Root/target/linux/generic/patches-3.7/863-gpiommc.patch

1--- /dev/null
2+++ b/drivers/mmc/host/gpiommc.c
3@@ -0,0 +1,609 @@
4+/*
5+ * Driver an MMC/SD card on a bitbanging GPIO SPI bus.
6+ * This module hooks up the mmc_spi and spi_gpio modules and also
7+ * provides a configfs interface.
8+ *
9+ * Copyright 2008 Michael Buesch <mb@bu3sch.de>
10+ *
11+ * Licensed under the GNU/GPL. See COPYING for details.
12+ */
13+
14+#include <linux/module.h>
15+#include <linux/mmc/gpiommc.h>
16+#include <linux/platform_device.h>
17+#include <linux/list.h>
18+#include <linux/mutex.h>
19+#include <linux/spi/spi_gpio_old.h>
20+#include <linux/configfs.h>
21+#include <linux/gpio.h>
22+#include <asm/atomic.h>
23+
24+
25+#define PFX "gpio-mmc: "
26+
27+
28+struct gpiommc_device {
29+ struct platform_device *pdev;
30+ struct platform_device *spi_pdev;
31+ struct spi_board_info boardinfo;
32+};
33+
34+
35+MODULE_DESCRIPTION("GPIO based MMC driver");
36+MODULE_AUTHOR("Michael Buesch");
37+MODULE_LICENSE("GPL");
38+
39+
40+static int gpiommc_boardinfo_setup(struct spi_board_info *bi,
41+ struct spi_master *master,
42+ void *data)
43+{
44+ struct gpiommc_device *d = data;
45+ struct gpiommc_platform_data *pdata = d->pdev->dev.platform_data;
46+
47+ /* Bind the SPI master to the MMC-SPI host driver. */
48+ strlcpy(bi->modalias, "mmc_spi", sizeof(bi->modalias));
49+
50+ bi->max_speed_hz = pdata->max_bus_speed;
51+ bi->bus_num = master->bus_num;
52+ bi->mode = pdata->mode;
53+
54+ return 0;
55+}
56+
57+static int gpiommc_probe(struct platform_device *pdev)
58+{
59+ struct gpiommc_platform_data *mmc_pdata = pdev->dev.platform_data;
60+ struct spi_gpio_platform_data spi_pdata;
61+ struct gpiommc_device *d;
62+ int err;
63+
64+ err = -ENXIO;
65+ if (!mmc_pdata)
66+ goto error;
67+
68+#ifdef CONFIG_MMC_SPI_MODULE
69+ err = request_module("mmc_spi");
70+ if (err) {
71+ printk(KERN_WARNING PFX
72+ "Failed to request mmc_spi module.\n");
73+ }
74+#endif /* CONFIG_MMC_SPI_MODULE */
75+
76+ /* Allocate the GPIO-MMC device */
77+ err = -ENOMEM;
78+ d = kzalloc(sizeof(*d), GFP_KERNEL);
79+ if (!d)
80+ goto error;
81+ d->pdev = pdev;
82+
83+ /* Create the SPI-GPIO device */
84+ d->spi_pdev = platform_device_alloc(SPI_GPIO_PLATDEV_NAME,
85+ spi_gpio_next_id());
86+ if (!d->spi_pdev)
87+ goto err_free_d;
88+
89+ memset(&spi_pdata, 0, sizeof(spi_pdata));
90+ spi_pdata.pin_clk = mmc_pdata->pins.gpio_clk;
91+ spi_pdata.pin_miso = mmc_pdata->pins.gpio_do;
92+ spi_pdata.pin_mosi = mmc_pdata->pins.gpio_di;
93+ spi_pdata.pin_cs = mmc_pdata->pins.gpio_cs;
94+ spi_pdata.cs_activelow = mmc_pdata->pins.cs_activelow;
95+ spi_pdata.no_spi_delay = mmc_pdata->no_spi_delay;
96+ spi_pdata.boardinfo_setup = gpiommc_boardinfo_setup;
97+ spi_pdata.boardinfo_setup_data = d;
98+
99+ err = platform_device_add_data(d->spi_pdev, &spi_pdata,
100+ sizeof(spi_pdata));
101+ if (err)
102+ goto err_free_pdev;
