drivers/net/wwan/t7xx/t7xx_port_trace.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2022 Intel Corporation.
 */

#include <linux/debugfs.h>
#include <linux/relay.h>
#include <linux/skbuff.h>
#include <linux/wwan.h>

#include "t7xx_port.h"
#include "t7xx_port_proxy.h"
#include "t7xx_state_monitor.h"

#define T7XX_TRC_SUB_BUFF_SIZE		131072
#define T7XX_TRC_N_SUB_BUFF		32

static struct dentry *t7xx_trace_create_buf_file_handler(const char *filename,
							 struct dentry *parent,
							 umode_t mode,
							 struct rchan_buf *buf,
							 int *is_global)
{
	*is_global = 1;
	return debugfs_create_file(filename, mode, parent, buf,
				   &relay_file_operations);
}

static int t7xx_trace_remove_buf_file_handler(struct dentry *dentry)
{
	debugfs_remove(dentry);
	return 0;
}

static int t7xx_trace_subbuf_start_handler(struct rchan_buf *buf, void *subbuf,
					   void *prev_subbuf, size_t prev_padding)
{
	if (relay_buf_full(buf)) {
		pr_err_ratelimited("Relay_buf full dropping traces");
		return 0;
	}

	return 1;
}

static struct rchan_callbacks relay_callbacks = {
	.subbuf_start = t7xx_trace_subbuf_start_handler,
	.create_buf_file = t7xx_trace_create_buf_file_handler,
	.remove_buf_file = t7xx_trace_remove_buf_file_handler,
};

static void t7xx_trace_port_uninit(struct t7xx_port *port)
{
	struct dentry *debugfs_dir = port->t7xx_dev->debugfs_dir;
	struct rchan *relaych = port->log.relaych;

	if (!relaych)
		return;

	relay_close(relaych);
	debugfs_remove_recursive(debugfs_dir);
	port->log.relaych = NULL;
}

static int t7xx_trace_port_recv_skb(struct t7xx_port *port, struct sk_buff *skb)
{
	struct rchan *relaych = port->log.relaych;

	if (!relaych)
		return -EINVAL;

	relay_write(relaych, skb->data, skb->len);
	dev_kfree_skb(skb);
	return 0;
}

static void t7xx_port_trace_md_state_notify(struct t7xx_port *port, unsigned int state)
{
	struct rchan *relaych = port->log.relaych;
	struct dentry *debugfs_wwan_dir;
	struct dentry *debugfs_dir;

	if (state != MD_STATE_READY || relaych)
		return;

	debugfs_wwan_dir = wwan_get_debugfs_dir(port->dev);
	if (IS_ERR(debugfs_wwan_dir))
		return;

	debugfs_dir = debugfs_create_dir(KBUILD_MODNAME, debugfs_wwan_dir);
	if (IS_ERR_OR_NULL(debugfs_dir)) {
		wwan_put_debugfs_dir(debugfs_wwan_dir);
		dev_err(port->dev, "Unable to create debugfs for trace");
		return;
	}

	relaych = relay_open("relay_ch", debugfs_dir, T7XX_TRC_SUB_BUFF_SIZE,
			     T7XX_TRC_N_SUB_BUFF, &relay_callbacks, NULL);
	if (!relaych)
		goto err_rm_debugfs_dir;

	wwan_put_debugfs_dir(debugfs_wwan_dir);
	port->log.relaych = relaych;
	port->t7xx_dev->debugfs_dir = debugfs_dir;
	return;

err_rm_debugfs_dir:
	debugfs_remove_recursive(debugfs_dir);
	wwan_put_debugfs_dir(debugfs_wwan_dir);
	dev_err(port->dev, "Unable to create trace port %s", port->port_conf->name);
}

struct port_ops t7xx_trace_port_ops = {
	.recv_skb = t7xx_trace_port_recv_skb,
	.uninit = t7xx_trace_port_uninit,
	.md_state_notify = t7xx_port_trace_md_state_notify,
};