[PATCH v2 1/8] firmware: add new extensible firmware API - sysdata_file_request*()

[Luis R. Rodriguez]

The firmware API has evolved over the years slowly, as it
grows we extend it by adding new routines or at times we extend
existing routines with more or less arguments. This doesn't scale
well, when new arguments are added to existing routines it means
we need to traverse the kernel with a slew of collateral
evolutions to adjust old driver users. The firmware API is also
now being used for things outside of the scope of what typically
would be considered "firmware", an example here is the p54 driver
enables users to provide a custom EEPROM through this interface.
Another example is optional CPU microcode updates. This list is
actually quite endless...

There are other subsystems which would like to make use of the
APIs for similar things (not firmware) but have different
requirements and criteria which they'd like to be met for the
requested file. If different requirements are needed it would
again mean adding more arguments and making a slew of collateral
evolutions, or adding yet-another-new-API-call.

Another sticking point over the current firmware API is that
some callers may need the usermode helper when its enabled.
No matter how much a lot of us now hate the usermode helper
(even Linus has called to deprecate it [0]), we've determined
we cannot get rid of it now [1]. There have even been hints
about further valid extended uses expected for the usermode
helper in the future... Although we cannot deprecate the usermode
helpers we can compartamentalize its uses to only valid uses then.

Even if we compartamentalize the usermode helpers uses, we still
need a flexible API for growing needs and requirements and new
features. This new extensible firmware API enables new extensions
to be added (an expected desirable feature for instance is firmware
signing support) by avoiding future unnecessary collateral
evolutions as this code / features get added and also provides
a clean way to enable folks who do wish to deprecate the usermode
helper to do so with certainty.

This new set of APIS leaves the old firmware API as-is, ignores all
consideration for usermode-helpers, labels the new API to reflect its
broad use outside of the scope of firmware: system data helpers, and
builds on top of the original firmware core code.

The new extensible "system data" set of helpers accepts that there
really are only two types of requests for accessing system data:

a) synchronous requests
b) asynchronous requests

Both of these requests may have a different set of requirements
which must be met. These requirements can simply be passed as a
descriptors to each type of request. The descriptor can be extended
over time to support different requirements as the kernel evolves.

Using the new system data helpers is only necessary if you have
requirements outside of what the existing old firmware API accepts
or alternatively if you want to ensure to avoid the usermode helper
at all times, regardless of what kernel your driver might run in.

Developers with new uses should extend the new new descriptors and system
data code to provide support for new features.

A few simple features added as part of the new set of system data
request APIs, other than making the new API easily extensible for
the future:

 - Usermode helpers is completely ignored, *always*
 - By default the kernel will free the system data file for you after
   your callbacks are called, you however are allowed to request that
   you wish to keep the system data file on the descriptor. The new
   sysdata API is able to free the sysdata file for you by requiring a
   consumer callback for the system data file.
 - You no longer need to declare and use your own completions, you
   can replace your completions with sysdata_synchronize_request() using
   the async_cookie set for you by sysdata_file_request_async(). When
   sysdata_file_request_async() completes you can rest assured all the
   work for both triggering, and processing the sysdata using any of
   your callbacks has completed.
 - Allow both asynchronous and synchronous request to specify that system data
   files are optional. With the old APIs we had added one full API call,
   request_firmware_direct() just for this purpose -- although it should be
   noted another of its goal was to also skip the usermode helper.
   The system data request APIs allow for you to annotate that a system
   data file is optional for both synchronous or asynchronous requests
   through the same two basic set of APIs.
 - The system data request APIs currently match the old synchronous firmware
   API calls to refcounted firmware_class module, but it should be easy
   to add support now to enable also refcounting the caller's module
   should it be be needed. Likewise the system data request APIs match the
   old asynchronous firmware API call and refcounts the caller's module.

v4 changes:

o Add SYSDATA_KEEP_SYNC() and SYSDATA_KEEP_ASYNC() macro helpers,
  drivers that want to keep the firmware are pretty common, however
  note that if we can figure out a way to avoid having drivers
  deal with releasing the firmware we're better off, that however
  can be an additional change to look forward to.

