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