summaryrefslogtreecommitdiffstats
path: root/drivers/gpio/gpio-winbond.c
blob: 7f8f5b02e31d5c6f15a623013ce85d3bcc6dbc11 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
// SPDX-License-Identifier: GPL-2.0+
/*
 * GPIO interface for Winbond Super I/O chips
 * Currently, only W83627UHG (Nuvoton NCT6627UD) is supported.
 *
 * Author: Maciej S. Szmigiero <mail@maciej.szmigiero.name>
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/gpio/driver.h>
#include <linux/ioport.h>
#include <linux/isa.h>
#include <linux/module.h>

#define WB_GPIO_DRIVER_NAME		KBUILD_MODNAME

#define WB_SIO_BASE			0x2e
#define WB_SIO_BASE_HIGH		0x4e

#define WB_SIO_EXT_ENTER_KEY		0x87
#define WB_SIO_EXT_EXIT_KEY		0xaa

/* global chip registers */

#define WB_SIO_REG_LOGICAL		0x07

#define WB_SIO_REG_CHIP_MSB		0x20
#define WB_SIO_REG_CHIP_LSB		0x21

#define WB_SIO_CHIP_ID_W83627UHG	0xa230
#define WB_SIO_CHIP_ID_W83627UHG_MASK	GENMASK(15, 4)

#define WB_SIO_REG_DPD			0x22
#define WB_SIO_REG_DPD_UARTA		4
#define WB_SIO_REG_DPD_UARTB		5

#define WB_SIO_REG_IDPD		0x23
#define WB_SIO_REG_IDPD_UARTC		4
#define WB_SIO_REG_IDPD_UARTD		5
#define WB_SIO_REG_IDPD_UARTE		6
#define WB_SIO_REG_IDPD_UARTF		7

#define WB_SIO_REG_GLOBAL_OPT		0x24
#define WB_SIO_REG_GO_ENFDC		1

#define WB_SIO_REG_OVTGPIO3456		0x29
#define WB_SIO_REG_OG3456_G3PP		3
#define WB_SIO_REG_OG3456_G4PP		4
#define WB_SIO_REG_OG3456_G5PP		5
#define WB_SIO_REG_OG3456_G6PP		7

#define WB_SIO_REG_I2C_PS		0x2a
#define WB_SIO_REG_I2CPS_I2CFS		1

#define WB_SIO_REG_GPIO1_MF		0x2c
#define WB_SIO_REG_G1MF_G1PP		6
#define WB_SIO_REG_G1MF_G2PP		7
#define WB_SIO_REG_G1MF_FS_MASK	GENMASK(1, 0)
#define WB_SIO_REG_G1MF_FS_IR_OFF	0
#define WB_SIO_REG_G1MF_FS_IR		1
#define WB_SIO_REG_G1MF_FS_GPIO1	2
#define WB_SIO_REG_G1MF_FS_UARTB	3

/* not an actual device number, just a value meaning 'no device' */
#define WB_SIO_DEV_NONE		0xff

/* registers with offsets >= 0x30 are specific for a particular device */

/* UART B logical device */
#define WB_SIO_DEV_UARTB		0x03
#define WB_SIO_UARTB_REG_ENABLE	0x30
#define WB_SIO_UARTB_ENABLE_ON		0

/* UART C logical device */
#define WB_SIO_DEV_UARTC		0x06
#define WB_SIO_UARTC_REG_ENABLE	0x30
#define WB_SIO_UARTC_ENABLE_ON		0

/* GPIO3, GPIO4 logical device */
#define WB_SIO_DEV_GPIO34		0x07
#define WB_SIO_GPIO34_REG_ENABLE	0x30
#define WB_SIO_GPIO34_ENABLE_3		0
#define WB_SIO_GPIO34_ENABLE_4		1
#define WB_SIO_GPIO34_REG_IO3		0xe0
#define WB_SIO_GPIO34_REG_DATA3	0xe1
#define WB_SIO_GPIO34_REG_INV3		0xe2
#define WB_SIO_GPIO34_REG_IO4		0xe4
#define WB_SIO_GPIO34_REG_DATA4	0xe5
#define WB_SIO_GPIO34_REG_INV4		0xe6