103+ err = platform_device_add(d->spi_pdev);
104+ if (err)
105+ goto err_free_pdata;
106+ platform_set_drvdata(pdev, d);
107+
108+ printk(KERN_INFO PFX "MMC-Card \"%s\" "
109+ "attached to GPIO pins di=%u, do=%u, clk=%u, cs=%u\n",
110+ mmc_pdata->name, mmc_pdata->pins.gpio_di,
111+ mmc_pdata->pins.gpio_do,
112+ mmc_pdata->pins.gpio_clk,
113+ mmc_pdata->pins.gpio_cs);
114+
115+ return 0;
116+
117+err_free_pdata:
118+ kfree(d->spi_pdev->dev.platform_data);
119+ d->spi_pdev->dev.platform_data = NULL;
120+err_free_pdev:
121+ platform_device_put(d->spi_pdev);
122+err_free_d:
123+ kfree(d);
124+error:
125+ return err;
126+}
127+
128+static int gpiommc_remove(struct platform_device *pdev)
129+{
130+ struct gpiommc_device *d = platform_get_drvdata(pdev);
131+ struct gpiommc_platform_data *pdata = d->pdev->dev.platform_data;
132+
133+ platform_device_unregister(d->spi_pdev);
134+ printk(KERN_INFO PFX "GPIO based MMC-Card \"%s\" removed\n",
135+ pdata->name);
136+ platform_device_put(d->spi_pdev);
137+
138+ return 0;
139+}
140+
141+#ifdef CONFIG_GPIOMMC_CONFIGFS
142+
143+/* A device that was created through configfs */
144+struct gpiommc_configfs_device {
145+ struct config_item item;
146+ /* The platform device, after registration. */
147+ struct platform_device *pdev;
148+ /* The configuration */
149+ struct gpiommc_platform_data pdata;
150+};
151+
152+#define GPIO_INVALID -1
153+
154+static inline bool gpiommc_is_registered(struct gpiommc_configfs_device *dev)
155+{
156+ return (dev->pdev != NULL);
157+}
158+
159+static inline struct gpiommc_configfs_device *ci_to_gpiommc(struct config_item *item)
160+{
161+ return item ? container_of(item, struct gpiommc_configfs_device, item) : NULL;
162+}
163+
164+static struct configfs_attribute gpiommc_attr_DI = {
165+ .ca_owner = THIS_MODULE,
166+ .ca_name = "gpio_data_in",
167+ .ca_mode = S_IRUGO | S_IWUSR,
168+};
169+
170+static struct configfs_attribute gpiommc_attr_DO = {
171+ .ca_owner = THIS_MODULE,
172+ .ca_name = "gpio_data_out",
173+ .ca_mode = S_IRUGO | S_IWUSR,
174+};
175+
176+static struct configfs_attribute gpiommc_attr_CLK = {
177+ .ca_owner = THIS_MODULE,
178+ .ca_name = "gpio_clock",
179+ .ca_mode = S_IRUGO | S_IWUSR,
180+};
181+
182+static struct configfs_attribute gpiommc_attr_CS = {
183+ .ca_owner = THIS_MODULE,
184+ .ca_name = "gpio_chipselect",
185+ .ca_mode = S_IRUGO | S_IWUSR,
186+};
187+
188+static struct configfs_attribute gpiommc_attr_CS_activelow = {
189+ .ca_owner = THIS_MODULE,
190+ .ca_name = "gpio_chipselect_activelow",
191+ .ca_mode = S_IRUGO | S_IWUSR,
192+};
193+
194+static struct configfs_attribute gpiommc_attr_spimode = {
195+ .ca_owner = THIS_MODULE,
196+ .ca_name = "spi_mode",
197+ .ca_mode = S_IRUGO | S_IWUSR,
198+};
199+
200+static struct configfs_attribute gpiommc_attr_spidelay = {
201+ .ca_owner = THIS_MODULE,
202+ .ca_name = "spi_delay",
203+ .ca_mode = S_IRUGO | S_IWUSR,
