From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on archive.lwn.net X-Spam-Level: X-Spam-Status: No, score=-5.8 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham autolearn_force=no version=3.4.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by archive.lwn.net (Postfix) with ESMTP id DA8E67DE78 for ; Mon, 7 May 2018 22:29:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752820AbeEGW3S (ORCPT ); Mon, 7 May 2018 18:29:18 -0400 Received: from foss.arm.com ([217.140.101.70]:50968 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752158AbeEGW3R (ORCPT ); Mon, 7 May 2018 18:29:17 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 0C5B480D; Mon, 7 May 2018 15:29:17 -0700 (PDT) Received: from dupont (usa-sjc-mx-foss1.foss.arm.com [217.140.101.70]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id AD86F3F592; Mon, 7 May 2018 15:29:16 -0700 (PDT) Date: Mon, 7 May 2018 17:29:15 -0500 From: Kim Phillips To: Mathieu Poirier Cc: Jonathan Corbet , linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: coresight: documentation: update sysfs section Message-Id: <20180507172915.c032cd71c07b1849bf419a5f@arm.com> Organization: Arm X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org - Align and show updated ls devices output from the TC2, based on current driver - Provide an example from an ETMv4 based system (Juno) - Reflect changes to the way the RAM write pointer is accessed since it got changed in commit 7d83d17795ef ("coresight: tmc: adding sysFS management entries"). Cc: Mathieu Poirier Cc: Jonathan Corbet Signed-off-by: Kim Phillips --- Documentation/trace/coresight.txt | 40 ++++++++++++++++++------------- 1 file changed, 24 insertions(+), 16 deletions(-) diff --git a/Documentation/trace/coresight.txt b/Documentation/trace/coresight.txt index 6f0120c3a4f1..d23d6354b372 100644 --- a/Documentation/trace/coresight.txt +++ b/Documentation/trace/coresight.txt @@ -144,10 +144,21 @@ If everything goes well during the registration process the new devices will show up under /sys/bus/coresight/devices, as showns here for a TC2 platform: root:~# ls /sys/bus/coresight/devices/ -replicator 20030000.tpiu 2201c000.ptm 2203c000.etm 2203e000.etm -20010000.etb 20040000.funnel 2201d000.ptm 2203d000.etm +20010000.etb 20040000.funnel 2201d000.ptm 2203d000.etm replicator +20030000.tpiu 2201c000.ptm 2203c000.etm 2203e000.etm root:~# +and here for a Juno platform: + +root@juno:~# ls /sys/bus/coresight/devices/ +20010000.etf 20120000.replicator 22040000.etm 230c0000.funnel +20030000.tpiu 20130000.funnel 220c0000.funnel 23140000.etm +20040000.funnel 20140000.etf 22140000.etm 23240000.etm +20070000.etr 20150000.funnel 23040000.etm 23340000.etm +root@juno:~# + +Note the Juno uses an Embedded Trace Router (ETR) instead of an ETB. + The functions take a "struct coresight_device", which looks like this: struct coresight_desc { @@ -193,16 +204,16 @@ the information carried in "THIS_MODULE". How to use the tracer modules ----------------------------- -Before trace collection can start, a coresight sink needs to be identify. +Before trace collection can start, a coresight sink needs to be identified. There is no limit on the amount of sinks (nor sources) that can be enabled at any given moment. As a generic operation, all device pertaining to the sink class will have an "active" entry in sysfs: root:/sys/bus/coresight/devices# ls -replicator 20030000.tpiu 2201c000.ptm 2203c000.etm 2203e000.etm -20010000.etb 20040000.funnel 2201d000.ptm 2203d000.etm +20010000.etb 20040000.funnel 2201d000.ptm 2203d000.etm replicator +20030000.tpiu 2201c000.ptm 2203c000.etm 2203e000.etm root:/sys/bus/coresight/devices# ls 20010000.etb -enable_sink status trigger_cntr +enable_sink mgmt power subsystem trigger_cntr uevent root:/sys/bus/coresight/devices# echo 1 > 20010000.etb/enable_sink root:/sys/bus/coresight/devices# cat 20010000.etb/enable_sink 1 @@ -216,16 +227,13 @@ trigger a trace capture: root:/sys/bus/coresight/devices# echo 1 > 2201c000.ptm/enable_source root:/sys/bus/coresight/devices# cat 2201c000.ptm/enable_source 1 -root:/sys/bus/coresight/devices# cat 20010000.etb/status -Depth: 0x2000 -Status: 0x1 -RAM read ptr: 0x0 -RAM wrt ptr: 0x19d3 <----- The write pointer is moving -Trigger cnt: 0x0 -Control: 0x1 -Flush status: 0x0 -Flush ctrl: 0x2001 -root:/sys/bus/coresight/devices# + +Observe the write pointer moving: + +root:/sys/bus/coresight/devices# cat 20010000.etb/mgmt/rwp +0x1a8 +root:/sys/bus/coresight/devices# cat 20010000.etb/mgmt/rwp +0x19a6 Trace collection is stopped the same way: -- 2.17.0 -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html