o 0-day-bot make htmldocs warning fixes

o When developing and testing the sysdata test driver I ended up
  running into tons of hairball code just to be able to come up
  with enough code to be able to tweak all possible knobs using
  a userspace test interface. This begged for a cleaner API and
  in testing found that async_schedule_domain() made life so much
  easier. This also added the sysdata_synchronize_request() helper
  which user can use to see if their async request completed. This
  should help users considerably as well. Updated code, commit log
  and documentation to reflect these changes.

o In testing found that to make semantics stronger we should
  require @optional to true on the descriptor if an optional
  callback is to be provided (with SYSDATA_SYNC_OPT_CB() or
  SYSDATA_ASYNC_OPT_CB()). Made notes to ensure to users
  that set @optional to true but are not providing a opt_fail_cb()
  should at the very least seriously consider using the returned
  using async_cookie to sysdata_synchronize_request() to ensure
  no lingering requests are kept out of bounds.

o Updated commit log to reflect how we can compartamentalize
  usermode helper code

o Adds SYSDATA_ASYNC_OPT_CB()

o Forces @optional on SYSDATA_SYNC_OPT_CB() to true

o Ensures sysdata_file_request() and sysdata_file_request_async()
  check for emptry string (name[0] == '\0') as follow up to
  Kees's check for empty string name 471b095dfe0d6 ("firmware_class:
  make sure fw requests contain a name") and later a fix by
  Brian through 715780ae4bb76d ("firmware: actually return NULL on
  failed request_firmware_nowait()).

[0] https://marc.info/?l=linux-kernel&m=144095832412928
[1] https://marc.info/?i=20151006090821.GB9030%40kroah.com

Signed-off-by: Luis R. Rodriguez <mcgrof@xxxxxxxxxx>
---
 Documentation/firmware_class/system_data.txt |  89 ++++++++
 MAINTAINERS                                  |   3 +-
 drivers/base/firmware_class.c                | 327 +++++++++++++++++++++++++++
 include/linux/sysdata.h                      | 244 ++++++++++++++++++++
 4 files changed, 662 insertions(+), 1 deletion(-)
 create mode 100644 Documentation/firmware_class/system_data.txt
 create mode 100644 include/linux/sysdata.h

diff --git a/Documentation/firmware_class/system_data.txt b/Documentation/firmware_class/system_data.txt
new file mode 100644
index 000000000000..53378ce4fcd0
--- /dev/null
+++ b/Documentation/firmware_class/system_data.txt
@@ -0,0 +1,89 @@
+System data requests API
+========================
+
+As the kernel evolves we keep extending the firmware_class set of APIs
+with more or less arguments, this creates a slew of collateral evolutions.
+The set of users of firmware request APIs has also grown now to include
+users which are not looking for "firmware" per se, but instead general
+system data files which for one reason or another has been decided to be
+kept oustide of the kernel, and/or to allow dynamic updates. The system data
+request set of APIs addresses rebranding of firmware as generic system data
+files, and provides a way to enable these APIs to easily be extended without
+much collateral evolutions.
+
+System data modes of operation
+==============================
+
+There are only two types of modes of operation for system data requests:
+
+  * synchronous  - sysdata_file_request()
+  * asynchronous - sysdata_file_request_async()
+
+Synchronous requests expect requests to be done immediately, asynchronous
+requests enable requests to be scheduled for a later time.
+
