summaryrefslogtreecommitdiff
path: root/target/linux/generic/patches-2.6.36/922-gpiommc.patch
blob: 379f4f9382948fb31944e6c064e3907df76881ed (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
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
--- /dev/null
+++ b/drivers/mmc/host/gpiommc.c
@@ -0,0 +1,608 @@
+/*
+ * Driver an MMC/SD card on a bitbanging GPIO SPI bus.
+ * This module hooks up the mmc_spi and spi_gpio modules and also
+ * provides a configfs interface.
+ *
+ * Copyright 2008 Michael Buesch <mb@bu3sch.de>
+ *
+ * Licensed under the GNU/GPL. See COPYING for details.
+ */
+
+#include <linux/mmc/gpiommc.h>
+#include <linux/platform_device.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/spi/spi_gpio_old.h>
+#include <linux/configfs.h>
+#include <linux/gpio.h>
+#include <asm/atomic.h>
+
+
+#define PFX				"gpio-mmc: "
+
+
+struct gpiommc_device {
+	struct platform_device *pdev;
+	struct platform_device *spi_pdev;
+	struct spi_board_info boardinfo;
+};
+
+
+MODULE_DESCRIPTION("GPIO based MMC driver");
+MODULE_AUTHOR("Michael Buesch");
+MODULE_LICENSE("GPL");
+
+
+static int gpiommc_boardinfo_setup(struct spi_board_info *bi,
+				   struct spi_master *master,
+				   void *data)
+{
+	struct gpiommc_device *d = data;
+	struct gpiommc_platform_data *pdata = d->pdev->dev.platform_data;
+
+	/* Bind the SPI master to the MMC-SPI host driver. */
+	strlcpy(bi->modalias, "mmc_spi", sizeof(bi->modalias));
+
+	bi->max_speed_hz = pdata->max_bus_speed;
+	bi->bus_num = master->bus_num;
+	bi->mode = pdata->mode;
+
+	return 0;
+}
+
+static int gpiommc_probe(struct platform_device *pdev)
+{
+	struct gpiommc_platform_data *mmc_pdata = pdev->dev.platform_data;
+	struct spi_gpio_platform_data spi_pdata;
+	struct gpiommc_device *d;
+	int err;
+
+	err = -ENXIO;
+	if (!mmc_pdata)
+		goto error;
+
+#ifdef CONFIG_MMC_SPI_MODULE
+	err = request_module("mmc_spi");
+	if (err) {
+		printk(KERN_WARNING PFX
+		       "Failed to request mmc_spi module.\n");
+	}
+#endif /* CONFIG_MMC_SPI_MODULE */
+
+	/* Allocate the GPIO-MMC device */
+	err = -ENOMEM;
+	d = kzalloc(sizeof(*d), GFP_KERNEL);
+	if (!d)
+		goto error;
+	d->pdev = pdev;
+
+	/* Create the SPI-GPIO device */
+	d->spi_pdev = platform_device_alloc(SPI_GPIO_PLATDEV_NAME,
+					    spi_gpio_next_id());
+	if (!d->spi_pdev)
+		goto err_free_d;
+
+	memset(&spi_pdata, 0, sizeof(spi_pdata));
+	spi_pdata.pin_clk = mmc_pdata->pins.gpio_clk;
+	spi_pdata.pin_miso = mmc_pdata->pins.gpio_do;
+	spi_pdata.pin_mosi = mmc_pdata->pins.gpio_di;
+	spi_pdata.pin_cs = mmc_pdata->pins.gpio_cs;
+	spi_pdata.cs_activelow = mmc_pdata->pins.cs_activelow;
+	spi_pdata.no_spi_delay = mmc_pdata->no_spi_delay;
