drm/xe: Add configfs to enable survivability mode

Registers a configfs subsystem called 'xe' that creates a
directory in the mounted configfs directory (/sys/kernel/config)
Userspace can then create the device that has to be configured
under the xe directory

	mkdir /sys/kernel/config/xe/0000:03:00.0

The device created will have the following attributes to be
configured

	/sys/kernel/config/xe/
		.. 0000:03:00.0/
			... survivability_mode

v2: fix kernel-doc
    fix return value (Lucas)

v3: fix kernel-doc (Lucas)

Signed-off-by: Riana Tauro <riana.tauro@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://lore.kernel.org/r/20250407051414.1651616-2-riana.tauro@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>

1 files changed, 188 insertions, 0 deletions

diff --git a/drivers/gpu/drm/xe/xe_configfs.c b/drivers/gpu/drm/xe/xe_configfs.c
new file mode 100644
index 000000000000..48a9f428bda9
--- /dev/null
+++ b/drivers/gpu/drm/xe/xe_configfs.c
@@ -0,0 +1,188 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright © 2025 Intel Corporation
+ */
+
+#include <linux/configfs.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+
+#include "xe_configfs.h"
+#include "xe_module.h"
+
+/**
+ * DOC: Xe Configfs
+ *
+ * Overview
+ * =========
+ *
+ * Configfs is a filesystem-based manager of kernel objects. XE KMD registers a
+ * configfs subsystem called ``'xe'`` that creates a directory in the mounted configfs directory
+ * The user can create devices under this directory and configure them as necessary
+ * See Documentation/filesystems/configfs.rst for more information about how configfs works.
+ *
+ * Create devices
+ * ===============
+ *
+ * In order to create a device, the user has to create a directory inside ``'xe'``::
+ *
+ *	mkdir /sys/kernel/config/xe/0000:03:00.0/
+ *
+ * Every device created is populated by the driver with entries that can be
+ * used to configure it::
+ *
+ *	/sys/kernel/config/xe/
+ *		.. 0000:03:00.0/
+ *			... survivability_mode
+ *
+ * Configure Attributes
+ * ====================
+ *
+ * Survivability mode:
+ * -------------------
+ *
+ * Enable survivability mode on supported cards. This setting only takes
+ * effect when probing the device. Example to enable it::
+ *
+ *	# echo 1 > /sys/kernel/config/xe/0000:03:00.0/survivability_mode
+ *	# echo 0000:03:00.0 > /sys/bus/pci/drivers/xe/bind  (Enters survivability mode if supported)
+ *
+ * Remove devices
+ * ==============
+ *
+ * The created device directories can be removed using ``rmdir``::
+ *
+ *	rmdir /sys/kernel/config/xe/0000:03:00.0/
+ */
+
+struct xe_config_device {
+	struct config_group group;
+
+	bool survivability_mode;
+
+	/* protects attributes */
+	struct mutex lock;
+};
+
+static struct xe_config_device *to_xe_config_device(struct config_item *item)
+{
+	return container_of(to_config_group(item), struct xe_config_device, group);
+}
+
+static ssize_t survivability_mode_show(struct config_item *item, char *page)
+{
+	struct xe_config_device *dev = to_xe_config_device(item);
+
+	return sprintf(page, "%d\n", dev->survivability_mode);
+}
+
+static ssize_t survivability_mode_store(struct config_item *item, const char *page, size_t len)
+{
+	struct xe_config_device *dev = to_xe_config_device(item);
+	bool survivability_mode;
+	int ret;
+
+	ret = kstrtobool(page, &survivability_mode);
+	if (ret)
+		return ret;
+
+	mutex_lock(&dev->lock);
+	dev->survivability_mode = survivability_mode;
+	mutex_unlock(&dev->lock);
+
+	return len;
+}
+
+CONFIGFS_ATTR(, survivability_mode);
+
+static struct configfs_attribute *xe_config_device_attrs[] = {
+	&attr_survivability_mode,
+	NULL,
+};
+
+static void xe_config_device_release(struct config_item *item)
+{
+	struct xe_config_device *dev = to_xe_config_device(item);
+
+	mutex_destroy(&dev->lock);
+	kfree(dev);
+}
+
+static struct configfs_item_operations xe_config_device_ops = {
+	.release	= xe_config_device_release,
+};
+
+static const struct config_item_type xe_config_device_type = {
+	.ct_item_ops	= &xe_config_device_ops,
+	.ct_attrs	= xe_config_device_attrs,
+	.ct_owner	= THIS_MODULE,
+};
+
+static struct config_group *xe_config_make_device_group(struct config_group *group,
+							const char *name)
+{
+	unsigned int domain, bus, slot, function;
+	struct xe_config_device *dev;
+	struct pci_dev *pdev;
+	int ret;
+
+	ret = sscanf(name, "%04x:%02x:%02x.%x", &domain, &bus, &slot, &function);
+	if (ret != 4)
+		return ERR_PTR(-EINVAL);
+
+	pdev = pci_get_domain_bus_and_slot(domain, bus, PCI_DEVFN(slot, function));
+	if (!pdev)
+		return ERR_PTR(-EINVAL);
+
+	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+	if (!dev)
+		return ERR_PTR(-ENOMEM);
+
+	config_group_init_type_name(&dev->group, name, &xe_config_device_type);
+
+	mutex_init(&dev->lock);
+
+	return &dev->group;
+}
+
+static struct configfs_group_operations xe_config_device_group_ops = {
+	.make_group	= xe_config_make_device_group,
+};
+
+static const struct config_item_type xe_configfs_type = {
+	.ct_group_ops	= &xe_config_device_group_ops,
+	.ct_owner	= THIS_MODULE,
+};
+
+static struct configfs_subsystem xe_configfs = {
+	.su_group = {
+		.cg_item = {
+			.ci_namebuf = "xe",
+			.ci_type = &xe_configfs_type,
+		},
+	},
+};
+
+int __init xe_configfs_init(void)
+{
+	struct config_group *root = &xe_configfs.su_group;
+	int ret;
+
+	config_group_init(root);
+	mutex_init(&xe_configfs.su_mutex);
+	ret = configfs_register_subsystem(&xe_configfs);
+	if (ret) {
+		pr_err("Error %d while registering %s subsystem\n",
+		       ret, root->cg_item.ci_namebuf);
+		return ret;
+	}
+
+	return 0;
+}
+
+void __exit xe_configfs_exit(void)
+{
+	configfs_unregister_subsystem(&xe_configfs);
+}
+