Root/target/linux/generic/patches-2.6.37/863-gpiommc.patch

1--- /dev/null
2+++ b/drivers/mmc/host/gpiommc.c
3@@ -0,0 +1,608 @@
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/mmc/gpiommc.h>
15+#include <linux/platform_device.h>
16+#include <linux/list.h>
17+#include <linux/mutex.h>
18+#include <linux/spi/spi_gpio_old.h>
19+#include <linux/configfs.h>
20+#include <linux/gpio.h>
21+#include <asm/atomic.h>
22+
23+
24+#define PFX "gpio-mmc: "
25+
26+
27+struct gpiommc_device {
28+ struct platform_device *pdev;
29+ struct platform_device *spi_pdev;
30+ struct spi_board_info boardinfo;
31+};
32+
33+
34+MODULE_DESCRIPTION("GPIO based MMC driver");
35+MODULE_AUTHOR("Michael Buesch");
36+MODULE_LICENSE("GPL");
37+
38+
39+static int gpiommc_boardinfo_setup(struct spi_board_info *bi,
40+ struct spi_master *master,
41+ void *data)
42+{
43+ struct gpiommc_device *d = data;
44+ struct gpiommc_platform_data *pdata = d->pdev->dev.platform_data;
45+
46+ /* Bind the SPI master to the MMC-SPI host driver. */
47+ strlcpy(bi->modalias, "mmc_spi", sizeof(bi->modalias));
48+
49+ bi->max_speed_hz = pdata->max_bus_speed;
50+ bi->bus_num = master->bus_num;
51+ bi->mode = pdata->mode;
52+
53+ return 0;
54+}
55+
56+static int gpiommc_probe(struct platform_device *pdev)
57+{
58+ struct gpiommc_platform_data *mmc_pdata = pdev->dev.platform_data;
59+ struct spi_gpio_platform_data spi_pdata;
60+ struct gpiommc_device *d;
61+ int err;
62+
63+ err = -ENXIO;
64+ if (!mmc_pdata)
65+ goto error;
66+
67+#ifdef CONFIG_MMC_SPI_MODULE
68+ err = request_module("mmc_spi");
69+ if (err) {
70+ printk(KERN_WARNING PFX
71+ "Failed to request mmc_spi module.\n");
72+ }
73+#endif /* CONFIG_MMC_SPI_MODULE */
74+
75+ /* Allocate the GPIO-MMC device */
76+ err = -ENOMEM;
77+ d = kzalloc(sizeof(*d), GFP_KERNEL);
78+ if (!d)
79+ goto error;
80+ d->pdev = pdev;
81+
82+ /* Create the SPI-GPIO device */
83+ d->spi_pdev = platform_device_alloc(SPI_GPIO_PLATDEV_NAME,
84+ spi_gpio_next_id());
85+ if (!d->spi_pdev)
86+ goto err_free_d;
87+
88+ memset(&spi_pdata, 0, sizeof(spi_pdata));
89+ spi_pdata.pin_clk = mmc_pdata->pins.gpio_clk;
90+ spi_pdata.pin_miso = mmc_pdata->pins.gpio_do;
91+ spi_pdata.pin_mosi = mmc_pdata->pins.gpio_di;
92+ spi_pdata.pin_cs = mmc_pdata->pins.gpio_cs;
93+ spi_pdata.cs_activelow = mmc_pdata->pins.cs_activelow;
94+ spi_pdata.no_spi_delay = mmc_pdata->no_spi_delay;
95+ spi_pdata.boardinfo_setup = gpiommc_boardinfo_setup;
96+ spi_pdata.boardinfo_setup_data = d;
97+
98+ err = platform_device_add_data(d->spi_pdev, &spi_pdata,
99+ sizeof(spi_pdata));
100+ if (err)
101+ goto err_free_pdev;
102+ err = platform_device_add(d->spi_pdev);
103+ if (err)
104+ goto err_free_pdata;
105+ platform_set_drvdata(pdev, d);
106+
107+ printk(KERN_INFO PFX "MMC-Card \"%s\" "
108+ "attached to GPIO pins di=%u, do=%u, clk=%u, cs=%u\n",
109+ mmc_pdata->name, mmc_pdata->pins.gpio_di,
110+ mmc_pdata->pins.gpio_do,
111+ mmc_pdata->pins.gpio_clk,
