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
  19 static void __iomem *uimask;
  20
  21 static ssize_t
  22 show_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
  28 static ssize_t
  29 store_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
  57 static SYSDEV_CLASS_ATTR(userimask, S_IRUSR | S_IWUSR,
  58                          show_intc_userimask, store_intc_userimask);
  59
  60
  61 static 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 }
  68 late_initcall(userimask_sysdev_init);
  69
  70 int 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 }