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);