linux/arch/avr32/kernel/ocd.c
Christoph Hellwig 8b88b0998e libfs: allow error return from simple attributes
Sometimes simple attributes might need to return an error, e.g. for
acquiring a mutex interruptibly.  In fact we have that situation in
spufs already which is the original user of the simple attributes.  This
patch merged the temporarily forked attributes in spufs back into the
main ones and allows to return errors.

[akpm@linux-foundation.org: build fix]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: <stefano.brivio@polimi.it>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg KH <greg@kroah.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-08 09:22:34 -08:00

167 lines
3.8 KiB
C

/*
* Copyright (C) 2007 Atmel Corporation
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/spinlock.h>
#include <asm/ocd.h>
static long ocd_count;
static spinlock_t ocd_lock;
/**
* ocd_enable - enable on-chip debugging
* @child: task to be debugged
*
* If @child is non-NULL, ocd_enable() first checks if debugging has
* already been enabled for @child, and if it has, does nothing.
*
* If @child is NULL (e.g. when debugging the kernel), or debugging
* has not already been enabled for it, ocd_enable() increments the
* reference count and enables the debugging hardware.
*/
void ocd_enable(struct task_struct *child)
{
u32 dc;
if (child)
pr_debug("ocd_enable: child=%s [%u]\n",
child->comm, child->pid);
else
pr_debug("ocd_enable (no child)\n");
if (!child || !test_and_set_tsk_thread_flag(child, TIF_DEBUG)) {
spin_lock(&ocd_lock);
ocd_count++;
dc = ocd_read(DC);
dc |= (1 << OCD_DC_MM_BIT) | (1 << OCD_DC_DBE_BIT);
ocd_write(DC, dc);
spin_unlock(&ocd_lock);
}
}
/**
* ocd_disable - disable on-chip debugging
* @child: task that was being debugged, but isn't anymore
*
* If @child is non-NULL, ocd_disable() checks if debugging is enabled
* for @child, and if it isn't, does nothing.
*
* If @child is NULL (e.g. when debugging the kernel), or debugging is
* enabled, ocd_disable() decrements the reference count, and if it
* reaches zero, disables the debugging hardware.
*/
void ocd_disable(struct task_struct *child)
{
u32 dc;
if (!child)
pr_debug("ocd_disable (no child)\n");
else if (test_tsk_thread_flag(child, TIF_DEBUG))
pr_debug("ocd_disable: child=%s [%u]\n",
child->comm, child->pid);
if (!child || test_and_clear_tsk_thread_flag(child, TIF_DEBUG)) {
spin_lock(&ocd_lock);
ocd_count--;
WARN_ON(ocd_count < 0);
if (ocd_count <= 0) {
dc = ocd_read(DC);
dc &= ~((1 << OCD_DC_MM_BIT) | (1 << OCD_DC_DBE_BIT));
ocd_write(DC, dc);
}
spin_unlock(&ocd_lock);
}
}
#ifdef CONFIG_DEBUG_FS
#include <linux/debugfs.h>
#include <linux/module.h>
static struct dentry *ocd_debugfs_root;
static struct dentry *ocd_debugfs_DC;
static struct dentry *ocd_debugfs_DS;
static struct dentry *ocd_debugfs_count;
static int ocd_DC_get(void *data, u64 *val)
{
*val = ocd_read(DC);
return 0;
}
static int ocd_DC_set(void *data, u64 val)
{
ocd_write(DC, val);
return 0;
}
DEFINE_SIMPLE_ATTRIBUTE(fops_DC, ocd_DC_get, ocd_DC_set, "0x%08llx\n");
static int ocd_DS_get(void *data, u64 *val)
{
*val = ocd_read(DS);
return 0;
}
DEFINE_SIMPLE_ATTRIBUTE(fops_DS, ocd_DS_get, NULL, "0x%08llx\n");
static int ocd_count_get(void *data, u64 *val)
{
*val = ocd_count;
return 0;
}
DEFINE_SIMPLE_ATTRIBUTE(fops_count, ocd_count_get, NULL, "%lld\n");
static void ocd_debugfs_init(void)
{
struct dentry *root;
root = debugfs_create_dir("ocd", NULL);
if (IS_ERR(root) || !root)
goto err_root;
ocd_debugfs_root = root;
ocd_debugfs_DC = debugfs_create_file("DC", S_IRUSR | S_IWUSR,
root, NULL, &fops_DC);
if (!ocd_debugfs_DC)
goto err_DC;
ocd_debugfs_DS = debugfs_create_file("DS", S_IRUSR, root,
NULL, &fops_DS);
if (!ocd_debugfs_DS)
goto err_DS;
ocd_debugfs_count = debugfs_create_file("count", S_IRUSR, root,
NULL, &fops_count);
if (!ocd_debugfs_count)
goto err_count;
return;
err_count:
debugfs_remove(ocd_debugfs_DS);
err_DS:
debugfs_remove(ocd_debugfs_DC);
err_DC:
debugfs_remove(ocd_debugfs_root);
err_root:
printk(KERN_WARNING "OCD: Failed to create debugfs entries\n");
}
#else
static inline void ocd_debugfs_init(void)
{
}
#endif
static int __init ocd_init(void)
{
spin_lock_init(&ocd_lock);
ocd_debugfs_init();
return 0;
}
arch_initcall(ocd_init);