+System data file descriptor
+===========================
+
+Variations of types of system data requests are specified by a system  data
+request descriptor. The system data request descriptor can grow as with new
+fields as requirements grow. The old firmware API provides two synchronous
+requests: request_firmware() and request_firmware_direct(), the later allowing
+the caller to specify that the "system data file" is optional. The system data
+request API allows a caller to set the optional nature of the system data file
+on the system data file descriptor using the same synchronous API. Since this
+requirement is part of the descriptor it also allows asynchronous requests
+to specify that the system data file is optional.
+
+Reference counting and releasing the system data file
+=====================================================
+
+As with the old firmware API both the device and module are bumped with
+reference counts during the system data requests. This prevents removal
+of the device and module making the system data request call until the
+system data request callbacks have completed, either synchronously or
+asynchronously.
+
+The old firmware APIs refcounted the firmware_class module for synchronous
+requests, meanwhile asynchronous requests refcounted the caller's module.
+The system data request API currently mimic this behaviour, for synchronous
+requests the firmware_class module is refcounted through the use of
+dfl_sync_reqs, although if in the future we may later enable use of
+also refcounting the caller's module as well. Likewise in the future we
+may extend asynchronous calls to refcount the firmware_class module.
+
+Typical use of the old synchronous firmware APIs consist of the caller
+requesting for "system data", consuming it after a request and finally
+freeing it. Typical asynchronous use of the old firmware APIs consist of
+the caller requesting for "system data" and then finally freeing it on
+asynchronous callback.
+
+The system data request API enables callers to provide a callback for both
+synchronous and asynchronous requests and since consumption can be expected
+in these callbacks it frees it for you by default after callback handlers
+are issued. If you wish to keep the system data around after your callbacks
+you must specify this through the system data request descriptor.
+
+Async cookies, replacing completions
+====================================
+
+With this new API you do not need to declare and use your own completions, you
+can replace your completions with sysdata_synchronize_request() using the
+async_cookie set for you by sysdata_file_request_async(). When
+sysdata_file_request_async() completes you can rest assured all the work for
+both triggering, and processing the sysdata using any of your callbacks has
+completed.
+
+User mode helper
+================
+
+The old firmware API provided support for an optional user mode helper. The
+new system data request API abandons all notions of the usermode helper.
+
+Tracking development enhancements and ideas
+===========================================
+
+To help track ongoing development for firmware_class and related items to
+firmware_class refer to the kernel newbies wiki page [0].
+
+[0] http://kernelnewbies.org/KernelProjects/firmware-class-enhancements
diff --git a/MAINTAINERS b/MAINTAINERS
index b030a95dcb97..4ebb7485a4d4 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -4778,7 +4778,7 @@ F:	include/linux/firewire.h
 F:	include/uapi/linux/firewire*.h
 F:	tools/firewire/
 
