1 /*
2  * HID over I2C protocol implementation
3  *
4  * Copyright (c) 2012 Benjamin Tissoires <benjamin.tissoires@gmail.com>
5  * Copyright (c) 2012 Ecole Nationale de l'Aviation Civile, France
6  * Copyright (c) 2012 Red Hat, Inc
7  *
8  * This code is partly based on "USB HID support for Linux":
9  *
10  *  Copyright (c) 1999 Andreas Gal
11  *  Copyright (c) 2000-2005 Vojtech Pavlik <vojtech@suse.cz>
12  *  Copyright (c) 2005 Michael Haboustak <mike-@cinci.rr.com> for Concept2, Inc
13  *  Copyright (c) 2007-2008 Oliver Neukum
14  *  Copyright (c) 2006-2010 Jiri Kosina
15  *
16  * This file is subject to the terms and conditions of the GNU General Public
17  * License.  See the file COPYING in the main directory of this archive for
18  * more details.
19  */
20 
21 #include <linux/module.h>
22 #include <linux/i2c.h>
23 #include <linux/interrupt.h>
24 #include <linux/input.h>
25 #include <linux/irq.h>
26 #include <linux/delay.h>
27 #include <linux/slab.h>
28 #include <linux/pm.h>
29 #include <linux/device.h>
30 #include <linux/wait.h>
31 #include <linux/err.h>
32 #include <linux/string.h>
33 #include <linux/list.h>
34 #include <linux/jiffies.h>
35 #include <linux/kernel.h>
36 #include <linux/hid.h>
37 #include <linux/mutex.h>
38 
39 #include "../hid-ids.h"
40 #include "i2c-hid.h"
41 
42 /* quirks to control the device */
43 #define I2C_HID_QUIRK_SET_PWR_WAKEUP_DEV	BIT(0)
44 #define I2C_HID_QUIRK_NO_IRQ_AFTER_RESET	BIT(1)
45 #define I2C_HID_QUIRK_BOGUS_IRQ			BIT(4)
46 #define I2C_HID_QUIRK_RESET_ON_RESUME		BIT(5)
47 #define I2C_HID_QUIRK_BAD_INPUT_SIZE		BIT(6)
48 #define I2C_HID_QUIRK_NO_WAKEUP_AFTER_RESET	BIT(7)
49 
50 
51 /* flags */
52 #define I2C_HID_STARTED		0
53 #define I2C_HID_RESET_PENDING	1
54 #define I2C_HID_READ_PENDING	2
55 
56 #define I2C_HID_PWR_ON		0x00
57 #define I2C_HID_PWR_SLEEP	0x01
58 
59 /* debug option */
60 static bool debug;
61 module_param(debug, bool, 0444);
62 MODULE_PARM_DESC(debug, "print a lot of debug information");
63 
64 #define i2c_hid_dbg(ihid, fmt, arg...)					  \
65 do {									  \
66 	if (debug)							  \
67 		dev_printk(KERN_DEBUG, &(ihid)->client->dev, fmt, ##arg); \
68 } while (0)
69 
70 struct i2c_hid_desc {
71 	__le16 wHIDDescLength;
72 	__le16 bcdVersion;
73 	__le16 wReportDescLength;
74 	__le16 wReportDescRegister;
75 	__le16 wInputRegister;
76 	__le16 wMaxInputLength;
77 	__le16 wOutputRegister;
78 	__le16 wMaxOutputLength;
79 	__le16 wCommandRegister;
80 	__le16 wDataRegister;
81 	__le16 wVendorID;
82 	__le16 wProductID;
83 	__le16 wVersionID;
84 	__le32 reserved;
85 } __packed;
86 
87 struct i2c_hid_cmd {
88 	unsigned int registerIndex;
89 	__u8 opcode;
90 	unsigned int length;
91 	bool wait;
92 };
93 
94 union command {
95 	u8 data[0];
96 	struct cmd {
97 		__le16 reg;
98 		__u8 reportTypeID;
99 		__u8 opcode;
100 	} __packed c;
101 };
102 
103 #define I2C_HID_CMD(opcode_) \
104 	.opcode = opcode_, .length = 4, \
105 	.registerIndex = offsetof(struct i2c_hid_desc, wCommandRegister)
106 
107 /* fetch HID descriptor */
108 static const struct i2c_hid_cmd hid_descr_cmd = { .length = 2 };
109 /* fetch report descriptors */
110 static const struct i2c_hid_cmd hid_report_descr_cmd = {
111 		.registerIndex = offsetof(struct i2c_hid_desc,
112 			wReportDescRegister),
113 		.opcode = 0x00,
114 		.length = 2 };
115 /* commands */
116 static const struct i2c_hid_cmd hid_reset_cmd =		{ I2C_HID_CMD(0x01),
117 							  .wait = true };
118 static const struct i2c_hid_cmd hid_get_report_cmd =	{ I2C_HID_CMD(0x02) };
119 static const struct i2c_hid_cmd hid_set_report_cmd =	{ I2C_HID_CMD(0x03) };
120 static const struct i2c_hid_cmd hid_set_power_cmd =	{ I2C_HID_CMD(0x08) };
121 static const struct i2c_hid_cmd hid_no_cmd =		{ .length = 0 };
122 
123 /*
124  * These definitions are not used here, but are defined by the spec.
125  * Keeping them here for documentation purposes.