+	spi_pdata.boardinfo_setup = gpiommc_boardinfo_setup;
+	spi_pdata.boardinfo_setup_data = d;
+
+	err = platform_device_add_data(d->spi_pdev, &spi_pdata,
+				       sizeof(spi_pdata));
+	if (err)
+		goto err_free_pdev;
+	err = platform_device_add(d->spi_pdev);
+	if (err)
+		goto err_free_pdata;
+	platform_set_drvdata(pdev, d);
+
+	printk(KERN_INFO PFX "MMC-Card \"%s\" "
+	       "attached to GPIO pins di=%u, do=%u, clk=%u, cs=%u\n",
+	       mmc_pdata->name, mmc_pdata->pins.gpio_di,
+	       mmc_pdata->pins.gpio_do,
+	       mmc_pdata->pins.gpio_clk,
+	       mmc_pdata->pins.gpio_cs);
+
+	return 0;
+
+err_free_pdata:
+	kfree(d->spi_pdev->dev.platform_data);
+	d->spi_pdev->dev.platform_data = NULL;
+err_free_pdev:
+	platform_device_put(d->spi_pdev);
+err_free_d:
+	kfree(d);
+error:
+	return err;
+}
+
+static int gpiommc_remove(struct platform_device *pdev)
+{
+	struct gpiommc_device *d = platform_get_drvdata(pdev);
+	struct gpiommc_platform_data *pdata = d->pdev->dev.platform_data;
+
+	platform_device_unregister(d->spi_pdev);
+	printk(KERN_INFO PFX "GPIO based MMC-Card \"%s\" removed\n",
+	       pdata->name);
+	platform_device_put(d->spi_pdev);
+
+	return 0;
+}
+
+#ifdef CONFIG_GPIOMMC_CONFIGFS
+
+/* A device that was created through configfs */
+struct gpiommc_configfs_device {
+	struct config_item item;
+	/* The platform device, after registration. */
+	struct platform_device *pdev;
+	/* The configuration */
+	struct gpiommc_platform_data pdata;
+};
+
+#define GPIO_INVALID	-1
+
+static inline bool gpiommc_is_registered(struct gpiommc_configfs_device *dev)
+{
+	return (dev->pdev != NULL);
+}
+
+static inline struct gpiommc_configfs_device *ci_to_gpiommc(struct config_item *item)
+{
+	return item ? container_of(item, struct gpiommc_configfs_device, item) : NULL;
+}
+
+static struct configfs_attribute gpiommc_attr_DI = {
+	.ca_owner = THIS_MODULE,
+	.ca_name = "gpio_data_in",
+	.ca_mode = S_IRUGO | S_IWUSR,
+};
+
+static struct configfs_attribute gpiommc_attr_DO = {
+	.ca_owner = THIS_MODULE,
+	.ca_name = "gpio_data_out",
+	.ca_mode = S_IRUGO | S_IWUSR,
+};
+
+static struct configfs_attribute gpiommc_attr_CLK = {
+	.ca_owner = THIS_MODULE,
+	.ca_name = "gpio_clock",
+	.ca_mode = S_IRUGO | S_IWUSR,
+};
+
+static struct configfs_attribute gpiommc_attr_CS = {
+	.ca_owner = THIS_MODULE,
+	.ca_name = "gpio_chipselect",
+	.ca_mode = S_IRUGO | S_IWUSR,
+};
+
+static struct configfs_attribute gpiommc_attr_CS_activelow = {
+	.ca_owner = THIS_MODULE,
+	.ca_name = "gpio_chipselect_activelow",
+	.ca_mode = S_IRUGO | S_IWUSR,
+};
+
+static struct configfs_attribute gpiommc_attr_spimode = {
+	.ca_owner = THIS_MODULE,
+	.ca_name = "spi_mode",
+	.ca_mode = S_IRUGO | S_IWUSR,
