Commit 770c69f0 authored by Mike Tipton's avatar Mike Tipton Committed by Georgi Djakov
Browse files

interconnect: Add debugfs test client 



It's often useful during test, debug, and development to issue path
votes from shell. Add a debugfs client for this purpose.

Example usage:
	cd /sys/kernel/debug/interconnect/test-client/

	# Configure node endpoints for the path from CPU to DDR on
	# qcom/sm8550.
	echo chm_apps > src_node
	echo ebi > dst_node

	# Get path between src_node and dst_node. This is only
	# necessary after updating the node endpoints.
	echo 1 > get

	# Set desired BW to 1GBps avg and 2GBps peak.
	echo 1000000 > avg_bw
	echo 2000000 > peak_bw

	# Vote for avg_bw and peak_bw on the latest path from "get".
	# Voting for multiple paths is possible by repeating this
	# process for different nodes endpoints.
	echo 1 > commit

Allowing userspace to directly enable and set bus rates can be dangerous
So, following in the footsteps of the regmap [0] and clk [1] frameworks,
keep these userspace controls compile-time disabled without Kconfig
options to enable them. Enabling this will require code changes to
define INTERCONNECT_ALLOW_WRITE_DEBUGFS.

[0] commit 09c6ecd3 ("regmap: Add support for writing to regmap registers via debugfs")
[1] commit 37215da5 ("clk: Add support for setting clk_rate via debugfs")

Signed-off-by: default avatarMike Tipton <quic_mdtipton@quicinc.com>
Link: https://lore.kernel.org/r/20230807142914.12480-4-quic_mdtipton@quicinc.com


Signed-off-by: default avatarGeorgi Djakov <djakov@kernel.org>
parent 1d13d3b7

Documentation/driver-api/interconnect.rst

+25 −0
Original line number Diff line number Diff line
@@ -113,3 +113,28 @@ through dot to generate diagrams in many graphical formats:: 


        $ cat /sys/kernel/debug/interconnect/interconnect_graph | \

                dot -Tsvg > interconnect_graph.svg



The ``test-client`` directory provides interfaces for issuing BW requests to

any arbitrary path. Note that for safety reasons, this feature is disabled by

default without a Kconfig to enable it. Enabling it requires code changes to

``#define INTERCONNECT_ALLOW_WRITE_DEBUGFS``. Example usage::



        cd /sys/kernel/debug/interconnect/test-client/



        # Configure node endpoints for the path from CPU to DDR on

        # qcom/sm8550.

        echo chm_apps > src_node

        echo ebi > dst_node



        # Get path between src_node and dst_node. This is only

        # necessary after updating the node endpoints.

        echo 1 > get



        # Set desired BW to 1GBps avg and 2GBps peak.

        echo 1000000 > avg_bw

        echo 2000000 > peak_bw



        # Vote for avg_bw and peak_bw on the latest path from "get".

        # Voting for multiple paths is possible by repeating this

        # process for different nodes endpoints.

        echo 1 > commit

drivers/interconnect/Makefile

+1 −1
Original line number Diff line number Diff line 
# SPDX-License-Identifier: GPL-2.0



CFLAGS_core.o				:= -I$(src)

icc-core-objs				:= core.o bulk.o

icc-core-objs				:= core.o bulk.o debugfs-client.o



obj-$(CONFIG_INTERCONNECT)		+= icc-core.o

obj-$(CONFIG_INTERCONNECT_IMX)		+= imx/

drivers/interconnect/core.c

+3 −0
Original line number Diff line number Diff line
@@ -1116,6 +1116,9 @@ static int __init icc_init(void) 
			    icc_debugfs_dir, NULL, &icc_summary_fops);

	debugfs_create_file("interconnect_graph", 0444,

			    icc_debugfs_dir, NULL, &icc_graph_fops);



	icc_debugfs_client_init(icc_debugfs_dir);



	return 0;

}

drivers/interconnect/debugfs-client.c

0 → 100644
+168 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0-only

/*

 * Copyright (c) 2023, Qualcomm Innovation Center, Inc. All rights reserved.

 */

#include <linux/debugfs.h>

#include <linux/interconnect.h>

#include <linux/platform_device.h>



#include "internal.h"



/*

 * This can be dangerous, therefore don't provide any real compile time

 * configuration option for this feature.

 * People who want to use this will need to modify the source code directly.