112+ mmc_pdata->pins.gpio_cs);
113+
114+ return 0;
115+
116+err_free_pdata:
117+ kfree(d->spi_pdev->dev.platform_data);
118+ d->spi_pdev->dev.platform_data = NULL;
119+err_free_pdev:
120+ platform_device_put(d->spi_pdev);
121+err_free_d:
122+ kfree(d);
123+error:
124+ return err;
125+}
126+
127+static int gpiommc_remove(struct platform_device *pdev)
128+{
129+ struct gpiommc_device *d = platform_get_drvdata(pdev);
130+ struct gpiommc_platform_data *pdata = d->pdev->dev.platform_data;
131+
132+ platform_device_unregister(d->spi_pdev);
133+ printk(KERN_INFO PFX "GPIO based MMC-Card \"%s\" removed\n",
134+ pdata->name);
135+ platform_device_put(d->spi_pdev);
136+
137+ return 0;
138+}
139+
140+#ifdef CONFIG_GPIOMMC_CONFIGFS
141+
142+/* A device that was created through configfs */
143+struct gpiommc_configfs_device {
144+ struct config_item item;
145+ /* The platform device, after registration. */
146+ struct platform_device *pdev;
147+ /* The configuration */
148+ struct gpiommc_platform_data pdata;
149+};
150+
151+#define GPIO_INVALID -1
152+
153+static inline bool gpiommc_is_registered(struct gpiommc_configfs_device *dev)
154+{
155+ return (dev->pdev != NULL);
156+}
157+
158+static inline struct gpiommc_configfs_device *ci_to_gpiommc(struct config_item *item)
159+{
160+ return item ? container_of(item, struct gpiommc_configfs_device, item) : NULL;
161+}
162+
163+static struct configfs_attribute gpiommc_attr_DI = {
164+ .ca_owner = THIS_MODULE,
165+ .ca_name = "gpio_data_in",
166+ .ca_mode = S_IRUGO | S_IWUSR,
167+};
168+
169+static struct configfs_attribute gpiommc_attr_DO = {
170+ .ca_owner = THIS_MODULE,
171+ .ca_name = "gpio_data_out",
172+ .ca_mode = S_IRUGO | S_IWUSR,
173+};
174+
175+static struct configfs_attribute gpiommc_attr_CLK = {
176+ .ca_owner = THIS_MODULE,
177+ .ca_name = "gpio_clock",
178+ .ca_mode = S_IRUGO | S_IWUSR,
179+};
180+
181+static struct configfs_attribute gpiommc_attr_CS = {
182+ .ca_owner = THIS_MODULE,
183+ .ca_name = "gpio_chipselect",
184+ .ca_mode = S_IRUGO | S_IWUSR,
185+};
186+
187+static struct configfs_attribute gpiommc_attr_CS_activelow = {
188+ .ca_owner = THIS_MODULE,
189+ .ca_name = "gpio_chipselect_activelow",
190+ .ca_mode = S_IRUGO | S_IWUSR,
191+};
192+
193+static struct configfs_attribute gpiommc_attr_spimode = {
194+ .ca_owner = THIS_MODULE,
195+ .ca_name = "spi_mode",
196+ .ca_mode = S_IRUGO | S_IWUSR,
197+};
198+
199+static struct configfs_attribute gpiommc_attr_spidelay = {
200+ .ca_owner = THIS_MODULE,
201+ .ca_name = "spi_delay",
202+ .ca_mode = S_IRUGO | S_IWUSR,
203+};
204+
205+static struct configfs_attribute gpiommc_attr_max_bus_speed = {
206+ .ca_owner = THIS_MODULE,
207+ .ca_name = "max_bus_speed",
208+ .ca_mode = S_IRUGO | S_IWUSR,
209+};
210+
211+static struct configfs_attribute gpiommc_attr_register = {
212+ .ca_owner = THIS_MODULE,
213+ .ca_name = "register",
214+ .ca_mode = S_IRUGO | S_IWUSR,
215+};
216+
217+static struct configfs_attribute *gpiommc_config_attrs[] = {
