Blackfin arch: Print out debug info, as early as possible

Print out debug info, as early as possible - even before the
kernel initializes the interrupt vectors. Now we can print out debug
messages almost anytime during the boot process.

Signed-off-by: Robin Getz <robin.getz@analog.com>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>

arch/blackfin/kernel/early_printk.c

@@ -38,13 +38,13 @@ extern struct console *bfin_earlyserial_init(unsigned int port,
 
 static struct console *early_console;
 
-/* Default console
- * Port n == ttyBFn
- * cflags == UART output modes
- */
+/* Default console */
 #define DEFAULT_PORT 0
 #define DEFAULT_CFLAG CS8|B57600
 
+/* Default console for early crashes */
+#define DEFAULT_EARLY_PORT "serial,uart0,57600"
+
 #ifdef CONFIG_SERIAL_CORE
 /* What should get here is "0,57600" */
 static struct console * __init earlyserial_init(char *buf)
@@ -158,4 +158,57 @@ int __init setup_early_printk(char *buf)
 	return 0;
 }
 
+/*
+ * Set up a temporary Event Vector Table, so if something bad happens before
+ * the kernel is fully started, it doesn't vector off into somewhere we don't
+ * know
+ */
+
+asmlinkage void __init init_early_exception_vectors(void)
+{
+	SSYNC();
+
+	/* cannot program in software:
+	 * evt0 - emulation (jtag)
+	 * evt1 - reset
+	 */
+	bfin_write_EVT2(early_trap);
+	bfin_write_EVT3(early_trap);
+	bfin_write_EVT5(early_trap);
+	bfin_write_EVT6(early_trap);
+	bfin_write_EVT7(early_trap);
+	bfin_write_EVT8(early_trap);
+	bfin_write_EVT9(early_trap);
+	bfin_write_EVT10(early_trap);
+	bfin_write_EVT11(early_trap);
+	bfin_write_EVT12(early_trap);
+	bfin_write_EVT13(early_trap);
+	bfin_write_EVT14(early_trap);
+	bfin_write_EVT15(early_trap);
+	CSYNC();
+
+	/* Set all the return from interupt, exception, NMI to a known place
+	 * so if we do a RETI, RETX or RETN by mistake - we go somewhere known
+	 * Note - don't change RETS - we are in a subroutine, or
+	 * RETE - since it might screw up if emulator is attached
+	 */
+	asm("\tRETI = %0; RETX = %0; RETN = %0;\n"
+		: : "p"(early_trap));
+
+}
+
+asmlinkage void __init early_trap_c(struct pt_regs *fp, void *retaddr)
+{
+	/* This can happen before the uart is initialized, so initialize
+	 * the UART now
+	 */
+	if (likely(early_console == NULL))
+		setup_early_printk(DEFAULT_EARLY_PORT);
+
+	dump_bfin_regs(fp, retaddr);
+	dump_bfin_trace_buffer();
+
+	panic("Died early");
+}
+
 early_param("earlyprintk", setup_early_printk);

arch/blackfin/mach-bf533/head.S

@@ -181,6 +181,12 @@ ENTRY(__start)
 	fp = sp;
 	usp = sp;
 
+#ifdef CONFIG_EARLY_PRINTK
+	SP += -12;
+	call _init_early_exception_vectors;
+	SP += 12;
+#endif
+
 	/* Put The Code for PLL Programming and SDRAM Programming in L1 ISRAM */
 	call _bf53x_relocate_l1_mem;
 #if CONFIG_BFIN_KERNEL_CLOCK

arch/blackfin/mach-bf537/head.S

@@ -224,6 +224,12 @@ ENTRY(__start)
 	fp = sp;
 	usp = sp;
 
