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