firmware: introduce sysfs driver for QEMU's fw_cfg device

What:		/sys/firmware/qemu_fw_cfg/

Date:		August 2015

Contact:	Gabriel Somlo <somlo@cmu.edu>

Description:

		Several different architectures supported by QEMU (x86, arm,

		sun4*, ppc/mac) are provisioned with a firmware configuration

		(fw_cfg) device, originally intended as a way for the host to

		provide configuration data to the guest firmware. Starting

		with QEMU v2.4, arbitrary fw_cfg file entries may be specified

		by the user on the command line, which makes fw_cfg additionally

		useful as an out-of-band, asynchronous mechanism for providing

		configuration data to the guest userspace.

		The authoritative guest-side hardware interface documentation

		to the fw_cfg device can be found in "docs/specs/fw_cfg.txt"

		in the QEMU source tree.

		=== SysFS fw_cfg Interface ===

		The fw_cfg sysfs interface described in this document is only

		intended to display discoverable blobs (i.e., those registered

		with the file directory), as there is no way to determine the

		presence or size of "legacy" blobs (with selector keys between

		0x0002 and 0x0018) programmatically.

		All fw_cfg information is shown under:

			/sys/firmware/qemu_fw_cfg/

		The only legacy blob displayed is the fw_cfg device revision:

			/sys/firmware/qemu_fw_cfg/rev

		--- Discoverable fw_cfg blobs by selector key ---

		All discoverable blobs listed in the fw_cfg file directory are

		displayed as entries named after their unique selector key

		value, e.g.:

			/sys/firmware/qemu_fw_cfg/by_key/32

			/sys/firmware/qemu_fw_cfg/by_key/33

			/sys/firmware/qemu_fw_cfg/by_key/34

			...

		Each such fw_cfg sysfs entry has the following values exported

		as attributes:

		name  	: The 56-byte nul-terminated ASCII string used as the

			  blob's 'file name' in the fw_cfg directory.

		size  	: The length of the blob, as given in the fw_cfg

			  directory.

		key	: The value of the blob's selector key as given in the

			  fw_cfg directory. This value is the same as used in

			  the parent directory name.

		raw	: The raw bytes of the blob, obtained by selecting the

			  entry via the control register, and reading a number

			  of bytes equal to the blob size from the data

			  register.

	  This option enables support for communicating with the firmware on the

	  Raspberry Pi.

config FW_CFG_SYSFS

	tristate "QEMU fw_cfg device support in sysfs"

	depends on SYSFS && (ARM || ARM64 || PPC_PMAC || SPARC || X86)

	default n

	help

	  Say Y or M here to enable the exporting of the QEMU firmware

	  configuration (fw_cfg) file entries via sysfs. Entries are

	  found under /sys/firmware/fw_cfg when this option is enabled

	  and loaded.

config FW_CFG_SYSFS_CMDLINE

	bool "QEMU fw_cfg device parameter parsing"

	depends on FW_CFG_SYSFS

	help

	  Allow the qemu_fw_cfg device to be initialized via the kernel

	  command line or using a module parameter.

	  WARNING: Using incorrect parameters (base address in particular)

	  may crash your system.

config QCOM_SCM

	bool

	depends on ARM || ARM64

obj-$(CONFIG_ISCSI_IBFT)	+= iscsi_ibft.o

obj-$(CONFIG_FIRMWARE_MEMMAP)	+= memmap.o

obj-$(CONFIG_RASPBERRYPI_FIRMWARE) += raspberrypi.o

obj-$(CONFIG_FW_CFG_SYSFS)	+= qemu_fw_cfg.o

obj-$(CONFIG_QCOM_SCM)		+= qcom_scm.o

obj-$(CONFIG_QCOM_SCM_64)	+= qcom_scm-64.o

obj-$(CONFIG_QCOM_SCM_32)	+= qcom_scm-32.o

/*

 * drivers/firmware/qemu_fw_cfg.c

 *

 * Copyright 2015 Carnegie Mellon University

 *

 * Expose entries from QEMU's firmware configuration (fw_cfg) device in

 * sysfs (read-only, under "/sys/firmware/qemu_fw_cfg/...").