126  *
127  * static const struct i2c_hid_cmd hid_get_idle_cmd = { I2C_HID_CMD(0x04) };
128  * static const struct i2c_hid_cmd hid_set_idle_cmd = { I2C_HID_CMD(0x05) };
129  * static const struct i2c_hid_cmd hid_get_protocol_cmd = { I2C_HID_CMD(0x06) };
130  * static const struct i2c_hid_cmd hid_set_protocol_cmd = { I2C_HID_CMD(0x07) };
131  */
132 
133 /* The main device structure */
134 struct i2c_hid {
135 	struct i2c_client	*client;	/* i2c client */
136 	struct hid_device	*hid;	/* pointer to corresponding HID dev */
137 	union {
138 		__u8 hdesc_buffer[sizeof(struct i2c_hid_desc)];
139 		struct i2c_hid_desc hdesc;	/* the HID Descriptor */
140 	};
141 	__le16			wHIDDescRegister; /* location of the i2c
142 						   * register of the HID
143 						   * descriptor. */
144 	unsigned int		bufsize;	/* i2c buffer size */
145 	u8			*inbuf;		/* Input buffer */
146 	u8			*rawbuf;	/* Raw Input buffer */
147 	u8			*cmdbuf;	/* Command buffer */
148 	u8			*argsbuf;	/* Command arguments buffer */
149 
150 	unsigned long		flags;		/* device flags */
151 	unsigned long		quirks;		/* Various quirks */
152 
153 	wait_queue_head_t	wait;		/* For waiting the interrupt */
154 
155 	bool			irq_wake_enabled;
156 	struct mutex		reset_lock;
157 
158 	struct i2chid_ops	*ops;
159 };
160 
161 static const struct i2c_hid_quirks {
162 	__u16 idVendor;
163 	__u16 idProduct;
164 	__u32 quirks;
165 } i2c_hid_quirks[] = {
166 	{ USB_VENDOR_ID_WEIDA, HID_ANY_ID,
167 		I2C_HID_QUIRK_SET_PWR_WAKEUP_DEV },
168 	{ I2C_VENDOR_ID_HANTICK, I2C_PRODUCT_ID_HANTICK_5288,
169 		I2C_HID_QUIRK_NO_IRQ_AFTER_RESET },
170 	{ I2C_VENDOR_ID_ITE, I2C_DEVICE_ID_ITE_VOYO_WINPAD_A15,
171 		I2C_HID_QUIRK_NO_IRQ_AFTER_RESET },
172 	{ I2C_VENDOR_ID_RAYDIUM, I2C_PRODUCT_ID_RAYDIUM_3118,
173 		I2C_HID_QUIRK_NO_IRQ_AFTER_RESET },
174 	{ USB_VENDOR_ID_ALPS_JP, HID_ANY_ID,
175 		 I2C_HID_QUIRK_RESET_ON_RESUME },
176 	{ I2C_VENDOR_ID_SYNAPTICS, I2C_PRODUCT_ID_SYNAPTICS_SYNA2393,
177 		 I2C_HID_QUIRK_RESET_ON_RESUME },
178 	{ USB_VENDOR_ID_ITE, I2C_DEVICE_ID_ITE_LENOVO_LEGION_Y720,
179 		I2C_HID_QUIRK_BAD_INPUT_SIZE },
180 	/*
181 	 * Sending the wakeup after reset actually break ELAN touchscreen controller
182 	 */
183 	{ USB_VENDOR_ID_ELAN, HID_ANY_ID,
184 		 I2C_HID_QUIRK_NO_WAKEUP_AFTER_RESET |
185 		 I2C_HID_QUIRK_BOGUS_IRQ },
186 	{ 0, 0 }
187 };
188 
189 /*
190  * i2c_hid_lookup_quirk: return any quirks associated with a I2C HID device
191  * @idVendor: the 16-bit vendor ID
192  * @idProduct: the 16-bit product ID
193  *
194  * Returns: a u32 quirks value.
195  */
196 static u32 i2c_hid_lookup_quirk(const u16 idVendor, const u16 idProduct)
197 {
198 	u32 quirks = 0;
199 	int n;
200 
201 	for (n = 0; i2c_hid_quirks[n].idVendor; n++)
202 		if (i2c_hid_quirks[n].idVendor == idVendor &&
203 		    (i2c_hid_quirks[n].idProduct == (__u16)HID_ANY_ID ||
204 		     i2c_hid_quirks[n].idProduct == idProduct))
205 			quirks = i2c_hid_quirks[n].quirks;
206 
207 	return quirks;
208 }
209 
210 static int __i2c_hid_command(struct i2c_client *client,
211 		const struct i2c_hid_cmd *command, u8 reportID,
212 		u8 reportType, u8 *args, int args_len,
213 		unsigned char *buf_recv, int data_len)
214 {
215 	struct i2c_hid *ihid = i2c_get_clientdata(client);
216 	union command *cmd = (union command *)ihid->cmdbuf;
217 	int ret;
218 	struct i2c_msg msg[2];
219 	int msg_num = 1;
220 
221 	int length = command->length;
222 	bool wait = command->wait;
223 	unsigned int registerIndex = command->registerIndex;
224 
225 	/* special case for hid_descr_cmd */
226 	if (command == &hid_descr_cmd) {
227 		cmd->c.reg = ihid->wHIDDescRegister;
228 	} else {
229 		cmd->data[0] = ihid->hdesc_buffer[registerIndex];
230 		cmd->data[1] = ihid->hdesc_buffer[registerIndex + 1];
231 	}
232 
233 	if (length > 2) {
234 		cmd->c.opcode = command->opcode;
235 		cmd->c.reportTypeID = reportID | reportType << 4;
236 	}
237 
238 	memcpy(cmd->data + length, args, args_len);
239 	length += args_len;
240 
241 	i2c_hid_dbg(ihid, "%s: cmd=%*ph\n", __func__, length, cmd->data);
242 
243 	msg[0].addr = client->addr;
244 	msg[0].flags = client->flags & I2C_M_TEN;
245 	msg[0].len = length;
246 	msg[0].buf = cmd->data;
247 	if (data_len > 0) {
248 		msg[1].addr = client->addr;
249 		msg[1].flags = client->flags & I2C_M_TEN;
250 		msg[1].flags |= I2C_M_RD;
251 		msg[1].len = data_len;
252 		msg[1].buf = buf_recv;
253 		msg_num = 2;
254 		set_bit(I2C_HID_READ_PENDING, &ihid->flags);