218+ &gpiommc_attr_DI,
219+ &gpiommc_attr_DO,
220+ &gpiommc_attr_CLK,
221+ &gpiommc_attr_CS,
222+ &gpiommc_attr_CS_activelow,
223+ &gpiommc_attr_spimode,
224+ &gpiommc_attr_spidelay,
225+ &gpiommc_attr_max_bus_speed,
226+ &gpiommc_attr_register,
227+ NULL,
228+};
229+
230+static ssize_t gpiommc_config_attr_show(struct config_item *item,
231+ struct configfs_attribute *attr,
232+ char *page)
233+{
234+ struct gpiommc_configfs_device *dev = ci_to_gpiommc(item);
235+ ssize_t count = 0;
236+ unsigned int gpio;
237+ int err = 0;
238+
239+ if (attr == &gpiommc_attr_DI) {
240+ gpio = dev->pdata.pins.gpio_di;
241+ if (gpio == GPIO_INVALID)
242+ count = snprintf(page, PAGE_SIZE, "not configured\n");
243+ else
244+ count = snprintf(page, PAGE_SIZE, "%u\n", gpio);
245+ goto out;
246+ }
247+ if (attr == &gpiommc_attr_DO) {
248+ gpio = dev->pdata.pins.gpio_do;
249+ if (gpio == GPIO_INVALID)
250+ count = snprintf(page, PAGE_SIZE, "not configured\n");
251+ else
252+ count = snprintf(page, PAGE_SIZE, "%u\n", gpio);
253+ goto out;
254+ }
255+ if (attr == &gpiommc_attr_CLK) {
256+ gpio = dev->pdata.pins.gpio_clk;
257+ if (gpio == GPIO_INVALID)
258+ count = snprintf(page, PAGE_SIZE, "not configured\n");
259+ else
260+ count = snprintf(page, PAGE_SIZE, "%u\n", gpio);
261+ goto out;
262+ }
263+ if (attr == &gpiommc_attr_CS) {
264+ gpio = dev->pdata.pins.gpio_cs;
265+ if (gpio == GPIO_INVALID)
266+ count = snprintf(page, PAGE_SIZE, "not configured\n");
267+ else
268+ count = snprintf(page, PAGE_SIZE, "%u\n", gpio);
269+ goto out;
270+ }
271+ if (attr == &gpiommc_attr_CS_activelow) {
272+ count = snprintf(page, PAGE_SIZE, "%u\n",
273+ dev->pdata.pins.cs_activelow);
274+ goto out;
275+ }
276+ if (attr == &gpiommc_attr_spimode) {
277+ count = snprintf(page, PAGE_SIZE, "%u\n",
278+ dev->pdata.mode);
279+ goto out;
280+ }
281+ if (attr == &gpiommc_attr_spidelay) {
282+ count = snprintf(page, PAGE_SIZE, "%u\n",
283+ !dev->pdata.no_spi_delay);
284+ goto out;
285+ }
286+ if (attr == &gpiommc_attr_max_bus_speed) {
287+ count = snprintf(page, PAGE_SIZE, "%u\n",
288+ dev->pdata.max_bus_speed);
289+ goto out;
290+ }
291+ if (attr == &gpiommc_attr_register) {
292+ count = snprintf(page, PAGE_SIZE, "%u\n",
293+ gpiommc_is_registered(dev));
294+ goto out;
295+ }
296+ WARN_ON(1);
297+ err = -ENOSYS;
298+out:
299+ return err ? err : count;
300+}
301+
302+static int gpiommc_do_register(struct gpiommc_configfs_device *dev,
303+ const char *name)
304+{
305+ int err;
306+
307+ if (gpiommc_is_registered(dev))
308+ return 0;
309+
310+ if (!gpio_is_valid(dev->pdata.pins.gpio_di) ||
311+ !gpio_is_valid(dev->pdata.pins.gpio_do) ||
312+ !gpio_is_valid(dev->pdata.pins.gpio_clk) ||
313+ !gpio_is_valid(dev->pdata.pins.gpio_cs)) {
314+ printk(KERN_ERR PFX
315+ "configfs: Invalid GPIO pin number(s)\n");
316+ return -EINVAL;
317+ }
318+
319+ strlcpy(dev->pdata.name, name,
320+ sizeof(dev->pdata.name));
321+
322+ dev->pdev = platform_device_alloc(GPIOMMC_PLATDEV_NAME,
323+ gpiommc_next_id());
324+ if (!dev->pdev)
325+ return -ENOMEM;
326+ err = platform_device_add_data(dev->pdev, &dev->pdata,
327+ sizeof(dev->pdata));
328+ if (err) {
329+ platform_device_put(dev->pdev);
330+ return err;
331+ }
332+ err = platform_device_add(dev->pdev);
333+ if (err) {
334+ platform_device_put(dev->pdev);
335+ return err;
336+ }
337+
338+ return 0;
339+}
340+
341+static void gpiommc_do_unregister(struct gpiommc_configfs_device *dev)
342+{
343+ if (!gpiommc_is_registered(dev))
344+ return;
345+
346+ platform_device_unregister(dev->pdev);
347+ dev->pdev = NULL;
348+}
349+
350+static ssize_t gpiommc_config_attr_store(struct config_item *item,
351+ struct configfs_attribute *attr,
352+ const char *page, size_t count)
353+{
354+ struct gpiommc_configfs_device *dev = ci_to_gpiommc(item);
355+ int err = -EINVAL;
356+ unsigned long data;
357+
358+ if (attr == &gpiommc_attr_register) {
359+ err = strict_strtoul(page, 10, &data);
360+ if (err)
361+ goto out;
362+ err = -EINVAL;
363+ if (data == 1)
364+ err = gpiommc_do_register(dev, item->ci_name);
365+ if (data == 0) {
366+ gpiommc_do_unregister(dev);
367+ err = 0;
368+ }
369+ goto out;
370+ }
371+
372+ if (gpiommc_is_registered(dev)) {
373+ /* The rest of the config parameters can only be set
374+ * as long as the device is not registered, yet. */
375+ err = -EBUSY;
376+ goto out;
377+ }
378+
379+ if (attr == &gpiommc_attr_DI) {
380+ err = strict_strtoul(page, 10, &data);
381+ if (err)
382+ goto out;
383+ err = -EINVAL;
384+ if (!gpio_is_valid(data))
385+ goto out;
386+ dev->pdata.pins.gpio_di = data;
387+ err = 0;
388+ goto out;
389+ }
390+ if (attr == &gpiommc_attr_DO) {
391+ err = strict_strtoul(page, 10, &data);
392+ if (err)
393+ goto out;
394+ err = -EINVAL;
395+ if (!gpio_is_valid(data))
396+ goto out;
397+ dev->pdata.pins.gpio_do = data;
398+ err = 0;
399+ goto out;
400+ }
401+ if (attr == &gpiommc_attr_CLK) {
402+ err = strict_strtoul(page, 10, &data);
403+ if (err)
404+ goto out;
405+ err = -EINVAL;
406+ if (!gpio_is_valid(data))
407+ goto out;
408+ dev->pdata.pins.gpio_clk = data;
409+ err = 0;
410+ goto out;
411+ }
412+ if (attr == &gpiommc_attr_CS) {
413+ err = strict_strtoul(page, 10, &data);
414+ if (err)
415+ goto out;
416+ err = -EINVAL;
417+ if (!gpio_is_valid(data))
418+ goto out;
419+ dev->pdata.pins.gpio_cs = data;
420+ err = 0;
421+ goto out;
422+ }
423+ if (attr == &gpiommc_attr_CS_activelow) {
424+ err = strict_strtoul(page, 10, &data);
425+ if (err)
426+ goto out;
427+ err = -EINVAL;
428+ if (data != 0 && data != 1)
429+ goto out;
430+ dev->pdata.pins.cs_activelow = data;
431+ err = 0;
432+ goto out;
433+ }
434+ if (attr == &gpiommc_attr_spimode) {
435+ err = strict_strtoul(page, 10, &data);
436+ if (err)
437+ goto out;
438+ err = -EINVAL;
439+ switch (data) {
440+ case 0:
441+ dev->pdata.mode = SPI_MODE_0;
442+ break;
443+ case 1:
444+ dev->pdata.mode = SPI_MODE_1;
445+ break;
446+ case 2:
447+ dev->pdata.mode = SPI_MODE_2;
448+ break;
449+ case 3:
450+ dev->pdata.mode = SPI_MODE_3;
451+ break;
452+ default:
453+ goto out;
454+ }
455+ err = 0;
456+ goto out;
457+ }
458+ if (attr == &gpiommc_attr_spidelay) {
459+ err = strict_strtoul(page, 10, &data);
460+ if (err)
461+ goto out;
462+ err = -EINVAL;
463+ if (data != 0 && data != 1)
464+ goto out;
465+ dev->pdata.no_spi_delay = !data;
466+ err = 0;
467+ goto out;
468+ }
469+ if (attr == &gpiommc_attr_max_bus_speed) {
470+ err = strict_strtoul(page, 10, &data);
471+ if (err)
472+ goto out;
473+ err = -EINVAL;
474+ if (data > UINT_MAX)
475+ goto out;
476+ dev->pdata.max_bus_speed = data;
477+ err = 0;
478+ goto out;
479+ }
480+ WARN_ON(1);
481+ err = -ENOSYS;
482+out:
483+ return err ? err : count;
484+}
485+
486+static void gpiommc_config_item_release(struct config_item *item)
487+{
488+ struct gpiommc_configfs_device *dev = ci_to_gpiommc(item);
489+
490+ kfree(dev);
491+}
492+
493+static struct configfs_item_operations gpiommc_config_item_ops = {
494+ .release = gpiommc_config_item_release,
495+ .show_attribute = gpiommc_config_attr_show,
496+ .store_attribute = gpiommc_config_attr_store,
497+};
498+
499+static struct config_item_type gpiommc_dev_ci_type = {
500+ .ct_item_ops = &gpiommc_config_item_ops,
501+ .ct_attrs = gpiommc_config_attrs,
502+ .ct_owner = THIS_MODULE,
503+};
504+
505+static struct config_item *gpiommc_make_item(struct config_group *group,
506+ const char *name)
507+{
508+ struct gpiommc_configfs_device *dev;
509+
510+ if (strlen(name) > GPIOMMC_MAX_NAMELEN) {
511+ printk(KERN_ERR PFX "configfs: device name too long\n");
512+ return NULL;
513+ }
514+
515+ dev = kzalloc(sizeof(*dev), GFP_KERNEL);
516+ if (!dev)
517+ return NULL;
518+
519+ config_item_init_type_name(&dev->item, name,
520+ &gpiommc_dev_ci_type);
521+
522+ /* Assign default configuration */
523+ dev->pdata.pins.gpio_di = GPIO_INVALID;
524+ dev->pdata.pins.gpio_do = GPIO_INVALID;
525+ dev->pdata.pins.gpio_clk = GPIO_INVALID;
526+ dev->pdata.pins.gpio_cs = GPIO_INVALID;
527+ dev->pdata.pins.cs_activelow = 1;
528+ dev->pdata.mode = SPI_MODE_0;
529+ dev->pdata.no_spi_delay = 0;
530+ dev->pdata.max_bus_speed = 5000000; /* 5 MHz */
531+
532+ return &(dev->item);
533+}
534+
535+static void gpiommc_drop_item(struct config_group *group,
536+ struct config_item *item)
537+{
538+ struct gpiommc_configfs_device *dev = ci_to_gpiommc(item);
539+
540+ gpiommc_do_unregister(dev);
541+ kfree(dev);
542+}
543+
544+static struct configfs_group_operations gpiommc_ct_group_ops = {
545+ .make_item = gpiommc_make_item,
546+ .drop_item = gpiommc_drop_item,
547+};
548+
549+static struct config_item_type gpiommc_ci_type = {
550+ .ct_group_ops = &gpiommc_ct_group_ops,
551+ .ct_owner = THIS_MODULE,
552+};
553+
554+static struct configfs_subsystem gpiommc_subsys = {
555+ .su_group = {
556+ .cg_item = {
557+ .ci_namebuf = GPIOMMC_PLATDEV_NAME,
558+ .ci_type = &gpiommc_ci_type,
559+ },
560+ },