204+};
205+
206+static struct configfs_attribute gpiommc_attr_max_bus_speed = {
207+ .ca_owner = THIS_MODULE,
208+ .ca_name = "max_bus_speed",
209+ .ca_mode = S_IRUGO | S_IWUSR,
210+};
211+
212+static struct configfs_attribute gpiommc_attr_register = {
213+ .ca_owner = THIS_MODULE,
214+ .ca_name = "register",
215+ .ca_mode = S_IRUGO | S_IWUSR,
216+};
217+
218+static struct configfs_attribute *gpiommc_config_attrs[] = {
219+ &gpiommc_attr_DI,
220+ &gpiommc_attr_DO,
221+ &gpiommc_attr_CLK,
222+ &gpiommc_attr_CS,
223+ &gpiommc_attr_CS_activelow,
224+ &gpiommc_attr_spimode,
225+ &gpiommc_attr_spidelay,
226+ &gpiommc_attr_max_bus_speed,
227+ &gpiommc_attr_register,
228+ NULL,
229+};
230+
231+static ssize_t gpiommc_config_attr_show(struct config_item *item,
232+ struct configfs_attribute *attr,
233+ char *page)
234+{
235+ struct gpiommc_configfs_device *dev = ci_to_gpiommc(item);
236+ ssize_t count = 0;
237+ unsigned int gpio;
238+ int err = 0;
239+
240+ if (attr == &gpiommc_attr_DI) {
241+ gpio = dev->pdata.pins.gpio_di;
242+ if (gpio == GPIO_INVALID)
243+ count = snprintf(page, PAGE_SIZE, "not configured\n");
244+ else
245+ count = snprintf(page, PAGE_SIZE, "%u\n", gpio);
246+ goto out;
247+ }
248+ if (attr == &gpiommc_attr_DO) {
249+ gpio = dev->pdata.pins.gpio_do;
250+ if (gpio == GPIO_INVALID)
251+ count = snprintf(page, PAGE_SIZE, "not configured\n");
252+ else
253+ count = snprintf(page, PAGE_SIZE, "%u\n", gpio);
254+ goto out;
255+ }
256+ if (attr == &gpiommc_attr_CLK) {
257+ gpio = dev->pdata.pins.gpio_clk;
258+ if (gpio == GPIO_INVALID)
259+ count = snprintf(page, PAGE_SIZE, "not configured\n");
260+ else
261+ count = snprintf(page, PAGE_SIZE, "%u\n", gpio);
262+ goto out;
263+ }
264+ if (attr == &gpiommc_attr_CS) {
265+ gpio = dev->pdata.pins.gpio_cs;
266+ if (gpio == GPIO_INVALID)
267+ count = snprintf(page, PAGE_SIZE, "not configured\n");
268+ else
269+ count = snprintf(page, PAGE_SIZE, "%u\n", gpio);
270+ goto out;
271+ }
272+ if (attr == &gpiommc_attr_CS_activelow) {
273+ count = snprintf(page, PAGE_SIZE, "%u\n",
274+ dev->pdata.pins.cs_activelow);
275+ goto out;
276+ }
277+ if (attr == &gpiommc_attr_spimode) {
278+ count = snprintf(page, PAGE_SIZE, "%u\n",
279+ dev->pdata.mode);
280+ goto out;
281+ }
282+ if (attr == &gpiommc_attr_spidelay) {
283+ count = snprintf(page, PAGE_SIZE, "%u\n",
284+ !dev->pdata.no_spi_delay);
285+ goto out;
286+ }
287+ if (attr == &gpiommc_attr_max_bus_speed) {
288+ count = snprintf(page, PAGE_SIZE, "%u\n",
289+ dev->pdata.max_bus_speed);
290+ goto out;
291+ }
292+ if (attr == &gpiommc_attr_register) {
293+ count = snprintf(page, PAGE_SIZE, "%u\n",
294+ gpiommc_is_registered(dev));
295+ goto out;
296+ }
297+ WARN_ON(1);
298+ err = -ENOSYS;
299+out:
300+ return err ? err : count;
301+}
302+
303+static int gpiommc_do_register(struct gpiommc_configfs_device *dev,
304+ const char *name)
305+{
306+ int err;