 *

 * The fw_cfg device may be instantiated via either an ACPI node (on x86

 * and select subsets of aarch64), a Device Tree node (on arm), or using

 * a kernel module (or command line) parameter with the following syntax:

 *

 *      [fw_cfg.]ioport=<size>@<base>[:<ctrl_off>:<data_off>]

 * or

 *      [fw_cfg.]mmio=<size>@<base>[:<ctrl_off>:<data_off>]

 *

 * where:

 *      <size>     := size of ioport or mmio range

 *      <base>     := physical base address of ioport or mmio range

 *      <ctrl_off> := (optional) offset of control register

 *      <data_off> := (optional) offset of data register

 *

 * e.g.:

 *      fw_cfg.ioport=2@0x510:0:1		(the default on x86)

 * or

 *      fw_cfg.mmio=0xA@0x9020000:8:0		(the default on arm)

 */

#include <linux/module.h>

#include <linux/platform_device.h>

#include <linux/acpi.h>

#include <linux/slab.h>

#include <linux/io.h>

#include <linux/ioport.h>

MODULE_AUTHOR("Gabriel L. Somlo <somlo@cmu.edu>");

MODULE_DESCRIPTION("QEMU fw_cfg sysfs support");

MODULE_LICENSE("GPL");

/* selector key values for "well-known" fw_cfg entries */

#define FW_CFG_SIGNATURE  0x00

#define FW_CFG_ID         0x01

#define FW_CFG_FILE_DIR   0x19

/* size in bytes of fw_cfg signature */

#define FW_CFG_SIG_SIZE 4

/* fw_cfg "file name" is up to 56 characters (including terminating nul) */

#define FW_CFG_MAX_FILE_PATH 56

/* fw_cfg file directory entry type */

struct fw_cfg_file {

	u32 size;

	u16 select;

	u16 reserved;

	char name[FW_CFG_MAX_FILE_PATH];

};

/* fw_cfg device i/o register addresses */

static bool fw_cfg_is_mmio;

static phys_addr_t fw_cfg_p_base;

static resource_size_t fw_cfg_p_size;

static void __iomem *fw_cfg_dev_base;

static void __iomem *fw_cfg_reg_ctrl;

static void __iomem *fw_cfg_reg_data;

/* atomic access to fw_cfg device (potentially slow i/o, so using mutex) */

static DEFINE_MUTEX(fw_cfg_dev_lock);

/* pick appropriate endianness for selector key */

static inline u16 fw_cfg_sel_endianness(u16 key)

{

	return fw_cfg_is_mmio ? cpu_to_be16(key) : cpu_to_le16(key);

}

/* read chunk of given fw_cfg blob (caller responsible for sanity-check) */

static inline void fw_cfg_read_blob(u16 key,

				    void *buf, loff_t pos, size_t count)

{

	mutex_lock(&fw_cfg_dev_lock);

	iowrite16(fw_cfg_sel_endianness(key), fw_cfg_reg_ctrl);

	while (pos-- > 0)

		ioread8(fw_cfg_reg_data);

	ioread8_rep(fw_cfg_reg_data, buf, count);

	mutex_unlock(&fw_cfg_dev_lock);

}

/* clean up fw_cfg device i/o */

static void fw_cfg_io_cleanup(void)

{

	if (fw_cfg_is_mmio) {

		iounmap(fw_cfg_dev_base);

		release_mem_region(fw_cfg_p_base, fw_cfg_p_size);

	} else {

		ioport_unmap(fw_cfg_dev_base);

		release_region(fw_cfg_p_base, fw_cfg_p_size);

	}

}

/* arch-specific ctrl & data register offsets are not available in ACPI, DT */

#if !(defined(FW_CFG_CTRL_OFF) && defined(FW_CTRL_DATA_OFF))