255 	}
256 
257 	if (wait)
258 		set_bit(I2C_HID_RESET_PENDING, &ihid->flags);
259 
260 	ret = i2c_transfer(client->adapter, msg, msg_num);
261 
262 	if (data_len > 0)
263 		clear_bit(I2C_HID_READ_PENDING, &ihid->flags);
264 
265 	if (ret != msg_num)
266 		return ret < 0 ? ret : -EIO;
267 
268 	ret = 0;
269 
270 	if (wait && (ihid->quirks & I2C_HID_QUIRK_NO_IRQ_AFTER_RESET)) {
271 		msleep(100);
272 	} else if (wait) {
273 		i2c_hid_dbg(ihid, "%s: waiting...\n", __func__);
274 		if (!wait_event_timeout(ihid->wait,
275 				!test_bit(I2C_HID_RESET_PENDING, &ihid->flags),
276 				msecs_to_jiffies(5000)))
277 			ret = -ENODATA;
278 		i2c_hid_dbg(ihid, "%s: finished.\n", __func__);
279 	}
280 
281 	return ret;
282 }
283 
284 static int i2c_hid_command(struct i2c_client *client,
285 		const struct i2c_hid_cmd *command,
286 		unsigned char *buf_recv, int data_len)
287 {
288 	return __i2c_hid_command(client, command, 0, 0, NULL, 0,
289 				buf_recv, data_len);
290 }
291 
292 static int i2c_hid_get_report(struct i2c_client *client, u8 reportType,
293 		u8 reportID, unsigned char *buf_recv, int data_len)
294 {
295 	struct i2c_hid *ihid = i2c_get_clientdata(client);
296 	u8 args[3];
297 	int ret;
298 	int args_len = 0;
299 	u16 readRegister = le16_to_cpu(ihid->hdesc.wDataRegister);
300 
301 	i2c_hid_dbg(ihid, "%s\n", __func__);
302 
303 	if (reportID >= 0x0F) {
304 		args[args_len++] = reportID;
305 		reportID = 0x0F;
306 	}
307 
308 	args[args_len++] = readRegister & 0xFF;
309 	args[args_len++] = readRegister >> 8;
310 
311 	ret = __i2c_hid_command(client, &hid_get_report_cmd, reportID,
312 		reportType, args, args_len, buf_recv, data_len);
313 	if (ret) {
314 		dev_err(&client->dev,
315 			"failed to retrieve report from device.\n");
316 		return ret;
317 	}
318 
319 	return 0;
320 }
321 
322 /**
323  * i2c_hid_set_or_send_report: forward an incoming report to the device
324  * @client: the i2c_client of the device
325  * @reportType: 0x03 for HID_FEATURE_REPORT ; 0x02 for HID_OUTPUT_REPORT
326  * @reportID: the report ID
327  * @buf: the actual data to transfer, without the report ID
328  * @data_len: size of buf
329  * @use_data: true: use SET_REPORT HID command, false: send plain OUTPUT report
330  */
331 static int i2c_hid_set_or_send_report(struct i2c_client *client, u8 reportType,
332 		u8 reportID, unsigned char *buf, size_t data_len, bool use_data)
333 {
334 	struct i2c_hid *ihid = i2c_get_clientdata(client);
335 	u8 *args = ihid->argsbuf;
336 	const struct i2c_hid_cmd *hidcmd;
337 	int ret;
338 	u16 dataRegister = le16_to_cpu(ihid->hdesc.wDataRegister);
339 	u16 outputRegister = le16_to_cpu(ihid->hdesc.wOutputRegister);
340 	u16 maxOutputLength = le16_to_cpu(ihid->hdesc.wMaxOutputLength);
341 	u16 size;
342 	int args_len;
343 	int index = 0;
344 
345 	i2c_hid_dbg(ihid, "%s\n", __func__);
346 
347 	if (data_len > ihid->bufsize)
348 		return -EINVAL;
349 
350 	size =		2			/* size */ +
351 			(reportID ? 1 : 0)	/* reportID */ +
352 			data_len		/* buf */;
353 	args_len =	(reportID >= 0x0F ? 1 : 0) /* optional third byte */ +
354 			2			/* dataRegister */ +
355 			size			/* args */;
356 
357 	if (!use_data && maxOutputLength == 0)
358 		return -ENOSYS;
359 
360 	if (reportID >= 0x0F) {
361 		args[index++] = reportID;
362 		reportID = 0x0F;
363 	}
364 
365 	/*
366 	 * use the data register for feature reports or if the device does not
367 	 * support the output register
368 	 */
369 	if (use_data) {
370 		args[index++] = dataRegister & 0xFF;
371 		args[index++] = dataRegister >> 8;
372 		hidcmd = &hid_set_report_cmd;
373 	} else {
374 		args[index++] = outputRegister & 0xFF;
375 		args[index++] = outputRegister >> 8;
376 		hidcmd = &hid_no_cmd;
377 	}
378 
379 	args[index++] = size & 0xFF;
380 	args[index++] = size >> 8;
381 
382 	if (reportID)
383 		args[index++] = reportID;
384 
385 	memcpy(&args[index], buf, data_len);
386 
387 	ret = __i2c_hid_command(client, hidcmd, reportID,
388 		reportType, args, args_len, NULL, 0);
389 	if (ret) {
390 		dev_err(&client->dev, "failed to set a report to device.\n");
391 		return ret;
392 	}
393 
394 	return data_len;
395 }
396 
397 static int i2c_hid_set_power(struct i2c_client *client, int power_state)
398 {
399 	struct i2c_hid *ihid = i2c_get_clientdata(client);
400 	int ret;
401 
402 	i2c_hid_dbg(ihid, "%s\n", __func__);
403 
404 	/*
405 	 * Some devices require to send a command to wakeup before power on.