/* WDTO, PLED, GPIO5, GPIO6 logical device */
#define WB_SIO_DEV_WDGPIO56		0x08
#define WB_SIO_WDGPIO56_REG_ENABLE	0x30
#define WB_SIO_WDGPIO56_ENABLE_5	1
#define WB_SIO_WDGPIO56_ENABLE_6	2
#define WB_SIO_WDGPIO56_REG_IO5	0xe0
#define WB_SIO_WDGPIO56_REG_DATA5	0xe1
#define WB_SIO_WDGPIO56_REG_INV5	0xe2
#define WB_SIO_WDGPIO56_REG_IO6	0xe4
#define WB_SIO_WDGPIO56_REG_DATA6	0xe5
#define WB_SIO_WDGPIO56_REG_INV6	0xe6

/* GPIO1, GPIO2, SUSLED logical device */
#define WB_SIO_DEV_GPIO12		0x09
#define WB_SIO_GPIO12_REG_ENABLE	0x30
#define WB_SIO_GPIO12_ENABLE_1		0
#define WB_SIO_GPIO12_ENABLE_2		1
#define WB_SIO_GPIO12_REG_IO1		0xe0
#define WB_SIO_GPIO12_REG_DATA1	0xe1
#define WB_SIO_GPIO12_REG_INV1		0xe2
#define WB_SIO_GPIO12_REG_IO2		0xe4
#define WB_SIO_GPIO12_REG_DATA2	0xe5
#define WB_SIO_GPIO12_REG_INV2		0xe6

/* UART D logical device */
#define WB_SIO_DEV_UARTD		0x0d
#define WB_SIO_UARTD_REG_ENABLE	0x30
#define WB_SIO_UARTD_ENABLE_ON		0

/* UART E logical device */
#define WB_SIO_DEV_UARTE		0x0e
#define WB_SIO_UARTE_REG_ENABLE	0x30
#define WB_SIO_UARTE_ENABLE_ON		0

/*
 * for a description what a particular field of this struct means please see
 * a description of the relevant module parameter at the bottom of this file
 */
struct winbond_gpio_params {
	unsigned long base;
	unsigned long gpios;
	unsigned long ppgpios;
	unsigned long odgpios;
	bool pledgpio;
	bool beepgpio;
	bool i2cgpio;
};

static struct winbond_gpio_params params;

static int winbond_sio_enter(unsigned long base)
{
	if (!request_muxed_region(base, 2, WB_GPIO_DRIVER_NAME))
		return -EBUSY;

	/*
	 * datasheet says two successive writes of the "key" value are needed
	 * in order for chip to enter the "Extended Function Mode"
	 */
	outb(WB_SIO_EXT_ENTER_KEY, base);
	outb(WB_SIO_EXT_ENTER_KEY, base);

	return 0;
}

static void winbond_sio_select_logical(unsigned long base, u8 dev)
{
	outb(WB_SIO_REG_LOGICAL, base);
	outb(dev, base + 1);
}

static void winbond_sio_leave(unsigned long base)
{
	outb(WB_SIO_EXT_EXIT_KEY, base);

	release_region(base, 2);
}

static void winbond_sio_reg_write(unsigned long base, u8 reg, u8 data)
{
	outb(reg, base);
	outb(data, base + 1);
}

static u8 winbond_sio_reg_read(unsigned long base, u8 reg)
{
	outb(reg, base);
	return inb(base + 1);
}

static void winbond_sio_reg_bset(unsigned long base, u8 reg, u8 bit)
{
	u8 val;

	val = winbond_sio_reg_read(base, reg);
	val |= BIT(bit);
	winbond_sio_reg_write(base, reg, val);
}

static void winbond_sio_reg_bclear(unsigned long base, u8 reg, u8 bit)
{
	u8 val;

	val = winbond_sio_reg_read(base, reg);
	val &= ~BIT(bit);
	winbond_sio_reg_write(base, reg, val);
}

static bool winbond_sio_reg_btest(unsigned long base, u8 reg, u8 bit)
{
	return winbond_sio_reg_read(base, reg) & BIT(bit);
}