+};
+
+static struct configfs_attribute gpiommc_attr_spidelay = {
+	.ca_owner = THIS_MODULE,
+	.ca_name = "spi_delay",
+	.ca_mode = S_IRUGO | S_IWUSR,
+};
+
+static struct configfs_attribute gpiommc_attr_max_bus_speed = {
+	.ca_owner = THIS_MODULE,
+	.ca_name = "max_bus_speed",
+	.ca_mode = S_IRUGO | S_IWUSR,
+};
+
+static struct configfs_attribute gpiommc_attr_register = {
+	.ca_owner = THIS_MODULE,
+	.ca_name = "register",
+	.ca_mode = S_IRUGO | S_IWUSR,
+};
+
+static struct configfs_attribute *gpiommc_config_attrs[] = {
+	&gpiommc_attr_DI,
+	&gpiommc_attr_DO,
+	&gpiommc_attr_CLK,
+	&gpiommc_attr_CS,
+	&gpiommc_attr_CS_activelow,
+	&gpiommc_attr_spimode,
+	&gpiommc_attr_spidelay,
+	&gpiommc_attr_max_bus_speed,
+	&gpiommc_attr_register,
+	NULL,
+};
+
+static ssize_t gpiommc_config_attr_show(struct config_item *item,
+					struct configfs_attribute *attr,
+					char *page)
+{
+	struct gpiommc_configfs_device *dev = ci_to_gpiommc(item);
+	ssize_t count = 0;
+	unsigned int gpio;
+	int err = 0;
+
+	if (attr == &gpiommc_attr_DI) {
+		gpio = dev->pdata.pins.gpio_di;
+		if (gpio == GPIO_INVALID)
+			count = snprintf(page, PAGE_SIZE, "not configured\n");
+		else
+			count = snprintf(page, PAGE_SIZE, "%u\n", gpio);
+		goto out;
+	}
+	if (attr == &gpiommc_attr_DO) {
+		gpio = dev->pdata.pins.gpio_do;
+		if (gpio == GPIO_INVALID)
+			count = snprintf(page, PAGE_SIZE, "not configured\n");
+		else
+			count = snprintf(page, PAGE_SIZE, "%u\n", gpio);
+		goto out;
+	}
+	if (attr == &gpiommc_attr_CLK) {
+		gpio = dev->pdata.pins.gpio_clk;
+		if (gpio == GPIO_INVALID)
+			count = snprintf(page, PAGE_SIZE, "not configured\n");
+		else
+			count = snprintf(page, PAGE_SIZE, "%u\n", gpio);
+		goto out;
+	}
+	if (attr == &gpiommc_attr_CS) {
+		gpio = dev->pdata.pins.gpio_cs;
+		if (gpio == GPIO_INVALID)
+			count = snprintf(page, PAGE_SIZE, "not configured\n");
+		else
+			count = snprintf(page, PAGE_SIZE, "%u\n", gpio);
+		goto out;
+	}
+	if (attr == &gpiommc_attr_CS_activelow) {
+		count = snprintf(page, PAGE_SIZE, "%u\n",
+				 dev->pdata.pins.cs_activelow);
+		goto out;
+	}
+	if (attr == &gpiommc_attr_spimode) {
+		count = snprintf(page, PAGE_SIZE, "%u\n",
+				 dev->pdata.mode);
+		goto out;
+	}
+	if (attr == &gpiommc_attr_spidelay) {
+		count = snprintf(page, PAGE_SIZE, "%u\n",
+				 !dev->pdata.no_spi_delay);
+		goto out;
+	}
+	if (attr == &gpiommc_attr_max_bus_speed) {
+		count = snprintf(page, PAGE_SIZE, "%u\n",
+				 dev->pdata.max_bus_speed);
+		goto out;
+	}
+	if (attr == &gpiommc_attr_register) {
+		count = snprintf(page, PAGE_SIZE, "%u\n",
+				 gpiommc_is_registered(dev));
+		goto out;
+	}
+	WARN_ON(1);
+	err = -ENOSYS;
+out:
