Message-Id: <20220203213053.360190-4-russell.h.weight@intel.com>
Date:   Thu,  3 Feb 2022 14:30:50 -0700
From:   Russ Weight <russell.h.weight@...el.com>
To:     mcgrof@...nel.org, gregkh@...uxfoundation.org, rafael@...nel.org,
        linux-kernel@...r.kernel.org
Cc:     trix@...hat.com, lgoncalv@...hat.com, yilun.xu@...el.com,
        hao.wu@...el.com, matthew.gerlach@...el.com,
        basheer.ahmed.muddebihal@...el.com, tianfei.zhang@...el.com,
        Russ Weight <russell.h.weight@...el.com>
Subject: [RFC PATCH 3/5] firmware_loader: Split fw_sysfs support from fallback

In preparation for sharing the "loading" and "data" sysfs nodes with the
new firmware upload support, split out sysfs functionality from fallback.c
and fallback.h into fw_sysfs.c and fw_sysfs.h. This includes the firmware
class driver code that is associated with the sysfs files and the
fw_fallback_config support for the timeout sysfs node.

CONFIG_FW_LOADER_SYSFS is created and is selected by
CONFIG_FW_LOADER_USER_HELPER in order to include fw_sysfs.o in
firmware_class-objs.

This is mostly just a code reorganization. There are a few symbols that
change in scope, and these can be identified by looking at the header
file changes. A few white-space warnings from checkpatch are also
addressed in this patch.

Signed-off-by: Russ Weight <russell.h.weight@...el.com>
---
 drivers/base/firmware_loader/Kconfig    |   4 +
 drivers/base/firmware_loader/Makefile   |   1 +
 drivers/base/firmware_loader/fallback.c | 430 ------------------------
 drivers/base/firmware_loader/fallback.h |  46 +--
 drivers/base/firmware_loader/fw_sysfs.c | 413 +++++++++++++++++++++++
 drivers/base/firmware_loader/fw_sysfs.h |  94 ++++++
 6 files changed, 513 insertions(+), 475 deletions(-)
 create mode 100644 drivers/base/firmware_loader/fw_sysfs.c
 create mode 100644 drivers/base/firmware_loader/fw_sysfs.h

diff --git a/drivers/base/firmware_loader/Kconfig b/drivers/base/firmware_loader/Kconfig
index 5b24f3959255..1bfe18900ed5 100644
--- a/drivers/base/firmware_loader/Kconfig
+++ b/drivers/base/firmware_loader/Kconfig
@@ -29,6 +29,9 @@ if FW_LOADER
 config FW_LOADER_PAGED_BUF
 	bool
 
+config FW_LOADER_SYSFS
+	bool
+
 config EXTRA_FIRMWARE
 	string "Build named firmware blobs into the kernel binary"
 	help
@@ -70,6 +73,7 @@ config EXTRA_FIRMWARE_DIR
 
 config FW_LOADER_USER_HELPER
 	bool "Enable the firmware sysfs fallback mechanism"
+	select FW_LOADER_SYSFS
 	select FW_LOADER_PAGED_BUF
 	help
 	  This option enables a sysfs loading facility to enable firmware
diff --git a/drivers/base/firmware_loader/Makefile b/drivers/base/firmware_loader/Makefile
index e87843408fe6..787c833d0c6e 100644
--- a/drivers/base/firmware_loader/Makefile
+++ b/drivers/base/firmware_loader/Makefile
@@ -6,5 +6,6 @@ obj-$(CONFIG_FW_LOADER)	+= firmware_class.o
 firmware_class-objs := main.o
 firmware_class-$(CONFIG_FW_LOADER_USER_HELPER) += fallback.o
 firmware_class-$(CONFIG_EFI_EMBEDDED_FIRMWARE) += fallback_platform.o
+firmware_class-$(CONFIG_FW_LOADER_SYSFS) += fw_sysfs.o
 
 obj-y += builtin/
diff --git a/drivers/base/firmware_loader/fallback.c b/drivers/base/firmware_loader/fallback.c
index d82e055a4297..bf68e3947814 100644
--- a/drivers/base/firmware_loader/fallback.c
+++ b/drivers/base/firmware_loader/fallback.c
@@ -3,12 +3,9 @@
 #include <linux/types.h>
 #include <linux/kconfig.h>
 #include <linux/list.h>
-#include <linux/slab.h>
 #include <linux/security.h>
-#include <linux/highmem.h>
 #include <linux/umh.h>
 #include <linux/sysctl.h>
-#include <linux/vmalloc.h>
 #include <linux/module.h>
 
 #include "fallback.h"
@@ -18,22 +15,6 @@
  * firmware fallback mechanism
  */
 
-MODULE_IMPORT_NS(FIRMWARE_LOADER_PRIVATE);
-
-extern struct firmware_fallback_config fw_fallback_config;
-
-/* These getters are vetted to use int properly */
-static inline int __firmware_loading_timeout(void)
-{
-	return fw_fallback_config.loading_timeout;
-}
-
-/* These setters are vetted to use int properly */
-static void __fw_fallback_set_timeout(int timeout)
-{
-	fw_fallback_config.loading_timeout = timeout;
-}
-
 /*
  * use small loading timeout for caching devices' firmware because all these
  * firmware images have been loaded successfully at lease once, also system is
@@ -58,52 +39,11 @@ static long firmware_loading_timeout(void)
 		__firmware_loading_timeout() * HZ : MAX_JIFFY_OFFSET;
 }
 
