Fixed mips_io_port_base build errors.
This patch has been sent on:
- 29 Sep 2007
Although mips_io_port_base is currently a part of IDE command, it is quite
fundamental for MIPS I/O port access such as in[bwl] and out[bwl]. So move
it to MIPS general part, and introduce `set_io_port_base()' from Linux.
This patch is triggered by multiple definition of `mips_io_port_base' build
error on gth2 (and tb0229 also needs this fix.)
board/gth2/libgth2.a(gth2.o): In function `log_serial_char':
/home/skuribay/devel/u-boot.git/board/gth2/gth2.c:47: multiple definition of `mips_io_port_base'
common/libcommon.a(cmd_ide.o):/home/skuribay/devel/u-boot.git/common/cmd_ide.c:712: first defined here
make: *** [u-boot] Error 1
Signed-off-by: Shinya Kuribayashi <skuribay@ruby.dti.ne.jp>
Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
diff --git a/include/asm-mips/io.h b/include/asm-mips/io.h
index cd4d5dc..1e060f7 100644
--- a/include/asm-mips/io.h
+++ b/include/asm-mips/io.h
@@ -71,7 +71,21 @@
* instruction, so the lower 16 bits must be zero. Should be true on
* on any sane architecture; generic code does not use this assumption.
*/
-extern unsigned long mips_io_port_base;
+extern const unsigned long mips_io_port_base;
+
+/*
+ * Gcc will generate code to load the value of mips_io_port_base after each
+ * function call which may be fairly wasteful in some cases. So we don't
+ * play quite by the book. We tell gcc mips_io_port_base is a long variable
+ * which solves the code generation issue. Now we need to violate the
+ * aliasing rules a little to make initialization possible and finally we
+ * will need the barrier() to fight side effects of the aliasing chat.
+ * This trickery will eventually collapse under gcc's optimizer. Oh well.
+ */
+static inline void set_io_port_base(unsigned long base)
+{
+ * (unsigned long *) &mips_io_port_base = base;
+}
/*
* Thanks to James van Artsdalen for a better timing-fix than