+	return err ? err : count;
+}
+
+static int gpiommc_do_register(struct gpiommc_configfs_device *dev,
+			       const char *name)
+{
+	int err;
+
+	if (gpiommc_is_registered(dev))
+		return 0;
+
+	if (!gpio_is_valid(dev->pdata.pins.gpio_di) ||
+	    !gpio_is_valid(dev->pdata.pins.gpio_do) ||
+	    !gpio_is_valid(dev->pdata.pins.gpio_clk) ||
+	    !gpio_is_valid(dev->pdata.pins.gpio_cs)) {
+		printk(KERN_ERR PFX
+		       "configfs: Invalid GPIO pin number(s)\n");
+		return -EINVAL;
+	}
+
+	strlcpy(dev->pdata.name, name,
+		sizeof(dev->pdata.name));
+
+	dev->pdev = platform_device_alloc(GPIOMMC_PLATDEV_NAME,
+					  gpiommc_next_id());
+	if (!dev->pdev)
+		return -ENOMEM;
+	err = platform_device_add_data(dev->pdev, &dev->pdata,
+				       sizeof(dev->pdata));
+	if (err) {
+		platform_device_put(dev->pdev);
+		return err;
+	}
+	err = platform_device_add(dev->pdev);
+	if (err) {
+		platform_device_put(dev->pdev);
+		return err;
+	}
+
+	return 0;
+}
+
+static void gpiommc_do_unregister(struct gpiommc_configfs_device *dev)
+{
+	if (!gpiommc_is_registered(dev))
+		return;
+
+	platform_device_unregister(dev->pdev);
+	dev->pdev = NULL;
+}
+
+static ssize_t gpiommc_config_attr_store(struct config_item *item,
+					 struct configfs_attribute *attr,
+					 const char *page, size_t count)
+{
+	struct gpiommc_configfs_device *dev = ci_to_gpiommc(item);
+	int err = -EINVAL;
+	unsigned long data;
+
+	if (attr == &gpiommc_attr_register) {
+		err = strict_strtoul(page, 10, &data);
+		if (err)
+			goto out;
+		err = -EINVAL;
+		if (data == 1)
+			err = gpiommc_do_register(dev, item->ci_name);
+		if (data == 0) {
+			gpiommc_do_unregister(dev);
+			err = 0;
+		}
+		goto out;
+	}
+
+	if (gpiommc_is_registered(dev)) {
+		/* The rest of the config parameters can only be set
+		 * as long as the device is not registered, yet. */
+		err = -EBUSY;
+		goto out;
+	}
+
+	if (attr == &gpiommc_attr_DI) {
+		err = strict_strtoul(page, 10, &data);
+		if (err)
+			goto out;
+		err = -EINVAL;
+		if (!gpio_is_valid(data))
+			goto out;
+		dev->pdata.pins.gpio_di = data;
+		err = 0;
+		goto out;
+	}
+	if (attr == &gpiommc_attr_DO) {
+		err = strict_strtoul(page, 10, &data);
+		if (err)
+			goto out;
+		err = -EINVAL;
+		if (!gpio_is_valid(data))
+			goto out;
+		dev->pdata.pins.gpio_do = data;
+		err = 0;
+		goto out;
+	}
+	if (attr == &gpiommc_attr_CLK) {
+		err = strict_strtoul(page, 10, &data);
+		if (err)
+			goto out;
+		err = -EINVAL;
+		if (!gpio_is_valid(data))
+			goto out;
+		dev->pdata.pins.gpio_clk = data;
+		err = 0;
+		goto out;
+	}
+	if (attr == &gpiommc_attr_CS) {
+		err = strict_strtoul(page, 10, &data);
+		if (err)
+			goto out;
+		err = -EINVAL;