406 	 * The call will get a return value (EREMOTEIO) but device will be
407 	 * triggered and activated. After that, it goes like a normal device.
408 	 */
409 	if (power_state == I2C_HID_PWR_ON &&
410 	    ihid->quirks & I2C_HID_QUIRK_SET_PWR_WAKEUP_DEV) {
411 		ret = i2c_hid_command(client, &hid_set_power_cmd, NULL, 0);
412 
413 		/* Device was already activated */
414 		if (!ret)
415 			goto set_pwr_exit;
416 	}
417 
418 	ret = __i2c_hid_command(client, &hid_set_power_cmd, power_state,
419 		0, NULL, 0, NULL, 0);
420 
421 	if (ret)
422 		dev_err(&client->dev, "failed to change power setting.\n");
423 
424 set_pwr_exit:
425 
426 	/*
427 	 * The HID over I2C specification states that if a DEVICE needs time
428 	 * after the PWR_ON request, it should utilise CLOCK stretching.
429 	 * However, it has been observered that the Windows driver provides a
430 	 * 1ms sleep between the PWR_ON and RESET requests.
431 	 * According to Goodix Windows even waits 60 ms after (other?)
432 	 * PWR_ON requests. Testing has confirmed that several devices
433 	 * will not work properly without a delay after a PWR_ON request.
434 	 */
435 	if (!ret && power_state == I2C_HID_PWR_ON)
436 		msleep(60);
437 
438 	return ret;
439 }
440 
441 static int i2c_hid_hwreset(struct i2c_client *client)
442 {
443 	struct i2c_hid *ihid = i2c_get_clientdata(client);
444 	int ret;
445 
446 	i2c_hid_dbg(ihid, "%s\n", __func__);
447 
448 	/*
449 	 * This prevents sending feature reports while the device is
450 	 * being reset. Otherwise we may lose the reset complete
451 	 * interrupt.
452 	 */
453 	mutex_lock(&ihid->reset_lock);
454 
455 	ret = i2c_hid_set_power(client, I2C_HID_PWR_ON);
456 	if (ret)
457 		goto out_unlock;
458 
459 	i2c_hid_dbg(ihid, "resetting...\n");
460 
461 	ret = i2c_hid_command(client, &hid_reset_cmd, NULL, 0);
462 	if (ret) {
463 		dev_err(&client->dev, "failed to reset device.\n");
464 		i2c_hid_set_power(client, I2C_HID_PWR_SLEEP);
465 		goto out_unlock;
466 	}
467 
468 	/* At least some SIS devices need this after reset */
469 	if (!(ihid->quirks & I2C_HID_QUIRK_NO_WAKEUP_AFTER_RESET))
470 		ret = i2c_hid_set_power(client, I2C_HID_PWR_ON);
471 
472 out_unlock:
473 	mutex_unlock(&ihid->reset_lock);
474 	return ret;
475 }
476 
477 static void i2c_hid_get_input(struct i2c_hid *ihid)
478 {
479 	int ret;
480 	u32 ret_size;
481 	int size = le16_to_cpu(ihid->hdesc.wMaxInputLength);
482 
483 	if (size > ihid->bufsize)
484 		size = ihid->bufsize;
485 
486 	ret = i2c_master_recv(ihid->client, ihid->inbuf, size);
487 	if (ret != size) {
488 		if (ret < 0)
489 			return;
490 
491 		dev_err(&ihid->client->dev, "%s: got %d data instead of %d\n",
492 			__func__, ret, size);
493 		return;
494 	}
495 
496 	ret_size = ihid->inbuf[0] | ihid->inbuf[1] << 8;
497 
498 	if (!ret_size) {
499 		/* host or device initiated RESET completed */
500 		if (test_and_clear_bit(I2C_HID_RESET_PENDING, &ihid->flags))
501 			wake_up(&ihid->wait);
502 		return;
503 	}
504 
505 	if (ihid->quirks & I2C_HID_QUIRK_BOGUS_IRQ && ret_size == 0xffff) {
506 		dev_warn_once(&ihid->client->dev, "%s: IRQ triggered but "
507 			      "there's no data\n", __func__);
508 		return;
509 	}
510 
511 	if ((ret_size > size) || (ret_size < 2)) {
512 		if (ihid->quirks & I2C_HID_QUIRK_BAD_INPUT_SIZE) {
513 			ihid->inbuf[0] = size & 0xff;
514 			ihid->inbuf[1] = size >> 8;
515 			ret_size = size;
516 		} else {
517 			dev_err(&ihid->client->dev, "%s: incomplete report (%d/%d)\n",
518 				__func__, size, ret_size);
519 			return;
520 		}
521 	}
522 
523 	i2c_hid_dbg(ihid, "input: %*ph\n", ret_size, ihid->inbuf);
524 
525 	if (test_bit(I2C_HID_STARTED, &ihid->flags))
526 		hid_input_report(ihid->hid, HID_INPUT_REPORT, ihid->inbuf + 2,
527 				ret_size - 2, 1);
528 
529 	return;
530 }
531 
532 static irqreturn_t i2c_hid_irq(int irq, void *dev_id)
533 {
534 	struct i2c_hid *ihid = dev_id;
535 
536 	if (test_bit(I2C_HID_READ_PENDING, &ihid->flags))
537 		return IRQ_HANDLED;
538 
539 	i2c_hid_get_input(ihid);
540 
541 	return IRQ_HANDLED;
542 }
543 
544 static int i2c_hid_get_report_length(struct hid_report *report)
545 {
546 	return ((report->size - 1) >> 3) + 1 +
547 		report->device->report_enum[report->type].numbered + 2;
