Blackfin: fix booting with older bootroms (no EVT1)

When dropping jump block support, the assumption was that all bootroms
supported entry point redirection via the EVT1 register.  Unfortunately,
this turned out to be incorrect for the oldest Blackfin parts (BF533-0.2
and older and BF561).  No one really noticed earlier because these parts
usually are booted by bypassing the bootrom entirely, and older BF533
parts are not supported at all (too many anomalies).

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

blackfin_config.mk

@@ -36,7 +36,9 @@ endif
 
 SYM_PREFIX = _
 
-LDR_FLAGS += -J
+LDR_FLAGS-y :=
+LDR_FLAGS-$(CONFIG_BFIN_BOOTROM_USES_EVT1) += -J
+
 LDR_FLAGS += --bmode $(subst BFIN_BOOT_,,$(CONFIG_BFIN_BOOT_MODE))
 LDR_FLAGS += --use-vmas
 ifneq ($(CONFIG_BFIN_BOOT_MODE),BFIN_BOOT_BYPASS)
@@ -45,3 +47,5 @@ endif
 ifneq (,$(findstring s,$(MAKEFLAGS)))
 LDR_FLAGS += --quiet
 endif
+
+LDR_FLAGS += $(LDR_FLAGS-y)

board/bf561-ezkit/u-boot.lds.S

@@ -42,12 +42,19 @@
 # define L1_DATA_B_SRAM_SIZE 0
 #endif
 
+/* The 0xC offset is so we don't clobber the tiny LDR jump block. */
+#ifdef CONFIG_BFIN_BOOTROM_USES_EVT1
+# define L1_CODE_ORIGIN L1_INST_SRAM
+#else
+# define L1_CODE_ORIGIN L1_INST_SRAM + 0xC
+#endif
+
 OUTPUT_ARCH(bfin)
 
 MEMORY
 {
 	ram     : ORIGIN = CONFIG_SYS_MONITOR_BASE, LENGTH = CONFIG_SYS_MONITOR_LEN
-	l1_code : ORIGIN = L1_INST_SRAM,            LENGTH = L1_INST_SRAM_SIZE
+	l1_code : ORIGIN = L1_CODE_ORIGIN,          LENGTH = L1_INST_SRAM_SIZE
 	l1_data : ORIGIN = L1_DATA_B_SRAM,          LENGTH = L1_DATA_B_SRAM_SIZE
 }
 

cpu/blackfin/cpu.c

@@ -25,12 +25,20 @@ ulong bfin_poweron_retx;
 __attribute__ ((__noreturn__))
 void cpu_init_f(ulong bootflag, ulong loaded_from_ldr)
 {
+	extern char _stext_l1;
+#ifndef CONFIG_BFIN_BOOTROM_USES_EVT1
+	/* Build a NOP slide over the LDR jump block.  Whee! */
+	char nops[0xC];
+	serial_early_puts("NOP Slide\n");
+	memset(nops, 0x00, sizeof(nops));
+	memcpy(&_stext_l1 - sizeof(nops), nops, sizeof(nops));
+#endif
+
 	if (!loaded_from_ldr) {
 		/* Relocate sections into L1 if the LDR didn't do it -- don't
 		 * check length because the linker script does the size
 		 * checking at build time.
 		 */
-		extern char _stext_l1;
 		serial_early_puts("L1 Relocate\n");
 		extern char _stext_l1, _etext_l1, _stext_l1_lma;
 		memcpy(&_stext_l1, &_stext_l1_lma, (&_etext_l1 - &_stext_l1));

cpu/blackfin/initcode.c

@@ -543,9 +543,11 @@ void initcode(ADI_BOOT_DATA *bootstruct)
 
 	serial_putc('T');
 
+#ifdef CONFIG_BFIN_BOOTROM_USES_EVT1
 	/* tell the bootrom where our entry point is */
 	if (CONFIG_BFIN_BOOT_MODE != BFIN_BOOT_BYPASS)
 		bfin_write_EVT1(CONFIG_SYS_MONITOR_BASE);
+#endif
 
 	serial_putc('>');
 	serial_putc('\n');

include/asm-blackfin/blackfin-config-pre.h

@@ -54,6 +54,14 @@ static inline const char *get_bfin_boot_mode(int bfin_boot)
 }
 #endif
 
+/* Most bootroms allow for EVT1 redirection */
+#if (defined(__ADSPBF531__) || defined(__ADSPBF532__) || defined(__ADSPBF533__) \
+     && __SILICON_REVISION__ < 3) || defined(__ADSPBF561__)
+# undef CONFIG_BFIN_BOOTROM_USES_EVT1
+#else
+# define CONFIG_BFIN_BOOTROM_USES_EVT1
+#endif
+
 /* Define the default SPI CS used when booting out of SPI */
 #if defined(__ADSPBF531__) || defined(__ADSPBF532__) || defined(__ADSPBF533__) || \
     defined(__ADSPBF538__) || defined(__ADSPBF539__) || defined(__ADSPBF561__) || \