ARM: mxs: detect SoC by checking CHIPID register

Both imx23 and imx28 have CHIPID register at address 0x8001c310, which
can be used to identify the SoC.  This patch changes cpu_is_xxx and
__arch_decomp_setup to use this CHIPID register than machine type to
detect the chip between imx23 and imx28, so that we do not need to
change these functions whenever a new board/machine gets added.
Suggested-by: Wolfram Sang <w.sang@pengutronix.de>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Acked-by: Wolfram Sang <w.sang@pengutronix.de>

arch/arm/mach-mxs/include/mach/digctl.h

@@ -18,4 +18,5 @@
 #define HW_DIGCTL_CTRL			0x0
 #define  BP_DIGCTL_CTRL_SAIF_CLKMUX	10
 #define  BM_DIGCTL_CTRL_SAIF_CLKMUX	(0x3 << 10)
+#define HW_DIGCTL_CHIPID		0x310
 #endif

arch/arm/mach-mxs/include/mach/mxs.h

@@ -23,21 +23,9 @@
 #include <linux/io.h>
 #endif
 #include <asm/mach-types.h>
+#include <mach/digctl.h>
 #include <mach/hardware.h>
 
-/*
- * MXS CPU types
- */
-#define cpu_is_mx23()		(					\
-		machine_is_mx23evk() ||					\
-		machine_is_stmp378x() ||				\
-		0)
-#define cpu_is_mx28()		(					\
-		machine_is_mx28evk() ||					\
-		machine_is_m28evk() ||					\
-		machine_is_tx28() ||					\
-		0)
-
 /*
  * IO addresses common to MXS-based
  */
@@ -109,6 +97,21 @@ static inline void __mxs_togl(u32 mask, void __iomem *reg)
 {
 	__raw_writel(mask, reg + MXS_TOG_ADDR);
 }
+
+/*
+ * MXS CPU types
+ */
+#define MXS_CHIPID (MXS_IO_ADDRESS(MXS_DIGCTL_BASE_ADDR) + HW_DIGCTL_CHIPID)
+
+static inline int cpu_is_mx23(void)
+{
+	return ((__raw_readl(MXS_CHIPID) >> 16) == 0x3780);
+}
+
+static inline int cpu_is_mx28(void)
+{
+	return ((__raw_readl(MXS_CHIPID) >> 16) == 0x2800);
+}
 #endif
 
 #endif /* __MACH_MXS_H__ */

arch/arm/mach-mxs/include/mach/uncompress.h

@@ -18,8 +18,6 @@
 #ifndef __MACH_MXS_UNCOMPRESS_H__
 #define __MACH_MXS_UNCOMPRESS_H__
 
-#include <asm/mach-types.h>
-
 unsigned long mxs_duart_base;
 
 #define MXS_DUART(x)	(*(volatile unsigned long *)(mxs_duart_base + (x)))
@@ -55,16 +53,17 @@ static inline void flush(void)
 
 #define MX23_DUART_BASE_ADDR	0x80070000
 #define MX28_DUART_BASE_ADDR	0x80074000
+#define MXS_DIGCTL_CHIPID	0x8001c310
 
 static inline void __arch_decomp_setup(unsigned long arch_id)
 {
-	switch (arch_id) {
-	case MACH_TYPE_MX23EVK:
+	u16 chipid = (*(volatile unsigned long *) MXS_DIGCTL_CHIPID) >> 16;
+
+	switch (chipid) {
+	case 0x3780:
 		mxs_duart_base = MX23_DUART_BASE_ADDR;
 		break;
-	case MACH_TYPE_MX28EVK:
-	case MACH_TYPE_M28EVK:
-	case MACH_TYPE_TX28:
+	case 0x2800:
 		mxs_duart_base = MX28_DUART_BASE_ADDR;
 		break;
 	default: