openwrt-owl/target/linux/generic/patches-4.3/863-gpiommc.patch

845 lines
22 KiB
Diff

--- /dev/null
+++ b/drivers/mmc/host/gpiommc.c
@@ -0,0 +1,609 @@
+/*
+ * 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/module.h>
+#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 = kstrtoul(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 = kstrtoul(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 = kstrtoul(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 = kstrtoul(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 = kstrtoul(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 = kstrtoul(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 = kstrtoul(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 = kstrtoul(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 = kstrtoul(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
@@ -565,6 +565,31 @@ config MMC_SDHI
This provides support for the SDHI SD/SDIO controller found in
SuperH and ARM SH-Mobile SoCs
+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
@@ -41,6 +41,7 @@ tmio_mmc_core-$(subst m,y,$(CONFIG_MMC_S
obj-$(CONFIG_MMC_SDHI) += sh_mobile_sdhi.o
obj-$(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_DW) += dw_mmc.o
obj-$(CONFIG_MMC_DW_PLTFM) += dw_mmc-pltfm.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
@@ -4800,6 +4800,11 @@ T: git git://linuxtv.org/anttip/media_tr
S: Maintained
F: drivers/media/usb/hackrf/
+GPIOMMC DRIVER
+P: Michael Buesch
+M: mb@bu3sch.de
+S: Maintained
+
HARDWARE MONITORING
M: Jean Delvare <jdelvare@suse.com>
M: Guenter Roeck <linux@roeck-us.net>