-static inline bool fw_sysfs_done(struct fw_priv *fw_priv)
-{
-	return __fw_state_check(fw_priv, FW_STATUS_DONE);
-}
-
-static inline bool fw_sysfs_loading(struct fw_priv *fw_priv)
-{
-	return __fw_state_check(fw_priv, FW_STATUS_LOADING);
-}
-
 static inline int fw_sysfs_wait_timeout(struct fw_priv *fw_priv,  long timeout)
 {
 	return __fw_state_wait_common(fw_priv, timeout);
 }
 
-struct fw_sysfs {
-	bool nowait;
-	struct device dev;
-	struct fw_priv *fw_priv;
-	struct firmware *fw;
-};
-
-static struct fw_sysfs *to_fw_sysfs(struct device *dev)
-{
-	return container_of(dev, struct fw_sysfs, dev);
-}
-
-static void __fw_load_abort(struct fw_priv *fw_priv)
-{
-	/*
-	 * There is a small window in which user can write to 'loading'
-	 * between loading done/aborted and disappearance of 'loading'
-	 */
-	if (fw_state_is_aborted(fw_priv) || fw_sysfs_done(fw_priv))
-		return;
-
-	fw_state_aborted(fw_priv);
-}
-
-static void fw_load_abort(struct fw_sysfs *fw_sysfs)
-{
-	struct fw_priv *fw_priv = fw_sysfs->fw_priv;
-
-	__fw_load_abort(fw_priv);
-}
-
 static LIST_HEAD(pending_fw_head);
 
 void kill_pending_fw_fallback_reqs(bool only_kill_custom)
@@ -120,376 +60,6 @@ void kill_pending_fw_fallback_reqs(bool only_kill_custom)
 	mutex_unlock(&fw_lock);
 }
 