561+ .su_mutex = __MUTEX_INITIALIZER(gpiommc_subsys.su_mutex),
562+};
563+
564+#endif /* CONFIG_GPIOMMC_CONFIGFS */
565+
566+static struct platform_driver gpiommc_plat_driver = {
567+ .probe = gpiommc_probe,
568+ .remove = gpiommc_remove,
569+ .driver = {
570+ .name = GPIOMMC_PLATDEV_NAME,
571+ .owner = THIS_MODULE,
572+ },
573+};
574+
575+int gpiommc_next_id(void)
576+{
577+ static atomic_t counter = ATOMIC_INIT(-1);
578+
579+ return atomic_inc_return(&counter);
580+}
581+EXPORT_SYMBOL(gpiommc_next_id);
582+
583+static int __init gpiommc_modinit(void)
584+{
585+ int err;
586+
587+ err = platform_driver_register(&gpiommc_plat_driver);
588+ if (err)
589+ return err;
590+
591+#ifdef CONFIG_GPIOMMC_CONFIGFS
592+ config_group_init(&gpiommc_subsys.su_group);
593+ err = configfs_register_subsystem(&gpiommc_subsys);
594+ if (err) {
595+ platform_driver_unregister(&gpiommc_plat_driver);
596+ return err;
597+ }
598+#endif /* CONFIG_GPIOMMC_CONFIGFS */
599+
600+ return 0;
601+}
602+module_init(gpiommc_modinit);
603+
604+static void __exit gpiommc_modexit(void)
605+{
606+#ifdef CONFIG_GPIOMMC_CONFIGFS
607+ configfs_unregister_subsystem(&gpiommc_subsys);
608+#endif
609+ platform_driver_unregister(&gpiommc_plat_driver);
610+}
611+module_exit(gpiommc_modexit);
612--- a/drivers/mmc/host/Kconfig
613+++ b/drivers/mmc/host/Kconfig
614@@ -414,6 +414,31 @@ config MMC_TMIO
615       This provides support for the SD/MMC cell found in TC6393XB,
616       T7L66XB and also HTC ASIC3
617 
618+config GPIOMMC
619+ tristate "MMC/SD over GPIO-based SPI"
620+ depends on MMC && MMC_SPI && SPI_GPIO_OLD
621+ help
622+ This driver hooks up the mmc_spi and spi_gpio modules so that
623+ MMC/SD cards can be used on a GPIO based bus by bitbanging
624+ the SPI protocol in software.
625+
626+ This driver provides a configfs interface to dynamically create
627+ and destroy GPIO-based MMC/SD card devices. It also provides
628+ a platform device interface API.
629+ See Documentation/gpiommc.txt for details.
630+
631+ The module will be called gpiommc.
632+
633+ If unsure, say N.
634+
635+config GPIOMMC_CONFIGFS
636+ bool
637+ depends on GPIOMMC && CONFIGFS_FS
638+ default y
639+ help
640+ This option automatically enables configfs support for gpiommc
641+ if configfs is available.
642+
643 config MMC_CB710
644     tristate "ENE CB710 MMC/SD Interface support"
645     depends on PCI
646--- a/drivers/mmc/host/Makefile
647+++ b/drivers/mmc/host/Makefile
648@@ -30,6 +30,7 @@ obj-$(CONFIG_MMC_SDRICOH_CS) += sdricoh_
649 obj-$(CONFIG_MMC_TMIO) += tmio_mmc.o
650 obj-$(CONFIG_MMC_CB710) += cb710-mmc.o
651 obj-$(CONFIG_MMC_VIA_SDMMC) += via-sdmmc.o
652+obj-$(CONFIG_GPIOMMC) += gpiommc.o
653 obj-$(CONFIG_SDH_BFIN) += bfin_sdh.o
654 obj-$(CONFIG_MMC_SH_MMCIF) += sh_mmcif.o
655 obj-$(CONFIG_MMC_JZ4740) += jz4740_mmc.o
656--- /dev/null
657+++ b/include/linux/mmc/gpiommc.h
658@@ -0,0 +1,71 @@
659+/*
660+ * Device driver for MMC/SD cards driven over a GPIO bus.