/**
 * struct winbond_gpio_port_conflict - possibly conflicting device information
 * @name:	device name (NULL means no conflicting device defined)
 * @dev:	Super I/O logical device number where the testreg register
 *		is located (or WB_SIO_DEV_NONE - don't select any
 *		logical device)
 * @testreg:	register number where the testbit bit is located
 * @testbit:	index of a bit to check whether an actual conflict exists
 * @warnonly:	if set then a conflict isn't fatal (just warn about it),
 *		otherwise disable the particular GPIO port if a conflict
 *		is detected
 */
struct winbond_gpio_port_conflict {
	const char *name;
	u8 dev;
	u8 testreg;
	u8 testbit;
	bool warnonly;
};

/**
 * struct winbond_gpio_info - information about a particular GPIO port (device)
 * @dev:		Super I/O logical device number of the registers
 *			specified below
 * @enablereg:		port enable bit register number
 * @enablebit:		index of a port enable bit
 * @outputreg:		output driver mode bit register number
 * @outputppbit:	index of a push-pull output driver mode bit
 * @ioreg:		data direction register number
 * @invreg:		pin data inversion register number
 * @datareg:		pin data register number
 * @conflict:		description of a device that possibly conflicts with
 *			this port
 */
struct winbond_gpio_info {
	u8 dev;
	u8 enablereg;
	u8 enablebit;
	u8 outputreg;
	u8 outputppbit;
	u8 ioreg;
	u8 invreg;
	u8 datareg;
	struct winbond_gpio_port_conflict conflict;
};

