[ARM] nommu: manage the CP15 things

All the current CP15 access codes in ARM arch can be categorized and
conditioned by the defines as follows:

     Related operation	Safe condition
  a. any CP15 access	!CPU_CP15
  b. alignment trap	CPU_CP15_MMU
  c. D-cache(C-bit)	CPU_CP15
  d. I-cache		CPU_CP15 && !( CPU_ARM610 || CPU_ARM710 ||
				CPU_ARM720 || CPU_ARM740 ||
				CPU_XSCALE || CPU_XSC3 )
  e. alternate vector	CPU_CP15 && !CPU_ARM740
  f. TTB		CPU_CP15_MMU
  g. Domain		CPU_CP15_MMU
  h. FSR/FAR		CPU_CP15_MMU

For example, alternate vector is supported if and only if
"CPU_CP15 && !CPU_ARM740" is satisfied.
Signed-off-by: Hyok S. Choi <hyok.choi@samsung.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/Kconfig

@@ -621,6 +621,7 @@ config LEDS_CPU
 
 config ALIGNMENT_TRAP
 	bool
+	depends on CPU_CP15_MMU
 	default y if !ARCH_EBSA110
 	help
 	  ARM processors can not fetch/store information which is not
@@ -852,7 +853,7 @@ source "drivers/base/Kconfig"
 
 source "drivers/connector/Kconfig"
 
-if ALIGNMENT_TRAP
+if ALIGNMENT_TRAP || !CPU_CP15_MMU
 source "drivers/mtd/Kconfig"
 endif
 

arch/arm/Kconfig-nommu

@@ -25,6 +25,14 @@ config FLASH_SIZE
 	hex 'FLASH Size' if SET_MEM_PARAM
 	default 0x00400000
 
+config PROCESSOR_ID
+	hex
+	default 0x00007700
+	depends on !CPU_CP15
+	help
+	  If processor has no CP15 register, this processor ID is
+	  used instead of the auto-probing which utilizes the register.
+
 config REMAP_VECTORS_TO_RAM
 	bool 'Install vectors to the begining of RAM' if DRAM_BASE
 	depends on DRAM_BASE

arch/arm/boot/compressed/Makefile

@@ -51,7 +51,11 @@ OBJS		+= head-at91rm9200.o
 endif
 
 ifeq ($(CONFIG_CPU_BIG_ENDIAN),y)
+ifeq ($(CONFIG_CPU_CP15),y)
 OBJS		+= big-endian.o
+else
+# The endian should be set by h/w design.
+endif
 endif
 
 #

arch/arm/boot/compressed/head.S

@@ -82,9 +82,11 @@
 		kphex	r6, 8		/* processor id */
 		kputc	#':'
 		kphex	r7, 8		/* architecture id */
+#ifdef CONFIG_CPU_CP15
 		kputc	#':'
 		mrc	p15, 0, r0, c1, c0
 		kphex	r0, 8		/* control reg */
+#endif
 		kputc	#'\n'
 		kphex	r5, 8		/* decompressed kernel start */
 		kputc	#'-'
@@ -507,7 +509,11 @@ call_kernel:	bl	cache_clean_flush
  */
 
 call_cache_fn:	adr	r12, proc_types
+#ifdef CONFIG_CPU_CP15
 		mrc	p15, 0, r6, c0, c0	@ get processor ID
+#else
+		ldr	r6, =CONFIG_PROCESSOR_ID
+#endif
 1:		ldr	r1, [r12, #0]		@ get value
 		ldr	r2, [r12, #4]		@ get mask
 		eor	r1, r1, r6		@ (real ^ match)

arch/arm/kernel/head-nommu.S

@@ -9,7 +9,6 @@
  * published by the Free Software Foundation.
  *
  *  Common kernel startup code (non-paged MM)
- *    for 32-bit CPUs which has a process ID register(CP15).
  *
  */
 #include <linux/linkage.h>
@@ -40,7 +39,11 @@
 ENTRY(stext)
 	msr	cpsr_c, #PSR_F_BIT | PSR_I_BIT | SVC_MODE @ ensure svc mode
 						@ and irqs disabled
+#ifndef CONFIG_CPU_CP15
+	ldr	r9, =CONFIG_PROCESSOR_ID
+#else
 	mrc	p15, 0, r9, c0, c0		@ get processor id
+#endif
 	bl	__lookup_processor_type		@ r5=procinfo r9=cpuid
 	movs	r10, r5				@ invalid processor (r5=0)?
 	beq	__error_p				@ yes, error 'p'
@@ -58,6 +61,7 @@ ENTRY(stext)
  */
 	.type	__after_proc_init, %function
 __after_proc_init:
+#ifdef CONFIG_CPU_CP15
 	mrc	p15, 0, r0, c1, c0, 0		@ read control reg
 #ifdef CONFIG_ALIGNMENT_TRAP
 	orr	r0, r0, #CR_A
@@ -74,6 +78,7 @@ __after_proc_init:
 	bic	r0, r0, #CR_I
 #endif
 	mcr	p15, 0, r0, c1, c0, 0		@ write control reg
+#endif /* CONFIG_CPU_CP15 */
 