# if (defined(CONFIG_ARM) || defined(CONFIG_ARM64))

#  define FW_CFG_CTRL_OFF 0x08

#  define FW_CFG_DATA_OFF 0x00

# elif (defined(CONFIG_PPC_PMAC) || defined(CONFIG_SPARC32)) /* ppc/mac,sun4m */

#  define FW_CFG_CTRL_OFF 0x00

#  define FW_CFG_DATA_OFF 0x02

# elif (defined(CONFIG_X86) || defined(CONFIG_SPARC64)) /* x86, sun4u */

#  define FW_CFG_CTRL_OFF 0x00

#  define FW_CFG_DATA_OFF 0x01

# else

#  warning "QEMU FW_CFG may not be available on this architecture!"

#  define FW_CFG_CTRL_OFF 0x00

#  define FW_CFG_DATA_OFF 0x01

# endif

#endif

/* initialize fw_cfg device i/o from platform data */

static int fw_cfg_do_platform_probe(struct platform_device *pdev)

{

	char sig[FW_CFG_SIG_SIZE];

	struct resource *range, *ctrl, *data;

	/* acquire i/o range details */

	fw_cfg_is_mmio = false;

	range = platform_get_resource(pdev, IORESOURCE_IO, 0);

	if (!range) {

		fw_cfg_is_mmio = true;

		range = platform_get_resource(pdev, IORESOURCE_MEM, 0);

		if (!range)

			return -EINVAL;

	}

	fw_cfg_p_base = range->start;

	fw_cfg_p_size = resource_size(range);

	if (fw_cfg_is_mmio) {

		if (!request_mem_region(fw_cfg_p_base,

					fw_cfg_p_size, "fw_cfg_mem"))

			return -EBUSY;

		fw_cfg_dev_base = ioremap(fw_cfg_p_base, fw_cfg_p_size);

		if (!fw_cfg_dev_base) {

			release_mem_region(fw_cfg_p_base, fw_cfg_p_size);

			return -EFAULT;

		}

	} else {

		if (!request_region(fw_cfg_p_base,

				    fw_cfg_p_size, "fw_cfg_io"))

			return -EBUSY;

		fw_cfg_dev_base = ioport_map(fw_cfg_p_base, fw_cfg_p_size);

		if (!fw_cfg_dev_base) {

			release_region(fw_cfg_p_base, fw_cfg_p_size);

			return -EFAULT;

		}

	}

	/* were custom register offsets provided (e.g. on the command line)? */

	ctrl = platform_get_resource_byname(pdev, IORESOURCE_REG, "ctrl");

	data = platform_get_resource_byname(pdev, IORESOURCE_REG, "data");

	if (ctrl && data) {

		fw_cfg_reg_ctrl = fw_cfg_dev_base + ctrl->start;

		fw_cfg_reg_data = fw_cfg_dev_base + data->start;

	} else {

		/* use architecture-specific offsets */

		fw_cfg_reg_ctrl = fw_cfg_dev_base + FW_CFG_CTRL_OFF;

		fw_cfg_reg_data = fw_cfg_dev_base + FW_CFG_DATA_OFF;

	}

	/* verify fw_cfg device signature */

	fw_cfg_read_blob(FW_CFG_SIGNATURE, sig, 0, FW_CFG_SIG_SIZE);

	if (memcmp(sig, "QEMU", FW_CFG_SIG_SIZE) != 0) {

		fw_cfg_io_cleanup();

		return -ENODEV;

	}

	return 0;

}

/* fw_cfg revision attribute, in /sys/firmware/qemu_fw_cfg top-level dir. */

static u32 fw_cfg_rev;

static ssize_t fw_cfg_showrev(struct kobject *k, struct attribute *a, char *buf)

{

	return sprintf(buf, "%u\n", fw_cfg_rev);

}

static const struct {

	struct attribute attr;

	ssize_t (*show)(struct kobject *k, struct attribute *a, char *buf);

} fw_cfg_rev_attr = {

	.attr = { .name = "rev", .mode = S_IRUSR },

	.show = fw_cfg_showrev,

};

/* fw_cfg_sysfs_entry type */

struct fw_cfg_sysfs_entry {

	struct kobject kobj;

	struct fw_cfg_file f;

	struct list_head list;

};

/* get fw_cfg_sysfs_entry from kobject member */

static inline struct fw_cfg_sysfs_entry *to_entry(struct kobject *kobj)

{

	return container_of(kobj, struct fw_cfg_sysfs_entry, kobj);

