LXR linux/drivers/sh/intc/userimask.c

   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
  20static void __iomem *uimask;
  21
  22static ssize_t
  23show_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
  29static ssize_t
  30store_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
  58static DEVICE_ATTR(userimask, S_IRUSR | S_IWUSR,
  59                   show_intc_userimask, store_intc_userimask);
  60
  61
  62static int __init userimask_sysdev_init(void)
  63{
  64        if (unlikely(!uimask))
  65                return -ENXIO;
  66
  67        return device_create_file(intc_subsys.dev_root, &dev_attr_userimask);
  68}
  69late_initcall(userimask_sysdev_init);
  70
  71int register_intc_userimask(unsigned long addr)
  72{
  73        if (unlikely(uimask))
  74                return -EBUSY;
  75
  76        uimask = ioremap(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}
  85