[PATCH v2 2/4] powerpc/fadump: reorganize /sys/kernel/fadump_* sysfs files

[Sourabh Jain <sourabhjain@linux.ibm.com>]

As the number of FADump sysfs files increases it is hard to manage all of
them inside /sys/kernel directory. It's better to have all the FADump
related sysfs files in a dedicated directory /sys/kernel/fadump. But in
order to maintain the backward compatibility the /sys/kernel/fadump_*
sysfs files are replicated inside /sys/kernel/fadump/ and eventually get
removed in future.

Consolidate ABI documentation for all the FADump sysfs file in a single
file Documentation/ABI/testing/sysfs-kernel-fadump.

Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
---
 Documentation/ABI/testing/sysfs-kernel-fadump | 41 +++++++++++++++++++
 arch/powerpc/kernel/fadump.c                  | 28 +++++++++++++
 arch/powerpc/platforms/powernv/opal-core.c    |  6 ++-
 3 files changed, 74 insertions(+), 1 deletion(-)
 create mode 100644 Documentation/ABI/testing/sysfs-kernel-fadump

diff --git a/Documentation/ABI/testing/sysfs-kernel-fadump b/Documentation/ABI/testing/sysfs-kernel-fadump
new file mode 100644
index 000000000000..dbf0606ba917
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-kernel-fadump
@@ -0,0 +1,41 @@
+What:		/sys/kernel/fadump/*
+Date:		Oct 2019
+Contact:	linuxppc-dev@lists.ozlabs.org
+Description:
+		The /sys/kernel/fadump/* is a collection of FADump sysfs
+		file provide information about the configuration status
+		of Firmware Assisted Dump (FADump).
+
+What:		/sys/kernel/fadump/fadump_enabled
+Date:		Oct 2019
+Contact:	linuxppc-dev@lists.ozlabs.org
+Description:	read only
+		Primarily used to identify whether the FADump is enabled in
+		the kernel or not.
+User:		Kdump service
+
+What:		/sys/kernel/fadump/fadump_registered
+Date:		Oct 2019
+Contact:	linuxppc-dev@lists.ozlabs.org
+Description:	read/write
+		Helps to control the dump collect feature from userspace.
+		Setting 1 to this file enables the system to collect the
+		dump and 0 to disable it.
+User:		Kdump service
+
+What:		/sys/kernel/fadump/fadump_release_mem
+Date:		Oct 2019
+Contact:	linuxppc-dev@lists.ozlabs.org
+Description:	write only
+		This is a special sysfs file and only available when
+		the system is booted to capture the vmcore using FADump.
+		It is used to release the memory reserved by FADump to
+		save the crash dump.
+
+What:		/sys/kernel/fadump/fadump_release_opalcore
+Date:		Oct 2019
+Contact:	linuxppc-dev@lists.ozlabs.org
+Description:	write only
+		The sysfs file is available when the system is booted to
+		collect the dump on OPAL based machine. It used to release
+		the memory used to collect the opalcore.
diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
index ed59855430b9..866eddc279d8 100644
--- a/arch/powerpc/kernel/fadump.c
+++ b/arch/powerpc/kernel/fadump.c
@@ -1418,6 +1418,9 @@ static int fadump_region_show(struct seq_file *m, void *private)
 	return 0;
 }
 
+struct kobject *fadump_kobj;
+EXPORT_SYMBOL_GPL(fadump_kobj);
+
 static struct kobj_attribute fadump_release_attr = __ATTR(fadump_release_mem,
 						0200, NULL,
 						fadump_release_memory_store);
@@ -1435,6 +1438,11 @@ static void fadump_init_files(void)
 	struct dentry *debugfs_file;
 	int rc = 0;
 
+	fadump_kobj = kobject_create_and_add("fadump", kernel_kobj);
+	if (!fadump_kobj) {
+		pr_err("failed to create fadump kobject\n");
+		return;
+	}
 	rc = sysfs_create_file(kernel_kobj, &fadump_attr.attr);
 	if (rc)
 		printk(KERN_ERR "fadump: unable to create sysfs file"
@@ -1458,6 +1466,26 @@ static void fadump_init_files(void)
 			printk(KERN_ERR "fadump: unable to create sysfs file"
 				" fadump_release_mem (%d)\n", rc);
 	}
+	/* Replicating the following sysfs attributes under FADump kobject.
+	 *
+	 *	- fadump_enabled
+	 *	- fadump_registered
+	 *	- fadump_release_mem
+	 */
+	rc = sysfs_create_file(fadump_kobj, &fadump_attr.attr);
+	if (rc)
+		pr_err("unable to create fadump/fadump_enabled sysfs file (%d)\n",
+		       rc);
+	rc = sysfs_create_file(fadump_kobj, &fadump_register_attr.attr);
+	if (rc)
+		pr_err("unable to create fadump/fadump_registered sysfs file (%d)\n",
+		       rc);
+	if (fw_dump.dump_active) {
+		rc = sysfs_create_file(fadump_kobj, &fadump_release_attr.attr);
+		if (rc)
+			pr_err("unable to create fadump/fadump_release_mem sysfs file (%d)\n",
+			       rc);
+	}
 	return;
 }
 
diff --git a/arch/powerpc/platforms/powernv/opal-core.c b/arch/powerpc/platforms/powernv/opal-core.c
index ed895d82c048..2c7355768d3f 100644
--- a/arch/powerpc/platforms/powernv/opal-core.c
+++ b/arch/powerpc/platforms/powernv/opal-core.c
@@ -625,7 +625,11 @@ static int __init opalcore_init(void)
 		return rc;
 	}
 
-	rc = sysfs_create_file(kernel_kobj, &opalcore_rel_attr.attr);
+	/*
+	 * Originally fadump_release_opalcore sysfs was part of kernel_kobj
+	 * later moved to fadump_kobj.
+	 */
+	rc = sysfs_create_file(fadump_kobj, &opalcore_rel_attr.attr);
 	if (rc) {
 		pr_warn("unable to create sysfs file fadump_release_opalcore (%d)\n",
 			rc);
-- 
2.17.2