-FIRMWARE LOADER (request_firmware)
+FIRMWARE LOADER (request_firmware, sysdata_file_request)
 M:	Ming Lei <ming.lei@xxxxxxxxxxxxx>
 M:	Luis R. Rodriguez <mcgrof@xxxxxxxxxx>
 L:	linux-kernel@xxxxxxxxxxxxxxx
@@ -4786,6 +4786,7 @@ S:	Maintained
 F:	Documentation/firmware_class/
 F:	drivers/base/firmware*.c
 F:	include/linux/firmware.h
+F:	include/linux/sysdata.h
 
 FLASH ADAPTER DRIVER (IBM Flash Adapter 900GB Full Height PCI Flash Card)
 M:	Joshua Morris <josh.h.morris@xxxxxxxxxx>
diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
index dca4f9cbf4db..913339fb844b 100644
--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -2,6 +2,7 @@
  * firmware_class.c - Multi purpose firmware loading support
  *
  * Copyright (c) 2003 Manuel Estrada Sainz
+ * Copyright (c) 2016 Luis R. Rodriguez <mcgrof@xxxxxxxxxx>
  *
  * Please see Documentation/firmware_class/ for more information.
  *
@@ -18,6 +19,7 @@
 #include <linux/mutex.h>
 #include <linux/workqueue.h>
 #include <linux/highmem.h>
+#include <linux/sysdata.h>
 #include <linux/firmware.h>
 #include <linux/slab.h>
 #include <linux/sched.h>
@@ -39,6 +41,12 @@ MODULE_AUTHOR("Manuel Estrada Sainz");
 MODULE_DESCRIPTION("Multi purpose firmware loading support");
 MODULE_LICENSE("GPL");
 
+static const struct sysdata_file_sync_reqs dfl_sync_reqs = {
+	.mode = SYNCDATA_SYNC,
+	.module = THIS_MODULE,
+	.gfp = GFP_KERNEL,
+};
+
 /* Builtin firmware support */
 
 #ifdef CONFIG_FW_LOADER
@@ -1300,6 +1308,184 @@ void release_firmware(const struct firmware *fw)
 }
 EXPORT_SYMBOL(release_firmware);
 
