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2be6bb0c PM |
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> | |
f4e73bfc | 13 | #include <linux/device.h> |
2be6bb0c PM |
14 | #include <linux/init.h> |
15 | #include <linux/io.h> | |
a102a088 | 16 | #include <linux/stat.h> |
2be6bb0c PM |
17 | #include <asm/sizes.h> |
18 | #include "internals.h" | |
19 | ||
20 | static void __iomem *uimask; | |
21 | ||
22 | static ssize_t | |
f4e73bfc KS |
23 | show_intc_userimask(struct device *dev, |
24 | struct device_attribute *attr, char *buf) | |
2be6bb0c PM |
25 | { |
26 | return sprintf(buf, "%d\n", (__raw_readl(uimask) >> 4) & 0xf); | |
27 | } | |
28 | ||
29 | static ssize_t | |
f4e73bfc KS |
30 | store_intc_userimask(struct device *dev, |
31 | struct device_attribute *attr, | |
2be6bb0c PM |
32 | const char *buf, size_t count) |
33 | { | |
34 | unsigned long level; | |
35 | ||
36 | level = simple_strtoul(buf, NULL, 10); | |
37 | ||
38 | /* | |
39 | * Minimal acceptable IRQ levels are in the 2 - 16 range, but | |
40 | * these are chomped so as to not interfere with normal IRQs. | |
41 | * | |
42 | * Level 1 is a special case on some CPUs in that it's not | |
43 | * directly settable, but given that USERIMASK cuts off below a | |
44 | * certain level, we don't care about this limitation here. | |
45 | * Level 0 on the other hand equates to user masking disabled. | |
46 | * | |
47 | * We use the default priority level as a cut off so that only | |
48 | * special case opt-in IRQs can be mangled. | |
49 | */ | |
50 | if (level >= intc_get_dfl_prio_level()) | |
51 | return -EINVAL; | |
52 | ||
53 | __raw_writel(0xa5 << 24 | level << 4, uimask); | |
54 | ||
55 | return count; | |
56 | } | |
57 | ||
f4e73bfc KS |
58 | static DEVICE_ATTR(userimask, S_IRUSR | S_IWUSR, |
59 | show_intc_userimask, store_intc_userimask); | |
2be6bb0c PM |
60 | |
61 | ||
62 | static int __init userimask_sysdev_init(void) | |
63 | { | |
64 | if (unlikely(!uimask)) | |
65 | return -ENXIO; | |
66 | ||
f4e73bfc | 67 | return device_create_file(intc_subsys.dev_root, &dev_attr_userimask); |
2be6bb0c PM |
68 | } |
69 | late_initcall(userimask_sysdev_init); | |
70 | ||
71 | int register_intc_userimask(unsigned long addr) | |
72 | { | |
73 | if (unlikely(uimask)) | |
74 | return -EBUSY; | |
75 | ||
76 | uimask = ioremap_nocache(addr, SZ_4K); | |
77 | if (unlikely(!uimask)) | |
78 | return -ENOMEM; | |
79 | ||
80 | pr_info("userimask support registered for levels 0 -> %d\n", | |
81 | intc_get_dfl_prio_level() - 1); | |
82 | ||
83 | return 0; | |
84 | } |