-static ssize_t timeout_show(struct class *class, struct class_attribute *attr,
-			    char *buf)
-{
-	return sysfs_emit(buf, "%d\n", __firmware_loading_timeout());
-}
-
-/**
- * timeout_store() - set number of seconds to wait for firmware
- * @class: device class pointer
- * @attr: device attribute pointer
- * @buf: buffer to scan for timeout value
- * @count: number of bytes in @buf
- *
- *	Sets the number of seconds to wait for the firmware.  Once
- *	this expires an error will be returned to the driver and no
- *	firmware will be provided.
- *
- *	Note: zero means 'wait forever'.
- **/
-static ssize_t timeout_store(struct class *class, struct class_attribute *attr,
-			     const char *buf, size_t count)
-{
-	int tmp_loading_timeout = simple_strtol(buf, NULL, 10);
-
-	if (tmp_loading_timeout < 0)
-		tmp_loading_timeout = 0;
-
-	__fw_fallback_set_timeout(tmp_loading_timeout);
-
-	return count;
-}
-static CLASS_ATTR_RW(timeout);
-
-static struct attribute *firmware_class_attrs[] = {
-	&class_attr_timeout.attr,
-	NULL,
-};
-ATTRIBUTE_GROUPS(firmware_class);
-
-static void fw_dev_release(struct device *dev)
-{
-	struct fw_sysfs *fw_sysfs = to_fw_sysfs(dev);
-
-	kfree(fw_sysfs);
-}
-
-static int do_firmware_uevent(struct fw_sysfs *fw_sysfs, struct kobj_uevent_env *env)
-{
-	if (add_uevent_var(env, "FIRMWARE=%s", fw_sysfs->fw_priv->fw_name))
-		return -ENOMEM;
-	if (add_uevent_var(env, "TIMEOUT=%i", __firmware_loading_timeout()))
-		return -ENOMEM;
-	if (add_uevent_var(env, "ASYNC=%d", fw_sysfs->nowait))
-		return -ENOMEM;
-
-	return 0;
-}
-
-static int firmware_uevent(struct device *dev, struct kobj_uevent_env *env)
-{
-	struct fw_sysfs *fw_sysfs = to_fw_sysfs(dev);
-	int err = 0;
-
-	mutex_lock(&fw_lock);
-	if (fw_sysfs->fw_priv)
-		err = do_firmware_uevent(fw_sysfs, env);
-	mutex_unlock(&fw_lock);
-	return err;
-}
-
-static struct class firmware_class = {
-	.name		= "firmware",
-	.class_groups	= firmware_class_groups,
-	.dev_uevent	= firmware_uevent,
-	.dev_release	= fw_dev_release,
-};
-
-int register_sysfs_loader(void)
-{
-	int ret = class_register(&firmware_class);
-
-	if (ret != 0)
-		return ret;
-	return register_firmware_config_sysctl();
-}
-
-void unregister_sysfs_loader(void)
-{
-	unregister_firmware_config_sysctl();
-	class_unregister(&firmware_class);
-}
-
-static ssize_t firmware_loading_show(struct device *dev,
-				     struct device_attribute *attr, char *buf)
-{
-	struct fw_sysfs *fw_sysfs = to_fw_sysfs(dev);
-	int loading = 0;
-
-	mutex_lock(&fw_lock);
-	if (fw_sysfs->fw_priv)
-		loading = fw_sysfs_loading(fw_sysfs->fw_priv);
-	mutex_unlock(&fw_lock);
-
-	return sysfs_emit(buf, "%d\n", loading);
-}
-
-/**
- * firmware_loading_store() - set value in the 'loading' control file
- * @dev: device pointer
- * @attr: device attribute pointer
- * @buf: buffer to scan for loading control value
- * @count: number of bytes in @buf
- *
- *	The relevant values are:
- *
- *	 1: Start a load, discarding any previous partial load.
- *	 0: Conclude the load and hand the data to the driver code.
- *	-1: Conclude the load with an error and discard any written data.
- **/
-static ssize_t firmware_loading_store(struct device *dev,
-				      struct device_attribute *attr,
-				      const char *buf, size_t count)
-{
-	struct fw_sysfs *fw_sysfs = to_fw_sysfs(dev);
-	struct fw_priv *fw_priv;
-	ssize_t written = count;
-	int loading = simple_strtol(buf, NULL, 10);
-
-	mutex_lock(&fw_lock);
-	fw_priv = fw_sysfs->fw_priv;
-	if (fw_state_is_aborted(fw_priv) || fw_state_is_done(fw_priv))
-		goto out;
-
-	switch (loading) {
-	case 1:
-		/* discarding any previous partial load */
-		if (!fw_sysfs_done(fw_priv)) {
-			fw_free_paged_buf(fw_priv);
-			fw_state_start(fw_priv);
-		}
-		break;
-	case 0:
-		if (fw_sysfs_loading(fw_priv)) {
-			int rc;
-
-			/*
-			 * Several loading requests may be pending on
-			 * one same firmware buf, so let all requests
-			 * see the mapped 'buf->data' once the loading
-			 * is completed.
-			 * */
-			rc = fw_map_paged_buf(fw_priv);
-			if (rc)
-				dev_err(dev, "%s: map pages failed\n",
-					__func__);
-			else
-				rc = security_kernel_post_load_data(fw_priv->data,
-						fw_priv->size,
-						LOADING_FIRMWARE, "blob");
-
-			/*
-			 * Same logic as fw_load_abort, only the DONE bit
-			 * is ignored and we set ABORT only on failure.
-			 */
-			if (rc) {
-				fw_state_aborted(fw_priv);
-				written = rc;
-			} else {
-				fw_state_done(fw_priv);
-			}
-			break;
-		}
-		fallthrough;
-	default:
-		dev_err(dev, "%s: unexpected value (%d)\n", __func__, loading);
-		fallthrough;
-	case -1:
-		fw_load_abort(fw_sysfs);
-		break;
-	}
-out:
-	mutex_unlock(&fw_lock);
-	return written;
-}
-
-static DEVICE_ATTR(loading, 0644, firmware_loading_show, firmware_loading_store);
-
-static void firmware_rw_data(struct fw_priv *fw_priv, char *buffer,
