1/*
2 *  Nano River Technologies viperboard i2c master driver
3 *
4 *  (C) 2012 by Lemonage GmbH
5 *  Author: Lars Poeschel <poeschel@lemonage.de>
6 *  All rights reserved.
7 *
8 *  This program is free software; you can redistribute  it and/or modify it
9 *  under  the terms of  the GNU General  Public License as published by the
10 *  Free Software Foundation;  either version 2 of the	License, or (at your
11 *  option) any later version.
12 *
13 */
14
15#include <linux/kernel.h>
16#include <linux/errno.h>
17#include <linux/module.h>
18#include <linux/slab.h>
19#include <linux/types.h>
20#include <linux/mutex.h>
21#include <linux/platform_device.h>
22
23#include <linux/usb.h>
24#include <linux/i2c.h>
25
26#include <linux/mfd/viperboard.h>
27
28struct vprbrd_i2c {
29	struct i2c_adapter i2c;
30	u8 bus_freq_param;
31};
32
33/* i2c bus frequency module parameter */
34static u8 i2c_bus_param;
35static unsigned int i2c_bus_freq = 100;
36module_param(i2c_bus_freq, int, 0);
37MODULE_PARM_DESC(i2c_bus_freq,
38	"i2c bus frequency in khz (default is 100) valid values: 10, 100, 200, 400, 1000, 3000, 6000");
39
40static int vprbrd_i2c_status(struct i2c_adapter *i2c,
41	struct vprbrd_i2c_status *status, bool prev_error)
42{
43	u16 bytes_xfer;
44	int ret;
45	struct vprbrd *vb = (struct vprbrd *)i2c->algo_data;
46
47	/* check for protocol error */
48	bytes_xfer = sizeof(struct vprbrd_i2c_status);
49
50	ret = usb_control_msg(vb->usb_dev, usb_rcvctrlpipe(vb->usb_dev, 0),
51		VPRBRD_USB_REQUEST_I2C, VPRBRD_USB_TYPE_IN, 0x0000, 0x0000,
52		status, bytes_xfer, VPRBRD_USB_TIMEOUT_MS);
53
54	if (ret != bytes_xfer)
55		prev_error = true;
56
57	if (prev_error) {
58		dev_err(&i2c->dev, "failure in usb communication\n");
59		return -EREMOTEIO;
60	}
61
62	dev_dbg(&i2c->dev, "  status = %d\n", status->status);
63	if (status->status != 0x00) {
64		dev_err(&i2c->dev, "failure: i2c protocol error\n");
65		return -EPROTO;
66	}
67	return 0;
68}
69
70static int vprbrd_i2c_receive(struct usb_device *usb_dev,
71	struct vprbrd_i2c_read_msg *rmsg, int bytes_xfer)
72{
73	int ret, bytes_actual;
74	int error = 0;
75
76	/* send the read request */
77	ret = usb_bulk_msg(usb_dev,
78		usb_sndbulkpipe(usb_dev, VPRBRD_EP_OUT), rmsg,
79		sizeof(struct vprbrd_i2c_read_hdr), &bytes_actual,
80		VPRBRD_USB_TIMEOUT_MS);
81
82	if ((ret < 0)
83		|| (bytes_actual != sizeof(struct vprbrd_i2c_read_hdr))) {
84		dev_err(&usb_dev->dev, "failure transmitting usb\n");
85		error = -EREMOTEIO;
86	}
87
88	/* read the actual data */
89	ret = usb_bulk_msg(usb_dev,
90		usb_rcvbulkpipe(usb_dev, VPRBRD_EP_IN), rmsg,
91		bytes_xfer, &bytes_actual, VPRBRD_USB_TIMEOUT_MS);
92
93	if ((ret < 0) || (bytes_xfer != bytes_actual)) {
94		dev_err(&usb_dev->dev, "failure receiving usb\n");
95		error = -EREMOTEIO;
96	}
97	return error;
98}
99
100static int vprbrd_i2c_addr(struct usb_device *usb_dev,
101	struct vprbrd_i2c_addr_msg *amsg)
102{
103	int ret, bytes_actual;
104
105	ret = usb_bulk_msg(usb_dev,
106		usb_sndbulkpipe(usb_dev, VPRBRD_EP_OUT), amsg,
107		sizeof(struct vprbrd_i2c_addr_msg), &bytes_actual,
108		VPRBRD_USB_TIMEOUT_MS);
109
110	if ((ret < 0) ||
111			(sizeof(struct vprbrd_i2c_addr_msg) != bytes_actual)) {
112		dev_err(&usb_dev->dev, "failure transmitting usb\n");
113		return -EREMOTEIO;
114	}
115	return 0;
116}
117
118static int vprbrd_i2c_read(struct vprbrd *vb, struct i2c_msg *msg)