661+ *
662+ * Copyright (c) 2008 Michael Buesch
663+ *
664+ * Licensed under the GNU/GPL version 2.
665+ */
666+#ifndef LINUX_GPIOMMC_H_
667+#define LINUX_GPIOMMC_H_
668+
669+#include <linux/types.h>
670+
671+
672+#define GPIOMMC_MAX_NAMELEN 15
673+#define GPIOMMC_MAX_NAMELEN_STR __stringify(GPIOMMC_MAX_NAMELEN)
674+
675+/**
676+ * struct gpiommc_pins - Hardware pin assignments
677+ *
678+ * @gpio_di: The GPIO number of the DATA IN pin
679+ * @gpio_do: The GPIO number of the DATA OUT pin
680+ * @gpio_clk: The GPIO number of the CLOCK pin
681+ * @gpio_cs: The GPIO number of the CHIPSELECT pin
682+ * @cs_activelow: If true, the chip is considered selected if @gpio_cs is low.
683+ */
684+struct gpiommc_pins {
685+ unsigned int gpio_di;
686+ unsigned int gpio_do;
687+ unsigned int gpio_clk;
688+ unsigned int gpio_cs;
689+ bool cs_activelow;
690+};
691+
692+/**
693+ * struct gpiommc_platform_data - Platform data for a MMC-over-SPI-GPIO device.
694+ *
695+ * @name: The unique name string of the device.
696+ * @pins: The hardware pin assignments.
697+ * @mode: The hardware mode. This is either SPI_MODE_0,
698+ * SPI_MODE_1, SPI_MODE_2 or SPI_MODE_3. See the SPI documentation.
699+ * @no_spi_delay: Do not use delays in the lowlevel SPI bitbanging code.
700+ * This is not standards compliant, but may be required for some
701+ * embedded machines to gain reasonable speed.
702+ * @max_bus_speed: The maximum speed of the SPI bus, in Hertz.
703+ */
704+struct gpiommc_platform_data {
705+ char name[GPIOMMC_MAX_NAMELEN + 1];
706+ struct gpiommc_pins pins;
707+ u8 mode;
708+ bool no_spi_delay;
709+ unsigned int max_bus_speed;
710+};
711+
712+/**
713+ * GPIOMMC_PLATDEV_NAME - The platform device name string.
714+ *
715+ * The name string that has to be used for platform_device_alloc
716+ * when allocating a gpiommc device.
717+ */
718+#define GPIOMMC_PLATDEV_NAME "gpiommc"
719+
720+/**
721+ * gpiommc_next_id - Get another platform device ID number.
722+ *
723+ * This returns the next platform device ID number that has to be used
724+ * for platform_device_alloc. The ID is opaque and should not be used for
725+ * anything else.
726+ */
727+int gpiommc_next_id(void);
728+
729+#endif /* LINUX_GPIOMMC_H_ */
730--- /dev/null
731+++ b/Documentation/gpiommc.txt
732@@ -0,0 +1,97 @@
733+GPIOMMC - Driver for an MMC/SD card on a bitbanging GPIO SPI bus
734+================================================================
735+
736+The gpiommc module hooks up the mmc_spi and spi_gpio modules for running an
737+MMC or SD card on GPIO pins.
738+
739+Two interfaces for registering a new MMC/SD card device are provided:
740+A static platform-device based mechanism and a dynamic configfs based interface.
741+
742+
743+Registering devices via platform-device
744+=======================================
745+
746+The platform-device interface is used for registering MMC/SD devices that are
747+part of the hardware platform. This is most useful only for embedded machines
748+with MMC/SD devices statically connected to the platform GPIO bus.