-			   loff_t offset, size_t count, bool read)
-{
-	if (read)
-		memcpy(buffer, fw_priv->data + offset, count);
-	else
-		memcpy(fw_priv->data + offset, buffer, count);
-}
-
-static void firmware_rw(struct fw_priv *fw_priv, char *buffer,
-			loff_t offset, size_t count, bool read)
-{
-	while (count) {
-		void *page_data;
-		int page_nr = offset >> PAGE_SHIFT;
-		int page_ofs = offset & (PAGE_SIZE-1);
-		int page_cnt = min_t(size_t, PAGE_SIZE - page_ofs, count);
-
-		page_data = kmap(fw_priv->pages[page_nr]);
-
-		if (read)
-			memcpy(buffer, page_data + page_ofs, page_cnt);
-		else
-			memcpy(page_data + page_ofs, buffer, page_cnt);
-
-		kunmap(fw_priv->pages[page_nr]);
-		buffer += page_cnt;
-		offset += page_cnt;
-		count -= page_cnt;
-	}
-}
-
-static ssize_t firmware_data_read(struct file *filp, struct kobject *kobj,
-				  struct bin_attribute *bin_attr,
-				  char *buffer, loff_t offset, size_t count)
-{
-	struct device *dev = kobj_to_dev(kobj);
-	struct fw_sysfs *fw_sysfs = to_fw_sysfs(dev);
-	struct fw_priv *fw_priv;
-	ssize_t ret_count;
-
-	mutex_lock(&fw_lock);
-	fw_priv = fw_sysfs->fw_priv;
-	if (!fw_priv || fw_sysfs_done(fw_priv)) {
-		ret_count = -ENODEV;
-		goto out;
-	}
-	if (offset > fw_priv->size) {
-		ret_count = 0;
-		goto out;
-	}
-	if (count > fw_priv->size - offset)
-		count = fw_priv->size - offset;
-
-	ret_count = count;
-
-	if (fw_priv->data)
-		firmware_rw_data(fw_priv, buffer, offset, count, true);
-	else
-		firmware_rw(fw_priv, buffer, offset, count, true);
-
-out:
-	mutex_unlock(&fw_lock);
-	return ret_count;
-}
-
-static int fw_realloc_pages(struct fw_sysfs *fw_sysfs, int min_size)
-{
-	int err;
-
-	err = fw_grow_paged_buf(fw_sysfs->fw_priv,
-				PAGE_ALIGN(min_size) >> PAGE_SHIFT);
-	if (err)
-		fw_load_abort(fw_sysfs);
-	return err;
-}
-
-/**
- * firmware_data_write() - write method for firmware
- * @filp: open sysfs file
- * @kobj: kobject for the device
- * @bin_attr: bin_attr structure
- * @buffer: buffer being written
- * @offset: buffer offset for write in total data store area
- * @count: buffer size
- *
- *	Data written to the 'data' attribute will be later handed to
- *	the driver as a firmware image.
- **/
-static ssize_t firmware_data_write(struct file *filp, struct kobject *kobj,
-				   struct bin_attribute *bin_attr,
-				   char *buffer, loff_t offset, size_t count)
-{
-	struct device *dev = kobj_to_dev(kobj);
-	struct fw_sysfs *fw_sysfs = to_fw_sysfs(dev);
-	struct fw_priv *fw_priv;
-	ssize_t retval;
-
-	if (!capable(CAP_SYS_RAWIO))
-		return -EPERM;
-
-	mutex_lock(&fw_lock);
-	fw_priv = fw_sysfs->fw_priv;
-	if (!fw_priv || fw_sysfs_done(fw_priv)) {
-		retval = -ENODEV;
-		goto out;
-	}
-
-	if (fw_priv->data) {
-		if (offset + count > fw_priv->allocated_size) {
-			retval = -ENOMEM;
-			goto out;
-		}
-		firmware_rw_data(fw_priv, buffer, offset, count, false);
-		retval = count;
-	} else {
-		retval = fw_realloc_pages(fw_sysfs, offset + count);
-		if (retval)
-			goto out;
-
-		retval = count;
-		firmware_rw(fw_priv, buffer, offset, count, false);
-	}
-
-	fw_priv->size = max_t(size_t, offset + count, fw_priv->size);
-out:
-	mutex_unlock(&fw_lock);
-	return retval;
-}
-
-static struct bin_attribute firmware_attr_data = {
-	.attr = { .name = "data", .mode = 0644 },
-	.size = 0,
-	.read = firmware_data_read,
-	.write = firmware_data_write,
-};
-
-static struct attribute *fw_dev_attrs[] = {
-	&dev_attr_loading.attr,
-	NULL
-};
-
-static struct bin_attribute *fw_dev_bin_attrs[] = {
-	&firmware_attr_data,
-	NULL
-};
-
-static const struct attribute_group fw_dev_attr_group = {
-	.attrs = fw_dev_attrs,
-	.bin_attrs = fw_dev_bin_attrs,
-};
-
-static const struct attribute_group *fw_dev_attr_groups[] = {
-	&fw_dev_attr_group,
-	NULL
-};
-
-static struct fw_sysfs *
-fw_create_instance(struct firmware *firmware, const char *fw_name,
-		   struct device *device, u32 opt_flags)
-{
-	struct fw_sysfs *fw_sysfs;
-	struct device *f_dev;
-
-	fw_sysfs = kzalloc(sizeof(*fw_sysfs), GFP_KERNEL);
-	if (!fw_sysfs) {
-		fw_sysfs = ERR_PTR(-ENOMEM);
-		goto exit;
-	}
-
-	fw_sysfs->nowait = !!(opt_flags & FW_OPT_NOWAIT);
-	fw_sysfs->fw = firmware;
-	f_dev = &fw_sysfs->dev;
-
-	device_initialize(f_dev);
-	dev_set_name(f_dev, "%s", fw_name);
-	f_dev->parent = device;
-	f_dev->class = &firmware_class;
-	f_dev->groups = fw_dev_attr_groups;
-exit:
-	return fw_sysfs;
-}
-
 /**
  * fw_load_sysfs_fallback() - load a firmware via the sysfs fallback mechanism
  * @fw_sysfs: firmware sysfs information for the firmware to load
diff --git a/drivers/base/firmware_loader/fallback.h b/drivers/base/firmware_loader/fallback.h
index 9f3055d3b4ca..52adc5a0bf52 100644
--- a/drivers/base/firmware_loader/fallback.h
+++ b/drivers/base/firmware_loader/fallback.h
@@ -6,29 +6,7 @@
 #include <linux/device.h>
 