307+
308+ if (gpiommc_is_registered(dev))
309+ return 0;
310+
311+ if (!gpio_is_valid(dev->pdata.pins.gpio_di) ||
312+ !gpio_is_valid(dev->pdata.pins.gpio_do) ||
313+ !gpio_is_valid(dev->pdata.pins.gpio_clk) ||
314+ !gpio_is_valid(dev->pdata.pins.gpio_cs)) {
315+ printk(KERN_ERR PFX
316+ "configfs: Invalid GPIO pin number(s)\n");
317+ return -EINVAL;
318+ }
319+
320+ strlcpy(dev->pdata.name, name,
321+ sizeof(dev->pdata.name));
322+
323+ dev->pdev = platform_device_alloc(GPIOMMC_PLATDEV_NAME,
324+ gpiommc_next_id());
325+ if (!dev->pdev)
326+ return -ENOMEM;
327+ err = platform_device_add_data(dev->pdev, &dev->pdata,
328+ sizeof(dev->pdata));
329+ if (err) {
330+ platform_device_put(dev->pdev);
331+ return err;
332+ }
333+ err = platform_device_add(dev->pdev);
334+ if (err) {
335+ platform_device_put(dev->pdev);
336+ return err;
337+ }
338+
339+ return 0;
340+}
341+
342+static void gpiommc_do_unregister(struct gpiommc_configfs_device *dev)
343+{
344+ if (!gpiommc_is_registered(dev))
345+ return;
346+
347+ platform_device_unregister(dev->pdev);
348+ dev->pdev = NULL;
349+}
350+
351+static ssize_t gpiommc_config_attr_store(struct config_item *item,
352+ struct configfs_attribute *attr,
353+ const char *page, size_t count)
354+{
355+ struct gpiommc_configfs_device *dev = ci_to_gpiommc(item);
356+ int err = -EINVAL;
357+ unsigned long data;
358+
359+ if (attr == &gpiommc_attr_register) {
360+ err = strict_strtoul(page, 10, &data);
361+ if (err)
362+ goto out;
363+ err = -EINVAL;
364+ if (data == 1)
365+ err = gpiommc_do_register(dev, item->ci_name);
366+ if (data == 0) {
367+ gpiommc_do_unregister(dev);
368+ err = 0;
369+ }
370+ goto out;
371+ }
372+
373+ if (gpiommc_is_registered(dev)) {
374+ /* The rest of the config parameters can only be set
375+ * as long as the device is not registered, yet. */
376+ err = -EBUSY;
377+ goto out;
378+ }
379+
380+ if (attr == &gpiommc_attr_DI) {
381+ err = strict_strtoul(page, 10, &data);
382+ if (err)
383+ goto out;
384+ err = -EINVAL;
385+ if (!gpio_is_valid(data))
386+ goto out;
387+ dev->pdata.pins.gpio_di = data;
388+ err = 0;
389+ goto out;
390+ }
391+ if (attr == &gpiommc_attr_DO) {
392+ err = strict_strtoul(page, 10, &data);
393+ if (err)
394+ goto out;
395+ err = -EINVAL;
396+ if (!gpio_is_valid(data))
397+ goto out;
398+ dev->pdata.pins.gpio_do = data;
399+ err = 0;
400+ goto out;
401+ }
402+ if (attr == &gpiommc_attr_CLK) {
403+ err = strict_strtoul(page, 10, &data);
404+ if (err)
405+ goto out;
406+ err = -EINVAL;
407+ if (!gpio_is_valid(data))
408+ goto out;
409+ dev->pdata.pins.gpio_clk = data;
410+ err = 0;
411+ goto out;
412+ }
413+ if (attr == &gpiommc_attr_CS) {
414+ err = strict_strtoul(page, 10, &data);
415+ if (err)
416+ goto out;
417+ err = -EINVAL;
418+ if (!gpio_is_valid(data))
419+ goto out;
420+ dev->pdata.pins.gpio_cs = data;
421+ err = 0;
422+ goto out;
423+ }