}

/* fw_cfg_sysfs_attribute type */

struct fw_cfg_sysfs_attribute {

	struct attribute attr;

	ssize_t (*show)(struct fw_cfg_sysfs_entry *entry, char *buf);

};

/* get fw_cfg_sysfs_attribute from attribute member */

static inline struct fw_cfg_sysfs_attribute *to_attr(struct attribute *attr)

{

	return container_of(attr, struct fw_cfg_sysfs_attribute, attr);

}

/* global cache of fw_cfg_sysfs_entry objects */

static LIST_HEAD(fw_cfg_entry_cache);

/* kobjects removed lazily by kernel, mutual exclusion needed */

static DEFINE_SPINLOCK(fw_cfg_cache_lock);

static inline void fw_cfg_sysfs_cache_enlist(struct fw_cfg_sysfs_entry *entry)

{

	spin_lock(&fw_cfg_cache_lock);

	list_add_tail(&entry->list, &fw_cfg_entry_cache);

	spin_unlock(&fw_cfg_cache_lock);

}

static inline void fw_cfg_sysfs_cache_delist(struct fw_cfg_sysfs_entry *entry)

{

	spin_lock(&fw_cfg_cache_lock);

	list_del(&entry->list);

	spin_unlock(&fw_cfg_cache_lock);

}

static void fw_cfg_sysfs_cache_cleanup(void)

{

	struct fw_cfg_sysfs_entry *entry, *next;

	list_for_each_entry_safe(entry, next, &fw_cfg_entry_cache, list) {

		/* will end up invoking fw_cfg_sysfs_cache_delist()

		 * via each object's release() method (i.e. destructor)

		 */

		kobject_put(&entry->kobj);

	}

}

/* default_attrs: per-entry attributes and show methods */

#define FW_CFG_SYSFS_ATTR(_attr) \

struct fw_cfg_sysfs_attribute fw_cfg_sysfs_attr_##_attr = { \

	.attr = { .name = __stringify(_attr), .mode = S_IRUSR }, \

	.show = fw_cfg_sysfs_show_##_attr, \

}

static ssize_t fw_cfg_sysfs_show_size(struct fw_cfg_sysfs_entry *e, char *buf)

{

	return sprintf(buf, "%u\n", e->f.size);

}

static ssize_t fw_cfg_sysfs_show_key(struct fw_cfg_sysfs_entry *e, char *buf)

{

	return sprintf(buf, "%u\n", e->f.select);

}

static ssize_t fw_cfg_sysfs_show_name(struct fw_cfg_sysfs_entry *e, char *buf)

{

	return sprintf(buf, "%s\n", e->f.name);

}

static FW_CFG_SYSFS_ATTR(size);

static FW_CFG_SYSFS_ATTR(key);

static FW_CFG_SYSFS_ATTR(name);

static struct attribute *fw_cfg_sysfs_entry_attrs[] = {

	&fw_cfg_sysfs_attr_size.attr,

	&fw_cfg_sysfs_attr_key.attr,

	&fw_cfg_sysfs_attr_name.attr,

	NULL,

};

/* sysfs_ops: find fw_cfg_[entry, attribute] and call appropriate show method */

static ssize_t fw_cfg_sysfs_attr_show(struct kobject *kobj, struct attribute *a,

				      char *buf)

{

	struct fw_cfg_sysfs_entry *entry = to_entry(kobj);

	struct fw_cfg_sysfs_attribute *attr = to_attr(a);

	return attr->show(entry, buf);

}

static const struct sysfs_ops fw_cfg_sysfs_attr_ops = {

	.show = fw_cfg_sysfs_attr_show,

};

/* release: destructor, to be called via kobject_put() */

static void fw_cfg_sysfs_release_entry(struct kobject *kobj)

{

	struct fw_cfg_sysfs_entry *entry = to_entry(kobj);

	fw_cfg_sysfs_cache_delist(entry);

	kfree(entry);

}

/* kobj_type: ties together all properties required to register an entry */

static struct kobj_type fw_cfg_sysfs_entry_ktype = {

	.default_attrs = fw_cfg_sysfs_entry_attrs,

	.sysfs_ops = &fw_cfg_sysfs_attr_ops,

	.release = fw_cfg_sysfs_release_entry,

};

