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/device.h> |
14 | #include <linux/init.h> |
15 | #include <linux/io.h> |
16 | #include <linux/stat.h> |
17 | #include <linux/sizes.h> |
18 | #include "internals.h" |
19 | |
20 | static void __iomem *uimask; |
21 | |
22 | static ssize_t |
23 | show_intc_userimask(struct device *dev, |
24 | struct device_attribute *attr, char *buf) |
25 | { |
26 | return sprintf(buf, fmt: "%d\n" , (__raw_readl(addr: uimask) >> 4) & 0xf); |
27 | } |
28 | |
29 | static ssize_t |
30 | store_intc_userimask(struct device *dev, |
31 | struct device_attribute *attr, |
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(val: 0xa5 << 24 | level << 4, addr: uimask); |
54 | |
55 | return count; |
56 | } |
57 | |
58 | static DEVICE_ATTR(userimask, S_IRUSR | S_IWUSR, |
59 | show_intc_userimask, store_intc_userimask); |
60 | |
61 | |
62 | static int __init userimask_sysdev_init(void) |
63 | { |
64 | struct device *dev_root; |
65 | int ret = 0; |
66 | |
67 | if (unlikely(!uimask)) |
68 | return -ENXIO; |
69 | |
70 | dev_root = bus_get_dev_root(bus: &intc_subsys); |
71 | if (dev_root) { |
72 | ret = device_create_file(device: dev_root, entry: &dev_attr_userimask); |
73 | put_device(dev: dev_root); |
74 | } |
75 | return ret; |
76 | } |
77 | late_initcall(userimask_sysdev_init); |
78 | |
79 | int register_intc_userimask(unsigned long addr) |
80 | { |
81 | if (unlikely(uimask)) |
82 | return -EBUSY; |
83 | |
84 | uimask = ioremap(offset: addr, SZ_4K); |
85 | if (unlikely(!uimask)) |
86 | return -ENOMEM; |
87 | |
88 | pr_info("userimask support registered for levels 0 -> %d\n" , |
89 | intc_get_dfl_prio_level() - 1); |
90 | |
91 | return 0; |
92 | } |
93 | |