+#ifdef CONFIG_EARLY_PRINTK
+	SP += -12;
+	call _init_early_exception_vectors;
+	SP += 12;
+#endif
+
 	/* Put The Code for PLL Programming and SDRAM Programming in L1 ISRAM */
 	call _bf53x_relocate_l1_mem;
 #if CONFIG_BFIN_KERNEL_CLOCK

arch/blackfin/mach-bf548/head.S

@@ -125,6 +125,12 @@ ENTRY(__stext)
 	FP = SP;
 	USP = SP;
 
+#ifdef CONFIG_EARLY_PRINTK
+	SP += -12;
+	call _init_early_exception_vectors;
+	SP += 12;
+#endif
+
 	/* Put The Code for PLL Programming and SDRAM Programming in L1 ISRAM */
 	call _bf53x_relocate_l1_mem;
 #if CONFIG_BFIN_KERNEL_CLOCK

arch/blackfin/mach-bf561/head.S

@@ -169,6 +169,12 @@ ENTRY(__start)
 	fp = sp;
 	usp = sp;
 
+#ifdef CONFIG_EARLY_PRINTK
+	SP += -12;
+	call _init_early_exception_vectors;
+	SP += 12;
+#endif
+
 	/* Put The Code for PLL Programming and SDRAM Programming in L1 ISRAM */
 	call _bf53x_relocate_l1_mem;
 #if CONFIG_BFIN_KERNEL_CLOCK

arch/blackfin/mach-common/entry.S

@@ -835,20 +835,59 @@ ENTRY(_ex_trace_buff_full)
 	P2 = [sp++];
 	P3 = [sp++];
 	jump _return_from_exception;
+ENDPROC(_ex_trace_buff_full)
 
 #if CONFIG_DEBUG_BFIN_HWTRACE_EXPAND_LEN == 4
 .data
 #else
 .section .l1.data.B
-#endif
+#endif /* CONFIG_DEBUG_BFIN_HWTRACE_EXPAND_LEN */
 ENTRY(_trace_buff_offset)
         .long 0;
 ALIGN
 ENTRY(_software_trace_buff)
 	.rept ((1 << CONFIG_DEBUG_BFIN_HWTRACE_EXPAND_LEN)*256);
 	.long 0
 	.endr
-#endif
+#endif /* CONFIG_DEBUG_BFIN_HWTRACE_EXPAND */
+
+#if CONFIG_EARLY_PRINTK
+.section .init.text
+ENTRY(_early_trap)
+	SAVE_ALL_SYS
+	trace_buffer_stop(p0,r0);
+
+	/* Turn caches off, to ensure we don't get double exceptions */
+
+	P4.L = LO(IMEM_CONTROL);
+	P4.H = HI(IMEM_CONTROL);
+
+	R5 = [P4];              /* Control Register*/
+	BITCLR(R5,ENICPLB_P);
+	CLI R1;
+	SSYNC;          /* SSYNC required before writing to IMEM_CONTROL. */
+	.align 8;
+	[P4] = R5;
+	SSYNC;
+
+	P4.L = LO(DMEM_CONTROL);
+	P4.H = HI(DMEM_CONTROL);
+	R5 = [P4];
+	BITCLR(R5,ENDCPLB_P);
+	SSYNC;          /* SSYNC required before writing to DMEM_CONTROL. */
+	.align 8;
+	[P4] = R5;
+	SSYNC;
+	STI R1;
+
+	r0 = sp;        /* stack frame pt_regs pointer argument ==> r0 */
+	r1 = RETX;
+
+	SP += -12;
+	call _early_trap_c;
+	SP += 12;
+ENDPROC(_early_trap)
+#endif /* CONFIG_EARLY_PRINTK */
 
 /*
  * Put these in the kernel data section - that should always be covered by

include/asm-blackfin/irq_handler.h

@@ -22,6 +22,7 @@ asmlinkage void evt_system_call(void);
 asmlinkage void init_exception_buff(void);
 asmlinkage void trap_c(struct pt_regs *fp);
 asmlinkage void ex_replaceable(void);
+asmlinkage void early_trap(void);
 
 extern void *ex_table[];
 extern void return_from_exception(void);