Root/arch/avr32/kernel/ocd.c

1/*
2 * Copyright (C) 2007 Atmel Corporation
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
7 */
8#include <linux/init.h>
9#include <linux/sched.h>
10#include <linux/spinlock.h>
11
12#include <asm/ocd.h>
13
14static long ocd_count;
15static spinlock_t ocd_lock;
16
17/**
18 * ocd_enable - enable on-chip debugging
19 * @child: task to be debugged
20 *
21 * If @child is non-NULL, ocd_enable() first checks if debugging has
22 * already been enabled for @child, and if it has, does nothing.
23 *
24 * If @child is NULL (e.g. when debugging the kernel), or debugging
25 * has not already been enabled for it, ocd_enable() increments the
26 * reference count and enables the debugging hardware.
27 */
28void ocd_enable(struct task_struct *child)
29{
30    u32 dc;
31
32    if (child)
33        pr_debug("ocd_enable: child=%s [%u]\n",
34                child->comm, child->pid);
35    else
36        pr_debug("ocd_enable (no child)\n");
37
38    if (!child || !test_and_set_tsk_thread_flag(child, TIF_DEBUG)) {
39        spin_lock(&ocd_lock);
40        ocd_count++;
41        dc = ocd_read(DC);
42        dc |= (1 << OCD_DC_MM_BIT) | (1 << OCD_DC_DBE_BIT);
43        ocd_write(DC, dc);
44        spin_unlock(&ocd_lock);
45    }
46}
47
48/**
49 * ocd_disable - disable on-chip debugging
50 * @child: task that was being debugged, but isn't anymore
51 *
52 * If @child is non-NULL, ocd_disable() checks if debugging is enabled
53 * for @child, and if it isn't, does nothing.
54 *
55 * If @child is NULL (e.g. when debugging the kernel), or debugging is
56 * enabled, ocd_disable() decrements the reference count, and if it
57 * reaches zero, disables the debugging hardware.
58 */
59void ocd_disable(struct task_struct *child)
60{
61    u32 dc;
62
63    if (!child)
64        pr_debug("ocd_disable (no child)\n");
65    else if (test_tsk_thread_flag(child, TIF_DEBUG))
66        pr_debug("ocd_disable: child=%s [%u]\n",
67                child->comm, child->pid);
68
69    if (!child || test_and_clear_tsk_thread_flag(child, TIF_DEBUG)) {
70        spin_lock(&ocd_lock);
71        ocd_count--;
72
73        WARN_ON(ocd_count < 0);
74
75        if (ocd_count <= 0) {
76            dc = ocd_read(DC);
77            dc &= ~((1 << OCD_DC_MM_BIT) | (1 << OCD_DC_DBE_BIT));
78            ocd_write(DC, dc);
79        }
80        spin_unlock(&ocd_lock);
81    }
82}
83
84#ifdef CONFIG_DEBUG_FS
85#include <linux/debugfs.h>
86#include <linux/module.h>
87
88static struct dentry *ocd_debugfs_root;
89static struct dentry *ocd_debugfs_DC;
90static struct dentry *ocd_debugfs_DS;
91static struct dentry *ocd_debugfs_count;
92
93static int ocd_DC_get(void *data, u64 *val)
94{
95    *val = ocd_read(DC);
96    return 0;
97}
98static int ocd_DC_set(void *data, u64 val)
99{
100    ocd_write(DC, val);
101    return 0;
102}
103DEFINE_SIMPLE_ATTRIBUTE(fops_DC, ocd_DC_get, ocd_DC_set, "0x%08llx\n");
104
105static int ocd_DS_get(void *data, u64 *val)
106{
107    *val = ocd_read(DS);
108    return 0;
109}
110DEFINE_SIMPLE_ATTRIBUTE(fops_DS, ocd_DS_get, NULL, "0x%08llx\n");
111
112static int ocd_count_get(void *data, u64 *val)
113{
114    *val = ocd_count;
115    return 0;
116}
117DEFINE_SIMPLE_ATTRIBUTE(fops_count, ocd_count_get, NULL, "%lld\n");
118
119static void ocd_debugfs_init(void)
120{
121    struct dentry *root;
122
123    root = debugfs_create_dir("ocd", NULL);
124    if (IS_ERR(root) || !root)
125        goto err_root;
126    ocd_debugfs_root = root;
127
128    ocd_debugfs_DC = debugfs_create_file("DC", S_IRUSR | S_IWUSR,
129                root, NULL, &fops_DC);
130    if (!ocd_debugfs_DC)
131        goto err_DC;
132
133    ocd_debugfs_DS = debugfs_create_file("DS", S_IRUSR, root,
134                NULL, &fops_DS);
135    if (!ocd_debugfs_DS)
136        goto err_DS;
137
138    ocd_debugfs_count = debugfs_create_file("count", S_IRUSR, root,
139                NULL, &fops_count);
140    if (!ocd_debugfs_count)
141        goto err_count;
142
143    return;
144
145err_count:
146    debugfs_remove(ocd_debugfs_DS);
147err_DS:
148    debugfs_remove(ocd_debugfs_DC);
149err_DC:
150    debugfs_remove(ocd_debugfs_root);
151err_root:
152    printk(KERN_WARNING "OCD: Failed to create debugfs entries\n");
153}
154#else
155static inline void ocd_debugfs_init(void)
156{
157
158}
159#endif
160
161static int __init ocd_init(void)
162{
163    spin_lock_init(&ocd_lock);
164    ocd_debugfs_init();
165    return 0;
166}
167arch_initcall(ocd_init);
168

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