ARM: imx31: Fix IIM mapping leak in revision check

[ Upstream commit ccb4b54 ]

mx31_read_cpu_rev() maps the IIM registers with of_iomap() to read the
silicon revision, but returns without unmapping the MMIO mapping.

Keep the normalized revision value in a local variable and route the
return path through iounmap() after the revision register has been read.

Fixes: 3172225 ("ARM: imx31: Retrieve the IIM base address from devicetree")
Signed-off-by: Yuho Choi <dbgh9129@gmail.com>
Signed-off-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: Uuuuuuho

arch/arm/mach-imx/cpu-imx31.c

@@ -36,6 +36,7 @@ static int mx31_read_cpu_rev(void)
 	void __iomem *iim_base;
 	struct device_node *np;
 	u32 i, srev;
+	int rev = IMX_CHIP_REVISION_UNKNOWN;
 
 	np = of_find_compatible_node(NULL, NULL, "fsl,imx31-iim");
 	iim_base = of_iomap(np, 0);
@@ -48,13 +49,17 @@ static int mx31_read_cpu_rev(void)
 
 	for (i = 0; i < ARRAY_SIZE(mx31_cpu_type); i++)
 		if (srev == mx31_cpu_type[i].srev) {
+			rev = mx31_cpu_type[i].rev;
 			imx_print_silicon_rev(mx31_cpu_type[i].name,
 						mx31_cpu_type[i].rev);
-			return mx31_cpu_type[i].rev;
+			goto out;
 		}
 
 	imx_print_silicon_rev("i.MX31", IMX_CHIP_REVISION_UNKNOWN);
-	return IMX_CHIP_REVISION_UNKNOWN;
+
+out:
+	iounmap(iim_base);
+	return rev;
 }
 
 int mx31_revision(void)