+		if (!gpio_is_valid(data))
+			goto out;
+		dev->pdata.pins.gpio_cs = data;
+		err = 0;
+		goto out;
+	}
+	if (attr == &gpiommc_attr_CS_activelow) {
+		err = strict_strtoul(page, 10, &data);
+		if (err)
+			goto out;
+		err = -EINVAL;
+		if (data != 0 && data != 1)
+			goto out;
+		dev->pdata.pins.cs_activelow = data;
+		err = 0;
+		goto out;
+	}
+	if (attr == &gpiommc_attr_spimode) {
+		err = strict_strtoul(page, 10, &data);
+		if (err)
+			goto out;
+		err = -EINVAL;
+		switch (data) {
+		case 0:
+			dev->pdata.mode = SPI_MODE_0;
+			break;
+		case 1:
+			dev->pdata.mode = SPI_MODE_1;
+			break;
+		case 2:
+			dev->pdata.mode = SPI_MODE_2;
+			break;
+		case 3:
+			dev->pdata.mode = SPI_MODE_3;
+			break;
+		default:
+			goto out;
+		}
+		err = 0;
+		goto out;
+	}
+	if (attr == &gpiommc_attr_spidelay) {
+		err = strict_strtoul(page, 10, &data);
+		if (err)
+			goto out;
+		err = -EINVAL;
+		if (data != 0 && data != 1)
+			goto out;
+		dev->pdata.no_spi_delay = !data;
+		err = 0;
+		goto out;
+	}
+	if (attr == &gpiommc_attr_max_bus_speed) {
+		err = strict_strtoul(page, 10, &data);
+		if (err)
+			goto out;
+		err = -EINVAL;
+		if (data > UINT_MAX)
+			goto out;
+		dev->pdata.max_bus_speed = data;
+		err = 0;
+		goto out;
+	}
+	WARN_ON(1);
+	err = -ENOSYS;
+out:
+	return err ? err : count;
+}
+
+static void gpiommc_config_item_release(struct config_item *item)
+{
+	struct gpiommc_configfs_device *dev = ci_to_gpiommc(item);
+
+	kfree(dev);
+}
+
+static struct configfs_item_operations gpiommc_config_item_ops = {
+	.release		= gpiommc_config_item_release,
+	.show_attribute		= gpiommc_config_attr_show,
+	.store_attribute	= gpiommc_config_attr_store,
+};
+
+static struct config_item_type gpiommc_dev_ci_type = {
+	.ct_item_ops	= &gpiommc_config_item_ops,
+	.ct_attrs	= gpiommc_config_attrs,
+	.ct_owner	= THIS_MODULE,
+};
+
+static struct config_item *gpiommc_make_item(struct config_group *group,
+					     const char *name)
+{
+	struct gpiommc_configfs_device *dev;
+
+	if (strlen(name) > GPIOMMC_MAX_NAMELEN) {
+		printk(KERN_ERR PFX "configfs: device name too long\n");
+		return NULL;
+	}
+
+	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+	if (!dev)
+		return NULL;
+
+	config_item_init_type_name(&dev->item, name,
+				   &gpiommc_dev_ci_type);
+
+	/* Assign default configuration */
+	dev->pdata.pins.gpio_di = GPIO_INVALID;
+	dev->pdata.pins.gpio_do = GPIO_INVALID;
+	dev->pdata.pins.gpio_clk = GPIO_INVALID;
+	dev->pdata.pins.gpio_cs = GPIO_INVALID;
+	dev->pdata.pins.cs_activelow = 1;
+	dev->pdata.mode = SPI_MODE_0;
+	dev->pdata.no_spi_delay = 0;
+	dev->pdata.max_bus_speed = 5000000; /* 5 MHz */
+
+	return &(dev->item);
+}
+