548 }
549 
550 /*
551  * Traverse the supplied list of reports and find the longest
552  */
553 static void i2c_hid_find_max_report(struct hid_device *hid, unsigned int type,
554 		unsigned int *max)
555 {
556 	struct hid_report *report;
557 	unsigned int size;
558 
559 	/* We should not rely on wMaxInputLength, as some devices may set it to
560 	 * a wrong length. */
561 	list_for_each_entry(report, &hid->report_enum[type].report_list, list) {
562 		size = i2c_hid_get_report_length(report);
563 		if (*max < size)
564 			*max = size;
565 	}
566 }
567 
568 static void i2c_hid_free_buffers(struct i2c_hid *ihid)
569 {
570 	kfree(ihid->inbuf);
571 	kfree(ihid->rawbuf);
572 	kfree(ihid->argsbuf);
573 	kfree(ihid->cmdbuf);
574 	ihid->inbuf = NULL;
575 	ihid->rawbuf = NULL;
576 	ihid->cmdbuf = NULL;
577 	ihid->argsbuf = NULL;
578 	ihid->bufsize = 0;
579 }
580 
581 static int i2c_hid_alloc_buffers(struct i2c_hid *ihid, size_t report_size)
582 {
583 	/* the worst case is computed from the set_report command with a
584 	 * reportID > 15 and the maximum report length */
585 	int args_len = sizeof(__u8) + /* ReportID */
586 		       sizeof(__u8) + /* optional ReportID byte */
587 		       sizeof(__u16) + /* data register */
588 		       sizeof(__u16) + /* size of the report */
589 		       report_size; /* report */
590 
591 	ihid->inbuf = kzalloc(report_size, GFP_KERNEL);
592 	ihid->rawbuf = kzalloc(report_size, GFP_KERNEL);
593 	ihid->argsbuf = kzalloc(args_len, GFP_KERNEL);
594 	ihid->cmdbuf = kzalloc(sizeof(union command) + args_len, GFP_KERNEL);
595 
596 	if (!ihid->inbuf || !ihid->rawbuf || !ihid->argsbuf || !ihid->cmdbuf) {
597 		i2c_hid_free_buffers(ihid);
598 		return -ENOMEM;
599 	}
600 
601 	ihid->bufsize = report_size;
602 
603 	return 0;
604 }
605 
606 static int i2c_hid_get_raw_report(struct hid_device *hid,
607 		unsigned char report_number, __u8 *buf, size_t count,
608 		unsigned char report_type)
609 {
610 	struct i2c_client *client = hid->driver_data;
611 	struct i2c_hid *ihid = i2c_get_clientdata(client);
612 	size_t ret_count, ask_count;
613 	int ret;
614 
615 	if (report_type == HID_OUTPUT_REPORT)
616 		return -EINVAL;
617 
618 	/* +2 bytes to include the size of the reply in the query buffer */
619 	ask_count = min(count + 2, (size_t)ihid->bufsize);
620 
621 	ret = i2c_hid_get_report(client,
622 			report_type == HID_FEATURE_REPORT ? 0x03 : 0x01,
623 			report_number, ihid->rawbuf, ask_count);
624 
625 	if (ret < 0)
626 		return ret;
627 
628 	ret_count = ihid->rawbuf[0] | (ihid->rawbuf[1] << 8);
629 
630 	if (ret_count <= 2)
631 		return 0;
632 
633 	ret_count = min(ret_count, ask_count);
634 
635 	/* The query buffer contains the size, dropping it in the reply */
636 	count = min(count, ret_count - 2);
637 	memcpy(buf, ihid->rawbuf + 2, count);
638 
639 	return count;
640 }
641 
642 static int i2c_hid_output_raw_report(struct hid_device *hid, __u8 *buf,
643 		size_t count, unsigned char report_type, bool use_data)
644 {
645 	struct i2c_client *client = hid->driver_data;
646 	struct i2c_hid *ihid = i2c_get_clientdata(client);
647 	int report_id = buf[0];
648 	int ret;
649 
650 	if (report_type == HID_INPUT_REPORT)
651 		return -EINVAL;
652 
653 	mutex_lock(&ihid->reset_lock);
654 
655 	if (report_id) {
656 		buf++;
657 		count--;
658 	}
659 
660 	ret = i2c_hid_set_or_send_report(client,
661 				report_type == HID_FEATURE_REPORT ? 0x03 : 0x02,
662 				report_id, buf, count, use_data);
663 
664 	if (report_id && ret >= 0)
665 		ret++; /* add report_id to the number of transfered bytes */
666 
667 	mutex_unlock(&ihid->reset_lock);
668 
669 	return ret;
670 }
671 
672 static int i2c_hid_output_report(struct hid_device *hid, __u8 *buf,
673 		size_t count)
674 {
675 	return i2c_hid_output_raw_report(hid, buf, count, HID_OUTPUT_REPORT,
676 			false);
677 }
678 
679 static int i2c_hid_raw_request(struct hid_device *hid, unsigned char reportnum,
680 			       __u8 *buf, size_t len, unsigned char rtype,
681 			       int reqtype)
682 {
683 	switch (reqtype) {
684 	case HID_REQ_GET_REPORT:
685 		return i2c_hid_get_raw_report(hid, reportnum, buf, len, rtype);
686 	case HID_REQ_SET_REPORT:
687 		if (buf[0] != reportnum)
688 			return -EINVAL;