 #include "firmware.h"
-
-/**
- * struct firmware_fallback_config - firmware fallback configuration settings
- *
- * Helps describe and fine tune the fallback mechanism.
- *
- * @force_sysfs_fallback: force the sysfs fallback mechanism to be used
- * 	as if one had enabled CONFIG_FW_LOADER_USER_HELPER_FALLBACK=y.
- * 	Useful to help debug a CONFIG_FW_LOADER_USER_HELPER_FALLBACK=y
- * 	functionality on a kernel where that config entry has been disabled.
- * @ignore_sysfs_fallback: force to disable the sysfs fallback mechanism.
- * 	This emulates the behaviour as if we had set the kernel
- * 	config CONFIG_FW_LOADER_USER_HELPER=n.
- * @old_timeout: for internal use
- * @loading_timeout: the timeout to wait for the fallback mechanism before
- * 	giving up, in seconds.
- */
-struct firmware_fallback_config {
-	unsigned int force_sysfs_fallback;
-	unsigned int ignore_sysfs_fallback;
-	int old_timeout;
-	int loading_timeout;
-};
+#include "fw_sysfs.h"
 
 #ifdef CONFIG_FW_LOADER_USER_HELPER
 int firmware_fallback_sysfs(struct firmware *fw, const char *name,
@@ -40,19 +18,6 @@ void kill_pending_fw_fallback_reqs(bool only_kill_custom);
 void fw_fallback_set_cache_timeout(void);
 void fw_fallback_set_default_timeout(void);
 
-int register_sysfs_loader(void);
-void unregister_sysfs_loader(void);
-#ifdef CONFIG_SYSCTL
-extern int register_firmware_config_sysctl(void);
-extern void unregister_firmware_config_sysctl(void);
-#else
-static inline int register_firmware_config_sysctl(void)
-{
-	return 0;
-}
-static inline void unregister_firmware_config_sysctl(void) { }
-#endif /* CONFIG_SYSCTL */
-
 #else /* CONFIG_FW_LOADER_USER_HELPER */
 static inline int firmware_fallback_sysfs(struct firmware *fw, const char *name,
 					  struct device *device,
@@ -66,15 +31,6 @@ static inline int firmware_fallback_sysfs(struct firmware *fw, const char *name,
 static inline void kill_pending_fw_fallback_reqs(bool only_kill_custom) { }
 static inline void fw_fallback_set_cache_timeout(void) { }
 static inline void fw_fallback_set_default_timeout(void) { }
-
-static inline int register_sysfs_loader(void)
-{
-	return 0;
-}
-
-static inline void unregister_sysfs_loader(void)
-{
-}
 #endif /* CONFIG_FW_LOADER_USER_HELPER */
 