+static void gpiommc_drop_item(struct config_group *group,
+			      struct config_item *item)
+{
+	struct gpiommc_configfs_device *dev = ci_to_gpiommc(item);
+
+	gpiommc_do_unregister(dev);
+	kfree(dev);
+}
+
+static struct configfs_group_operations gpiommc_ct_group_ops = {
+	.make_item	= gpiommc_make_item,
+	.drop_item	= gpiommc_drop_item,
+};
+
+static struct config_item_type gpiommc_ci_type = {
+	.ct_group_ops	= &gpiommc_ct_group_ops,
+	.ct_owner	= THIS_MODULE,
+};
+
+static struct configfs_subsystem gpiommc_subsys = {
+	.su_group = {
+		.cg_item = {
+			.ci_namebuf = GPIOMMC_PLATDEV_NAME,
+			.ci_type = &gpiommc_ci_type,
+		},
+	},
+	.su_mutex = __MUTEX_INITIALIZER(gpiommc_subsys.su_mutex),
+};
+
+#endif /* CONFIG_GPIOMMC_CONFIGFS */
+
+static struct platform_driver gpiommc_plat_driver = {
+	.probe	= gpiommc_probe,
+	.remove	= gpiommc_remove,
+	.driver	= {
+		.name	= GPIOMMC_PLATDEV_NAME,
+		.owner	= THIS_MODULE,
+	},
+};
+
+int gpiommc_next_id(void)
+{
+	static atomic_t counter = ATOMIC_INIT(-1);
+
+	return atomic_inc_return(&counter);
+}
+EXPORT_SYMBOL(gpiommc_next_id);
+
+static int __init gpiommc_modinit(void)
+{
+	int err;
+
+	err = platform_driver_register(&gpiommc_plat_driver);
+	if (err)
+		return err;
+
+#ifdef CONFIG_GPIOMMC_CONFIGFS
+	config_group_init(&gpiommc_subsys.su_group);
+	err = configfs_register_subsystem(&gpiommc_subsys);
+	if (err) {
+		platform_driver_unregister(&gpiommc_plat_driver);
+		return err;
+	}
+#endif /* CONFIG_GPIOMMC_CONFIGFS */
+
+	return 0;
+}
+module_init(gpiommc_modinit);
+
+static void __exit gpiommc_modexit(void)
+{
+#ifdef CONFIG_GPIOMMC_CONFIGFS
+	configfs_unregister_subsystem(&gpiommc_subsys);
+#endif
+	platform_driver_unregister(&gpiommc_plat_driver);
+}
+module_exit(gpiommc_modexit);
--- a/drivers/mmc/host/Kconfig
+++ b/drivers/mmc/host/Kconfig
@@ -382,6 +382,31 @@ config MMC_TMIO
 	  This provides support for the SD/MMC cell found in TC6393XB,
 	  T7L66XB and also HTC ASIC3
 
+config GPIOMMC
+	tristate "MMC/SD over GPIO-based SPI"
+	depends on MMC && MMC_SPI && SPI_GPIO_OLD
+	help
+	  This driver hooks up the mmc_spi and spi_gpio modules so that
+	  MMC/SD cards can be used on a GPIO based bus by bitbanging
+	  the SPI protocol in software.
+
+	  This driver provides a configfs interface to dynamically create
+	  and destroy GPIO-based MMC/SD card devices. It also provides
+	  a platform device interface API.
+	  See Documentation/gpiommc.txt for details.
+
+	  The module will be called gpiommc.
+
+	  If unsure, say N.
+
+config GPIOMMC_CONFIGFS
+	bool
+	depends on GPIOMMC && CONFIGFS_FS
+	default y
+	help
+	  This option automatically enables configfs support for gpiommc
+	  if configfs is available.