+static void sysdata_file_update(struct sysdata_file *sysdata)
+{
+	struct firmware *fw;
+	struct firmware_buf *buf;
+
+	if (!sysdata || !sysdata->priv)
+		return;
+
+	fw = sysdata->priv;
+	if (!fw->priv)
+		return;
+
+	buf = fw->priv;
+
+	sysdata->size = buf->size;
+	sysdata->data = buf->data;
+
+	pr_debug("%s: fw-%s buf=%p data=%p size=%u",
+		 __func__, buf->fw_id, buf, buf->data,
+		 (unsigned int)buf->size);
+}
+
+/*
+ * prepare firmware and firmware_buf structs;
+ * return 0 if a firmware is already assigned, 1 if need to load one,
+ * or a negative error code
+ */
+static int
+_request_sysdata_prepare(struct sysdata_file **sysdata_p, const char *name,
+			  struct device *device)
+{
+	struct sysdata_file *sysdata;
+	struct firmware *fw;
+	int ret;
+
+	*sysdata_p = sysdata = kzalloc(sizeof(*sysdata), GFP_KERNEL);
+	if (!sysdata) {
+		dev_err(device, "%s: kmalloc(struct sysdata) failed\n",
+			__func__);
+		return -ENOMEM;
+	}
+
+	ret = _request_firmware_prepare(&fw, name, device, NULL, 0);
+	if (ret >= 0)
+		sysdata->priv = fw;
+
+	return ret;
+}
+
+/**
+ * release_sysdata_file: - release the resource associated with the sysdata file
+ * @sysdata: sysdata file resource to release
+ **/
+void release_sysdata_file(const struct sysdata_file *sysdata)
+{
+	struct firmware *fw;
+
+	if (sysdata) {
+		if (sysdata->priv) {
+			fw = sysdata->priv;
+			release_firmware(fw);
+		}
+	}
+	kfree(sysdata);
+}
+EXPORT_SYMBOL_GPL(release_sysdata_file);
+
+/*
+ * sysdata_p is always set to be NULL unless a proper system
+ * data file was found.
+ */
+static int _sysdata_file_request(const struct sysdata_file **sysdata_p,
+				 const char *name,
+				 const struct sysdata_file_desc *desc,
+				 struct device *device)
+{
+	struct sysdata_file *sysdata = NULL;
+	struct firmware *fw = NULL;
+	int ret = -EINVAL;
+
+	if (!sysdata_p)
+		goto out;
+
+	if (!desc)
+		goto out;
+
+	if (!name || name[0] == '\0')
+		goto out;
+
+	ret = _request_sysdata_prepare(&sysdata, name, device);
+	if (ret <= 0) /* error or already assigned */
+		goto out;
+
+	fw = sysdata->priv;
+
+	ret = fw_get_filesystem_firmware(device, fw->priv);
+	if (ret && !desc->optional)
+		pr_err("Direct system data load for %s failed with error %d\n",
+		       name, ret);
+
+	if (!ret)
+		ret = assign_firmware_buf(fw, device, FW_OPT_UEVENT);
+
+ out:
+	if (ret < 0) {
+		release_sysdata_file(sysdata);
+		sysdata = NULL;
+	}
+
+	sysdata_file_update(sysdata);
+
+	*sysdata_p = sysdata;
+
+	return ret;
+}
+
+/**
+ * sysdata_file_request - synchronous request for a system data file
+ * @name: name of the system data file
+ * @desc: system data file descriptor, it provides all the requirements
+ * 	which must be met for the file being requested.
+ * @device: device for which firmware is being loaded
+ *
+ * This performs a synchronous system data file lookup with the requirements
+ * specified on @desc, if the file was found meeting the criteria requested
+ * 0 is returned. Access to the system data file data can be accessed through
+ * an optional callback set on the @desc. If the system data file is optional
+ * you must specify that on the @desc and if set you may provide an alternative
+ * callback which if set would be run if the system data file was not found.
+ *
+ * The system data file passed to the callbacks will be NULL unless it was
+ * found matching all the criteria on @desc. 0 is always returned if the file
+ * was found unless a callback was provided, in which case the callback's
+ * return value will be passed. Unless the desc->keep was set the kernel will
+ * release the system data file for you after your callbacks were processed.
+ *
+ * Reference counting is used during the duration of this call on both the
+ * device and module that made the request. This prevents any callers from
+ * freeing either the device or module prior to completion of this call.
+ */
+int sysdata_file_request(const char *name,
+			 const struct sysdata_file_desc *desc,
+			 struct device *device)
+{
+	const struct sysdata_file *sysdata;
+	const struct sysdata_file_sync_reqs *sync_reqs;
+	int ret;
+
+	if (!device || !desc || !name || name[0] == '\0')
+		return -EINVAL;
+
+	if (desc->sync_reqs.mode != SYNCDATA_SYNC)
+		return -EINVAL;
+
+	if (desc_sync_opt_cb(desc) && !desc->optional)
+		return -EINVAL;
+
+	sync_reqs = &dfl_sync_reqs;
+
+	__module_get(sync_reqs->module);
+	get_device(device);
+
+	ret = _sysdata_file_request(&sysdata, name, desc, device);
+	if (ret && desc->optional)
+		ret = desc_sync_opt_call_cb(desc);
+	else
+		ret = desc_sync_found_call_cb(desc, sysdata);
+
+	if (!desc->keep)
+		release_sysdata_file(sysdata);
+
+	put_device(device);
+	module_put(sync_reqs->module);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(sysdata_file_request);
+
 /* Async support */
 struct firmware_work {
 	struct work_struct work;
@@ -1388,6 +1574,145 @@ request_firmware_nowait(
 }
 EXPORT_SYMBOL(request_firmware_nowait);
 
