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authorDavid Howells <dhowells@redhat.com>2014-03-06 08:35:59 -0500
committerWolfram Sang <wsa@the-dreams.de>2014-03-13 17:12:53 -0400
commitd9a83d62b326574fb4831b64317a82a42642a9a2 (patch)
tree6b195735ecb69aec92374d4034280b4ad2ff5110
parent392debf11656dedd79da44416747d5b2b1747f5e (diff)
i2c: Add message transfer tracepoints for I2C
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/enable and will dump messages that can be viewed in /sys/kernel/debug/tracing/trace that look like: ... i2c_write: i2c-5 #0 a=044 f=0000 l=2 [02-14] ... i2c_read: i2c-5 #1 a=044 f=0001 l=4 ... i2c_reply: i2c-5 #1 a=044 f=0001 l=4 [33-00-00-00] ... i2c_result: i2c-5 n=2 ret=2 formatted as: i2c-<adapter-nr> #<message-array-index> a=<addr> f=<flags> l=<datalen> n=<message-array-size> ret=<result> [<data>] 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 <rostedt@goodmis.org> Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> [wsa: adapted path for 'enable' in the commit msg] Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Diffstat
-rw-r--r--drivers/i2c/i2c-core.c37
-rw-r--r--include/trace/events/i2c.h150
2 files changed, 187 insertions, 0 deletions
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index 98a5fd950f16..bdedbee85c01 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -48,10 +48,13 @@
48#include <linux/rwsem.h> 48#include <linux/rwsem.h>
49#include <linux/pm_runtime.h> 49#include <linux/pm_runtime.h>
50#include <linux/acpi.h> 50#include <linux/acpi.h>
51#include <linux/jump_label.h>
51#include <asm/uaccess.h> 52#include <asm/uaccess.h>
52 53
53#include "i2c-core.h" 54#include "i2c-core.h"
54 55
56#define CREATE_TRACE_POINTS
57#include <trace/events/i2c.h>
55 58
56/* core_lock protects i2c_adapter_idr, and guarantees 59/* core_lock protects i2c_adapter_idr, and guarantees
57 that device detection, deletion of detected devices, and attach_adapter 60 that device detection, deletion of detected devices, and attach_adapter
@@ -62,6 +65,18 @@ static DEFINE_IDR(i2c_adapter_idr);
62static struct device_type i2c_client_type; 65static struct device_type i2c_client_type;
63static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver); 66static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver);
64 67
68static struct static_key i2c_trace_msg = STATIC_KEY_INIT_FALSE;
69
70void i2c_transfer_trace_reg(void)
71{
72 static_key_slow_inc(&i2c_trace_msg);
73}
74
75void i2c_transfer_trace_unreg(void)
76{
77 static_key_slow_dec(&i2c_trace_msg);
78}
79
65/* ------------------------------------------------------------------------- */ 80/* ------------------------------------------------------------------------- */
66 81
67static const struct i2c_device_id *i2c_match_id(const struct i2c_device_id *id, 82static const struct i2c_device_id *i2c_match_id(const struct i2c_device_id *id,
@@ -1686,6 +1701,7 @@ static void __exit i2c_exit(void)
1686 class_compat_unregister(i2c_adapter_compat_class); 1701 class_compat_unregister(i2c_adapter_compat_class);
1687#endif 1702#endif
1688 bus_unregister(&i2c_bus_type); 1703 bus_unregister(&i2c_bus_type);
1704 tracepoint_synchronize_unregister();
1689} 1705}
1690 1706
1691/* We must initialize early, because some subsystems register i2c drivers 1707/* We must initialize early, because some subsystems register i2c drivers
@@ -1716,6 +1732,19 @@ int __i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
1716 unsigned long orig_jiffies; 1732 unsigned long orig_jiffies;
1717 int ret, try; 1733 int ret, try;
1718 1734
1735 /* i2c_trace_msg gets enabled when tracepoint i2c_transfer gets
1736 * enabled. This is an efficient way of keeping the for-loop from
1737 * being executed when not needed.
1738 */
1739 if (static_key_false(&i2c_trace_msg)) {
1740 int i;
1741 for (i = 0; i < num; i++)
1742 if (msgs[i].flags & I2C_M_RD)
1743 trace_i2c_read(adap, &msgs[i], i);
1744 else
1745 trace_i2c_write(adap, &msgs[i], i);
1746 }
1747
1719 /* Retry automatically on arbitration loss */ 1748 /* Retry automatically on arbitration loss */
1720 orig_jiffies = jiffies; 1749 orig_jiffies = jiffies;
1721 for (ret = 0, try = 0; try <= adap->retries; try++) { 1750 for (ret = 0, try = 0; try <= adap->retries; try++) {
@@ -1726,6 +1755,14 @@ int __i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
1726 break; 1755 break;
1727 } 1756 }
1728 1757
1758 if (static_key_false(&i2c_trace_msg)) {
1759 int i;
1760 for (i = 0; i < ret; i++)
1761 if (msgs[i].flags & I2C_M_RD)
1762 trace_i2c_reply(adap, &msgs[i], i);
1763 trace_i2c_result(adap, i, ret);
1764 }
1765
1729 return ret; 1766 return ret;
1730} 1767}
1731EXPORT_SYMBOL(__i2c_transfer); 1768EXPORT_SYMBOL(__i2c_transfer);
diff --git a/include/trace/events/i2c.h b/include/trace/events/i2c.h
new file mode 100644
index 000000000000..4800207269a2
--- /dev/null
+++ b/include/trace/events/i2c.h
@@ -0,0 +1,150 @@
1/* I2C message transfer tracepoints
2 *
3 * Copyright (C) 2013 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public Licence
8 * as published by the Free Software Foundation; either version
9 * 2 of the Licence, or (at your option) any later version.
