ARM: Defer lookup of machine_type to setup.c

Since the debug macros no longer depend on the machine type information,
the machine type lookup can be deferred to setup_arch() in setup.c which
simplifies the code somewhat.

We also move the __error_a functionality into setup.c for displaying a
message when a bad machine ID is passed to the kernel via the LL debug
code.  We also log this into the kernel ring buffer which makes it
possible to retrieve the message via a debugger.

Original idea from Grant Likely.
Acked-by: NGrant Likely <grant.likely@secretlab.ca>
Tested-by: NTony Lindgren <tony@atomide.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

arch/arm/kernel/head-common.S

@@ -25,83 +25,6 @@
  * machine ID for example).
  */
 	__HEAD
-__error_a:
-#ifdef CONFIG_DEBUG_LL
-	mov	r4, r1				@ preserve machine ID
-	adr	r0, str_a1
-	bl	printascii
-	mov	r0, r4
-	bl	printhex8
-	adr	r0, str_a2
-	bl	printascii
-	adr	r3, __lookup_machine_type_data
-	ldmia	r3, {r4, r5, r6}		@ get machine desc list
-	sub	r4, r3, r4			@ get offset between virt&phys
-	add	r5, r5, r4			@ convert virt addresses to
-	add	r6, r6, r4			@ physical address space
-1:	ldr	r0, [r5, #MACHINFO_TYPE]	@ get machine type
-	bl	printhex8
-	mov	r0, #'\t'
-	bl	printch
-	ldr     r0, [r5, #MACHINFO_NAME]	@ get machine name
-	add	r0, r0, r4
-	bl	printascii
-	mov	r0, #'\n'
-	bl	printch
-	add	r5, r5, #SIZEOF_MACHINE_DESC	@ next machine_desc
-	cmp	r5, r6
-	blo	1b
-	adr	r0, str_a3
-	bl	printascii
-	b	__error
-ENDPROC(__error_a)
-
-str_a1:	.asciz	"\nError: unrecognized/unsupported machine ID (r1 = 0x"
-str_a2:	.asciz	").\n\nAvailable machine support:\n\nID (hex)\tNAME\n"
-str_a3:	.asciz	"\nPlease check your kernel config and/or bootloader.\n"
-	.align
-#else
-	b	__error
-#endif
-
-/*
- * Lookup machine architecture in the linker-build list of architectures.
- * Note that we can't use the absolute addresses for the __arch_info
- * lists since we aren't running with the MMU on (and therefore, we are
- * not in the correct address space).  We have to calculate the offset.
- *
- *  r1 = machine architecture number
- * Returns:
- *  r3, r4, r6 corrupted
- *  r5 = mach_info pointer in physical address space
- */
-__lookup_machine_type:
-	adr	r3, __lookup_machine_type_data
-	ldmia	r3, {r4, r5, r6}
-	sub	r3, r3, r4			@ get offset between virt&phys
-	add	r5, r5, r3			@ convert virt addresses to
-	add	r6, r6, r3			@ physical address space
-1:	ldr	r3, [r5, #MACHINFO_TYPE]	@ get machine type
-	teq	r3, r1				@ matches loader number?
-	beq	2f				@ found
-	add	r5, r5, #SIZEOF_MACHINE_DESC	@ next machine_desc
-	cmp	r5, r6
-	blo	1b
-	mov	r5, #0				@ unknown machine
-2:	mov	pc, lr
-ENDPROC(__lookup_machine_type)
-
-/*
- * Look in arch/arm/kernel/arch.[ch] for information about the
- * __arch_info structures.
- */
-	.align	2
-	.type	__lookup_machine_type_data, %object
-__lookup_machine_type_data:
-	.long	.
-	.long	__arch_info_begin
-	.long	__arch_info_end
-	.size	__lookup_machine_type_data, . - __lookup_machine_type_data
 
 /* Determine validity of the r2 atags pointer.  The heuristic requires
  * that the pointer be aligned, in the first 16k of physical RAM and
@@ -109,8 +32,6 @@ __lookup_machine_type_data:
  * of this function may be more lenient with the physical address and
  * may also be able to move the ATAGS block if necessary.
  *
- * r8  = machinfo
- *
  * Returns:
  *  r2 either valid atags pointer, or zero
  *  r5, r6 corrupted
@@ -184,17 +105,6 @@ __mmap_switched_data:
 	.long	init_thread_union + THREAD_START_SP @ sp
 	.size	__mmap_switched_data, . - __mmap_switched_data
 