+struct sysdata_file_work {
+	const char *name;
+	struct sysdata_file_desc desc;
+	struct device *device;
+};
+
+static ASYNC_DOMAIN(sysdata_async_domain);
+
+static void request_sysdata_file_work_func(void *data, async_cookie_t cookie)
+{
+	struct sysdata_file_work *sys_work = data;
+	const struct sysdata_file_desc *desc;
+	const struct sysdata_file_sync_reqs *sync_reqs;
+	const struct sysdata_file *sysdata;
+	int ret;
+
+	desc = &sys_work->desc;
+	sync_reqs = &desc->sync_reqs;
+
+	ret = _sysdata_file_request(&sysdata, sys_work->name,
+				    desc, sys_work->device);
+	if (ret && desc->optional)
+		desc_async_opt_call_cb(desc);
+	else
+		desc_async_found_call_cb(sysdata, desc);
+
+	if (!desc->keep)
+		release_sysdata_file(sysdata);
+
+	put_device(sys_work->device);
+	module_put(sync_reqs->module);
+
+	kfree_const(sys_work->name);
+	kfree(sys_work);
+}
+
+/**
+ * sysdata_file_request_async - asynchronous request for a system data file
+ * @name: name of the system data file
+ * @desc: system data file descriptor, it provides all the requirements
+ * 	which must be met for the file being requested.
+ * @device: device for which firmware is being loaded
+ * @async_cookie: used for checkpointing your async request
+ *
+ * This performs an asynchronous system data file lookup with the requirements
+ * specified on @desc. The request for the actual system data file lookup will
+ * be scheduled with async_schedule_domain() to be run at a later time. 0 is
+ * returned if we were able to asynchronously schedlue your work to be run.
+ *
+ * Reference counting is used during the duration of this scheduled call on
+ * both the device and module that made the request. This prevents any callers
+ * from freeing either the device or module prior to completion of the
+ * scheduled work.
+ *
+ * Access to the system data file data can be accessed through an optional
+ * callback set on the @desc. If the system data file is optional you must
+ * specify that on the @desc and if set you may provide an alternative
+ * callback which if set would be run if the system data file was not found.
+ *
+ * The system data file passed to the callbacks will always be NULL unless
+ * it was found matching all the criteria on @desc. Unless the desc->keep
+ * was set the kernel will release the system data file for you after your
+ * callbacks were processed on the scheduled work.
+ *
+ * You should use rely on async_cookie to determine if your asynchronous work
+ * has been scheduled and completed. If you need to wait for completion of
+ * processing of your sysdata through your callbacks, or if you just want to
+ * know the hunt is over you can sysdata_synchronize_request() with the
+ * async_cookie.
+ */
+int sysdata_file_request_async(const char *name,
+			       const struct sysdata_file_desc *desc,
+			       struct device *device,
+			       async_cookie_t *async_cookie)
+{
+	struct sysdata_file_work *sys_work;
+	const struct sysdata_file_sync_reqs *sync_reqs;
+
+	if (!device || !desc || !name || name[0] == '\0')
+		return -EINVAL;
+
+	if (desc->sync_reqs.mode != SYNCDATA_ASYNC)
+		return -EINVAL;
+
+	if (desc_async_opt_cb(desc) && !desc->optional)
+		return -EINVAL;
+
+	sync_reqs = &desc->sync_reqs;
+
+	sys_work = kzalloc(sizeof(struct sysdata_file_work), sync_reqs->gfp);
+	if (!sys_work)
+		return -ENOMEM;
+
+	sys_work->device = device;
+	memcpy(&sys_work->desc, desc, sizeof(struct sysdata_file_desc));
+	sys_work->name = kstrdup_const(name, sync_reqs->gfp);
+	if (!sys_work->name) {
+		kfree(sys_work);
+		return -ENOMEM;
+	}
+
+	if (!try_module_get(sync_reqs->module)) {
+		kfree_const(sys_work->name);
+		kfree(sys_work);
+		return -EFAULT;
+	}
+
+	get_device(sys_work->device);
+
+	*async_cookie = async_schedule_domain(request_sysdata_file_work_func,
+					      sys_work,
+					      &sysdata_async_domain);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(sysdata_file_request_async);
+
+/**
+ * sysdata_synchronize_request - wait until your async sysdata calls complete
+ * @async_cookie: async cookie
+ *
+ * Waits until all asynchronous sysdata calls prior to and up to @async_cookie
+ * have been completed. You can use this to wait for completion of your own
+ * async callback. Your wait will end after request_sysdata_file_work_func()
+ * is called for your cookie. At this point you can rest assured your
+ * series of async callbacks would have been called if supplied.
+ *
+ * async_cookie+1 is used as async_synchronize_cookie_domain() only waits
+ * until at least your own call is next in queue to be run, we want the
+ * next item after yours to be in queue, this tells us we have run already.
+ * Should there not be any other async scheduled item after yours this will
+ * simply wait until all async sysdata calls are complete.
+ */
+void sysdata_synchronize_request(async_cookie_t async_cookie)
+{
+	async_synchronize_cookie_domain(async_cookie+1, &sysdata_async_domain);
+}
+EXPORT_SYMBOL_GPL(sysdata_synchronize_request);
+
 #ifdef CONFIG_PM_SLEEP
 static ASYNC_DOMAIN_EXCLUSIVE(fw_cache_domain);
 
