tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * Support for hardware-assisted userspace interrupt masking.
3 *
4 * Copyright (C) 2010 Paul Mundt
5 *
6 * This file is subject to the terms and conditions of the GNU General Public
7 * License. See the file "COPYING" in the main directory of this archive
8 * for more details.
9 */
10#define pr_fmt(fmt) "intc: " fmt
11
12#include <linux/errno.h>
13#include <linux/sysdev.h>
14#include <linux/init.h>
15#include <linux/io.h>
16#include <asm/sizes.h>
17#include "internals.h"
18
19static void __iomem *uimask;
20
21static ssize_t
22show_intc_userimask(struct sysdev_class *cls,
23 struct sysdev_class_attribute *attr, char *buf)
24{
25 return sprintf(buf, "%d\n", (__raw_readl(uimask) >> 4) & 0xf);
26}
27
28static ssize_t
29store_intc_userimask(struct sysdev_class *cls,
30 struct sysdev_class_attribute *attr,
31 const char *buf, size_t count)
32{
33 unsigned long level;
34
35 level = simple_strtoul(buf, NULL, 10);
36
37 /*
38 * Minimal acceptable IRQ levels are in the 2 - 16 range, but
39 * these are chomped so as to not interfere with normal IRQs.
40 *
41 * Level 1 is a special case on some CPUs in that it's not
42 * directly settable, but given that USERIMASK cuts off below a
43 * certain level, we don't care about this limitation here.
44 * Level 0 on the other hand equates to user masking disabled.
45 *
46 * We use the default priority level as a cut off so that only
47 * special case opt-in IRQs can be mangled.
48 */
49 if (level >= intc_get_dfl_prio_level())
50 return -EINVAL;
51
52 __raw_writel(0xa5 << 24 | level << 4, uimask);
53
54 return count;
55}
56
57static SYSDEV_CLASS_ATTR(userimask, S_IRUSR | S_IWUSR,
58 show_intc_userimask, store_intc_userimask);
59
60
61static int __init userimask_sysdev_init(void)
62{
63 if (unlikely(!uimask))
64 return -ENXIO;
65
66 return sysdev_class_create_file(&intc_sysdev_class, &attr_userimask);
67}
68late_initcall(userimask_sysdev_init);
69
70int register_intc_userimask(unsigned long addr)
71{
72 if (unlikely(uimask))
73 return -EBUSY;
74
75 uimask = ioremap_nocache(addr, SZ_4K);
76 if (unlikely(!uimask))
77 return -ENOMEM;
78
79 pr_info("userimask support registered for levels 0 -> %d\n",
80 intc_get_dfl_prio_level() - 1);
81
82 return 0;
83}