1 files changed, 84 insertions, 0 deletions
diff --git a/kernel/drivers/sh/intc/userimask.c b/kernel/drivers/sh/intc/userimask.c
new file mode 100644
index 000000000..e649ceaaa
--- /dev/null
+++ b/kernel/drivers/sh/intc/userimask.c
@@ -0,0 +1,84 @@
+/*
+ * 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\n", (__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\n",
+		intc_get_dfl_prio_level() - 1);
+
+	return 0;
+}