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, "%d\n", (__raw_readl(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(0xa5 << 24 | level << 4, 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(&intc_subsys); 71 if (dev_root) { 72 ret = device_create_file(dev_root, &dev_attr_userimask); 73 put_device(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(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