[ARM] 4712/2: Adds functions to read and write IXP4xx "feature" bits

Adds functions to read and write IXP4xx "feature" (aka "fuse")
bits, containing information about available/enabled CPU features.

The uncompress.h included by boot/compressed/misc.c resides in
a different space than rest of the kernel and thus can't use
asm/hardware.h (including asm/arch/cpu.h - which, in turn, may use
EXPORTed symbol "processor_id").

Posted to linux-arm-kernel on 2 Dec 2007 and revised.

Signed-off-by: Krzysztof Halasa <[e-mail]>
Signed-off-by: Russell King <[e-mail]>

arch/arm/kernel/setup.c

···
 extern void _stext, _text, _etext, __data_start, _edata, _end;
 
 unsigned int processor_id;
+EXPORT_SYMBOL(processor_id);
 unsigned int __machine_arch_type;
 EXPORT_SYMBOL(__machine_arch_type);
 

include/asm-arm/arch-ixp4xx/cpu.h

···
 #define cpu_is_ixp46x()	((processor_id & IXP4XX_PROCESSOR_ID_MASK) == \
 			  IXP465_PROCESSOR_ID_VALUE)
 
+static inline u32 ixp4xx_read_feature_bits(void)
+{
+	unsigned int val = ~*IXP4XX_EXP_CFG2;
+	val &= ~IXP4XX_FEATURE_RESERVED;
+	if (!cpu_is_ixp46x())
+		val &= ~IXP4XX_FEATURE_IXP46X_ONLY;
+
+	return val;
+}
+
+static inline void ixp4xx_write_feature_bits(u32 value)
+{
+	*IXP4XX_EXP_CFG2 = ~value;
+}
+
 #endif  /* _ASM_ARCH_CPU_H */

include/asm-arm/arch-ixp4xx/hardware.h

···
 
 #define pcibios_assign_all_busses()	1
 
+/* Register locations and bits */
+#include "ixp4xx-regs.h"
+
 #ifndef __ASSEMBLER__
 #include <asm/arch/cpu.h>
 #endif
-
-/* Register locations and bits */
-#include "ixp4xx-regs.h"
 
 /* Platform helper functions and definitions */
 #include "platform.h"

include/asm-arm/arch-ixp4xx/ixp4xx-regs.h

···
  *
  */
 
-#ifndef __ASM_ARCH_HARDWARE_H__
-#error "Do not include this directly, instead #include <asm/hardware.h>"
-#endif
-
 #ifndef _ASM_ARM_IXP4XX_H_
 #define _ASM_ARM_IXP4XX_H_
 
···
 #define USIR1_IR15	(1 << 7)	/* Interrup request ep 15 */
 
 #define DCMD_LENGTH	0x01fff		/* length mask (max = 8K - 1) */
+
+/* "fuse" bits of IXP_EXP_CFG2 */
+#define IXP4XX_FEATURE_RCOMP		(1 << 0)
+#define IXP4XX_FEATURE_USB_DEVICE	(1 << 1)
+#define IXP4XX_FEATURE_HASH		(1 << 2)
+#define IXP4XX_FEATURE_AES		(1 << 3)
+#define IXP4XX_FEATURE_DES		(1 << 4)
+#define IXP4XX_FEATURE_HDLC		(1 << 5)
+#define IXP4XX_FEATURE_AAL		(1 << 6)
+#define IXP4XX_FEATURE_HSS		(1 << 7)
+#define IXP4XX_FEATURE_UTOPIA		(1 << 8)
+#define IXP4XX_FEATURE_NPEB_ETH0	(1 << 9)
+#define IXP4XX_FEATURE_NPEC_ETH		(1 << 10)
+#define IXP4XX_FEATURE_RESET_NPEA	(1 << 11)
+#define IXP4XX_FEATURE_RESET_NPEB	(1 << 12)
+#define IXP4XX_FEATURE_RESET_NPEC	(1 << 13)
+#define IXP4XX_FEATURE_PCI		(1 << 14)
+#define IXP4XX_FEATURE_ECC_TIMESYNC	(1 << 15)
+#define IXP4XX_FEATURE_UTOPIA_PHY_LIMIT	(3 << 16)
+#define IXP4XX_FEATURE_USB_HOST		(1 << 18)
+#define IXP4XX_FEATURE_NPEA_ETH		(1 << 19)
+#define IXP4XX_FEATURE_NPEB_ETH_1_TO_3	(1 << 20)
+#define IXP4XX_FEATURE_RSA		(1 << 21)
+#define IXP4XX_FEATURE_XSCALE_MAX_FREQ	(3 << 22)
+#define IXP4XX_FEATURE_RESERVED		(0xFF << 24)
+
+#define IXP4XX_FEATURE_IXP46X_ONLY (IXP4XX_FEATURE_ECC_TIMESYNC |	\
+				    IXP4XX_FEATURE_USB_HOST |		\
+				    IXP4XX_FEATURE_NPEA_ETH |		\
+				    IXP4XX_FEATURE_NPEB_ETH_1_TO_3 |	\
+				    IXP4XX_FEATURE_RSA |		\
+				    IXP4XX_FEATURE_XSCALE_MAX_FREQ)
 
 #endif

include/asm-arm/arch-ixp4xx/uncompress.h

···
 #ifndef _ARCH_UNCOMPRESS_H_
 #define _ARCH_UNCOMPRESS_H_
 
-#include <asm/hardware.h>
+#include "ixp4xx-regs.h"
 #include <asm/mach-types.h>
 #include <linux/serial_reg.h>