 	mov	pc, r13				@ clear the BSS and jump
 						@ to start_kernel

arch/arm/kernel/process.c

@@ -221,16 +221,26 @@ void __show_regs(struct pt_regs *regs)
 		processor_modes[processor_mode(regs)],
 		thumb_mode(regs) ? " (T)" : "",
 		get_fs() == get_ds() ? "kernel" : "user");
+#if CONFIG_CPU_CP15
 	{
-		unsigned int ctrl, transbase, dac;
+		unsigned int ctrl;
 		  __asm__ (
 		"	mrc p15, 0, %0, c1, c0\n"
-		"	mrc p15, 0, %1, c2, c0\n"
-		"	mrc p15, 0, %2, c3, c0\n"
-		: "=r" (ctrl), "=r" (transbase), "=r" (dac));
-		printk("Control: %04X  Table: %08X  DAC: %08X\n",
-		  	ctrl, transbase, dac);
+		: "=r" (ctrl));
+		printk("Control: %04X\n", ctrl);
 	}
+#ifdef CONFIG_CPU_CP15_MMU
+	{
+		unsigned int transbase, dac;
+		  __asm__ (
+		"	mrc p15, 0, %0, c2, c0\n"
+		"	mrc p15, 0, %1, c3, c0\n"
+		: "=r" (transbase), "=r" (dac));
+		printk("Table: %08X  DAC: %08X\n",
+		  	transbase, dac);
+	}
+#endif
+#endif
 }
 
 void show_regs(struct pt_regs * regs)

arch/arm/mm/Kconfig

@@ -445,15 +445,15 @@ config CPU_BIG_ENDIAN
 	  of your chipset/board/processor.
 
 config CPU_ICACHE_DISABLE
-	bool "Disable I-Cache"
-	depends on CPU_ARM920T || CPU_ARM922T || CPU_ARM925T || CPU_ARM926T || CPU_ARM1020 || CPU_V6
+	bool "Disable I-Cache (I-bit)"
+	depends on CPU_CP15 && !(CPU_ARM610 || CPU_ARM710 || CPU_ARM720T || CPU_ARM740T || CPU_XSCALE || CPU_XSC3)
 	help
 	  Say Y here to disable the processor instruction cache. Unless
 	  you have a reason not to or are unsure, say N.
 
 config CPU_DCACHE_DISABLE
-	bool "Disable D-Cache"
-	depends on CPU_ARM920T || CPU_ARM922T || CPU_ARM925T || CPU_ARM926T || CPU_ARM1020 || CPU_V6
+	bool "Disable D-Cache (C-bit)"
+	depends on CPU_CP15
 	help
 	  Say Y here to disable the processor data cache. Unless
 	  you have a reason not to or are unsure, say N.

arch/arm/mm/cache-v4.S

@@ -29,9 +29,13 @@ ENTRY(v4_flush_user_cache_all)
  *	Clean and invalidate the entire cache.
  */
 ENTRY(v4_flush_kern_cache_all)
+#ifdef CPU_CP15
 	mov	r0, #0
 	mcr	p15, 0, r0, c7, c7, 0		@ flush ID cache
 	mov	pc, lr
+#else
+	/* FALLTHROUGH */
+#endif
 
 /*
  *	flush_user_cache_range(start, end, flags)
@@ -44,9 +48,13 @@ ENTRY(v4_flush_kern_cache_all)
  *	- flags	- vma_area_struct flags describing address space
  */
 ENTRY(v4_flush_user_cache_range)
+#ifdef CPU_CP15
 	mov	ip, #0
 	mcreq	p15, 0, ip, c7, c7, 0		@ flush ID cache
 	mov	pc, lr
+#else
+	/* FALLTHROUGH */
+#endif
 
 /*
  *	coherent_kern_range(start, end)
@@ -108,8 +116,10 @@ ENTRY(v4_dma_inv_range)
  *	- end	 - virtual end address
  */
 ENTRY(v4_dma_flush_range)
+#ifdef CPU_CP15
 	mov	r0, #0
 	mcr	p15, 0, r0, c7, c7, 0		@ flush ID cache
+#endif
 	/* FALLTHROUGH */
 
 /*

include/asm-arm/system.h

@@ -46,6 +46,7 @@
 #define CPUID_TCM	2
 #define CPUID_TLBTYPE	3
 
+#ifdef CONFIG_CPU_CP15
 #define read_cpuid(reg)							\
 	({								\
 		unsigned int __val;					\
@@ -55,6 +56,9 @@
 		    : "cc");						\
 		__val;							\
 	})
+#else
+#define read_cpuid(reg) (processor_id)
+#endif
 
 /*
  * This is used to ensure the compiler did actually allocate the register we