[i.MX] add function to determine chip revision

arch/arm/mach-imx/Makefile

@@ -1,6 +1,6 @@
 obj-y += clocksource.o
 obj-$(CONFIG_ARCH_IMX1) += speed-imx1.o gpio.o
-obj-$(CONFIG_ARCH_IMX27) += speed-imx27.o gpio.o
+obj-$(CONFIG_ARCH_IMX27) += speed-imx27.o gpio.o imx27.o
 obj-$(CONFIG_ARCH_IMX31) += speed-imx31.o gpio-imx31.o
 obj-y += speed.o
 

arch/arm/mach-imx/imx27.c

@@ -0,0 +1,25 @@
+/*
+ * 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; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#include <common.h>
+#include <asm/arch/imx-regs.h>
+
+int imx_silicon_revision(void)
+{
+        return CID >> 28;
+}
+

include/asm-arm/arch-imx/generic.h

@@ -0,0 +1,4 @@
+
+int imx_silicon_revision(void);
+#define IMX27_CHIP_REVISION_1_0   0
+#define IMX27_CHIP_REVISION_2_0   1