From patchwork Thu Jan 9 21:49:54 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Howells X-Patchwork-Id: 308958 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id B31662C00A1 for ; Fri, 10 Jan 2014 08:50:46 +1100 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757688AbaAIVuX (ORCPT ); Thu, 9 Jan 2014 16:50:23 -0500 Received: from mx1.redhat.com ([209.132.183.28]:5352 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757673AbaAIVuS (ORCPT ); Thu, 9 Jan 2014 16:50:18 -0500 Received: from int-mx12.intmail.prod.int.phx2.redhat.com (int-mx12.intmail.prod.int.phx2.redhat.com [10.5.11.25]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id s09Lnv8x030731 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Thu, 9 Jan 2014 16:49:57 -0500 Received: from warthog.procyon.org.uk (ovpn-113-65.phx2.redhat.com [10.3.113.65]) by int-mx12.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id s09LntOD018365; Thu, 9 Jan 2014 16:49:56 -0500 Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 Subject: [PATCH 1/2] i2c: Add message transfer tracepoints for I2C From: David Howells To: wolfram@the-dreams.de Cc: khali@linux-fr.org, dhowells@redhat.com, linux-i2c@vger.kernel.org, Steven Rostedt , linux-kernel@vger.kernel.org Date: Thu, 09 Jan 2014 21:49:54 +0000 Message-ID: <20140109214954.25590.73057.stgit@warthog.procyon.org.uk> User-Agent: StGit/0.17-dirty MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.68 on 10.5.11.25 Sender: linux-i2c-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.org Add tracepoints into the I2C message transfer function to retrieve the message sent or received. The following config options must be turned on to make use of the facility: CONFIG_FTRACE CONFIG_ENABLE_DEFAULT_TRACERS The I2C tracepoint can be enabled thusly: echo 1 >/sys/kernel/debug/tracing/events/i2c/i2c_transfer/enable and will dump messages that can be viewed in /sys/kernel/debug/tracing/trace that look like: ... i2c_write: i2c-5 #0 f=00 a=44 l=2 [0214] ... i2c_read: i2c-5 #1 f=01 a=44 l=4 ... i2c_reply: i2c-5 #1 f=01 a=44 l=4 [33000000] ... i2c_result: i2c-5 n=2 ret=2 formatted as: i2c- # f= a= l= n= ret= [] The operation is done between the i2c_write/i2c_read lines and the i2c_reply and i2c_result lines so that if the hardware hangs, the trace buffer can be consulted to determine the problematic operation. The adapters to be traced can be selected by something like: echo adapter_nr==1 >/sys/kernel/debug/tracing/events/i2c/filter These changes are based on code from Steven Rostedt. Signed-off-by: Steven Rostedt Signed-off-by: David Howells Reviewed-by: Steven Rostedt --- drivers/i2c/i2c-core.c | 37 +++++++++++ include/trace/events/i2c.h | 150 ++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 187 insertions(+) create mode 100644 include/trace/events/i2c.h -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c index d74c0b34248e..c8b97490461d 100644 --- a/drivers/i2c/i2c-core.c +++ b/drivers/i2c/i2c-core.c @@ -48,10 +48,13 @@ #include #include #include +#include #include #include "i2c-core.h" +#define CREATE_TRACE_POINTS +#include /* core_lock protects i2c_adapter_idr, and guarantees that device detection, deletion of detected devices, and attach_adapter @@ -62,6 +65,18 @@ static DEFINE_IDR(i2c_adapter_idr); static struct device_type i2c_client_type; static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver); +static struct static_key i2c_trace_msg = STATIC_KEY_INIT_FALSE; + +void i2c_transfer_trace_reg(void) +{ + static_key_slow_inc(&i2c_trace_msg); +} + +void i2c_transfer_trace_unreg(void) +{ + static_key_slow_dec(&i2c_trace_msg); +} + /* ------------------------------------------------------------------------- */ static const struct i2c_device_id *i2c_match_id(const struct i2c_device_id *id, @@ -1680,6 +1695,7 @@ static void __exit i2c_exit(void) class_compat_unregister(i2c_adapter_compat_class); #endif bus_unregister(&i2c_bus_type); + tracepoint_synchronize_unregister(); } /* We must initialize early, because some subsystems register i2c drivers @@ -1710,6 +1726,19 @@ int __i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) unsigned long orig_jiffies; int ret, try; + /* i2c_trace_msg gets enabled when tracepoint i2c_transfer gets + * enabled. This is an efficient way of keeping the for-loop from + * being executed when not needed. + */ + if (static_key_false(&i2c_trace_msg)) { + int i; + for (i = 0; i < num; i++) + if (msgs[i].flags & I2C_M_RD) + trace_i2c_read(adap, &msgs[i], i); + else + trace_i2c_write(adap, &msgs[i], i); + } + /* Retry automatically on arbitration loss */ orig_jiffies = jiffies; for (ret = 0, try = 0; try <= adap->retries; try++) { @@ -1720,6 +1749,14 @@ int __i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) break; } + if (static_key_false(&i2c_trace_msg)) { + int i; + for (i = 0; i < ret; i++) + if (msgs[i].flags & I2C_M_RD) + trace_i2c_reply(adap, &msgs[i], i); + trace_i2c_result(adap, i, ret); + } + return ret; } EXPORT_SYMBOL(__i2c_transfer); diff --git a/include/trace/events/i2c.h b/include/trace/events/i2c.h new file mode 100644 index 000000000000..d30f008527b2 --- /dev/null +++ b/include/trace/events/i2c.h @@ -0,0 +1,150 @@ +/* I2C message transfer tracepoints + * + * Copyright (C) 2013 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public Licence + * as published by the Free Software Foundation; either version + * 2 of the Licence, or (at your option) any later version. + */ +#undef TRACE_SYSTEM +#define TRACE_SYSTEM i2c + +#if !defined(_TRACE_I2C_H) || defined(TRACE_HEADER_MULTI_READ) +#define _TRACE_I2C_H + +#include +#include + +/* + * drivers/i2c/i2c-core.c + */ +extern void i2c_transfer_trace_reg(void); +extern void i2c_transfer_trace_unreg(void); + +/* + * __i2c_transfer() write request + */ +TRACE_EVENT_FN(i2c_write, + TP_PROTO(const struct i2c_adapter *adap, const struct i2c_msg *msg, + int num), + TP_ARGS(adap, msg, num), + TP_STRUCT__entry( + __field(int, adapter_nr ) + __field(__u16, msg_nr ) + __field(__u16, addr ) + __field(__u16, flags ) + __field(__u16, len ) + __dynamic_array(__u8, buf, msg->len) ), + TP_fast_assign( + __entry->adapter_nr = adap->nr; + __entry->msg_nr = num; + __entry->addr = msg->addr; + __entry->flags = msg->flags; + __entry->len = msg->len; + memcpy(__get_dynamic_array(buf), msg->buf, msg->len); + ), + TP_printk("i2c-%d #%u f=%02x a=%02x l=%u [%*phN]", + __entry->adapter_nr, + __entry->msg_nr, + __entry->flags, + __entry->addr, + __entry->len, + __entry->len, __get_dynamic_array(buf) + ), + i2c_transfer_trace_reg, + i2c_transfer_trace_unreg); + +/* + * __i2c_transfer() read request + */ +TRACE_EVENT_FN(i2c_read, + TP_PROTO(const struct i2c_adapter *adap, const struct i2c_msg *msg, + int num), + TP_ARGS(adap, msg, num), + TP_STRUCT__entry( + __field(int, adapter_nr ) + __field(__u16, msg_nr ) + __field(__u16, addr ) + __field(__u16, flags ) + __field(__u16, len ) + ), + TP_fast_assign( + __entry->adapter_nr = adap->nr; + __entry->msg_nr = num; + __entry->addr = msg->addr; + __entry->flags = msg->flags; + __entry->len = msg->len; + ), + TP_printk("i2c-%d #%u f=%02x a=%02x l=%u", + __entry->adapter_nr, + __entry->msg_nr, + __entry->flags, + __entry->addr, + __entry->len + ), + i2c_transfer_trace_reg, + i2c_transfer_trace_unreg); + +/* + * __i2c_transfer() read reply + */ +TRACE_EVENT_FN(i2c_reply, + TP_PROTO(const struct i2c_adapter *adap, const struct i2c_msg *msg, + int num), + TP_ARGS(adap, msg, num), + TP_STRUCT__entry( + __field(int, adapter_nr ) + __field(__u16, msg_nr ) + __field(__u16, addr ) + __field(__u16, flags ) + __field(__u16, len ) + __dynamic_array(__u8, buf, msg->len) ), + TP_fast_assign( + __entry->adapter_nr = adap->nr; + __entry->msg_nr = num; + __entry->addr = msg->addr; + __entry->flags = msg->flags; + __entry->len = msg->len; + memcpy(__get_dynamic_array(buf), msg->buf, msg->len); + ), + TP_printk("i2c-%d #%u f=%02x a=%02x l=%u [%*phN]", + __entry->adapter_nr, + __entry->msg_nr, + __entry->flags, + __entry->addr, + __entry->len, + __entry->len, __get_dynamic_array(buf) + ), + i2c_transfer_trace_reg, + i2c_transfer_trace_unreg); + +/* + * __i2c_transfer() result + */ +TRACE_EVENT_FN(i2c_result, + TP_PROTO(const struct i2c_adapter *adap, int num, int ret), + TP_ARGS(adap, num, ret), + TP_STRUCT__entry( + __field(int, adapter_nr ) + __field(__u16, nr_msgs ) + __field(__s16, ret ) + ), + TP_fast_assign( + __entry->adapter_nr = adap->nr; + __entry->nr_msgs = num; + __entry->ret = ret; + ), + TP_printk("i2c-%d n=%u ret=%d", + __entry->adapter_nr, + __entry->nr_msgs, + __entry->ret + ), + i2c_transfer_trace_reg, + i2c_transfer_trace_unreg); + +#endif /* _TRACE_I2C_H */ + +/* This part must be outside protection */ +#include