@@ -1761,6 +2086,7 @@ static int __init firmware_class_init(void)
 
 static void __exit firmware_class_exit(void)
 {
+	async_synchronize_full_domain(&sysdata_async_domain);
 #ifdef CONFIG_PM_SLEEP
 	unregister_syscore_ops(&fw_syscore_ops);
 	unregister_pm_notifier(&fw_cache.pm_notify);
@@ -1769,6 +2095,7 @@ static void __exit firmware_class_exit(void)
 	unregister_reboot_notifier(&fw_shutdown_nb);
 	class_unregister(&firmware_class);
 #endif
+	async_unregister_domain(&sysdata_async_domain);
 }
 
 fs_initcall(firmware_class_init);
diff --git a/include/linux/sysdata.h b/include/linux/sysdata.h
new file mode 100644
index 000000000000..6c16829981ce
--- /dev/null
+++ b/include/linux/sysdata.h
@@ -0,0 +1,244 @@
+#ifndef _LINUX_SYSDATA_H
+#define _LINUX_SYSDATA_H
+
+#include <linux/types.h>
+#include <linux/compiler.h>
+#include <linux/gfp.h>
+#include <linux/device.h>
+#include <linux/async.h>
+
+/*
+ * System Data internals
+ *
+ * Copyright (C) 2015 Luis R. Rodriguez <mcgrof@xxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+struct sysdata_file {
+	size_t size;
+	const u8 *data;
+
+	/* sysdata loader private fields */
+	void *priv;
+};
+
+/**
+ * enum sync_data_mode - system data mode of operation
+ *
+ * SYNCDATA_SYNC: your call to request system data is synchronous. We will
+ * 	look for the system data file you have requested immediatley.
+ * SYNCDATA_ASYNC: your call to request system data is asynchronous. We will
+ * 	schedule the search for your system data file to be run at a later
+ * 	time.
+ */
+enum sync_data_mode {
+	SYNCDATA_SYNC,
+	SYNCDATA_ASYNC,
+};
+
+/* one per sync_data_mode */
+union sysdata_file_cbs {
+	struct {
+		int __must_check (*found_cb)(void *, const struct sysdata_file *);
+		void *found_context;
+
+		int __must_check (*opt_fail_cb)(void *);
+		void *opt_fail_context;
+	} sync;
+	struct {
+		void (*found_cb)(const struct sysdata_file *, void *);
+		void *found_context;
+
+		void (*opt_fail_cb)(void *);
+		void *opt_fail_context;
+	} async;
+};
+
+struct sysdata_file_sync_reqs {
+	enum sync_data_mode mode;
+	struct module *module;
+	gfp_t gfp;
+};
+
+/**
+ * struct sysdata_file_desc - system data file descriptor
+ * @optional: if true it is not a hard requirement by the caller that this
+ *	file be present. An error will not be recorded if the file is not
+ *	found. You must set this to true if you have provided a opt_fail_cb
+ *	callback, SYSDATA_SYNC_OPT_CB() and SYSDATA_ASYNC_OPT_CB() ensures
+ *	this is done for you. If you set this to true and are using an
+ *	asynchronous request but not providing a opt_fail_cb() you should
+ *	seriously consider using at the very least using async_cookie provided
+ *	to you to sysdata_synchronize_request() to ensure no lingering
+ *	requests are kept out of bounds.
+ * @keep: if set the caller wants to claim ownership over the system data
+ *	through one of its callbacks, it must later free it with
+ *	release_sysdata_file(). By default this is set to false and the kernel
+ *	will release the system data file for you after callback processing
+ *	has completed.
+ * @sync_reqs: synchronization requirements, this will be taken care for you
+ *	by default if you are usingy sdata_file_request(), otherwise you
+ *	should provide your own requirements.
+ *
+ * This structure is set the by the driver and passed to the system data
+ * file helpers sysdata_file_request() or sysdata_file_request_async().
+ * It is intended to carry all requirements and specifications required
+ * to complete the task to get the requested system date file to the caller.
+ * If you wish to extend functionality of system data file requests you
+ * should extend this data structure and make use of the extensions on
+ * the callers to avoid unnecessary collateral evolutions.
+ *
+ * You are allowed to provide a callback to handle if a system data file was
+ * found or not. You do not need to provide a callback. You may also set
+ * an optional flag which would enable you to declare that the system data
+ * file is optional and that if it is not found an alternative callback be
+ * run for you.
+ *
+ * Refer to sysdata_file_request() and sysdata_file_request_async() for more
+ * details.
+ */
+struct sysdata_file_desc {
+	bool optional;
+	bool keep;
+	struct sysdata_file_sync_reqs sync_reqs;