static const struct winbond_gpio_info winbond_gpio_infos[6] = {
	{ /* 0 */
		.dev = WB_SIO_DEV_GPIO12,
		.enablereg = WB_SIO_GPIO12_REG_ENABLE,
		.enablebit = WB_SIO_GPIO12_ENABLE_1,
		.outputreg = WB_SIO_REG_GPIO1_MF,
		.outputppbit = WB_SIO_REG_G1MF_G1PP,
		.ioreg = WB_SIO_GPIO12_REG_IO1,
		.invreg = WB_SIO_GPIO12_REG_INV1,
		.datareg = WB_SIO_GPIO12_REG_DATA1,
		.conflict = {
			.name = "UARTB",
			.dev = WB_SIO_DEV_UARTB,
			.testreg = WB_SIO_UARTB_REG_ENABLE,
			.testbit = WB_SIO_UARTB_ENABLE_ON,
			.warnonly = true
		}
	},
	{ /* 1 */
		.dev = WB_SIO_DEV_GPIO12,
		.enablereg = WB_SIO_GPIO12_REG_ENABLE,
		.enablebit = WB_SIO_GPIO12_ENABLE_2,
		.outputreg = WB_SIO_REG_GPIO1_MF,
		.outputppbit = WB_SIO_REG_G1MF_G2PP,
		.ioreg = WB_SIO_GPIO12_REG_IO2,
		.invreg = WB_SIO_GPIO12_REG_INV2,
		.datareg = WB_SIO_GPIO12_REG_DATA2
		/* special conflict handling so doesn't use conflict data */
	},
	{ /* 2 */
		.dev = WB_SIO_DEV_GPIO34,
		.enablereg = WB_SIO_GPIO34_REG_ENABLE,
		.enablebit = WB_SIO_GPIO34_ENABLE_3,
		.outputreg = WB_SIO_REG_OVTGPIO3456,
		.outputppbit = WB_SIO_REG_OG3456_G3PP,
		.ioreg = WB_SIO_GPIO34_REG_IO3,
		.invreg = WB_SIO_GPIO34_REG_INV3,
		.datareg = WB_SIO_GPIO34_REG_DATA3,
		.conflict = {
			.name = "UARTC",
			.dev = WB_SIO_DEV_UARTC,
			.testreg = WB_SIO_UARTC_REG_ENABLE,
			.testbit = WB_SIO_UARTC_ENABLE_ON,
			.warnonly = true
		}
	},
	{ /* 3 */
		.dev = WB_SIO_DEV_GPIO34,
		.enablereg = WB_SIO_GPIO34_REG_ENABLE,
		.enablebit = WB_SIO_GPIO34_ENABLE_4,
		.outputreg = WB_SIO_REG_OVTGPIO3456,
		.outputppbit = WB_SIO_REG_OG3456_G4PP,
		.ioreg = WB_SIO_GPIO34_REG_IO4,
		.invreg = WB_SIO_GPIO34_REG_INV4,
		.datareg = WB_SIO_GPIO34_REG_DATA4,
		.conflict = {
			.name = "UARTD",
			.dev = WB_SIO_DEV_UARTD,
			.testreg = WB_SIO_UARTD_REG_ENABLE,
			.testbit = WB_SIO_UARTD_ENABLE_ON,
			.warnonly = true
		}
	},
	{ /* 4 */
		.dev = WB_SIO_DEV_WDGPIO56,
		.enablereg = WB_SIO_WDGPIO56_REG_ENABLE,
		.enablebit = WB_SIO_WDGPIO56_ENABLE_5,
		.outputreg = WB_SIO_REG_OVTGPIO3456,
		.outputppbit = WB_SIO_REG_OG3456_G5PP,
		.ioreg = WB_SIO_WDGPIO56_REG_IO5,
		.invreg = WB_SIO_WDGPIO56_REG_INV5,
		.datareg = WB_SIO_WDGPIO56_REG_DATA5,
		.conflict = {
			.name = "UARTE",
			.dev = WB_SIO_DEV_UARTE,
			.testreg = WB_SIO_UARTE_REG_ENABLE,
			.testbit = WB_SIO_UARTE_ENABLE_ON,
			.warnonly = true
		}
	},
	{ /* 5 */
		.dev = WB_SIO_DEV_WDGPIO56,
		.enablereg = WB_SIO_WDGPIO56_REG_ENABLE,
		.enablebit = WB_SIO_WDGPIO56_ENABLE_6,
		.outputreg = WB_SIO_REG_OVTGPIO3456,
		.outputppbit = WB_SIO_REG_OG3456_G6PP,
		.ioreg = WB_SIO_WDGPIO56_REG_IO6,
		.invreg = WB_SIO_WDGPIO56_REG_INV6,
		.datareg = WB_SIO_WDGPIO56_REG_DATA6,
		.conflict = {
			.name = "FDC",
			.dev = WB_SIO_DEV_NONE,
			.testreg = WB_SIO_REG_GLOBAL_OPT,
			.testbit = WB_SIO_REG_GO_ENFDC,
			.warnonly = false
		}
	}
};

/* returns whether changing a pin is allowed */
static bool winbond_gpio_get_info(unsigned int *gpio_num,
				  const struct winbond_gpio_info **info)
{
	bool allow_changing = true;
	unsigned long i;

	for_each_set_bit(i, &params.gpios, BITS_PER_LONG) {
		if (*gpio_num < 8)
			break;

		*gpio_num -= 8;
	}

	*info = &winbond_gpio_infos[i];