749+
750+The data structures are declared in <linux/mmc/gpiommc.h>.
751+
752+To register a new device, define an instance of struct gpiommc_platform_data.
753+This structure holds any information about how the device is hooked up to the
754+GPIO pins and what hardware modes the device supports. See the docbook-style
755+documentation in the header file for more information on the struct fields.
756+
757+Then allocate a new instance of a platform device by doing:
758+
759+ pdev = platform_device_alloc(GPIOMMC_PLATDEV_NAME, gpiommc_next_id());
760+
761+This will allocate the platform device data structures and hook it up to the
762+gpiommc driver.
763+Then add the gpiommc_platform_data to the platform device.
764+
765+ err = platform_device_add_data(pdev, pdata, sizeof(struct gpiommc_platform_data));
766+
767+You may free the local instance of struct gpiommc_platform_data now. (So the
768+struct may be allocated on the stack, too).
769+Now simply register the platform device.
770+
771+ err = platform_device_add(pdev);
772+
773+Done. The gpiommc probe routine will be invoked now and you should see a kernel
774+log message for the added device.
775+
776+
777+Registering devices via configfs
778+================================
779+
780+MMC/SD cards connected via GPIO often are a pretty dynamic thing, as for example
781+selfmade hacks for soldering an MMC/SD card to standard GPIO pins on embedded
782+hardware are a common situation.
783+So we provide a dynamic interface to conveniently handle adding and removing
784+devices from userspace, without the need to recompile the kernel.
785+
786+The "gpiommc" subdirectory at the configfs mountpoint is used for handling
787+the dynamic configuration.
788+
789+To create a new device, it must first be allocated with mkdir.
790+The following command will allocate a device named "my_mmc":
791+ mkdir /config/gpiommc/my_mmc
792+
793+There are several configuration files available in the new
794+/config/gpiommc/my_mmc/ directory:
795+
796+gpio_data_in = The SPI data-IN GPIO pin number.
797+gpio_data_out = The SPI data-OUT GPIO pin number.
798+gpio_clock = The SPI Clock GPIO pin number.
799+gpio_chipselect = The SPI Chipselect GPIO pin number.
800+gpio_chipselect_activelow = Boolean. If 0, Chipselect is active-HIGH.
801+ If 1, Chipselect is active-LOW.
802+spi_mode = The SPI data mode. Can be 0-3.
803+spi_delay = Enable all delays in the lowlevel bitbanging.
804+max_bus_speed = The maximum SPI bus speed. In Hertz.
805+
806+register = Not a configuration parameter.
807+ Used to register the configured card
808+ with the kernel.
809+
810+The device must first get configured and then registered by writing "1" to
811+the "register" file.
812+The configuration parameters "gpio_data_in", "gpio_data_out", "gpio_clock"
813+and "gpio_chipselect" are essential and _must_ be configured before writing
814+"1" to the "register" file. The registration will fail, otherwise.
815+
816+The default values for the other parameters are:
817+gpio_chipselect_activelow = 1 (CS active-LOW)
818+spi_mode = 0 (SPI_MODE_0)
819+spi_delay = 1 (enabled)
820+max_bus_speed = 5000000 (5 Mhz)
821+
822+Configuration values can not be changed after registration. To unregister
823+the device, write a "0" to the "register" file. The configuration can be
824+changed again after unregistering.
825+
826+To completely remove the device, simply rmdir the directory
827+(/config/gpiommc/my_mmc in this example).
828+There's no need to first unregister the device before removing it. That will
829+be done automatically.
830--- a/MAINTAINERS
831+++ b/MAINTAINERS
832@@ -2723,6 +2723,11 @@ T: git git://git.kernel.org/pub/scm/linu
833 S: Maintained
834 F: drivers/media/video/gspca/
835 
836+GPIOMMC DRIVER
837+P: Michael Buesch
838+M: mb@bu3sch.de
839+S: Maintained
840+
841 HARDWARE MONITORING
842 M: Jean Delvare <khali@linux-fr.org>
843 M: Guenter Roeck <guenter.roeck@ericsson.com>
844

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