gpu: nvgpu: Add debugfs wrapper for exposing profilers

The current debugfs code is completely specific to FIFO's kickoff
profiler. But exposing these debugfs nodes is really a perfectly
generic operation to any given profiler.

Therefore add a generic debugfs interface for exposing profilers.
Any code that implements a profiler can now use a single function
call to export a profiler to the GPU debugfs area.

JIRA NVGPU-5606

Change-Id: I67a5bd9998fcfac94678e465442b9a38ab7e7612
Signed-off-by: Alex Waterman <alexw@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nvgpu/+/2358382
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>

drivers/gpu/nvgpu/os/linux/swprofile_debugfs.c

@@ -0,0 +1,114 @@
+/*
+ * Copyright (C) 2020 NVIDIA Corporation.  All rights reserved.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/debugfs.h>
+#include <linux/seq_file.h>
+
+#include <nvgpu/swprofile.h>
+#include <nvgpu/debug.h>
+
+static int nvgpu_debugfs_swprofile_enable(void *data, u64 val)
+{
+	struct nvgpu_swprofiler *p = (struct nvgpu_swprofiler *) data;
+
+	if (val == 0) {
+		nvgpu_swprofile_close(p);
+		return 0;
+	} else {
+		return nvgpu_swprofile_open(p->g, p);
+	}
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(
+	nvgpu_debugfs_swprofile_enable_debugfs_fops,
+	NULL,
+	nvgpu_debugfs_swprofile_enable,
+	"%llu\n"
+);
+
+static void nvgpu_debugfs_write_to_seqfile_no_nl(void *ctx, const char *str)
+{
+	seq_printf((struct seq_file *)ctx, str);
+}
+
+static int nvgpu_debugfs_swprofile_stats(struct seq_file *s, void *unused)
+{
+	struct nvgpu_swprofiler *p = s->private;
+	struct nvgpu_debug_context o = {
+		.fn = nvgpu_debugfs_write_to_seqfile_no_nl,
+		.ctx = s,
+	};
+
+	nvgpu_swprofile_print_ranges(p->g, p, &o);
+
+	return 0;
+}
+
+static int nvgpu_debugfs_swprofile_stats_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, nvgpu_debugfs_swprofile_stats, inode->i_private);
+}
+
+static const struct file_operations nvgpu_debugfs_swprofile_stats_debugfs_fops = {
+	.open		= nvgpu_debugfs_swprofile_stats_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+};
+
+static int nvgpu_debugfs_swprofile_raw_data(struct seq_file *s, void *unused)
+{
+	struct nvgpu_swprofiler *p = s->private;
+	struct nvgpu_debug_context o = {
+		.fn = nvgpu_debugfs_write_to_seqfile_no_nl,
+		.ctx = s,
+	};
+
+	nvgpu_swprofile_print_raw_data(p->g, p, &o);
+
+	return 0;
+}
+
+static int nvgpu_debugfs_swprofile_raw_data_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, nvgpu_debugfs_swprofile_raw_data, inode->i_private);
+}
+
+static const struct file_operations nvgpu_debugfs_swprofile_raw_data_debugfs_fops = {
+	.open		= nvgpu_debugfs_swprofile_raw_data_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+};
+
+void nvgpu_debugfs_swprofile_init(struct gk20a *g,
+				  struct dentry *root,
+				  struct nvgpu_swprofiler *p,
+				  const char *name)
+{
+	struct dentry *swprofile_root;
+
+	swprofile_root = debugfs_create_dir(name, root);
+	if (IS_ERR_OR_NULL(swprofile_root))
+		return;
+
+	debugfs_create_file("enable", 0600, swprofile_root, p,
+		&nvgpu_debugfs_swprofile_enable_debugfs_fops);
+
+	debugfs_create_file("percentiles", 0600, swprofile_root, p,
+		&nvgpu_debugfs_swprofile_stats_debugfs_fops);
+
+	debugfs_create_file("raw_data", 0600, swprofile_root, p,
+		&nvgpu_debugfs_swprofile_raw_data_debugfs_fops);
+}