 */

#undef INTERCONNECT_ALLOW_WRITE_DEBUGFS



#if defined(INTERCONNECT_ALLOW_WRITE_DEBUGFS) && defined(CONFIG_DEBUG_FS)



static LIST_HEAD(debugfs_paths);

static DEFINE_MUTEX(debugfs_lock);



static struct platform_device *pdev;

static struct icc_path *cur_path;



static char *src_node;

static char *dst_node;

static u32 avg_bw;

static u32 peak_bw;

static u32 tag;



struct debugfs_path {

	const char *src;

	const char *dst;

	struct icc_path *path;

	struct list_head list;

};



static struct icc_path *get_path(const char *src, const char *dst)

{

	struct debugfs_path *path;



	list_for_each_entry(path, &debugfs_paths, list) {

		if (!strcmp(path->src, src) && !strcmp(path->dst, dst))

			return path->path;

	}



	return NULL;

}



static int icc_get_set(void *data, u64 val)

{

	struct debugfs_path *debugfs_path;

	char *src, *dst;

	int ret = 0;



	mutex_lock(&debugfs_lock);



	rcu_read_lock();

	src = rcu_dereference(src_node);

	dst = rcu_dereference(dst_node);



	/*

	 * If we've already looked up a path, then use the existing one instead

	 * of calling icc_get() again. This allows for updating previous BW

	 * votes when "get" is written to multiple times for multiple paths.

	 */

	cur_path = get_path(src, dst);

	if (cur_path) {

		rcu_read_unlock();

		goto out;

	}



	src = kstrdup(src, GFP_ATOMIC);

	dst = kstrdup(dst, GFP_ATOMIC);

	rcu_read_unlock();



	if (!src || !dst) {

		ret = -ENOMEM;

		goto err_free;

	}



	cur_path = icc_get(&pdev->dev, src, dst);

	if (IS_ERR(cur_path)) {

		ret = PTR_ERR(cur_path);

		goto err_free;

	}



	debugfs_path = kzalloc(sizeof(*debugfs_path), GFP_KERNEL);

	if (!debugfs_path) {

		ret = -ENOMEM;

		goto err_put;

	}



	debugfs_path->path = cur_path;

	debugfs_path->src = src;

	debugfs_path->dst = dst;

	list_add_tail(&debugfs_path->list, &debugfs_paths);



	goto out;



err_put:

	icc_put(cur_path);

err_free:

	kfree(src);

	kfree(dst);

out:

	mutex_unlock(&debugfs_lock);

	return ret;

}



DEFINE_DEBUGFS_ATTRIBUTE(icc_get_fops, NULL, icc_get_set, "%llu\n");



static int icc_commit_set(void *data, u64 val)

{

	int ret;



	mutex_lock(&debugfs_lock);



	if (IS_ERR_OR_NULL(cur_path)) {

		ret = PTR_ERR(cur_path);

		goto out;

	}



	icc_set_tag(cur_path, tag);

	ret = icc_set_bw(cur_path, avg_bw, peak_bw);

out:

	mutex_unlock(&debugfs_lock);

	return ret;

}



DEFINE_DEBUGFS_ATTRIBUTE(icc_commit_fops, NULL, icc_commit_set, "%llu\n");



int icc_debugfs_client_init(struct dentry *icc_dir)

{

	struct dentry *client_dir;

	int ret;



	pdev = platform_device_alloc("icc-debugfs-client", PLATFORM_DEVID_NONE);



	ret = platform_device_add(pdev);

	if (ret) {

		pr_err("%s: failed to add platform device: %d\n", __func__, ret);

		platform_device_put(pdev);

		return ret;

	}



	client_dir = debugfs_create_dir("test_client", icc_dir);



	debugfs_create_str("src_node", 0600, client_dir, &src_node);

	debugfs_create_str("dst_node", 0600, client_dir, &dst_node);

	debugfs_create_file("get", 0200, client_dir, NULL, &icc_get_fops);

	debugfs_create_u32("avg_bw", 0600, client_dir, &avg_bw);

	debugfs_create_u32("peak_bw", 0600, client_dir, &peak_bw);

	debugfs_create_u32("tag", 0600, client_dir, &tag);

	debugfs_create_file("commit", 0200, client_dir, NULL, &icc_commit_fops);



	return 0;

}



#else



int icc_debugfs_client_init(struct dentry *icc_dir)

{

	return 0;

}



#endif

drivers/interconnect/internal.h

+1 −0
Original line number Diff line number Diff line
@@ -42,5 +42,6 @@ struct icc_path { 
};



struct icc_path *icc_get(struct device *dev, const char *src, const char *dst);

int icc_debugfs_client_init(struct dentry *icc_dir);



#endif