	/*
	 * GPIO2 (the second port) shares some pins with a basic PC
	 * functionality, which is very likely controlled by the firmware.
	 * Don't allow changing these pins by default.
	 */
	if (i == 1) {
		if (*gpio_num == 0 && !params.pledgpio)
			allow_changing = false;
		else if (*gpio_num == 1 && !params.beepgpio)
			allow_changing = false;
		else if ((*gpio_num == 5 || *gpio_num == 6) && !params.i2cgpio)
			allow_changing = false;
	}

	return allow_changing;
}

static int winbond_gpio_get(struct gpio_chip *gc, unsigned int offset)
{
	unsigned long *base = gpiochip_get_data(gc);
	const struct winbond_gpio_info *info;
	bool val;

	winbond_gpio_get_info(&offset, &info);

	val = winbond_sio_enter(*base);
	if (val)
		return val;

	winbond_sio_select_logical(*base, info->dev);

	val = winbond_sio_reg_btest(*base, info->datareg, offset);
	if (winbond_sio_reg_btest(*base, info->invreg, offset))
		val = !val;

	winbond_sio_leave(*base);

	return val;
}

static int winbond_gpio_direction_in(struct gpio_chip *gc, unsigned int offset)
{
	unsigned long *base = gpiochip_get_data(gc);
	const struct winbond_gpio_info *info;
	int ret;

	if (!winbond_gpio_get_info(&offset, &info))
		return -EACCES;

	ret = winbond_sio_enter(*base);
	if (ret)
		return ret;

	winbond_sio_select_logical(*base, info->dev);

	winbond_sio_reg_bset(*base, info->ioreg, offset);

	winbond_sio_leave(*base);

	return 0;
}

static int winbond_gpio_direction_out(struct gpio_chip *gc,
				      unsigned int offset,
				      int val)
{
	unsigned long *base = gpiochip_get_data(gc);
	const struct winbond_gpio_info *info;
	int ret;

	if (!winbond_gpio_get_info(&offset, &info))
		return -EACCES;

	ret = winbond_sio_enter(*base);
	if (ret)
		return ret;

	winbond_sio_select_logical(*base, info->dev);

	winbond_sio_reg_bclear(*base, info->ioreg, offset);

	if (winbond_sio_reg_btest(*base, info->invreg, offset))
		val = !val;

	if (val)
		winbond_sio_reg_bset(*base, info->datareg, offset);
	else
		winbond_sio_reg_bclear(*base, info->datareg, offset);

	winbond_sio_leave(*base);

	return 0;
}

static void winbond_gpio_set(struct gpio_chip *gc, unsigned int offset,
			     int val)
{
	unsigned long *base = gpiochip_get_data(gc);
	const struct winbond_gpio_info *info;

	if (!winbond_gpio_get_info(&offset, &info))
		return;

	if (winbond_sio_enter(*base) != 0)
		return;

	winbond_sio_select_logical(*base, info->dev);

	if (winbond_sio_reg_btest(*base, info->invreg, offset))
		val = !val;

	if (val)
		winbond_sio_reg_bset(*base, info->datareg, offset);
	else
		winbond_sio_reg_bclear(*base, info->datareg, offset);

	winbond_sio_leave(*base);
}

static struct gpio_chip winbond_gpio_chip = {
	.base			= -1,
	.label			= WB_GPIO_DRIVER_NAME,
	.owner			= THIS_MODULE,
	.can_sleep		= true,
	.get			= winbond_gpio_get,
	.direction_input	= winbond_gpio_direction_in,
	.set			= winbond_gpio_set,
	.direction_output	= winbond_gpio_direction_out,
};

static void winbond_gpio_configure_port0_pins(unsigned long base)
{
	unsigned int val;

	val = winbond_sio_reg_read(base, WB_SIO_REG_GPIO1_MF);
	if ((val & WB_SIO_REG_G1MF_FS_MASK) == WB_SIO_REG_G1MF_FS_GPIO1)
		return;

	pr_warn("GPIO1 pins were connected to something else (%.2x), fixing\n",
		val);

	val &= ~WB_SIO_REG_G1MF_FS_MASK;
	val |= WB_SIO_REG_G1MF_FS_GPIO1;