 #ifdef CONFIG_EFI_EMBEDDED_FIRMWARE
diff --git a/drivers/base/firmware_loader/fw_sysfs.c b/drivers/base/firmware_loader/fw_sysfs.c
new file mode 100644
index 000000000000..70cb1d67ffb2
--- /dev/null
+++ b/drivers/base/firmware_loader/fw_sysfs.c
@@ -0,0 +1,413 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/highmem.h>
+#include <linux/module.h>
+#include <linux/security.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+
+#include "firmware.h"
+#include "fw_sysfs.h"
+
+/*
+ * sysfs support for firmware loader
+ */
+
+MODULE_IMPORT_NS(FIRMWARE_LOADER_PRIVATE);
+
+static inline bool fw_sysfs_done(struct fw_priv *fw_priv)
+{
+	return __fw_state_check(fw_priv, FW_STATUS_DONE);
+}
+
+static inline bool fw_sysfs_loading(struct fw_priv *fw_priv)
+{
+	return __fw_state_check(fw_priv, FW_STATUS_LOADING);
+}
+
+void __fw_load_abort(struct fw_priv *fw_priv)
+{
+	/*
+	 * There is a small window in which user can write to 'loading'
+	 * between loading done/aborted and disappearance of 'loading'
+	 */
+	if (fw_state_is_aborted(fw_priv) || fw_sysfs_done(fw_priv))
+		return;
+
+	fw_state_aborted(fw_priv);
+}
+
+static ssize_t timeout_show(struct class *class, struct class_attribute *attr,
+			    char *buf)
+{
+	return sysfs_emit(buf, "%d\n", __firmware_loading_timeout());
+}
+
+/**
+ * timeout_store() - set number of seconds to wait for firmware
+ * @class: device class pointer
+ * @attr: device attribute pointer
+ * @buf: buffer to scan for timeout value
+ * @count: number of bytes in @buf
+ *
+ *	Sets the number of seconds to wait for the firmware.  Once
+ *	this expires an error will be returned to the driver and no
+ *	firmware will be provided.
+ *
+ *	Note: zero means 'wait forever'.
+ **/
+static ssize_t timeout_store(struct class *class, struct class_attribute *attr,
+			     const char *buf, size_t count)
+{
+	int tmp_loading_timeout = simple_strtol(buf, NULL, 10);
+
+	if (tmp_loading_timeout < 0)
+		tmp_loading_timeout = 0;
+
+	__fw_fallback_set_timeout(tmp_loading_timeout);
+
+	return count;
+}
+static CLASS_ATTR_RW(timeout);
+
+static struct attribute *firmware_class_attrs[] = {
+	&class_attr_timeout.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(firmware_class);
+
+static void fw_dev_release(struct device *dev)
+{
+	struct fw_sysfs *fw_sysfs = to_fw_sysfs(dev);
+
+	kfree(fw_sysfs);
+}
+
+#ifdef CONFIG_FW_LOADER_USER_HELPER
+static int do_firmware_uevent(struct fw_sysfs *fw_sysfs, struct kobj_uevent_env *env)
+{
+	if (add_uevent_var(env, "FIRMWARE=%s", fw_sysfs->fw_priv->fw_name))
+		return -ENOMEM;
+	if (add_uevent_var(env, "TIMEOUT=%i", __firmware_loading_timeout()))
+		return -ENOMEM;
+	if (add_uevent_var(env, "ASYNC=%d", fw_sysfs->nowait))
+		return -ENOMEM;
+
+	return 0;
+}
+
+static int firmware_uevent(struct device *dev, struct kobj_uevent_env *env)
+{
+	struct fw_sysfs *fw_sysfs = to_fw_sysfs(dev);
+	int err = 0;
+
+	mutex_lock(&fw_lock);
+	if (fw_sysfs->fw_priv)
+		err = do_firmware_uevent(fw_sysfs, env);
+	mutex_unlock(&fw_lock);
+	return err;
+}
+#endif /* CONFIG_FW_LOADER_USER_HELPER */
+
+static struct class firmware_class = {
+	.name		= "firmware",
+	.class_groups	= firmware_class_groups,
+#ifdef CONFIG_FW_LOADER_USER_HELPER
+	.dev_uevent	= firmware_uevent,
+#endif
+	.dev_release	= fw_dev_release,
+};
+
+int register_sysfs_loader(void)
+{
+	int ret = class_register(&firmware_class);
+
+	if (ret != 0)
+		return ret;
+	return register_firmware_config_sysctl();
+}
+
+void unregister_sysfs_loader(void)
+{
+	unregister_firmware_config_sysctl();
+	class_unregister(&firmware_class);
+}
+
+static ssize_t firmware_loading_show(struct device *dev,
+				     struct device_attribute *attr, char *buf)
+{
+	struct fw_sysfs *fw_sysfs = to_fw_sysfs(dev);
+	int loading = 0;
+
+	mutex_lock(&fw_lock);
+	if (fw_sysfs->fw_priv)
+		loading = fw_sysfs_loading(fw_sysfs->fw_priv);
+	mutex_unlock(&fw_lock);
+
+	return sysfs_emit(buf, "%d\n", loading);
+}
+
+/**
+ * firmware_loading_store() - set value in the 'loading' control file
+ * @dev: device pointer
+ * @attr: device attribute pointer
+ * @buf: buffer to scan for loading control value
+ * @count: number of bytes in @buf
+ *
+ *	The relevant values are:
+ *
+ *	 1: Start a load, discarding any previous partial load.
+ *	 0: Conclude the load and hand the data to the driver code.
+ *	-1: Conclude the load with an error and discard any written data.
+ **/
+static ssize_t firmware_loading_store(struct device *dev,
+				      struct device_attribute *attr,
