firmware_loader: Split 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 sysfs.c and 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 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.

Reviewed-by: Luis Chamberlain <[e-mail]>
Reviewed-by: Tianfei zhang <[e-mail]>
Tested-by: Matthew Gerlach <[e-mail]>
Signed-off-by: Russ Weight <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/base/firmware_loader/Kconfig

···
 config FW_LOADER_PAGED_BUF
 	bool
 
+config FW_LOADER_SYSFS
+	bool
+
 config EXTRA_FIRMWARE
 	string "Build named firmware blobs into the kernel binary"
 	help
···
 
 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

drivers/base/firmware_loader/Makefile

···
 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) += sysfs.o
 
 obj-y += builtin/

drivers/base/firmware_loader/fallback.c

···
 #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"
···
 /*
  * 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
···
 	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_state_is_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)
···
 			 __fw_load_abort(fw_priv);
 	}
 	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_state_is_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 */
-		fw_free_paged_buf(fw_priv);
-		fw_state_start(fw_priv);
-		break;
-	case 0:
-		if (fw_state_is_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_state_is_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_state_is_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;
 }
 
 /**

drivers/base/firmware_loader/fallback.h

···
 #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 "sysfs.h"
 
 #ifdef CONFIG_FW_LOADER_USER_HELPER
 int firmware_fallback_sysfs(struct firmware *fw, const char *name,
···
 
 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,
···
 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

drivers/base/firmware_loader/sysfs.c

···
+// 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 "sysfs.h"
+
+/*
+ * sysfs support for firmware loader
+ */
+
+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_state_is_done(fw_priv))
+		return;
+
+	fw_state_aborted(fw_priv);
+}
+
+#ifdef CONFIG_FW_LOADER_USER_HELPER
+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 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 void fw_dev_release(struct device *dev)
+{
+	struct fw_sysfs *fw_sysfs = to_fw_sysfs(dev);
+
+	kfree(fw_sysfs);
+}
+
+static struct class firmware_class = {
+	.name		= "firmware",
+#ifdef CONFIG_FW_LOADER_USER_HELPER
+	.class_groups	= firmware_class_groups,
+	.dev_uevent	= firmware_uevent,
+#endif
+	.dev_release	= fw_dev_release,
+};
+
+#ifdef CONFIG_FW_LOADER_USER_HELPER
+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);
+}
+#endif
+
+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_state_is_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 */
+		fw_free_paged_buf(fw_priv);
+		fw_state_start(fw_priv);
+		break;
+	case 0:
+		if (fw_state_is_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_state_is_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_state_is_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;
+}

drivers/base/firmware_loader/sysfs.h

···
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __FIRMWARE_SYSFS_H
+#define __FIRMWARE_SYSFS_H
+
+#include <linux/device.h>
+
+MODULE_IMPORT_NS(FIRMWARE_LOADER_PRIVATE);
+
+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;
+};
+
+/* 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;
+}
+
+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);
+}
+
+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 */