tegra_bootloader_debug: Register resume callbacks

1. Register resume_noirq handler for profiling the time when early
driver resume sequence is started. Since this driver is loaded after
boot, this should get called very early in the resume sequence.

2. Register PM notifier to know when resume is complete. This helps
in profiling the time when entire resume sequence is complete.

These 2 timestamps should approximately indicate the time it takes
for Linux to resume.

Adding this code in this driver removes dependency of providing this
information from some other driver.

Bug 4454722

Signed-off-by: Bharat Nihalani <bnihalani@nvidia.com>
Change-Id: I214eb4ff2808ecb87b828cb4556a2a00cc2d4545
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nv-oot/+/3047836
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nv-oot/+/3062030
GVS: Gerrit_Virtual_Submit <buildbot_gerritrpt@nvidia.com>

Documentation/devicetree/bindings/platform/tegra/tegra_bootloader_debug.yaml

@@ -0,0 +1,31 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/platform/tegra/tegra_bootloader_debug.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Device tree binding for NVIDIA Tegra Bootloader Debug
+
+maintainers:
+  - Deepak Nibade <dnibade@nvidia.com>
+
+description: |
+   The tegra_bootloader_debug driver provides infrastructure to profile Boot and Resume KPIs
+
+properties:
+  compatible:
+    enum:
+      - nvidia,tegra_bl_debug
+
+required:
+  - compatible
+
+additionalProperties: false
+
+examples:
+  - |
+    profiler_device {
+        compatible = "nvidia,tegra_bl_debug";
+        status = "okay";
+    };
+...

drivers/platform/tegra/tegra_bootloader_debug.c

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0
-// SPDX-FileCopyrightText: Copyright (c) 2022-2023 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+// SPDX-FileCopyrightText: Copyright (c) 2022-2024 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
 
 #include <linux/init.h>
 #include <linux/module.h>
@@ -18,6 +18,9 @@
 #include <linux/platform_device.h>
 #include <linux/of.h>
 #include <linux/of_address.h>
+#include <linux/notifier.h>
+#include <linux/pm.h>
+#include <linux/suspend.h>
 
 #include "tegra_bootloader_debug.h"
 
@@ -336,11 +339,44 @@ static int dbg_golden_register_open_cpu_bl( __attribute((unused))struct inode *i
 }
 #endif /* CONFIG_DEBUG_FS */
 
+/*
+ * Notifier for capturing Linux Resume done stage timestamp.
+ * Note that this notifier will get called for both suspend and resume cases. But we currently do
+ * not have a way to measure Linux Suspend time because we cannot print the profiler stats anyways
+ * when the device goes to suspend. And so there is no check added in the notifier function to check
+ * if this is for suspend or resume.
+ */
+static int profiler_resume_notifier(struct notifier_block *nb, unsigned long event, void *data)
+{
+	tegra_bl_add_profiler_entry("Guest Linux Resume Notifier", 27);
+	return NOTIFY_OK;
+}
+
+static struct notifier_block profiler_notifier = {
+	.notifier_call = profiler_resume_notifier,
+};
+
+/*
+ * Handler for SC7 Resume to profile the start of driver resume.
+ * Since this driver is loaded after all drivers are loaded, it
+ * is expected that this driver's resume handler will get called first.
+ */
+static int profiler_resume_noirq_handler(struct device *dev)
+{
+	tegra_bl_add_profiler_entry("Profiler Driver Resume Start", 28);
+	return 0;
+}
+
+static struct dev_pm_ops profiler_pm_ops = {
+	.resume_noirq = profiler_resume_noirq_handler,
+};
+
 static int __init tegra_bootloader_debuginit(void)
 {
 	void __iomem *ptr_bl_prof_ro_carveout = NULL;
 	void __iomem *ptr_bl_prof_carveout = NULL;
 	int bl_debug_verify_file_entry;
+	int ret;
 #ifdef CONFIG_DEBUG_FS
 	void __iomem *ptr_bl_debug_data_start = NULL;
 	void __iomem *ptr_bl_boot_cfg_start = NULL;
@@ -352,6 +388,13 @@ static int __init tegra_bootloader_debuginit(void)
 		return -ENODEV;
 	}
 
+	/* Register SC7 resume notifier to profile SC7 Resume done */
+	ret = register_pm_notifier(&profiler_notifier);
+	if (ret) {
+		pr_err("%s: Failed to register resume notifier: %d\n", __func__, ret);
+		/* continue even if this fails */
+	}
+
 #ifdef CONFIG_DEBUG_FS
 	if (debugfs_initialized()) {
 		bl_debug_node = debugfs_create_dir(dir_name, NULL);
@@ -698,6 +741,7 @@ static struct platform_driver tegra_bl_debug_driver = {
 	.remove = tegra_bl_debug_remove,
 	.driver = {
 		.name = "tegra_bl_debug",
+		.pm = &profiler_pm_ops,
 		.of_match_table = tegra_bl_debug_of_match,
 	},
 };
@@ -774,6 +818,7 @@ static void __exit tegra_bl_debuginit_module_exit(void)
 		iounmap(usc);
 
 	platform_driver_unregister(&tegra_bl_debug_driver);
+	unregister_pm_notifier(&profiler_notifier);
 }
 
 module_param(bl_debug_data, charp, 0400);