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path: root/drivers/sh/intc/userimask.c
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Diffstat (limited to 'drivers/sh/intc/userimask.c')
-rw-r--r--drivers/sh/intc/userimask.c83
1 files changed, 83 insertions, 0 deletions
diff --git a/drivers/sh/intc/userimask.c b/drivers/sh/intc/userimask.c
new file mode 100644
index 000000000000..e32304b66cf1
--- /dev/null
+++ b/drivers/sh/intc/userimask.c
@@ -0,0 +1,83 @@
+/*
+ * 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/sysdev.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <asm/sizes.h>
+#include "internals.h"
+
+static void __iomem *uimask;
+
+static ssize_t
+show_intc_userimask(struct sysdev_class *cls,
+ struct sysdev_class_attribute *attr, char *buf)
+{
+ return sprintf(buf, "%d\n", (__raw_readl(uimask) >> 4) & 0xf);
+}
+
+static ssize_t
+store_intc_userimask(struct sysdev_class *cls,
+ struct sysdev_class_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 SYSDEV_CLASS_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 sysdev_class_create_file(&intc_sysdev_class, &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;
+}