+
 config MMC_CB710
 	tristate "ENE CB710 MMC/SD Interface support"
 	depends on PCI
--- a/drivers/mmc/host/Makefile
+++ b/drivers/mmc/host/Makefile
@@ -34,6 +34,7 @@ obj-$(CONFIG_MMC_SDRICOH_CS)	+= sdricoh_
 obj-$(CONFIG_MMC_TMIO)		+= tmio_mmc.o
 obj-$(CONFIG_MMC_CB710)	+= cb710-mmc.o
 obj-$(CONFIG_MMC_VIA_SDMMC)	+= via-sdmmc.o
+obj-$(CONFIG_GPIOMMC)		+= gpiommc.o
 obj-$(CONFIG_SDH_BFIN)		+= bfin_sdh.o
 obj-$(CONFIG_MMC_SH_MMCIF)	+= sh_mmcif.o
 
--- /dev/null
+++ b/include/linux/mmc/gpiommc.h
@@ -0,0 +1,71 @@
+/*
+ * Device driver for MMC/SD cards driven over a GPIO bus.
+ *
+ * Copyright (c) 2008 Michael Buesch
+ *
+ * Licensed under the GNU/GPL version 2.
+ */
+#ifndef LINUX_GPIOMMC_H_
+#define LINUX_GPIOMMC_H_
+
+#include <linux/types.h>
+
+
+#define GPIOMMC_MAX_NAMELEN		15
+#define GPIOMMC_MAX_NAMELEN_STR		__stringify(GPIOMMC_MAX_NAMELEN)
+
+/**
+ * struct gpiommc_pins - Hardware pin assignments
+ *
+ * @gpio_di: The GPIO number of the DATA IN pin
+ * @gpio_do: The GPIO number of the DATA OUT pin
+ * @gpio_clk: The GPIO number of the CLOCK pin
+ * @gpio_cs: The GPIO number of the CHIPSELECT pin
+ * @cs_activelow: If true, the chip is considered selected if @gpio_cs is low.
+ */
+struct gpiommc_pins {
+	unsigned int gpio_di;
+	unsigned int gpio_do;
+	unsigned int gpio_clk;
+	unsigned int gpio_cs;
+	bool cs_activelow;
+};
+
+/**
+ * struct gpiommc_platform_data - Platform data for a MMC-over-SPI-GPIO device.
+ *
+ * @name: The unique name string of the device.
+ * @pins: The hardware pin assignments.
+ * @mode: The hardware mode. This is either SPI_MODE_0,
+ *        SPI_MODE_1, SPI_MODE_2 or SPI_MODE_3. See the SPI documentation.
+ * @no_spi_delay: Do not use delays in the lowlevel SPI bitbanging code.
+ *                This is not standards compliant, but may be required for some
+ *                embedded machines to gain reasonable speed.
+ * @max_bus_speed: The maximum speed of the SPI bus, in Hertz.
+ */
+struct gpiommc_platform_data {
+	char name[GPIOMMC_MAX_NAMELEN + 1];
+	struct gpiommc_pins pins;
+	u8 mode;
+	bool no_spi_delay;
+	unsigned int max_bus_speed;
+};
+
+/**
+ * GPIOMMC_PLATDEV_NAME - The platform device name string.
+ *
+ * The name string that has to be used for platform_device_alloc
+ * when allocating a gpiommc device.
+ */
+#define GPIOMMC_PLATDEV_NAME	"gpiommc"
+
+/**
+ * gpiommc_next_id - Get another platform device ID number.
+ *
+ * This returns the next platform device ID number that has to be used
+ * for platform_device_alloc. The ID is opaque and should not be used for
+ * anything else.
+ */
+int gpiommc_next_id(void);
+
+#endif /* LINUX_GPIOMMC_H_ */
--- /dev/null
+++ b/Documentation/gpiommc.txt
@@ -0,0 +1,97 @@
+GPIOMMC - Driver for an MMC/SD card on a bitbanging GPIO SPI bus
+================================================================
+
+The gpiommc module hooks up the mmc_spi and spi_gpio modules for running an
+MMC or SD card on GPIO pins.
+
+Two interfaces for registering a new MMC/SD card device are provided:
+A static platform-device based mechanism and a dynamic configfs based interface.
+
+
+Registering devices via platform-device
+=======================================
+
+The platform-device interface is used for registering MMC/SD devices that are
+part of the hardware platform. This is most useful only for embedded machines
+with MMC/SD devices statically connected to the platform GPIO bus.