424+ if (attr == &gpiommc_attr_CS_activelow) {
425+ err = strict_strtoul(page, 10, &data);
426+ if (err)
427+ goto out;
428+ err = -EINVAL;
429+ if (data != 0 && data != 1)
430+ goto out;
431+ dev->pdata.pins.cs_activelow = data;
432+ err = 0;
433+ goto out;
434+ }
435+ if (attr == &gpiommc_attr_spimode) {
436+ err = strict_strtoul(page, 10, &data);
437+ if (err)
438+ goto out;
439+ err = -EINVAL;
440+ switch (data) {
441+ case 0:
442+ dev->pdata.mode = SPI_MODE_0;
443+ break;
444+ case 1:
445+ dev->pdata.mode = SPI_MODE_1;
446+ break;
447+ case 2:
448+ dev->pdata.mode = SPI_MODE_2;
449+ break;
450+ case 3:
451+ dev->pdata.mode = SPI_MODE_3;
452+ break;
453+ default:
454+ goto out;
455+ }
456+ err = 0;
457+ goto out;
458+ }
459+ if (attr == &gpiommc_attr_spidelay) {
460+ err = strict_strtoul(page, 10, &data);
461+ if (err)
462+ goto out;
463+ err = -EINVAL;
464+ if (data != 0 && data != 1)
465+ goto out;
466+ dev->pdata.no_spi_delay = !data;
467+ err = 0;
468+ goto out;
469+ }
470+ if (attr == &gpiommc_attr_max_bus_speed) {
471+ err = strict_strtoul(page, 10, &data);
472+ if (err)
473+ goto out;
474+ err = -EINVAL;
475+ if (data > UINT_MAX)
476+ goto out;
477+ dev->pdata.max_bus_speed = data;
478+ err = 0;
479+ goto out;
480+ }
481+ WARN_ON(1);
482+ err = -ENOSYS;
483+out:
484+ return err ? err : count;
485+}
486+
487+static void gpiommc_config_item_release(struct config_item *item)
488+{
489+ struct gpiommc_configfs_device *dev = ci_to_gpiommc(item);
490+
491+ kfree(dev);
492+}
493+
494+static struct configfs_item_operations gpiommc_config_item_ops = {
495+ .release = gpiommc_config_item_release,
496+ .show_attribute = gpiommc_config_attr_show,
497+ .store_attribute = gpiommc_config_attr_store,
498+};
499+
500+static struct config_item_type gpiommc_dev_ci_type = {
501+ .ct_item_ops = &gpiommc_config_item_ops,
502+ .ct_attrs = gpiommc_config_attrs,
503+ .ct_owner = THIS_MODULE,
504+};
505+
506+static struct config_item *gpiommc_make_item(struct config_group *group,
507+ const char *name)
508+{
509+ struct gpiommc_configfs_device *dev;
510+
511+ if (strlen(name) > GPIOMMC_MAX_NAMELEN) {
512+ printk(KERN_ERR PFX "configfs: device name too long\n");
513+ return NULL;
514+ }
515+
516+ dev = kzalloc(sizeof(*dev), GFP_KERNEL);
517+ if (!dev)
518+ return NULL;
519+
520+ config_item_init_type_name(&dev->item, name,
521+ &gpiommc_dev_ci_type);
522+
523+ /* Assign default configuration */
524+ dev->pdata.pins.gpio_di = GPIO_INVALID;
525+ dev->pdata.pins.gpio_do = GPIO_INVALID;
526+ dev->pdata.pins.gpio_clk = GPIO_INVALID;
527+ dev->pdata.pins.gpio_cs = GPIO_INVALID;
528+ dev->pdata.pins.cs_activelow = 1;
529+ dev->pdata.mode = SPI_MODE_0;
530+ dev->pdata.no_spi_delay = 0;
531+ dev->pdata.max_bus_speed = 5000000; /* 5 MHz */
532+
533+ return &(dev->item);
534+}
535+
536+static void gpiommc_drop_item(struct config_group *group,
537+ struct config_item *item)
538+{
