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
  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         if (unlikely(!uimask))
  65                 return -ENXIO;
  66
  67         return device_create_file(intc_subsys.dev_root, &dev_attr_userimask);
  68 }
  69 late_initcall(userimask_sysdev_init);
  70
  71 int 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 }