exit(vprbrd_i2c_exit);
462 
463 MODULE_AUTHOR("Lars Poeschel <poeschel@lemonage.de>");
464 MODULE_DESCRIPTION("I2C master driver for Nano River Techs Viperboard");
465 MODULE_LICENSE("GPL");
466 MODULE_ALIAS("platform:viperboard-i2c");
467