689 		return i2c_hid_output_raw_report(hid, buf, len, rtype, true);
690 	default:
691 		return -EIO;
692 	}
693 }
694 
695 static int i2c_hid_parse(struct hid_device *hid)
696 {
697 	struct i2c_client *client = hid->driver_data;
698 	struct i2c_hid *ihid = i2c_get_clientdata(client);
699 	struct i2c_hid_desc *hdesc = &ihid->hdesc;
700 	unsigned int rsize;
701 	char *rdesc;
702 	int ret;
703 	int tries = 3;
704 	char *use_override;
705 
706 	i2c_hid_dbg(ihid, "entering %s\n", __func__);
707 
708 	rsize = le16_to_cpu(hdesc->wReportDescLength);
709 	if (!rsize || rsize > HID_MAX_DESCRIPTOR_SIZE) {
710 		dbg_hid("weird size of report descriptor (%u)\n", rsize);
711 		return -EINVAL;
712 	}
713 
714 	do {
715 		ret = i2c_hid_hwreset(client);
716 		if (ret)
717 			msleep(1000);
718 	} while (tries-- > 0 && ret);
719 
720 	if (ret)
721 		return ret;
722 
723 	use_override = i2c_hid_get_dmi_hid_report_desc_override(client->name,
724 								&rsize);
725 
726 	if (use_override) {
727 		rdesc = use_override;
728 		i2c_hid_dbg(ihid, "Using a HID report descriptor override\n");
729 	} else {
730 		rdesc = kzalloc(rsize, GFP_KERNEL);
731 
732 		if (!rdesc) {
733 			dbg_hid("couldn't allocate rdesc memory\n");
734 			return -ENOMEM;
735 		}
736 
737 		i2c_hid_dbg(ihid, "asking HID report descriptor\n");
738 
739 		ret = i2c_hid_command(client, &hid_report_descr_cmd,
740 				      rdesc, rsize);
741 		if (ret) {
742 			hid_err(hid, "reading report descriptor failed\n");
743 			kfree(rdesc);
744 			return -EIO;
745 		}
746 	}
747 
748 	i2c_hid_dbg(ihid, "Report Descriptor: %*ph\n", rsize, rdesc);
749 
750 	ret = hid_parse_report(hid, rdesc, rsize);
751 	if (!use_override)
752 		kfree(rdesc);
753 
754 	if (ret) {
755 		dbg_hid("parsing report descriptor failed\n");
756 		return ret;
757 	}
758 
759 	return 0;
760 }
761 
762 static int i2c_hid_start(struct hid_device *hid)
763 {
764 	struct i2c_client *client = hid->driver_data;
765 	struct i2c_hid *ihid = i2c_get_clientdata(client);
766 	int ret;
767 	unsigned int bufsize = HID_MIN_BUFFER_SIZE;
768 
769 	i2c_hid_find_max_report(hid, HID_INPUT_REPORT, &bufsize);
770 	i2c_hid_find_max_report(hid, HID_OUTPUT_REPORT, &bufsize);
771 	i2c_hid_find_max_report(hid, HID_FEATURE_REPORT, &bufsize);
772 
773 	if (bufsize > ihid->bufsize) {
774 		disable_irq(client->irq);
775 		i2c_hid_free_buffers(ihid);
776 
777 		ret = i2c_hid_alloc_buffers(ihid, bufsize);
778 		enable_irq(client->irq);
779 
780 		if (ret)
781 			return ret;
782 	}
783 
784 	return 0;
785 }
786 
787 static void i2c_hid_stop(struct hid_device *hid)
788 {
789 	hid->claimed = 0;
790 }
791 
792 static int i2c_hid_open(struct hid_device *hid)
793 {
794 	struct i2c_client *client = hid->driver_data;
795 	struct i2c_hid *ihid = i2c_get_clientdata(client);
796 
797 	set_bit(I2C_HID_STARTED, &ihid->flags);
798 	return 0;
799 }
800 
801 static void i2c_hid_close(struct hid_device *hid)
802 {
803 	struct i2c_client *client = hid->driver_data;
804 	struct i2c_hid *ihid = i2c_get_clientdata(client);
805 
806 	clear_bit(I2C_HID_STARTED, &ihid->flags);
807 }
808 
809 struct hid_ll_driver i2c_hid_ll_driver = {
810 	.parse = i2c_hid_parse,
811 	.start = i2c_hid_start,
812 	.stop = i2c_hid_stop,
813 	.open = i2c_hid_open,
814 	.close = i2c_hid_close,
815 	.output_report = i2c_hid_output_report,
816 	.raw_request = i2c_hid_raw_request,
817 };
818 EXPORT_SYMBOL_GPL(i2c_hid_ll_driver);
819 
820 static int i2c_hid_init_irq(struct i2c_client *client)
821 {
822 	struct i2c_hid *ihid = i2c_get_clientdata(client);
823 	unsigned long irqflags = 0;
824 	int ret;
825 
826 	dev_dbg(&client->dev, "Requesting IRQ: %d\n", client->irq);
827 
828 	if (!irq_get_trigger_type(client->irq))
829 		irqflags = IRQF_TRIGGER_LOW;
830 
831 	ret = request_threaded_irq(client->irq, NULL, i2c_hid_irq,
832 				   irqflags | IRQF_ONESHOT, client->name, ihid);
833 	if (ret < 0) {
834 		dev_warn(&client->dev,
835 			"Could not register for %s interrupt, irq = %d,"
836 			" ret = %d\n",
837 			client->name, client->irq, ret);
838 
839 		return ret;
840 	}
841 
842 	return 0;
843 }
844 
845 static int i2c_hid_fetch_hid_descriptor(struct i2c_hid *ihid)
846 {
847 	struct i2c_client *client = ihid->client;
848 	struct i2c_hid_desc *hdesc = &ihid->hdesc;
