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kernel/linux-imx6_3.14.28/drivers/sh/intc/userimask.c 2.05 KB
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  /*
   * Support for hardware-assisted userspace interrupt masking.
   *
   * Copyright (C) 2010  Paul Mundt
   *
   * This file is subject to the terms and conditions of the GNU General Public
   * License.  See the file "COPYING" in the main directory of this archive
   * for more details.
   */
  #define pr_fmt(fmt) "intc: " fmt
  
  #include <linux/errno.h>
  #include <linux/device.h>
  #include <linux/init.h>
  #include <linux/io.h>
  #include <linux/stat.h>
  #include <asm/sizes.h>
  #include "internals.h"
  
  static void __iomem *uimask;
  
  static ssize_t
  show_intc_userimask(struct device *dev,
  		    struct device_attribute *attr, char *buf)
  {
  	return sprintf(buf, "%d
  ", (__raw_readl(uimask) >> 4) & 0xf);
  }
  
  static ssize_t
  store_intc_userimask(struct device *dev,
  		     struct device_attribute *attr,
  		     const char *buf, size_t count)
  {
  	unsigned long level;
  
  	level = simple_strtoul(buf, NULL, 10);
  
  	/*
  	 * Minimal acceptable IRQ levels are in the 2 - 16 range, but
  	 * these are chomped so as to not interfere with normal IRQs.
  	 *
  	 * Level 1 is a special case on some CPUs in that it's not
  	 * directly settable, but given that USERIMASK cuts off below a
  	 * certain level, we don't care about this limitation here.
  	 * Level 0 on the other hand equates to user masking disabled.
  	 *
  	 * We use the default priority level as a cut off so that only
  	 * special case opt-in IRQs can be mangled.
  	 */
  	if (level >= intc_get_dfl_prio_level())
  		return -EINVAL;
  
  	__raw_writel(0xa5 << 24 | level << 4, uimask);
  
  	return count;
  }
  
  static DEVICE_ATTR(userimask, S_IRUSR | S_IWUSR,
  		   show_intc_userimask, store_intc_userimask);
  
  
  static int __init userimask_sysdev_init(void)
  {
  	if (unlikely(!uimask))
  		return -ENXIO;
  
  	return device_create_file(intc_subsys.dev_root, &dev_attr_userimask);
  }
  late_initcall(userimask_sysdev_init);
  
  int register_intc_userimask(unsigned long addr)
  {
  	if (unlikely(uimask))
  		return -EBUSY;
  
  	uimask = ioremap_nocache(addr, SZ_4K);
  	if (unlikely(!uimask))
  		return -ENOMEM;
  
  	pr_info("userimask support registered for levels 0 -> %d
  ",
  		intc_get_dfl_prio_level() - 1);
  
  	return 0;
  }