119{
120	int ret;
121	u16 remain_len, len1, len2, start = 0x0000;
122	struct vprbrd_i2c_read_msg *rmsg =
123		(struct vprbrd_i2c_read_msg *)vb->buf;
124
125	remain_len = msg->len;
126	rmsg->header.cmd = VPRBRD_I2C_CMD_READ;
127	while (remain_len > 0) {
128		rmsg->header.addr = cpu_to_le16(start + 0x4000);
129		if (remain_len <= 255) {
130			len1 = remain_len;
131			len2 = 0x00;
132			rmsg->header.len0 = remain_len;
133			rmsg->header.len1 = 0x00;
134			rmsg->header.len2 = 0x00;
135			rmsg->header.len3 = 0x00;
136			rmsg->header.len4 = 0x00;
137			rmsg->header.len5 = 0x00;
138			remain_len = 0;
139		} else if (remain_len <= 510) {
140			len1 = remain_len;
141			len2 = 0x00;
142			rmsg->header.len0 = remain_len - 255;
143			rmsg->header.len1 = 0xff;
144			rmsg->header.len2 = 0x00;
145			rmsg->header.len3 = 0x00;
146			rmsg->header.len4 = 0x00;
147			rmsg->header.len5 = 0x00;
148			remain_len = 0;
149		} else if (remain_len <= 512) {
150			len1 = remain_len;
151			len2 = 0x00;
152			rmsg->header.len0 = remain_len - 510;
153			rmsg->header.len1 = 0xff;
154			rmsg->header.len2 = 0xff;
155			rmsg->header.len3 = 0x00;
156			rmsg->header.len4 = 0x00;
157			rmsg->header.len5 = 0x00;
158			remain_len = 0;
159		} else if (remain_len <= 767) {
160			len1 = 512;
161			len2 = remain_len - 512;
162			rmsg->header.len0 = 0x02;
163			rmsg->header.len1 = 0xff;
164			rmsg->header.len2 = 0xff;
165			rmsg->header.len3 = remain_len - 512;
166			rmsg->header.len4 = 0x00;
167			rmsg->header.len5 = 0x00;
168			remain_len = 0;
169		} else if (remain_len <= 1022) {
170			len1 = 512;
171			len2 = remain_len - 512;
172			rmsg->header.len0 = 0x02;
173			rmsg->header.len1 = 0xff;
174			rmsg->header.len2 = 0xff;
175			rmsg->header.len3 = remain_len - 767;
176			rmsg->header.len4 = 0xff;
177			rmsg->header.len5 = 0x00;
178			remain_len = 0;
179		} else if (remain_len <= 1024) {
180			len1 = 512;
181			len2 = remain_len - 512;
182			rmsg->header.len0 = 0x02;
183			rmsg->header.len1 = 0xff;
184			rmsg->header.len2 = 0xff;
185			rmsg->header.len3 = remain_len - 1022;
186			rmsg->header.len4 = 0xff;
187			rmsg->header.len5 = 0xff;
188			remain_len = 0;
189		} else {
190			len1 = 512;
191			len2 = 512;
192			rmsg->header.len0 = 0x02;
193			rmsg->header.len1 = 0xff;
194			rmsg->header.len2 = 0xff;
195			rmsg->header.len3 = 0x02;
196			rmsg->header.len4 = 0xff;
197			rmsg->header.len5 = 0xff;
198			remain_len -= 1024;
199			start += 1024;
200		}
201		rmsg->header.tf1 = cpu_to_le16(len1);
202		rmsg->header.tf2 = cpu_to_le16(len2);
203
204		/* first read transfer */
205		ret = vprbrd_i2c_receive(vb->usb_dev, rmsg, len1);
206		if (ret < 0)
207			return ret;
208		/* copy the received data */
209		memcpy(msg->buf + start, rmsg, len1);
210
211		/* second read transfer if neccessary */
212		if (len2 > 0) {
213			ret = vprbrd_i2c_receive(vb->usb_dev, rmsg, len2);
214			if (ret < 0)
215				return ret;
216			/* copy the received data */
217			memcpy(msg->buf + start + 512, rmsg, len2);
218		}
219	}
220	return 0;
221}
222
223static int vprbrd_i2c_write(struct vprbrd *vb, struct i2c_msg *msg)
224{
225	int ret, bytes_actual;
226	u16 remain_len, bytes_xfer,
227		start = 0x0000;
228	struct vprbrd_i2c_write_msg *wmsg =
229		(struct vprbrd_i2c_write_msg *)vb->buf;
230
231	remain_len = msg->len;
232	wmsg->header.cmd = VPRBRD_I2C_CMD_WRITE;
233	wmsg->header.last = 0x00;