/* raw-read method and attribute */

static ssize_t fw_cfg_sysfs_read_raw(struct file *filp, struct kobject *kobj,

				     struct bin_attribute *bin_attr,

				     char *buf, loff_t pos, size_t count)

{

	struct fw_cfg_sysfs_entry *entry = to_entry(kobj);

	if (pos > entry->f.size)

		return -EINVAL;

	if (count > entry->f.size - pos)

		count = entry->f.size - pos;

	fw_cfg_read_blob(entry->f.select, buf, pos, count);

	return count;

}

static struct bin_attribute fw_cfg_sysfs_attr_raw = {

	.attr = { .name = "raw", .mode = S_IRUSR },

	.read = fw_cfg_sysfs_read_raw,

};

/* kobjects representing top-level and by_key folders */

static struct kobject *fw_cfg_top_ko;

static struct kobject *fw_cfg_sel_ko;

/* register an individual fw_cfg file */

static int fw_cfg_register_file(const struct fw_cfg_file *f)

{

	int err;

	struct fw_cfg_sysfs_entry *entry;

	/* allocate new entry */

	entry = kzalloc(sizeof(*entry), GFP_KERNEL);

	if (!entry)

		return -ENOMEM;

	/* set file entry information */

	memcpy(&entry->f, f, sizeof(struct fw_cfg_file));

	/* register entry under "/sys/firmware/qemu_fw_cfg/by_key/" */

	err = kobject_init_and_add(&entry->kobj, &fw_cfg_sysfs_entry_ktype,

				   fw_cfg_sel_ko, "%d", entry->f.select);

	if (err)

		goto err_register;

	/* add raw binary content access */

	err = sysfs_create_bin_file(&entry->kobj, &fw_cfg_sysfs_attr_raw);

	if (err)

		goto err_add_raw;

	/* success, add entry to global cache */

	fw_cfg_sysfs_cache_enlist(entry);

	return 0;

err_add_raw:

	kobject_del(&entry->kobj);

err_register:

	kfree(entry);

	return err;

}

/* iterate over all fw_cfg directory entries, registering each one */

static int fw_cfg_register_dir_entries(void)

{

	int ret = 0;

	u32 count, i;

	struct fw_cfg_file *dir;

	size_t dir_size;

	fw_cfg_read_blob(FW_CFG_FILE_DIR, &count, 0, sizeof(count));

	count = be32_to_cpu(count);

	dir_size = count * sizeof(struct fw_cfg_file);

	dir = kmalloc(dir_size, GFP_KERNEL);

	if (!dir)

		return -ENOMEM;

	fw_cfg_read_blob(FW_CFG_FILE_DIR, dir, sizeof(count), dir_size);

	for (i = 0; i < count; i++) {

		dir[i].size = be32_to_cpu(dir[i].size);

		dir[i].select = be16_to_cpu(dir[i].select);

		ret = fw_cfg_register_file(&dir[i]);

		if (ret)

			break;

	}

	kfree(dir);

	return ret;

}

/* unregister top-level or by_key folder */

static inline void fw_cfg_kobj_cleanup(struct kobject *kobj)

{

	kobject_del(kobj);

	kobject_put(kobj);

}

static int fw_cfg_sysfs_probe(struct platform_device *pdev)

{

	int err;

	/* NOTE: If we supported multiple fw_cfg devices, we'd first create

	 * a subdirectory named after e.g. pdev->id, then hang per-device

	 * by_key subdirectories underneath it. However, only

	 * one fw_cfg device exist system-wide, so if one was already found

	 * earlier, we might as well stop here.