-/*
- * This provides a C-API version of __lookup_machine_type
- */
-ENTRY(lookup_machine_type)
-	stmfd	sp!, {r4 - r6, lr}
-	mov	r1, r0
-	bl	__lookup_machine_type
-	mov	r0, r5
-	ldmfd	sp!, {r4 - r6, pc}
-ENDPROC(lookup_machine_type)
-
 /*
  * This provides a C-API version of __lookup_processor_type
  */

arch/arm/kernel/head-nommu.S

@@ -44,9 +44,6 @@ ENTRY(stext)
 	bl	__lookup_processor_type		@ r5=procinfo r9=cpuid
 	movs	r10, r5				@ invalid processor (r5=0)?
 	beq	__error_p				@ yes, error 'p'
-	bl	__lookup_machine_type		@ r5=machinfo
-	movs	r8, r5				@ invalid machine (r5=0)?
-	beq	__error_a			@ yes, error 'a'
 
 	adr	lr, BSYM(__after_proc_init)	@ return (PIC) address
  ARM(	add	pc, r10, #PROCINFO_INITFUNC	)

arch/arm/kernel/head.S

@@ -87,14 +87,10 @@ ENTRY(stext)
 	movs	r10, r5				@ invalid processor (r5=0)?
  THUMB( it	eq )		@ force fixup-able long branch encoding
 	beq	__error_p			@ yes, error 'p'
-	bl	__lookup_machine_type		@ r5=machinfo
-	movs	r8, r5				@ invalid machine (r5=0)?
- THUMB( it	eq )		@ force fixup-able long branch encoding
-	beq	__error_a			@ yes, error 'a'
 
 	/*
 	 * r1 = machine no, r2 = atags,
-	 * r8 = machinfo, r9 = cpuid, r10 = procinfo
+	 * r9 = cpuid, r10 = procinfo
 	 */
 	bl	__vet_atags
 #ifdef CONFIG_SMP_ON_UP
@@ -105,7 +101,7 @@ ENTRY(stext)
 	/*
 	 * The following calls CPU specific code in a position independent
 	 * manner.  See arch/arm/mm/proc-*.S for details.  r10 = base of
-	 * xxx_proc_info structure selected by __lookup_machine_type
+	 * xxx_proc_info structure selected by __lookup_processor_type
 	 * above.  On return, the CPU will be ready for the MMU to be
 	 * turned on, and r0 will hold the CPU control register value.
 	 */
@@ -124,7 +120,6 @@ ENDPROC(stext)
  * amount which are required to get the kernel running, which
  * generally means mapping in the kernel code.
  *
- * r8  = machinfo
  * r9  = cpuid
  * r10 = procinfo
  *

arch/arm/kernel/setup.c

@@ -308,7 +308,44 @@ static void __init cacheid_init(void)
  * already provide the required functionality.
  */
 extern struct proc_info_list *lookup_processor_type(unsigned int);
-extern struct machine_desc *lookup_machine_type(unsigned int);
+
+static void __init early_print(const char *str, ...)
+{
+	extern void printascii(const char *);
+	char buf[256];
+	va_list ap;
+
+	va_start(ap, str);
+	vsnprintf(buf, sizeof(buf), str, ap);
+	va_end(ap);
+
+#ifdef CONFIG_DEBUG_LL
+	printascii(buf);
+#endif
+	printk("%s", buf);
+}
+
+static struct machine_desc * __init lookup_machine_type(unsigned int type)
+{
+	extern struct machine_desc __arch_info_begin[], __arch_info_end[];
+	struct machine_desc *p;
+
+	for (p = __arch_info_begin; p < __arch_info_end; p++)
+		if (type == p->nr)
+			return p;
+
+	early_print("\n"
+		"Error: unrecognized/unsupported machine ID (r1 = 0x%08x).\n\n"
+		"Available machine support:\n\nID (hex)\tNAME\n", type);
+
+	for (p = __arch_info_begin; p < __arch_info_end; p++)
+		early_print("%08x\t%s\n", p->nr, p->name);
+
+	early_print("\nPlease check your kernel config and/or bootloader.\n");
+
+	while (true)
+		/* can't use cpu_relax() here as it may require MMU setup */;
+}
 
 static void __init feat_v6_fixup(void)
 {