userimask.c
2.05 KB
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/*
* Support for hardware-assisted userspace interrupt masking.
*
* Copyright (C) 2010 Paul Mundt
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*/
#define pr_fmt(fmt) "intc: " fmt
#include <linux/errno.h>
#include <linux/device.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/stat.h>
#include <asm/sizes.h>
#include "internals.h"
static void __iomem *uimask;
static ssize_t
show_intc_userimask(struct device *dev,
struct device_attribute *attr, char *buf)
{
return sprintf(buf, "%d\n", (__raw_readl(uimask) >> 4) & 0xf);
}
static ssize_t
store_intc_userimask(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
unsigned long level;
level = simple_strtoul(buf, NULL, 10);
/*
* Minimal acceptable IRQ levels are in the 2 - 16 range, but
* these are chomped so as to not interfere with normal IRQs.
*
* Level 1 is a special case on some CPUs in that it's not
* directly settable, but given that USERIMASK cuts off below a
* certain level, we don't care about this limitation here.
* Level 0 on the other hand equates to user masking disabled.
*
* We use the default priority level as a cut off so that only
* special case opt-in IRQs can be mangled.
*/
if (level >= intc_get_dfl_prio_level())
return -EINVAL;
__raw_writel(0xa5 << 24 | level << 4, uimask);
return count;
}
static DEVICE_ATTR(userimask, S_IRUSR | S_IWUSR,
show_intc_userimask, store_intc_userimask);
static int __init userimask_sysdev_init(void)
{
if (unlikely(!uimask))
return -ENXIO;
return device_create_file(intc_subsys.dev_root, &dev_attr_userimask);
}
late_initcall(userimask_sysdev_init);
int register_intc_userimask(unsigned long addr)
{
if (unlikely(uimask))
return -EBUSY;
uimask = ioremap_nocache(addr, SZ_4K);
if (unlikely(!uimask))
return -ENOMEM;
pr_info("userimask support registered for levels 0 -> %d\n",
intc_get_dfl_prio_level() - 1);
return 0;
}