+				      const char *buf, size_t count)
+{
+	struct fw_sysfs *fw_sysfs = to_fw_sysfs(dev);
+	struct fw_priv *fw_priv;
+	ssize_t written = count;
+	int loading = simple_strtol(buf, NULL, 10);
+
+	mutex_lock(&fw_lock);
+	fw_priv = fw_sysfs->fw_priv;
+	if (fw_state_is_aborted(fw_priv) || fw_state_is_done(fw_priv))
+		goto out;
+
+	switch (loading) {
+	case 1:
+		/* discarding any previous partial load */
+		if (!fw_sysfs_done(fw_priv)) {
+			fw_free_paged_buf(fw_priv);
+			fw_state_start(fw_priv);
+		}
+		break;
+	case 0:
+		if (fw_sysfs_loading(fw_priv)) {
+			int rc;
+
+			/*
+			 * Several loading requests may be pending on
+			 * one same firmware buf, so let all requests
+			 * see the mapped 'buf->data' once the loading
+			 * is completed.
+			 */
+			rc = fw_map_paged_buf(fw_priv);
+			if (rc)
+				dev_err(dev, "%s: map pages failed\n",
+					__func__);
+			else
+				rc = security_kernel_post_load_data(fw_priv->data,
+								    fw_priv->size,
+								    LOADING_FIRMWARE,
+								    "blob");
+
+			/*
+			 * Same logic as fw_load_abort, only the DONE bit
+			 * is ignored and we set ABORT only on failure.
+			 */
+			if (rc) {
+				fw_state_aborted(fw_priv);
+				written = rc;
+			} else {
+				fw_state_done(fw_priv);
+			}
+			break;
+		}
+		fallthrough;
+	default:
+		dev_err(dev, "%s: unexpected value (%d)\n", __func__, loading);
+		fallthrough;
+	case -1:
+		fw_load_abort(fw_sysfs);
+		break;
+	}
+out:
+	mutex_unlock(&fw_lock);
+	return written;
+}
+
+static DEVICE_ATTR(loading, 0644, firmware_loading_show, firmware_loading_store);
+
+static void firmware_rw_data(struct fw_priv *fw_priv, char *buffer,
+			     loff_t offset, size_t count, bool read)
+{
+	if (read)
+		memcpy(buffer, fw_priv->data + offset, count);
+	else
+		memcpy(fw_priv->data + offset, buffer, count);
+}
+
+static void firmware_rw(struct fw_priv *fw_priv, char *buffer,
+			loff_t offset, size_t count, bool read)
+{
+	while (count) {
+		void *page_data;
+		int page_nr = offset >> PAGE_SHIFT;
+		int page_ofs = offset & (PAGE_SIZE - 1);
+		int page_cnt = min_t(size_t, PAGE_SIZE - page_ofs, count);
+
+		page_data = kmap(fw_priv->pages[page_nr]);
+
+		if (read)
+			memcpy(buffer, page_data + page_ofs, page_cnt);
+		else
+			memcpy(page_data + page_ofs, buffer, page_cnt);
+
+		kunmap(fw_priv->pages[page_nr]);
+		buffer += page_cnt;
+		offset += page_cnt;
+		count -= page_cnt;
+	}
+}
+
+static ssize_t firmware_data_read(struct file *filp, struct kobject *kobj,
+				  struct bin_attribute *bin_attr,
+				  char *buffer, loff_t offset, size_t count)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	struct fw_sysfs *fw_sysfs = to_fw_sysfs(dev);
+	struct fw_priv *fw_priv;
+	ssize_t ret_count;
+
+	mutex_lock(&fw_lock);
+	fw_priv = fw_sysfs->fw_priv;
+	if (!fw_priv || fw_sysfs_done(fw_priv)) {
+		ret_count = -ENODEV;
+		goto out;
+	}
+	if (offset > fw_priv->size) {
+		ret_count = 0;
+		goto out;
+	}
+	if (count > fw_priv->size - offset)
+		count = fw_priv->size - offset;
+
+	ret_count = count;
+
+	if (fw_priv->data)
+		firmware_rw_data(fw_priv, buffer, offset, count, true);
+	else
+		firmware_rw(fw_priv, buffer, offset, count, true);
+
+out:
+	mutex_unlock(&fw_lock);
+	return ret_count;
+}
+
+static int fw_realloc_pages(struct fw_sysfs *fw_sysfs, int min_size)
+{
+	int err;
+
+	err = fw_grow_paged_buf(fw_sysfs->fw_priv,
+				PAGE_ALIGN(min_size) >> PAGE_SHIFT);
+	if (err)
+		fw_load_abort(fw_sysfs);
+	return err;
+}
+
+/**
+ * firmware_data_write() - write method for firmware
+ * @filp: open sysfs file
+ * @kobj: kobject for the device
+ * @bin_attr: bin_attr structure
+ * @buffer: buffer being written
+ * @offset: buffer offset for write in total data store area
+ * @count: buffer size
+ *
+ *	Data written to the 'data' attribute will be later handed to
+ *	the driver as a firmware image.
+ **/
+static ssize_t firmware_data_write(struct file *filp, struct kobject *kobj,
+				   struct bin_attribute *bin_attr,
+				   char *buffer, loff_t offset, size_t count)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	struct fw_sysfs *fw_sysfs = to_fw_sysfs(dev);
+	struct fw_priv *fw_priv;
+	ssize_t retval;
+
+	if (!capable(CAP_SYS_RAWIO))
+		return -EPERM;
+
+	mutex_lock(&fw_lock);
+	fw_priv = fw_sysfs->fw_priv;
+	if (!fw_priv || fw_sysfs_done(fw_priv)) {
+		retval = -ENODEV;
+		goto out;
+	}
+
+	if (fw_priv->data) {
+		if (offset + count > fw_priv->allocated_size) {
+			retval = -ENOMEM;
+			goto out;
+		}