849 	unsigned int dsize;
850 	int ret;
851 
852 	/* i2c hid fetch using a fixed descriptor size (30 bytes) */
853 	if (i2c_hid_get_dmi_i2c_hid_desc_override(client->name)) {
854 		i2c_hid_dbg(ihid, "Using a HID descriptor override\n");
855 		ihid->hdesc =
856 			*i2c_hid_get_dmi_i2c_hid_desc_override(client->name);
857 	} else {
858 		i2c_hid_dbg(ihid, "Fetching the HID descriptor\n");
859 		ret = i2c_hid_command(client, &hid_descr_cmd,
860 				      ihid->hdesc_buffer,
861 				      sizeof(struct i2c_hid_desc));
862 		if (ret) {
863 			dev_err(&client->dev, "hid_descr_cmd failed\n");
864 			return -ENODEV;
865 		}
866 	}
867 
868 	/* Validate the length of HID descriptor, the 4 first bytes:
869 	 * bytes 0-1 -> length
870 	 * bytes 2-3 -> bcdVersion (has to be 1.00) */
871 	/* check bcdVersion == 1.0 */
872 	if (le16_to_cpu(hdesc->bcdVersion) != 0x0100) {
873 		dev_err(&client->dev,
874 			"unexpected HID descriptor bcdVersion (0x%04hx)\n",
875 			le16_to_cpu(hdesc->bcdVersion));
876 		return -ENODEV;
877 	}
878 
879 	/* Descriptor length should be 30 bytes as per the specification */
880 	dsize = le16_to_cpu(hdesc->wHIDDescLength);
881 	if (dsize != sizeof(struct i2c_hid_desc)) {
882 		dev_err(&client->dev, "weird size of HID descriptor (%u)\n",
883 			dsize);
884 		return -ENODEV;
885 	}
886 	i2c_hid_dbg(ihid, "HID Descriptor: %*ph\n", dsize, ihid->hdesc_buffer);
887 	return 0;
888 }
889 
890 static int i2c_hid_core_power_up(struct i2c_hid *ihid)
891 {
892 	if (!ihid->ops->power_up)
893 		return 0;
894 
895 	return ihid->ops->power_up(ihid->ops);
896 }
897 
898 static void i2c_hid_core_power_down(struct i2c_hid *ihid)
899 {
900 	if (!ihid->ops->power_down)
901 		return;
902 
903 	ihid->ops->power_down(ihid->ops);
904 }
905 
906 static void i2c_hid_core_shutdown_tail(struct i2c_hid *ihid)
907 {
908 	if (!ihid->ops->shutdown_tail)
909 		return;
910 
911 	ihid->ops->shutdown_tail(ihid->ops);
912 }
913 
914 int i2c_hid_core_probe(struct i2c_client *client, struct i2chid_ops *ops,
915 		       u16 hid_descriptor_address)
916 {
917 	int ret;
918 	struct i2c_hid *ihid;
919 	struct hid_device *hid;
920 
921 	dbg_hid("HID probe called for i2c 0x%02x\n", client->addr);
922 
923 	if (!client->irq) {
924 		dev_err(&client->dev,
925 			"HID over i2c has not been provided an Int IRQ\n");
926 		return -EINVAL;
927 	}
928 
929 	if (client->irq < 0) {
930 		if (client->irq != -EPROBE_DEFER)
931 			dev_err(&client->dev,
932 				"HID over i2c doesn't have a valid IRQ\n");
933 		return client->irq;
934 	}
935 
936 	ihid = devm_kzalloc(&client->dev, sizeof(*ihid), GFP_KERNEL);
937 	if (!ihid)
938 		return -ENOMEM;
939 
940 	ihid->ops = ops;
941 
942 	ret = i2c_hid_core_power_up(ihid);
943 	if (ret)
944 		return ret;
945 
946 	i2c_set_clientdata(client, ihid);
947 
948 	ihid->client = client;
949 
950 	ihid->wHIDDescRegister = cpu_to_le16(hid_descriptor_address);
951 
952 	init_waitqueue_head(&ihid->wait);
953 	mutex_init(&ihid->reset_lock);
954 
955 	/* we need to allocate the command buffer without knowing the maximum
956 	 * size of the reports. Let's use HID_MIN_BUFFER_SIZE, then we do the
957 	 * real computation later. */
958 	ret = i2c_hid_alloc_buffers(ihid, HID_MIN_BUFFER_SIZE);
959 	if (ret < 0)
960 		goto err_powered;
961 
962 	device_enable_async_suspend(&client->dev);
963 
964 	/* Make sure there is something at this address */
965 	ret = i2c_smbus_read_byte(client);
966 	if (ret < 0) {
967 		dev_dbg(&client->dev, "nothing at this address: %d\n", ret);
968 		ret = -ENXIO;
969 		goto err_powered;
970 	}
971 
972 	ret = i2c_hid_fetch_hid_descriptor(ihid);
973 	if (ret < 0) {
974 		dev_err(&client->dev,
975 			"Failed to fetch the HID Descriptor\n");
976 		goto err_powered;
977 	}
978 
979 	ret = i2c_hid_init_irq(client);
980 	if (ret < 0)
981 		goto err_powered;
982 
983 	hid = hid_allocate_device();
984 	if (IS_ERR(hid)) {
985 		ret = PTR_ERR(hid);
986 		goto err_irq;
987 	}
988 
989 	ihid->hid = hid;
990 
991 	hid->driver_data = client;
992 	hid->ll_driver = &i2c_hid_ll_driver;
993 	hid->dev.parent = &client->dev;
994 	hid->bus = BUS_I2C;
995 	hid->version = le16_to_cpu(ihid->hdesc.bcdVersion);
996 	hid->vendor = le16_to_cpu(ihid->hdesc.wVendorID);