539+ struct gpiommc_configfs_device *dev = ci_to_gpiommc(item);
540+
541+ gpiommc_do_unregister(dev);
542+ kfree(dev);
543+}
544+
545+static struct configfs_group_operations gpiommc_ct_group_ops = {
546+ .make_item = gpiommc_make_item,
547+ .drop_item = gpiommc_drop_item,
548+};
549+
550+static struct config_item_type gpiommc_ci_type = {
551+ .ct_group_ops = &gpiommc_ct_group_ops,
552+ .ct_owner = THIS_MODULE,
553+};
554+
555+static struct configfs_subsystem gpiommc_subsys = {
556+ .su_group = {
557+ .cg_item = {
558+ .ci_namebuf = GPIOMMC_PLATDEV_NAME,
559+ .ci_type = &gpiommc_ci_type,
560+ },
561+ },
562+ .su_mutex = __MUTEX_INITIALIZER(gpiommc_subsys.su_mutex),
563+};
564+
565+#endif /* CONFIG_GPIOMMC_CONFIGFS */
566+
567+static struct platform_driver gpiommc_plat_driver = {
568+ .probe = gpiommc_probe,
569+ .remove = gpiommc_remove,
570+ .driver = {
571+ .name = GPIOMMC_PLATDEV_NAME,
572+ .owner = THIS_MODULE,
573+ },
574+};
575+
576+int gpiommc_next_id(void)
577+{
578+ static atomic_t counter = ATOMIC_INIT(-1);
579+
580+ return atomic_inc_return(&counter);
581+}
582+EXPORT_SYMBOL(gpiommc_next_id);
583+
584+static int __init gpiommc_modinit(void)
585+{
586+ int err;
587+
588+ err = platform_driver_register(&gpiommc_plat_driver);
589+ if (err)
590+ return err;
591+
592+#ifdef CONFIG_GPIOMMC_CONFIGFS
593+ config_group_init(&gpiommc_subsys.su_group);
594+ err = configfs_register_subsystem(&gpiommc_subsys);
595+ if (err) {
596+ platform_driver_unregister(&gpiommc_plat_driver);
597+ return err;
598+ }
599+#endif /* CONFIG_GPIOMMC_CONFIGFS */
600+
601+ return 0;
602+}
603+module_init(gpiommc_modinit);
604+
605+static void __exit gpiommc_modexit(void)
606+{
607+#ifdef CONFIG_GPIOMMC_CONFIGFS
608+ configfs_unregister_subsystem(&gpiommc_subsys);
609+#endif
610+ platform_driver_unregister(&gpiommc_plat_driver);
611+}
612+module_exit(gpiommc_modexit);
613--- a/drivers/mmc/host/Kconfig
614+++ b/drivers/mmc/host/Kconfig
615@@ -467,6 +467,31 @@ config MMC_SDHI
616       This provides support for the SDHI SD/SDIO controller found in
617       SuperH and ARM SH-Mobile SoCs
618 
619+config GPIOMMC
620+ tristate "MMC/SD over GPIO-based SPI"
621+ depends on MMC && MMC_SPI && SPI_GPIO_OLD
622+ help
623+ This driver hooks up the mmc_spi and spi_gpio modules so that
624+ MMC/SD cards can be used on a GPIO based bus by bitbanging
625+ the SPI protocol in software.
626+
627+ This driver provides a configfs interface to dynamically create
628+ and destroy GPIO-based MMC/SD card devices. It also provides
629+ a platform device interface API.
630+ See Documentation/gpiommc.txt for details.
631+
632+ The module will be called gpiommc.
633+
634+ If unsure, say N.
635+
636+config GPIOMMC_CONFIGFS
637+ bool
638+ depends on GPIOMMC && CONFIGFS_FS
639+ default y
640+ help
641+ This option automatically enables configfs support for gpiommc
642+ if configfs is available.
