DCE-KMD: Add support for logging infra

- Allocate DMA mapped buffer from DCE-KMD and pass it to DCE FW through
  admin-cmd calls.
- Add debugfs node to retrieve buffer data and print through seq file.
- Add support to clear log buffer

JIRA TDS-15963

Change-Id: Ied4ffe1df14c8db61cfe15e6442f55e8306530b8
Signed-off-by: jaiyasha <jaiyasha@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nv-oot/+/3117241
GVS: buildbot_gerritrpt <buildbot_gerritrpt@nvidia.com>
Reviewed-by: Mahesh Kumar <mahkumar@nvidia.com>
Tested-by: Mahesh Kumar <mahkumar@nvidia.com>
Reviewed-by: Vinod Gopalakrishnakurup <vinodg@nvidia.com>

drivers/platform/tegra/dce/dce-debug-logging.c

@@ -0,0 +1,154 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * SPDX-FileCopyrightText: Copyright (c) 2025 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+ */
+
+#include <linux/errno.h>
+#include <linux/debugfs.h>
+#include <linux/uaccess.h>
+
+#include <dce-os-utils.h>
+#include <dce-debug-logging.h>
+#include <dce-os-log.h>
+#include <dce-logging.h>
+#include <dce.h>
+
+static int dbg_dce_log_help_fops_show(struct seq_file *s, void *data)
+{
+/**
+ * Writing:
+ * '0' to /sys/kernel/debug/tegra_dce/dce_logs/logs
+ *    - Clear the circular buffer region data.
+ *
+ * Reading:
+ *  cat /sys/kernel/debug/tegra_dce/dce_logs/logs
+ *    - Prints the data stored in the buffer.
+ *    - Current size of buffer is 512KB and on overflow starts overwriting the circular
+ *		portion of the buffer in FIFO manner
+ */
+	seq_printf(s, " DCE logs capture\n"
+				"---------------------------------------------------------------\n"
+				" echo '0' > dce_logs/logs: Clear circular region of buffer\n"
+				"---------------------------------------------------------------\n"
+				" cat dce_logs/logs: Print buffer data\n"
+				"---------------------------------------------------------------\n");
+	return 0;
+}
+
+int dbg_dce_log_help_fops_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, dbg_dce_log_help_fops_show,
+			   inode->i_private);
+}
+
+static int dbg_dce_log_fops_show(struct seq_file *s, void *data)
+{
+	int ret = 0;
+	uint32_t offset;
+	uint64_t bytes_written;
+	uint32_t cur_buf_idx;
+	struct tegra_dce *d				= s->private;
+	char *base_addr					= (char *)d->dce_log_buff.cpu_base;
+	uint32_t log_buf_size			= d->dce_log_buff.size;
+	struct dce_ipc_message *msg		= NULL;
+	struct dce_admin_ipc_resp *resp_msg;
+
+	msg = dce_admin_channel_client_buffer_get(d, DCE_ADMIN_CH_CL_DBG_BUFF,
+		0 /* reserved flags */);
+
+	if (!msg) {
+		ret = -1;
+		dce_os_err(d, "IPC msg allocation failed");
+		goto out;
+	}
+
+	/** Retrieve logging info */
+	ret = dce_admin_get_log_info(d, msg);
+	if (ret) {
+		dce_os_err(d, "Failed to retrieve logging info, ret = 0x%x", ret);
+		goto out;
+	}
+
+	resp_msg = (struct dce_admin_ipc_resp *) (msg->rx.data);
+
+	bytes_written	= resp_msg->args.log.get_log_info.bytes_written;
+	offset			= resp_msg->args.log.get_log_info.offset;
+
+	/** If complete buffer size is zero then buffer is invalid */
+	if (log_buf_size == 0) {
+		seq_printf(s, "%s", "Invalid log buffer\n");
+		goto out;
+	}
+
+	if (bytes_written == 0U || (log_buf_size <= offset)) {
+		seq_printf(s, "%.*s", offset, base_addr);
+		goto out;
+	}
+
+	/** Find total bytes written currently in circular region of buffer */
+	cur_buf_idx = (bytes_written)%(log_buf_size - offset);
+
+	/** If circular buffer is not yet wrapped around */
+	if (bytes_written <= log_buf_size - offset) {
+		seq_printf(s, "%.*s", offset, base_addr);
+		seq_printf(s, "%.*s", cur_buf_idx, base_addr + offset);
+		goto out;
+	}
+
+	/** If circular buffer region has been overwritten */
+	/** Print initial logs till offset */
+	seq_printf(s, "%.*s", offset, base_addr);
+	/** Print logs stored in circular buffer region */
+	seq_printf(s, "%.*s", log_buf_size - cur_buf_idx - offset, base_addr + offset + cur_buf_idx);
+	seq_printf(s, "%.*s", cur_buf_idx, base_addr + offset);
+
+out:
+	if (msg)
+		dce_admin_channel_client_buffer_put(d, msg);
+	return ret;
+}
+
+int dbg_dce_log_fops_open(struct inode *inode, struct file *file)
+{
+	size_t seq_buf_size = 100*PAGE_SIZE;
+
+	return single_open_size(file, &dbg_dce_log_fops_show, inode->i_private, seq_buf_size);
+}
+
+ssize_t dbg_dce_log_fops_write(struct file *file, const char __user *user_buf,
+				size_t count, loff_t *ppos)
+{
+	int ret = 0;
+	char buf[32];
+	uint32_t buf_size;
+	uint32_t log_op;
+	struct dce_ipc_message *msg = NULL;
+	struct tegra_dce *d = ((struct seq_file *)file->private_data)->private;
+
+	buf_size = min(count, (sizeof(buf)-1));
+
+	msg = dce_admin_channel_client_buffer_get(d, DCE_ADMIN_CH_CL_DBG_BUFF,
+		0 /* reserved flags */);
+	if (!msg) {
+		dce_os_err(d, "IPC msg allocation failed");
+		goto out;
+	}
+
+	ret = kstrtou32_from_user(user_buf, buf_size, 10, &log_op);
+	if (ret) {
+		dce_os_err(d, "Invalid format!");
+		goto out;
+	}
+
+	if (log_op == 0U) {
+		dce_os_err(d, "Clearing circular region of log buffer");
+		ret = dce_log_clear_buffer(d, msg);
+		if (ret)
+			dce_os_err(d, "Failed to clear log buffer!");
+	}
+
+out:
+	if (msg)
+		dce_admin_channel_client_buffer_put(d, msg);
+	return count;
+}