	winbond_sio_reg_write(base, WB_SIO_REG_GPIO1_MF, val);
}

static void winbond_gpio_configure_port1_check_i2c(unsigned long base)
{
	params.i2cgpio = !winbond_sio_reg_btest(base, WB_SIO_REG_I2C_PS,
						WB_SIO_REG_I2CPS_I2CFS);
	if (!params.i2cgpio)
		pr_warn("disabling GPIO2.5 and GPIO2.6 as I2C is enabled\n");
}

static bool winbond_gpio_configure_port(unsigned long base, unsigned int idx)
{
	const struct winbond_gpio_info *info = &winbond_gpio_infos[idx];
	const struct winbond_gpio_port_conflict *conflict = &info->conflict;

	/* is there a possible conflicting device defined? */
	if (conflict->name != NULL) {
		if (conflict->dev != WB_SIO_DEV_NONE)
			winbond_sio_select_logical(base, conflict->dev);

		if (winbond_sio_reg_btest(base, conflict->testreg,
					  conflict->testbit)) {
			if (conflict->warnonly)
				pr_warn("enabled GPIO%u share pins with active %s\n",
					idx + 1, conflict->name);
			else {
				pr_warn("disabling GPIO%u as %s is enabled\n",
					idx + 1, conflict->name);
				return false;
			}
		}
	}

	/* GPIO1 and GPIO2 need some (additional) special handling */
	if (idx == 0)
		winbond_gpio_configure_port0_pins(base);
	else if (idx == 1)
		winbond_gpio_configure_port1_check_i2c(base);

	winbond_sio_select_logical(base, info->dev);

	winbond_sio_reg_bset(base, info->enablereg, info->enablebit);

	if (params.ppgpios & BIT(idx))
		winbond_sio_reg_bset(base, info->outputreg,
				     info->outputppbit);
	else if (params.odgpios & BIT(idx))
		winbond_sio_reg_bclear(base, info->outputreg,
				       info->outputppbit);
	else
		pr_notice("GPIO%u pins are %s\n", idx + 1,
			  winbond_sio_reg_btest(base, info->outputreg,
						info->outputppbit) ?
			  "push-pull" :
			  "open drain");

	return true;
}

static int winbond_gpio_configure(unsigned long base)
{
	unsigned long i;

	for_each_set_bit(i, &params.gpios, BITS_PER_LONG)
		if (!winbond_gpio_configure_port(base, i))
			__clear_bit(i, &params.gpios);

	if (!params.gpios) {
		pr_err("please use 'gpios' module parameter to select some active GPIO ports to enable\n");
		return -EINVAL;
	}

	return 0;
}

static int winbond_gpio_check_chip(unsigned long base)
{
	int ret;
	unsigned int chip;

	ret = winbond_sio_enter(base);
	if (ret)
		return ret;

	chip = winbond_sio_reg_read(base, WB_SIO_REG_CHIP_MSB) << 8;
	chip |= winbond_sio_reg_read(base, WB_SIO_REG_CHIP_LSB);

	pr_notice("chip ID at %lx is %.4x\n", base, chip);

	if ((chip & WB_SIO_CHIP_ID_W83627UHG_MASK) !=
	    WB_SIO_CHIP_ID_W83627UHG) {
		pr_err("not an our chip\n");
		ret = -ENODEV;
	}

	winbond_sio_leave(base);

	return ret;
}

static int winbond_gpio_imatch(struct device *dev, unsigned int id)
{
	unsigned long gpios_rem;
	int ret;

	gpios_rem = params.gpios & ~GENMASK(ARRAY_SIZE(winbond_gpio_infos) - 1,
					    0);
	if (gpios_rem) {
		pr_warn("unknown ports (%lx) enabled in GPIO ports bitmask\n",
			gpios_rem);
		params.gpios &= ~gpios_rem;
	}

	if (params.ppgpios & params.odgpios) {
		pr_err("some GPIO ports are set both to push-pull and open drain mode at the same time\n");
		return 0;
	}

	if (params.base != 0)
		return winbond_gpio_check_chip(params.base) == 0;