643+
644 config MMC_CB710
645     tristate "ENE CB710 MMC/SD Interface support"
646     depends on PCI
647--- a/drivers/mmc/host/Makefile
648+++ b/drivers/mmc/host/Makefile
649@@ -36,6 +36,7 @@ tmio_mmc_core-$(subst m,y,$(CONFIG_MMC_S
650 obj-$(CONFIG_MMC_SDHI) += sh_mobile_sdhi.o
651 obj-$(CONFIG_MMC_CB710) += cb710-mmc.o
652 obj-$(CONFIG_MMC_VIA_SDMMC) += via-sdmmc.o
653+obj-$(CONFIG_GPIOMMC) += gpiommc.o
654 obj-$(CONFIG_SDH_BFIN) += bfin_sdh.o
655 obj-$(CONFIG_MMC_DW) += dw_mmc.o
656 obj-$(CONFIG_MMC_DW_PLTFM) += dw_mmc-pltfm.o
657--- /dev/null
658+++ b/include/linux/mmc/gpiommc.h
659@@ -0,0 +1,71 @@
660+/*
661+ * Device driver for MMC/SD cards driven over a GPIO bus.
662+ *
663+ * Copyright (c) 2008 Michael Buesch
664+ *
665+ * Licensed under the GNU/GPL version 2.
666+ */
667+#ifndef LINUX_GPIOMMC_H_
668+#define LINUX_GPIOMMC_H_
669+
670+#include <linux/types.h>
671+
672+
673+#define GPIOMMC_MAX_NAMELEN 15
674+#define GPIOMMC_MAX_NAMELEN_STR __stringify(GPIOMMC_MAX_NAMELEN)
675+
676+/**
677+ * struct gpiommc_pins - Hardware pin assignments
678+ *
679+ * @gpio_di: The GPIO number of the DATA IN pin
680+ * @gpio_do: The GPIO number of the DATA OUT pin
681+ * @gpio_clk: The GPIO number of the CLOCK pin
682+ * @gpio_cs: The GPIO number of the CHIPSELECT pin
683+ * @cs_activelow: If true, the chip is considered selected if @gpio_cs is low.
684+ */
685+struct gpiommc_pins {
686+ unsigned int gpio_di;
687+ unsigned int gpio_do;
688+ unsigned int gpio_clk;
689+ unsigned int gpio_cs;
690+ bool cs_activelow;
691+};
692+
693+/**
694+ * struct gpiommc_platform_data - Platform data for a MMC-over-SPI-GPIO device.
695+ *
696+ * @name: The unique name string of the device.
697+ * @pins: The hardware pin assignments.
698+ * @mode: The hardware mode. This is either SPI_MODE_0,
699+ * SPI_MODE_1, SPI_MODE_2 or SPI_MODE_3. See the SPI documentation.
700+ * @no_spi_delay: Do not use delays in the lowlevel SPI bitbanging code.
701+ * This is not standards compliant, but may be required for some
702+ * embedded machines to gain reasonable speed.
703+ * @max_bus_speed: The maximum speed of the SPI bus, in Hertz.
704+ */
705+struct gpiommc_platform_data {
706+ char name[GPIOMMC_MAX_NAMELEN + 1];
707+ struct gpiommc_pins pins;
708+ u8 mode;
709+ bool no_spi_delay;
710+ unsigned int max_bus_speed;
711+};
712+
713+/**
714+ * GPIOMMC_PLATDEV_NAME - The platform device name string.
715+ *
716+ * The name string that has to be used for platform_device_alloc
717+ * when allocating a gpiommc device.
718+ */
719+#define GPIOMMC_PLATDEV_NAME "gpiommc"
720+
721+/**
722+ * gpiommc_next_id - Get another platform device ID number.
723+ *
724+ * This returns the next platform device ID number that has to be used
725+ * for platform_device_alloc. The ID is opaque and should not be used for
726+ * anything else.
727+ */
728+int gpiommc_next_id(void);
729+
730+#endif /* LINUX_GPIOMMC_H_ */
731--- /dev/null
732+++ b/Documentation/gpiommc.txt
733@@ -0,0 +1,97 @@
734+GPIOMMC - Driver for an MMC/SD card on a bitbanging GPIO SPI bus
735+================================================================
736+
737+The gpiommc module hooks up the mmc_spi and spi_gpio modules for running an
738+MMC or SD card on GPIO pins.
739+
740+Two interfaces for registering a new MMC/SD card device are provided:
741+A static platform-device based mechanism and a dynamic configfs based interface.
742+
743+
744+Registering devices via platform-device
745+=======================================
746+
747+The platform-device interface is used for registering MMC/SD devices that are
748+part of the hardware platform. This is most useful only for embedded machines
749+with MMC/SD devices statically connected to the platform GPIO bus.