+		firmware_rw_data(fw_priv, buffer, offset, count, false);
+		retval = count;
+	} else {
+		retval = fw_realloc_pages(fw_sysfs, offset + count);
+		if (retval)
+			goto out;
+
+		retval = count;
+		firmware_rw(fw_priv, buffer, offset, count, false);
+	}
+
+	fw_priv->size = max_t(size_t, offset + count, fw_priv->size);
+out:
+	mutex_unlock(&fw_lock);
+	return retval;
+}
+
+static struct bin_attribute firmware_attr_data = {
+	.attr = { .name = "data", .mode = 0644 },
+	.size = 0,
+	.read = firmware_data_read,
+	.write = firmware_data_write,
+};
+
+static struct attribute *fw_dev_attrs[] = {
+	&dev_attr_loading.attr,
+	NULL
+};
+
+static struct bin_attribute *fw_dev_bin_attrs[] = {
+	&firmware_attr_data,
+	NULL
+};
+
+static const struct attribute_group fw_dev_attr_group = {
+	.attrs = fw_dev_attrs,
+	.bin_attrs = fw_dev_bin_attrs,
+};
+
+static const struct attribute_group *fw_dev_attr_groups[] = {
+	&fw_dev_attr_group,
+	NULL
+};
+
+struct fw_sysfs *
+fw_create_instance(struct firmware *firmware, const char *fw_name,
+		   struct device *device, u32 opt_flags)
+{
+	struct fw_sysfs *fw_sysfs;
+	struct device *f_dev;
+
+	fw_sysfs = kzalloc(sizeof(*fw_sysfs), GFP_KERNEL);
+	if (!fw_sysfs) {
+		fw_sysfs = ERR_PTR(-ENOMEM);
+		goto exit;
+	}
+
+	fw_sysfs->nowait = !!(opt_flags & FW_OPT_NOWAIT);
+	fw_sysfs->fw = firmware;
+	f_dev = &fw_sysfs->dev;
+
+	device_initialize(f_dev);
+	dev_set_name(f_dev, "%s", fw_name);
+	f_dev->parent = device;
+	f_dev->class = &firmware_class;
+	f_dev->groups = fw_dev_attr_groups;
+exit:
+	return fw_sysfs;
+}
diff --git a/drivers/base/firmware_loader/fw_sysfs.h b/drivers/base/firmware_loader/fw_sysfs.h
new file mode 100644
index 000000000000..0ca7f72892b0
--- /dev/null
+++ b/drivers/base/firmware_loader/fw_sysfs.h
@@ -0,0 +1,94 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __FIRMWARE_SYSFS_H
+#define __FIRMWARE_SYSFS_H
+
+#include <linux/device.h>
+
+extern struct firmware_fallback_config fw_fallback_config;
+
+#ifdef CONFIG_FW_LOADER_USER_HELPER
+/**
+ * struct firmware_fallback_config - firmware fallback configuration settings
+ *
+ * Helps describe and fine tune the fallback mechanism.
+ *
+ * @force_sysfs_fallback: force the sysfs fallback mechanism to be used
+ *	as if one had enabled CONFIG_FW_LOADER_USER_HELPER_FALLBACK=y.
+ *	Useful to help debug a CONFIG_FW_LOADER_USER_HELPER_FALLBACK=y
+ *	functionality on a kernel where that config entry has been disabled.
+ * @ignore_sysfs_fallback: force to disable the sysfs fallback mechanism.
+ *	This emulates the behaviour as if we had set the kernel
+ *	config CONFIG_FW_LOADER_USER_HELPER=n.
+ * @old_timeout: for internal use
+ * @loading_timeout: the timeout to wait for the fallback mechanism before
+ *	giving up, in seconds.
+ */
+struct firmware_fallback_config {
+	unsigned int force_sysfs_fallback;
+	unsigned int ignore_sysfs_fallback;
+	int old_timeout;
+	int loading_timeout;
+};
+
+int register_sysfs_loader(void);
+void unregister_sysfs_loader(void);
+#ifdef CONFIG_SYSCTL
+int register_firmware_config_sysctl(void);
+void unregister_firmware_config_sysctl(void);
+#else
+static inline int register_firmware_config_sysctl(void)
+{
+	return 0;
+}
+
+static inline void unregister_firmware_config_sysctl(void) { }
+#endif /* CONFIG_SYSCTL */
+#else /* CONFIG_FW_LOADER_USER_HELPER */
+static inline int register_sysfs_loader(void)
+{
+	return 0;
+}
+
+static inline void unregister_sysfs_loader(void)
+{
+}
+#endif /* CONFIG_FW_LOADER_USER_HELPER */
+
+struct fw_sysfs {
+	bool nowait;
+	struct device dev;
+	struct fw_priv *fw_priv;
+	struct firmware *fw;
+};
+
+static inline struct fw_sysfs *to_fw_sysfs(struct device *dev)
+{
+	return container_of(dev, struct fw_sysfs, dev);
+}
+
+/* These getters are vetted to use int properly */
+static inline int __firmware_loading_timeout(void)
+{
+	return fw_fallback_config.loading_timeout;
+}
+
+/* These setters are vetted to use int properly */
+static inline void __fw_fallback_set_timeout(int timeout)
+{
+	fw_fallback_config.loading_timeout = timeout;
+}
+
+void __fw_load_abort(struct fw_priv *fw_priv);
+
+static inline void fw_load_abort(struct fw_sysfs *fw_sysfs)
+{
+	struct fw_priv *fw_priv = fw_sysfs->fw_priv;
+
+	__fw_load_abort(fw_priv);
+}
+
+struct fw_sysfs *
+fw_create_instance(struct firmware *firmware, const char *fw_name,
+		   struct device *device, u32 opt_flags);
+
+#endif /* __FIRMWARE_SYSFS_H */
-- 
2.25.1

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