	/*
	 * if the 'base' module parameter is unset probe two chip default
	 * I/O port bases
	 */
	params.base = WB_SIO_BASE;
	ret = winbond_gpio_check_chip(params.base);
	if (ret == 0)
		return 1;
	if (ret != -ENODEV && ret != -EBUSY)
		return 0;

	params.base = WB_SIO_BASE_HIGH;
	return winbond_gpio_check_chip(params.base) == 0;
}

static int winbond_gpio_iprobe(struct device *dev, unsigned int id)
{
	int ret;

	if (params.base == 0)
		return -EINVAL;

	ret = winbond_sio_enter(params.base);
	if (ret)
		return ret;

	ret = winbond_gpio_configure(params.base);

	winbond_sio_leave(params.base);

	if (ret)
		return ret;

	/*
	 * Add 8 gpios for every GPIO port that was enabled in gpios
	 * module parameter (that wasn't disabled earlier in
	 * winbond_gpio_configure() & co. due to, for example, a pin conflict).
	 */
	winbond_gpio_chip.ngpio = hweight_long(params.gpios) * 8;

	/*
	 * GPIO6 port has only 5 pins, so if it is enabled we have to adjust
	 * the total count appropriately
	 */
	if (params.gpios & BIT(5))
		winbond_gpio_chip.ngpio -= (8 - 5);

	winbond_gpio_chip.parent = dev;

	return devm_gpiochip_add_data(dev, &winbond_gpio_chip, &params.base);
}

static struct isa_driver winbond_gpio_idriver = {
	.driver = {
		.name	= WB_GPIO_DRIVER_NAME,
	},
	.match	= winbond_gpio_imatch,
	.probe	= winbond_gpio_iprobe,
};

module_isa_driver(winbond_gpio_idriver, 1);

module_param_named(base, params.base, ulong, 0444);
MODULE_PARM_DESC(base,
		 "I/O port base (when unset - probe chip default ones)");

/* This parameter sets which GPIO devices (ports) we enable */
module_param_named(gpios, params.gpios, ulong, 0444);
MODULE_PARM_DESC(gpios,
		 "bitmask of GPIO ports to enable (bit 0 - GPIO1, bit 1 - GPIO2, etc.");

/*
 * These two parameters below set how we configure GPIO ports output drivers.
 * It can't be a one bitmask since we need three values per port: push-pull,
 * open-drain and keep as-is (this is the default).
 */
module_param_named(ppgpios, params.ppgpios, ulong, 0444);
MODULE_PARM_DESC(ppgpios,
		 "bitmask of GPIO ports to set to push-pull mode (bit 0 - GPIO1, bit 1 - GPIO2, etc.");

module_param_named(odgpios, params.odgpios, ulong, 0444);
MODULE_PARM_DESC(odgpios,
		 "bitmask of GPIO ports to set to open drain mode (bit 0 - GPIO1, bit 1 - GPIO2, etc.");

/*
 * GPIO2.0 and GPIO2.1 control a basic PC functionality that we
 * don't allow tinkering with by default (it is very likely that the
 * firmware owns these pins).
 * These two parameters below allow overriding these prohibitions.
 */
module_param_named(pledgpio, params.pledgpio, bool, 0644);
MODULE_PARM_DESC(pledgpio,
		 "enable changing value of GPIO2.0 bit (Power LED), default no.");

module_param_named(beepgpio, params.beepgpio, bool, 0644);
MODULE_PARM_DESC(beepgpio,
		 "enable changing value of GPIO2.1 bit (BEEP), default no.");

MODULE_AUTHOR("Maciej S. Szmigiero <mail@maciej.szmigiero.name>");
MODULE_DESCRIPTION("GPIO interface for Winbond Super I/O chips");
MODULE_LICENSE("GPL");