234	wmsg->header.chan = 0x00;
235	wmsg->header.spi = 0x0000;
236	while (remain_len > 0) {
237		wmsg->header.addr = cpu_to_le16(start + 0x4000);
238		if (remain_len > 503) {
239			wmsg->header.len1 = 0xff;
240			wmsg->header.len2 = 0xf8;
241			remain_len -= 503;
242			bytes_xfer = 503 + sizeof(struct vprbrd_i2c_write_hdr);
243			start += 503;
244		} else if (remain_len > 255) {
245			wmsg->header.len1 = 0xff;
246			wmsg->header.len2 = (remain_len - 255);
247			bytes_xfer = remain_len +
248				sizeof(struct vprbrd_i2c_write_hdr);
249			remain_len = 0;
250		} else {
251			wmsg->header.len1 = remain_len;
252			wmsg->header.len2 = 0x00;
253			bytes_xfer = remain_len +
254				sizeof(struct vprbrd_i2c_write_hdr);
255			remain_len = 0;
256		}
257		memcpy(wmsg->data, msg->buf + start,
258			bytes_xfer - sizeof(struct vprbrd_i2c_write_hdr));
259
260		ret = usb_bulk_msg(vb->usb_dev,
261			usb_sndbulkpipe(vb->usb_dev,
262			VPRBRD_EP_OUT), wmsg,
263			bytes_xfer, &bytes_actual, VPRBRD_USB_TIMEOUT_MS);
264		if ((ret < 0) || (bytes_xfer != bytes_actual))
265			return -EREMOTEIO;
266	}
267	return 0;
268}
269
270static int vprbrd_i2c_xfer(struct i2c_adapter *i2c, struct i2c_msg *msgs,
271		int num)
272{
273	struct i2c_msg *pmsg;
274	int i, ret,
275		error = 0;
276	struct vprbrd *vb = (struct vprbrd *)i2c->algo_data;
277	struct vprbrd_i2c_addr_msg *amsg =
278		(struct vprbrd_i2c_addr_msg *)vb->buf;
279	struct vprbrd_i2c_status *smsg = (struct vprbrd_i2c_status *)vb->buf;
280
281	dev_dbg(&i2c->dev, "master xfer %d messages:\n", num);
282
283	for (i = 0 ; i < num ; i++) {
284		pmsg = &msgs[i];
285
286		dev_dbg(&i2c->dev,
287			"  %d: %s (flags %d) %d bytes to 0x%02x\n",
288			i, pmsg->flags & I2C_M_RD ? "read" : "write",
289			pmsg->flags, pmsg->len, pmsg->addr);
290
291		mutex_lock(&vb->lock);
292		/* directly send the message */
293		if (pmsg->flags & I2C_M_RD) {
294			/* read data */
295			amsg->cmd = VPRBRD_I2C_CMD_ADDR;
296			amsg->unknown2 = 0x00;
297			amsg->unknown3 = 0x00;
298			amsg->addr = pmsg->addr;
299			amsg->unknown1 = 0x01;
300			amsg->len = cpu_to_le16(pmsg->len);
301			/* send the addr and len, we're interested to board */
302			ret = vprbrd_i2c_addr(vb->usb_dev, amsg);
303			if (ret < 0)
304				error = ret;
305
306			ret = vprbrd_i2c_read(vb, pmsg);
307			if (ret < 0)
308				error = ret;
309
310			ret = vprbrd_i2c_status(i2c, smsg, error);
311			if (ret < 0)
312				error = ret;
313			/* in case of protocol error, return the error */
314			if (error < 0)
315				goto error;
316		} else {
317			/* write data */
318			ret = vprbrd_i2c_write(vb, pmsg);
319
320			amsg->cmd = VPRBRD_I2C_CMD_ADDR;
321			amsg->unknown2 = 0x00;
322			amsg->unknown3 = 0x00;
323			amsg->addr = pmsg->addr;
324			amsg->unknown1 = 0x00;
325			amsg->len = cpu_to_le16(pmsg->len);
326			/* send the addr, the data goes to to board */
327			ret = vprbrd_i2c_addr(vb->usb_dev, amsg);
328			if (ret < 0)
329				error = ret;
330
331			ret = vprbrd_i2c_status(i2c, smsg, error);
332			if (ret < 0)
333				error = ret;
334
335			if (error < 0)
336				goto error;
337		}
338		mutex_unlock(&vb->lock);
339	}
340	return 0;
341error:
342	mutex_unlock(&vb->lock);
343	return error;
344}
345
346static u32 vprbrd_i2c_func(struct i2c_adapter *i2c)
347{
348	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
349}
350
351/* This is the actual algorithm we define */