997 	hid->product = le16_to_cpu(ihid->hdesc.wProductID);
998 
999 	snprintf(hid->name, sizeof(hid->name), "%s %04X:%04X",
1000 		 client->name, (u16)hid->vendor, (u16)hid->product);
1001 	strlcpy(hid->phys, dev_name(&client->dev), sizeof(hid->phys));
1002 
1003 	ihid->quirks = i2c_hid_lookup_quirk(hid->vendor, hid->product);
1004 
1005 	ret = hid_add_device(hid);
1006 	if (ret) {
1007 		if (ret != -ENODEV)
1008 			hid_err(client, "can't add hid device: %d\n", ret);
1009 		goto err_mem_free;
1010 	}
1011 
1012 	return 0;
1013 
1014 err_mem_free:
1015 	hid_destroy_device(hid);
1016 
1017 err_irq:
1018 	free_irq(client->irq, ihid);
1019 
1020 err_powered:
1021 	i2c_hid_core_power_down(ihid);
1022 	i2c_hid_free_buffers(ihid);
1023 	return ret;
1024 }
1025 EXPORT_SYMBOL_GPL(i2c_hid_core_probe);
1026 
1027 int i2c_hid_core_remove(struct i2c_client *client)
1028 {
1029 	struct i2c_hid *ihid = i2c_get_clientdata(client);
1030 	struct hid_device *hid;
1031 
1032 	hid = ihid->hid;
1033 	hid_destroy_device(hid);
1034 
1035 	free_irq(client->irq, ihid);
1036 
1037 	if (ihid->bufsize)
1038 		i2c_hid_free_buffers(ihid);
1039 
1040 	i2c_hid_core_power_down(ihid);
1041 
1042 	return 0;
1043 }
1044 EXPORT_SYMBOL_GPL(i2c_hid_core_remove);
1045 
1046 void i2c_hid_core_shutdown(struct i2c_client *client)
1047 {
1048 	struct i2c_hid *ihid = i2c_get_clientdata(client);
1049 
1050 	i2c_hid_set_power(client, I2C_HID_PWR_SLEEP);
1051 	free_irq(client->irq, ihid);
1052 
1053 	i2c_hid_core_shutdown_tail(ihid);
1054 }
1055 EXPORT_SYMBOL_GPL(i2c_hid_core_shutdown);
1056 
1057 #ifdef CONFIG_PM_SLEEP
1058 static int i2c_hid_core_suspend(struct device *dev)
1059 {
1060 	struct i2c_client *client = to_i2c_client(dev);
1061 	struct i2c_hid *ihid = i2c_get_clientdata(client);
1062 	struct hid_device *hid = ihid->hid;
1063 	int ret;
1064 	int wake_status;
1065 
1066 	if (hid->driver && hid->driver->suspend) {
1067 		ret = hid->driver->suspend(hid, PMSG_SUSPEND);
1068 		if (ret < 0)
1069 			return ret;
1070 	}
1071 
1072 	/* Save some power */
1073 	i2c_hid_set_power(client, I2C_HID_PWR_SLEEP);
1074 
1075 	disable_irq(client->irq);
1076 
1077 	if (device_may_wakeup(&client->dev)) {
1078 		wake_status = enable_irq_wake(client->irq);
1079 		if (!wake_status)
1080 			ihid->irq_wake_enabled = true;
1081 		else
1082 			hid_warn(hid, "Failed to enable irq wake: %d\n",
1083 				wake_status);
1084 	} else {
1085 		i2c_hid_core_power_down(ihid);
1086 	}
1087 
1088 	return 0;
1089 }
1090 
1091 static int i2c_hid_core_resume(struct device *dev)
1092 {
1093 	int ret;
1094 	struct i2c_client *client = to_i2c_client(dev);
1095 	struct i2c_hid *ihid = i2c_get_clientdata(client);
1096 	struct hid_device *hid = ihid->hid;
1097 	int wake_status;
1098 
1099 	if (!device_may_wakeup(&client->dev)) {
1100 		i2c_hid_core_power_up(ihid);
1101 	} else if (ihid->irq_wake_enabled) {
1102 		wake_status = disable_irq_wake(client->irq);
1103 		if (!wake_status)
1104 			ihid->irq_wake_enabled = false;
1105 		else
1106 			hid_warn(hid, "Failed to disable irq wake: %d\n",
1107 				wake_status);
1108 	}
1109 
1110 	enable_irq(client->irq);
1111 
1112 	/* Instead of resetting device, simply powers the device on. This
1113 	 * solves "incomplete reports" on Raydium devices 2386:3118 and
1114 	 * 2386:4B33 and fixes various SIS touchscreens no longer sending
1115 	 * data after a suspend/resume.
1116 	 *
1117 	 * However some ALPS touchpads generate IRQ storm without reset, so
1118 	 * let's still reset them here.
1119 	 */
1120 	if (ihid->quirks & I2C_HID_QUIRK_RESET_ON_RESUME)
1121 		ret = i2c_hid_hwreset(client);
1122 	else
1123 		ret = i2c_hid_set_power(client, I2C_HID_PWR_ON);
1124 
1125 	if (ret)
1126 		return ret;
1127 
1128 	if (hid->driver && hid->driver->reset_resume) {
1129 		ret = hid->driver->reset_resume(hid);
1130 		return ret;
1131 	}
1132 
1133 	return 0;
1134 }
1135 #endif
1136 
1137 const struct dev_pm_ops i2c_hid_core_pm = {
1138 	SET_SYSTEM_SLEEP_PM_OPS(i2c_hid_core_suspend, i2c_hid_core_resume)
1139 };
1140 EXPORT_SYMBOL_GPL(i2c_hid_core_pm);
1141 
1142 MODULE_DESCRIPTION("HID over I2C core driver");
1143 MODULE_AUTHOR("Benjamin Tissoires <benjamin.tissoires@gmail.com>");
1144 MODULE_LICENSE("GPL");
1145