	 */

	if (fw_cfg_sel_ko)

		return -EBUSY;

	/* create by_key subdirectory of /sys/firmware/qemu_fw_cfg/ */

	err = -ENOMEM;

	fw_cfg_sel_ko = kobject_create_and_add("by_key", fw_cfg_top_ko);

	if (!fw_cfg_sel_ko)

		goto err_sel;

	/* initialize fw_cfg device i/o from platform data */

	err = fw_cfg_do_platform_probe(pdev);

	if (err)

		goto err_probe;

	/* get revision number, add matching top-level attribute */

	fw_cfg_read_blob(FW_CFG_ID, &fw_cfg_rev, 0, sizeof(fw_cfg_rev));

	fw_cfg_rev = le32_to_cpu(fw_cfg_rev);

	err = sysfs_create_file(fw_cfg_top_ko, &fw_cfg_rev_attr.attr);

	if (err)

		goto err_rev;

	/* process fw_cfg file directory entry, registering each file */

	err = fw_cfg_register_dir_entries();

	if (err)

		goto err_dir;

	/* success */

	pr_debug("fw_cfg: loaded.\n");

	return 0;

err_dir:

	fw_cfg_sysfs_cache_cleanup();

	sysfs_remove_file(fw_cfg_top_ko, &fw_cfg_rev_attr.attr);

err_rev:

	fw_cfg_io_cleanup();

err_probe:

	fw_cfg_kobj_cleanup(fw_cfg_sel_ko);

err_sel:

	return err;

}

static int fw_cfg_sysfs_remove(struct platform_device *pdev)

{

	pr_debug("fw_cfg: unloading.\n");

	fw_cfg_sysfs_cache_cleanup();

	fw_cfg_kobj_cleanup(fw_cfg_sel_ko);

	fw_cfg_io_cleanup();

	return 0;

}

static const struct of_device_id fw_cfg_sysfs_mmio_match[] = {

	{ .compatible = "qemu,fw-cfg-mmio", },

	{},

};

MODULE_DEVICE_TABLE(of, fw_cfg_sysfs_mmio_match);

#ifdef CONFIG_ACPI

static const struct acpi_device_id fw_cfg_sysfs_acpi_match[] = {

	{ "QEMU0002", },

	{},

};

MODULE_DEVICE_TABLE(acpi, fw_cfg_sysfs_acpi_match);

#endif

static struct platform_driver fw_cfg_sysfs_driver = {

	.probe = fw_cfg_sysfs_probe,

	.remove = fw_cfg_sysfs_remove,

	.driver = {

		.name = "fw_cfg",

		.of_match_table = fw_cfg_sysfs_mmio_match,

		.acpi_match_table = ACPI_PTR(fw_cfg_sysfs_acpi_match),

	},

};

#ifdef CONFIG_FW_CFG_SYSFS_CMDLINE

static struct platform_device *fw_cfg_cmdline_dev;

/* this probably belongs in e.g. include/linux/types.h,

 * but right now we are the only ones doing it...

 */

#ifdef CONFIG_PHYS_ADDR_T_64BIT

#define __PHYS_ADDR_PREFIX "ll"

#else

#define __PHYS_ADDR_PREFIX ""

#endif

/* use special scanf/printf modifier for phys_addr_t, resource_size_t */

#define PH_ADDR_SCAN_FMT "@%" __PHYS_ADDR_PREFIX "i%n" \

			 ":%" __PHYS_ADDR_PREFIX "i" \

			 ":%" __PHYS_ADDR_PREFIX "i%n"

#define PH_ADDR_PR_1_FMT "0x%" __PHYS_ADDR_PREFIX "x@" \

			 "0x%" __PHYS_ADDR_PREFIX "x"

#define PH_ADDR_PR_3_FMT PH_ADDR_PR_1_FMT \

			 ":%" __PHYS_ADDR_PREFIX "u" \

			 ":%" __PHYS_ADDR_PREFIX "u"

static int fw_cfg_cmdline_set(const char *arg, const struct kernel_param *kp)

{

	struct resource res[3] = {};

	char *str;

	phys_addr_t base;

	resource_size_t size, ctrl_off, data_off;

	int processed, consumed = 0;

	/* only one fw_cfg device can exist system-wide, so if one

	 * was processed on the command line already, we might as

	 * well stop here.