352static const struct i2c_algorithm vprbrd_algorithm = {
353	.master_xfer	= vprbrd_i2c_xfer,
354	.functionality	= vprbrd_i2c_func,
355};
356
357static struct i2c_adapter_quirks vprbrd_quirks = {
358	.max_read_len = 2048,
359	.max_write_len = 2048,
360};
361
362static int vprbrd_i2c_probe(struct platform_device *pdev)
363{
364	struct vprbrd *vb = dev_get_drvdata(pdev->dev.parent);
365	struct vprbrd_i2c *vb_i2c;
366	int ret;
367	int pipe;
368
369	vb_i2c = devm_kzalloc(&pdev->dev, sizeof(*vb_i2c), GFP_KERNEL);
370	if (vb_i2c == NULL)
371		return -ENOMEM;
372
373	/* setup i2c adapter description */
374	vb_i2c->i2c.owner = THIS_MODULE;
375	vb_i2c->i2c.class = I2C_CLASS_HWMON;
376	vb_i2c->i2c.algo = &vprbrd_algorithm;
377	vb_i2c->i2c.quirks = &vprbrd_quirks;
378	vb_i2c->i2c.algo_data = vb;
379	/* save the param in usb capabable memory */
380	vb_i2c->bus_freq_param = i2c_bus_param;
381
382	snprintf(vb_i2c->i2c.name, sizeof(vb_i2c->i2c.name),
383		 "viperboard at bus %03d device %03d",
384		 vb->usb_dev->bus->busnum, vb->usb_dev->devnum);
385
386	/* setting the bus frequency */
387	if ((i2c_bus_param <= VPRBRD_I2C_FREQ_10KHZ)
388		&& (i2c_bus_param >= VPRBRD_I2C_FREQ_6MHZ)) {
389		pipe = usb_sndctrlpipe(vb->usb_dev, 0);
390		ret = usb_control_msg(vb->usb_dev, pipe,
391			VPRBRD_USB_REQUEST_I2C_FREQ, VPRBRD_USB_TYPE_OUT,
392			0x0000, 0x0000, &vb_i2c->bus_freq_param, 1,
393			VPRBRD_USB_TIMEOUT_MS);
394		if (ret != 1) {
395			dev_err(&pdev->dev, "failure setting i2c_bus_freq to %d\n",
396				i2c_bus_freq);
397			return -EIO;
398		}
399	} else {
400		dev_err(&pdev->dev,
401			"invalid i2c_bus_freq setting:%d\n", i2c_bus_freq);
402		return -EIO;
403	}
404
405	vb_i2c->i2c.dev.parent = &pdev->dev;
406
407	/* attach to i2c layer */
408	i2c_add_adapter(&vb_i2c->i2c);
409
410	platform_set_drvdata(pdev, vb_i2c);
411
412	return 0;
413}
414
415static int vprbrd_i2c_remove(struct platform_device *pdev)
416{
417	struct vprbrd_i2c *vb_i2c = platform_get_drvdata(pdev);
418
419	i2c_del_adapter(&vb_i2c->i2c);
420
421	return 0;
422}
423
424static struct platform_driver vprbrd_i2c_driver = {
425	.driver.name	= "viperboard-i2c",
426	.driver.owner	= THIS_MODULE,
427	.probe		= vprbrd_i2c_probe,
428	.remove		= vprbrd_i2c_remove,
429};
430
431static int __init vprbrd_i2c_init(void)
432{
433	switch (i2c_bus_freq) {
434	case 6000:
435		i2c_bus_param = VPRBRD_I2C_FREQ_6MHZ;
436		break;
437	case 3000:
438		i2c_bus_param = VPRBRD_I2C_FREQ_3MHZ;
439		break;
440	case 1000:
441		i2c_bus_param = VPRBRD_I2C_FREQ_1MHZ;
442		break;
443	case 400:
444		i2c_bus_param = VPRBRD_I2C_FREQ_400KHZ;
445		break;
446	case 200:
447		i2c_bus_param = VPRBRD_I2C_FREQ_200KHZ;
448		break;
449	case 100:
450		i2c_bus_param = VPRBRD_I2C_FREQ_100KHZ;
451		break;
452	case 10:
453		i2c_bus_param = VPRBRD_I2C_FREQ_10KHZ;
454		break;
455	default:
456		pr_warn("invalid i2c_bus_freq (%d)\n", i2c_bus_freq);
457		i2c_bus_param = VPRBRD_I2C_FREQ_100KHZ;
458	}
459
460	return platform_driver_register(&vprbrd_i2c_driver);
461}
462subsys_initcall(vprbrd_i2c_init);
463
464static void __exit vprbrd_i2c_exit(void)
465{
466	platform_driver_unregister(&vprbrd_i2c_driver);
467}
468module_exit(vprbrd_i2c_exit);
469
470MODULE_AUTHOR("Lars Poeschel <poeschel@lemonage.de>");
471MODULE_DESCRIPTION("I2C master driver for Nano River Techs Viperboard");
472MODULE_LICENSE("GPL");
473MODULE_ALIAS("platform:viperboard-i2c");
474