i.MX51: determine silicon revision dynamically

Freescale redboot passes the silicon revision via
ATAG_REVISION. Remove this bootloader dependency by
doing the same as redboot does in the Kernel.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

2 files changed, 60 insertions, 6 deletions

diff --git a/arch/arm/mach-mx5/cpu.c b/arch/arm/mach-mx5/cpu.c
index 41c769f08c4d..2d37785e3857 100644
--- a/arch/arm/mach-mx5/cpu.c
+++ b/arch/arm/mach-mx5/cpu.c
@@ -14,9 +14,62 @@
 #include <linux/types.h>
 #include <linux/kernel.h>
 #include <linux/init.h>
+#include <linux/module.h>
 #include <mach/hardware.h>
 #include <asm/io.h>
 
+static int cpu_silicon_rev = -1;
+
+#define SI_REV 0x48
+
+static void query_silicon_parameter(void)
+{
+        void __iomem *rom = ioremap(MX51_IROM_BASE_ADDR, MX51_IROM_SIZE);
+        u32 rev;
+
+        if (!rom) {
+                cpu_silicon_rev = -EINVAL;
+                return;
+        }
+
+        rev = readl(rom + SI_REV);
+        switch (rev) {
+        case 0x1:
+                cpu_silicon_rev = MX51_CHIP_REV_1_0;
+                break;
+        case 0x2:
+                cpu_silicon_rev = MX51_CHIP_REV_1_1;
+                break;
+        case 0x10:
+                cpu_silicon_rev = MX51_CHIP_REV_2_0;
+                break;
+        case 0x20:
+                cpu_silicon_rev = MX51_CHIP_REV_3_0;
+                break;
+        default:
+                cpu_silicon_rev = 0;
+        }
+
+        iounmap(rom);
+}
+
+/*
+ * Returns:
+ *      the silicon revision of the cpu
+ *      -EINVAL - not a mx51
+ */
+int mx51_revision(void)
+{
+        if (!cpu_is_mx51())
+                return -EINVAL;
+
+        if (cpu_silicon_rev == -1)
+                query_silicon_parameter();
+
+        return cpu_silicon_rev;
+}
+EXPORT_SYMBOL(mx51_revision);
+
 static int __init post_cpu_init(void)
 {
         unsigned int reg;
diff --git a/arch/arm/plat-mxc/include/mach/mx51.h b/arch/arm/plat-mxc/include/mach/mx51.h
index f1396bd5621f..fd255a9dbcdc 100644
--- a/arch/arm/plat-mxc/include/mach/mx51.h
+++ b/arch/arm/plat-mxc/include/mach/mx51.h
@@ -28,6 +28,12 @@
  */
 
 /*
+ * IROM
+ */
+#define MX51_IROM_BASE_ADDR             0x0
+#define MX51_IROM_SIZE                  SZ_64K
+
+/*
  * IRAM
  */
 #define MX51_IRAM_BASE_ADDR             0x1FFE0000      /* internal ram */
@@ -438,12 +444,7 @@
 
 #if !defined(__ASSEMBLY__) && !defined(__MXC_BOOT_UNCOMPRESS)
 
-extern unsigned int system_rev;
-
-static inline unsigned int mx51_revision(void)
-{
-        return system_rev;
-}
+extern int mx51_revision(void);
 #endif
 
 #endif  /*  __ASM_ARCH_MXC_MX51_H__ */