+
+The data structures are declared in <linux/mmc/gpiommc.h>.
+
+To register a new device, define an instance of struct gpiommc_platform_data.
+This structure holds any information about how the device is hooked up to the
+GPIO pins and what hardware modes the device supports. See the docbook-style
+documentation in the header file for more information on the struct fields.
+
+Then allocate a new instance of a platform device by doing:
+
+	pdev = platform_device_alloc(GPIOMMC_PLATDEV_NAME, gpiommc_next_id());
+
+This will allocate the platform device data structures and hook it up to the
+gpiommc driver.
+Then add the gpiommc_platform_data to the platform device.
+
+	err = platform_device_add_data(pdev, pdata, sizeof(struct gpiommc_platform_data));
+
+You may free the local instance of struct gpiommc_platform_data now. (So the
+struct may be allocated on the stack, too).
+Now simply register the platform device.
+
+	err = platform_device_add(pdev);
+
+Done. The gpiommc probe routine will be invoked now and you should see a kernel
+log message for the added device.
+
+
+Registering devices via configfs
+================================
+
+MMC/SD cards connected via GPIO often are a pretty dynamic thing, as for example
+selfmade hacks for soldering an MMC/SD card to standard GPIO pins on embedded
+hardware are a common situation.
+So we provide a dynamic interface to conveniently handle adding and removing
+devices from userspace, without the need to recompile the kernel.
+
+The "gpiommc" subdirectory at the configfs mountpoint is used for handling
+the dynamic configuration.
+
+To create a new device, it must first be allocated with mkdir.
+The following command will allocate a device named "my_mmc":
+	mkdir /config/gpiommc/my_mmc
+
+There are several configuration files available in the new
+/config/gpiommc/my_mmc/ directory:
+
+gpio_data_in			= The SPI data-IN GPIO pin number.
+gpio_data_out			= The SPI data-OUT GPIO pin number.
+gpio_clock			= The SPI Clock GPIO pin number.
+gpio_chipselect			= The SPI Chipselect GPIO pin number.
+gpio_chipselect_activelow	= Boolean. If 0, Chipselect is active-HIGH.
+				  If 1, Chipselect is active-LOW.
+spi_mode			= The SPI data mode. Can be 0-3.
+spi_delay			= Enable all delays in the lowlevel bitbanging.
+max_bus_speed			= The maximum SPI bus speed. In Hertz.
+
+register			= Not a configuration parameter.
+				  Used to register the configured card
+				  with the kernel.
+
+The device must first get configured and then registered by writing "1" to
+the "register" file.
+The configuration parameters "gpio_data_in", "gpio_data_out", "gpio_clock"
+and "gpio_chipselect" are essential and _must_ be configured before writing
+"1" to the "register" file. The registration will fail, otherwise.
+
+The default values for the other parameters are:
+gpio_chipselect_activelow	= 1		(CS active-LOW)
+spi_mode			= 0		(SPI_MODE_0)
+spi_delay			= 1		(enabled)
+max_bus_speed			= 5000000	(5 Mhz)
+
+Configuration values can not be changed after registration. To unregister
+the device, write a "0" to the "register" file. The configuration can be
+changed again after unregistering.
+
+To completely remove the device, simply rmdir the directory
+(/config/gpiommc/my_mmc in this example).
+There's no need to first unregister the device before removing it. That will
+be done automatically.
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2591,6 +2591,11 @@ T:	git git://git.kernel.org/pub/scm/linu
 S:	Maintained
 F:	drivers/media/video/gspca/
 
+GPIOMMC DRIVER
+P:	Michael Buesch
+M:	mb@bu3sch.de
+S:	Maintained
+
 HARDWARE MONITORING
 L:	lm-sensors@lm-sensors.org
 W:	http://www.lm-sensors.org/