	 */

	if (fw_cfg_cmdline_dev) {

		/* avoid leaking previously registered device */

		platform_device_unregister(fw_cfg_cmdline_dev);

		return -EINVAL;

	}

	/* consume "<size>" portion of command line argument */

	size = memparse(arg, &str);

	/* get "@<base>[:<ctrl_off>:<data_off>]" chunks */

	processed = sscanf(str, PH_ADDR_SCAN_FMT,

			   &base, &consumed,

			   &ctrl_off, &data_off, &consumed);

	/* sscanf() must process precisely 1 or 3 chunks:

	 * <base> is mandatory, optionally followed by <ctrl_off>

	 * and <data_off>;

	 * there must be no extra characters after the last chunk,

	 * so str[consumed] must be '\0'.

	 */

	if (str[consumed] ||

	    (processed != 1 && processed != 3))

		return -EINVAL;

	res[0].start = base;

	res[0].end = base + size - 1;

	res[0].flags = !strcmp(kp->name, "mmio") ? IORESOURCE_MEM :

						   IORESOURCE_IO;

	/* insert register offsets, if provided */

	if (processed > 1) {

		res[1].name = "ctrl";

		res[1].start = ctrl_off;

		res[1].flags = IORESOURCE_REG;

		res[2].name = "data";

		res[2].start = data_off;

		res[2].flags = IORESOURCE_REG;

	}

	/* "processed" happens to nicely match the number of resources

	 * we need to pass in to this platform device.

	 */

	fw_cfg_cmdline_dev = platform_device_register_simple("fw_cfg",

					PLATFORM_DEVID_NONE, res, processed);

	if (IS_ERR(fw_cfg_cmdline_dev))

		return PTR_ERR(fw_cfg_cmdline_dev);

	return 0;

}

static int fw_cfg_cmdline_get(char *buf, const struct kernel_param *kp)

{

	/* stay silent if device was not configured via the command

	 * line, or if the parameter name (ioport/mmio) doesn't match

	 * the device setting

	 */

	if (!fw_cfg_cmdline_dev ||

	    (!strcmp(kp->name, "mmio") ^

	     (fw_cfg_cmdline_dev->resource[0].flags == IORESOURCE_MEM)))

		return 0;

	switch (fw_cfg_cmdline_dev->num_resources) {

	case 1:

		return snprintf(buf, PAGE_SIZE, PH_ADDR_PR_1_FMT,

				resource_size(&fw_cfg_cmdline_dev->resource[0]),

				fw_cfg_cmdline_dev->resource[0].start);

	case 3:

		return snprintf(buf, PAGE_SIZE, PH_ADDR_PR_3_FMT,

				resource_size(&fw_cfg_cmdline_dev->resource[0]),

				fw_cfg_cmdline_dev->resource[0].start,

				fw_cfg_cmdline_dev->resource[1].start,

				fw_cfg_cmdline_dev->resource[2].start);

	}

	/* Should never get here */

	WARN(1, "Unexpected number of resources: %d\n",

		fw_cfg_cmdline_dev->num_resources);

	return 0;

}

static const struct kernel_param_ops fw_cfg_cmdline_param_ops = {

	.set = fw_cfg_cmdline_set,

	.get = fw_cfg_cmdline_get,

};

device_param_cb(ioport, &fw_cfg_cmdline_param_ops, NULL, S_IRUSR);

device_param_cb(mmio, &fw_cfg_cmdline_param_ops, NULL, S_IRUSR);

#endif /* CONFIG_FW_CFG_SYSFS_CMDLINE */

static int __init fw_cfg_sysfs_init(void)

{

	/* create /sys/firmware/qemu_fw_cfg/ top level directory */

	fw_cfg_top_ko = kobject_create_and_add("qemu_fw_cfg", firmware_kobj);

	if (!fw_cfg_top_ko)

		return -ENOMEM;

	return platform_driver_register(&fw_cfg_sysfs_driver);

}

static void __exit fw_cfg_sysfs_exit(void)

{

	platform_driver_unregister(&fw_cfg_sysfs_driver);

#ifdef CONFIG_FW_CFG_SYSFS_CMDLINE

	platform_device_unregister(fw_cfg_cmdline_dev);

#endif

	/* clean up /sys/firmware/qemu_fw_cfg/ */

	fw_cfg_kobj_cleanup(fw_cfg_top_ko);

}

module_init(fw_cfg_sysfs_init);

module_exit(fw_cfg_sysfs_exit);