powerpc: Split-out common MSI bitmap logic into msi_bitmap.c

There are now two almost identical implementations of an MSI bitmap
allocator, one in mpic_msi.c and the other in fsl_msi.c.

Merge them together and put the result in msi_bitmap.c.  Some of the
MPIC bits will remain to provide a nicer interface for the MPIC users.

In the process we fix two buglets.  The first is that the allocation
routines, now msi_bitmap_alloc_hwirqs(), returned an unsigned result,
even though they use -1 to indicate allocation failure.  Although all
the callers were checking correctly, it is much better for the routine
to just return an int.  At least until someone wants > ~2 billion MSIs.

The second buglet is that the device tree reservation logic only
allowed power-of-two reservations.  AFAICT that didn't effect any
existing code but it's nicer if we can reserve arbitrary irqs from MSI
use.

We also add some selftests, which exposed the two buglets and now test
for them, as well as some basic sanity tests.  The tests are only built
when CONFIG_DEBUG_KERNEL=y.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 35 insertions, 0 deletions

diff --git a/arch/powerpc/include/asm/msi_bitmap.h b/arch/powerpc/include/asm/msi_bitmap.h
new file mode 100644
index 000000000000..97ac3f46ae0d
--- /dev/null
+++ b/arch/powerpc/include/asm/msi_bitmap.h
@@ -0,0 +1,35 @@
+#ifndef _POWERPC_SYSDEV_MSI_BITMAP_H
+#define _POWERPC_SYSDEV_MSI_BITMAP_H
+
+/*
+ * Copyright 2008, Michael Ellerman, IBM Corporation.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; version 2 of the
+ * License.
+ *
+ */
+
+#include <linux/of.h>
+#include <asm/irq.h>
+
+struct msi_bitmap {
+	struct device_node	*of_node;
+	unsigned long		*bitmap;
+	spinlock_t		lock;
+	unsigned int		irq_count;
+};
+
+int msi_bitmap_alloc_hwirqs(struct msi_bitmap *bmp, int num);
+void msi_bitmap_free_hwirqs(struct msi_bitmap *bmp, unsigned int offset,
+			    unsigned int num);
+void msi_bitmap_reserve_hwirq(struct msi_bitmap *bmp, unsigned int hwirq);
+
+int msi_bitmap_reserve_dt_hwirqs(struct msi_bitmap *bmp);
+
+int msi_bitmap_alloc(struct msi_bitmap *bmp, unsigned int irq_count,
+		     struct device_node *of_node);
+void msi_bitmap_free(struct msi_bitmap *bmp);
+
+#endif /* _POWERPC_SYSDEV_MSI_BITMAP_H */