+	const union sysdata_file_cbs cbs;
+};
+
+/*
+ * We keep these template definitions to a minimum for the most
+ * popular requests.
+ */
+
+/* Typical sync data case */
+#define SYSDATA_SYNC_FOUND(__found_cb, __context)			\
+	.cbs.sync.found_cb = __found_cb,				\
+	.cbs.sync.found_context = __context
+
+#define SYSDATA_DEFAULT_SYNC(__found_cb, __context)			\
+	SYSDATA_SYNC_FOUND(__found_cb, __context)
+
+#define SYSDATA_KEEP_SYNC(__found_cb, __context)			\
+	SYSDATA_DEFAULT_SYNC(__found_cb, __context),			\
+	.keep= true
+
+/* If you have one fallback routine */
+#define SYSDATA_SYNC_OPT_CB(__fail_cb, __context)			\
+	.optional = true,						\
+	.cbs.sync.opt_fail_cb = __fail_cb,				\
+	.cbs.sync.opt_fail_context = __context
+
+/*
+ * Used to define the default asynchronization requirements for
+ * sysdata_file_request_async(). Drivers can override.
+ */
+#define SYSDATA_DEFAULT_ASYNC(__found_cb, __context)			\
+	.sync_reqs = {							\
+		.mode = SYNCDATA_ASYNC,					\
+		.module = THIS_MODULE,					\
+		.gfp = GFP_KERNEL,					\
+	},								\
+	.cbs.async = {							\
+		.found_cb = __found_cb,					\
+		.found_context = __context,				\
+	}
+
+#define SYSDATA_KEEP_ASYNC(__found_cb, __context)			\
+	SYSDATA_DEFAULT_ASYNC(__found_cb, __context),			\
+	.keep = true
+
+#define SYSDATA_ASYNC_OPT_CB(__fail_cb, __context)			\
+	.optional = true,						\
+	.cbs.async.opt_fail_cb = __fail_cb,				\
+	.cbs.async.opt_fail_context = __context
+
+#define desc_sync_found_cb(desc)	((desc)->cbs.sync.found_cb)
+#define desc_sync_found_context(desc)	((desc)->cbs.sync.found_context)
+static inline int desc_sync_found_call_cb(const struct sysdata_file_desc *desc,
+					  const struct sysdata_file *sysdata)
+{
+	if (desc->sync_reqs.mode != SYNCDATA_SYNC)
+		return -EINVAL;
+	if (!desc_sync_found_cb(desc)) {
+		if (sysdata)
+			return 0;
+		return -ENOENT;
+	}
+	return desc_sync_found_cb(desc)(desc_sync_found_context(desc),
+					sysdata);
+}
+
+#define desc_sync_opt_cb(desc)		((desc)->cbs.sync.opt_fail_cb)
+#define desc_sync_opt_context(desc)	((desc)->cbs.sync.opt_fail_context)
+static inline int desc_sync_opt_call_cb(const struct sysdata_file_desc *desc)
+{
+	if (desc->sync_reqs.mode != SYNCDATA_SYNC)
+		return -EINVAL;
+	if (!desc_sync_opt_cb(desc))
+		return 0;
+	return desc_sync_opt_cb(desc)(desc_sync_opt_context(desc));
+}
+
+#define desc_async_found_cb(desc)	((desc)->cbs.async.found_cb)
+#define desc_async_found_context(desc)	((desc)->cbs.async.found_context)
+static inline void desc_async_found_call_cb(const struct sysdata_file *sysdata,
+					    const struct sysdata_file_desc *desc)
+{
+	if (desc->sync_reqs.mode != SYNCDATA_ASYNC)
+		return;
+	if (!desc_async_found_cb(desc))
+		return;
+	desc_async_found_cb(desc)(sysdata, desc_async_found_context(desc));
+}
+
+#define desc_async_opt_cb(desc)		((desc)->cbs.async.opt_fail_cb)
+#define desc_async_opt_context(desc)	((desc)->cbs.async.opt_fail_context)
+static inline void desc_async_opt_call_cb(const struct sysdata_file_desc *desc)
+{
+	if (desc->sync_reqs.mode != SYNCDATA_ASYNC)
+		return;
+	if (!desc_async_opt_cb(desc))
+		return;
+	desc_async_opt_cb(desc)(desc_async_opt_context(desc));
+}
+
+
+#if defined(CONFIG_FW_LOADER) || (defined(CONFIG_FW_LOADER_MODULE) && defined(MODULE))
+int sysdata_file_request(const char *name,
+			 const struct sysdata_file_desc *desc,
+			 struct device *device);
+int sysdata_file_request_async(const char *name,
+			       const struct sysdata_file_desc *desc,
+			       struct device *device,
+			       async_cookie_t *async_cookie);
+void release_sysdata_file(const struct sysdata_file *sysdata);
+void sysdata_synchronize_request(async_cookie_t async_cookie);
+#else
+static inline int sysdata_file_request(const char *name,
+				       const struct sysdata_file_desc *desc,
+				       struct device *device)
+{
+	return -EINVAL;
+}
+
+static inline int sysdata_file_request_async(const char *name,
+					     const struct sysdata_file_desc *desc,
+					     struct device *device,
+					     async_cookie_t *async_cookie);
+{
+	return -EINVAL;
+}
+
+static inline void release_sysdata_file(const struct sysdata_file *sysdata)
+{
+}
+
+void sysdata_synchronize_request(async_cookie_t async_cookie)
+{
+}
+#endif
+
+#endif /* _LINUX_SYSDATA_H */
-- 
2.8.2