750+
751+The data structures are declared in <linux/mmc/gpiommc.h>.
752+
753+To register a new device, define an instance of struct gpiommc_platform_data.
754+This structure holds any information about how the device is hooked up to the
755+GPIO pins and what hardware modes the device supports. See the docbook-style
756+documentation in the header file for more information on the struct fields.
757+
758+Then allocate a new instance of a platform device by doing:
759+
760+ pdev = platform_device_alloc(GPIOMMC_PLATDEV_NAME, gpiommc_next_id());
761+
762+This will allocate the platform device data structures and hook it up to the
763+gpiommc driver.
764+Then add the gpiommc_platform_data to the platform device.
765+
766+ err = platform_device_add_data(pdev, pdata, sizeof(struct gpiommc_platform_data));
767+
768+You may free the local instance of struct gpiommc_platform_data now. (So the
769+struct may be allocated on the stack, too).
770+Now simply register the platform device.
771+
772+ err = platform_device_add(pdev);
773+
774+Done. The gpiommc probe routine will be invoked now and you should see a kernel
775+log message for the added device.
776+
777+
778+Registering devices via configfs
779+================================
780+
781+MMC/SD cards connected via GPIO often are a pretty dynamic thing, as for example
782+selfmade hacks for soldering an MMC/SD card to standard GPIO pins on embedded
783+hardware are a common situation.
784+So we provide a dynamic interface to conveniently handle adding and removing
785+devices from userspace, without the need to recompile the kernel.
786+
787+The "gpiommc" subdirectory at the configfs mountpoint is used for handling
788+the dynamic configuration.
789+
790+To create a new device, it must first be allocated with mkdir.
791+The following command will allocate a device named "my_mmc":
792+ mkdir /config/gpiommc/my_mmc
793+
794+There are several configuration files available in the new
795+/config/gpiommc/my_mmc/ directory:
796+
797+gpio_data_in = The SPI data-IN GPIO pin number.
798+gpio_data_out = The SPI data-OUT GPIO pin number.
799+gpio_clock = The SPI Clock GPIO pin number.
800+gpio_chipselect = The SPI Chipselect GPIO pin number.
801+gpio_chipselect_activelow = Boolean. If 0, Chipselect is active-HIGH.
802+ If 1, Chipselect is active-LOW.
803+spi_mode = The SPI data mode. Can be 0-3.
804+spi_delay = Enable all delays in the lowlevel bitbanging.
805+max_bus_speed = The maximum SPI bus speed. In Hertz.
806+
807+register = Not a configuration parameter.
808+ Used to register the configured card
809+ with the kernel.
810+
811+The device must first get configured and then registered by writing "1" to
812+the "register" file.
813+The configuration parameters "gpio_data_in", "gpio_data_out", "gpio_clock"
814+and "gpio_chipselect" are essential and _must_ be configured before writing
815+"1" to the "register" file. The registration will fail, otherwise.
816+
817+The default values for the other parameters are:
818+gpio_chipselect_activelow = 1 (CS active-LOW)
819+spi_mode = 0 (SPI_MODE_0)
820+spi_delay = 1 (enabled)
821+max_bus_speed = 5000000 (5 Mhz)
822+
823+Configuration values can not be changed after registration. To unregister
824+the device, write a "0" to the "register" file. The configuration can be
825+changed again after unregistering.
826+
827+To completely remove the device, simply rmdir the directory
828+(/config/gpiommc/my_mmc in this example).
829+There's no need to first unregister the device before removing it. That will
830+be done automatically.
831--- a/MAINTAINERS
832+++ b/MAINTAINERS
833@@ -3409,6 +3409,11 @@ L: linuxppc-dev@lists.ozlabs.org
834 S: Odd Fixes
835 F: drivers/tty/hvc/
836 
837+GPIOMMC DRIVER
838+P: Michael Buesch
839+M: mb@bu3sch.de
840+S: Maintained
841+
842 HARDWARE MONITORING
843 M: Jean Delvare <khali@linux-fr.org>
844 M: Guenter Roeck <linux@roeck-us.net>
845

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