10 */
11#undef TRACE_SYSTEM
12#define TRACE_SYSTEM i2c
13
14#if !defined(_TRACE_I2C_H) || defined(TRACE_HEADER_MULTI_READ)
15#define _TRACE_I2C_H
16
17#include <linux/i2c.h>
18#include <linux/tracepoint.h>
19
20/*
21 * drivers/i2c/i2c-core.c
22 */
23extern void i2c_transfer_trace_reg(void);
24extern void i2c_transfer_trace_unreg(void);
25
26/*
27 * __i2c_transfer() write request
28 */
29TRACE_EVENT_FN(i2c_write,
30 TP_PROTO(const struct i2c_adapter *adap, const struct i2c_msg *msg,
31 int num),
32 TP_ARGS(adap, msg, num),
33 TP_STRUCT__entry(
34 __field(int, adapter_nr )
35 __field(__u16, msg_nr )
36 __field(__u16, addr )
37 __field(__u16, flags )
38 __field(__u16, len )
39 __dynamic_array(__u8, buf, msg->len) ),
40 TP_fast_assign(
41 __entry->adapter_nr = adap->nr;
42 __entry->msg_nr = num;
43 __entry->addr = msg->addr;
44 __entry->flags = msg->flags;
45 __entry->len = msg->len;
46 memcpy(__get_dynamic_array(buf), msg->buf, msg->len);
47 ),
48 TP_printk("i2c-%d #%u a=%03x f=%04x l=%u [%*phD]",
49 __entry->adapter_nr,
50 __entry->msg_nr,
51 __entry->addr,
52 __entry->flags,
53 __entry->len,
54 __entry->len, __get_dynamic_array(buf)
55 ),
56 i2c_transfer_trace_reg,
57 i2c_transfer_trace_unreg);
58
59/*
60 * __i2c_transfer() read request
61 */
62TRACE_EVENT_FN(i2c_read,
63 TP_PROTO(const struct i2c_adapter *adap, const struct i2c_msg *msg,
64 int num),
65 TP_ARGS(adap, msg, num),
66 TP_STRUCT__entry(
67 __field(int, adapter_nr )
68 __field(__u16, msg_nr )
69 __field(__u16, addr )
70 __field(__u16, flags )
71 __field(__u16, len )
72 ),
73 TP_fast_assign(
74 __entry->adapter_nr = adap->nr;
75 __entry->msg_nr = num;
76 __entry->addr = msg->addr;
77 __entry->flags = msg->flags;
78 __entry->len = msg->len;
79 ),
80 TP_printk("i2c-%d #%u a=%03x f=%04x l=%u",
81 __entry->adapter_nr,
82 __entry->msg_nr,
83 __entry->addr,
84 __entry->flags,
85 __entry->len
86 ),
87 i2c_transfer_trace_reg,
88 i2c_transfer_trace_unreg);
89
90/*
91 * __i2c_transfer() read reply
92 */
93TRACE_EVENT_FN(i2c_reply,
94 TP_PROTO(const struct i2c_adapter *adap, const struct i2c_msg *msg,
95 int num),
96 TP_ARGS(adap, msg, num),
97 TP_STRUCT__entry(
98 __field(int, adapter_nr )
99 __field(__u16, msg_nr )
100 __field(__u16, addr )
101 __field(__u16, flags )
102 __field(__u16, len )
103 __dynamic_array(__u8, buf, msg->len) ),
104 TP_fast_assign(
105 __entry->adapter_nr = adap->nr;
106 __entry->msg_nr = num;
107 __entry->addr = msg->addr;
108 __entry->flags = msg->flags;
109 __entry->len = msg->len;
110 memcpy(__get_dynamic_array(buf), msg->buf, msg->len);
111 ),
112 TP_printk("i2c-%d #%u a=%03x f=%04x l=%u [%*phD]",
113 __entry->adapter_nr,
114 __entry->msg_nr,
115 __entry->addr,
116 __entry->flags,
117 __entry->len,
118 __entry->len, __get_dynamic_array(buf)
119 ),
120 i2c_transfer_trace_reg,
121 i2c_transfer_trace_unreg);
122
123/*
124 * __i2c_transfer() result
125 */
126TRACE_EVENT_FN(i2c_result,
127 TP_PROTO(const struct i2c_adapter *adap, int num, int ret),
128 TP_ARGS(adap, num, ret),
129 TP_STRUCT__entry(
130 __field(int, adapter_nr )
131 __field(__u16, nr_msgs )
132 __field(__s16, ret )
133 ),
134 TP_fast_assign(
135 __entry->adapter_nr = adap->nr;
136 __entry->nr_msgs = num;
137 __entry->ret = ret;
138 ),
139 TP_printk("i2c-%d n=%u ret=%d",
140 __entry->adapter_nr,
141 __entry->nr_msgs,
142 __entry->ret
143 ),
144 i2c_transfer_trace_reg,
145 i2c_transfer_trace_unreg);
146
147#endif /* _TRACE_I2C_H */
148
149/* This part must be outside protection */
150#include <trace/define_trace.h>
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