Fix MP15x boot detect

Author: danngreen

linkscript-mp15x.ld

@@ -9,7 +9,6 @@ ENTRY(_Reset);
 
 __STACK_START = 0x30000000;
 __HEAP_SIZE = 0x0;
-boot_mode_table_addr = 0x30000004;
 
 SECTIONS {
     .text : {

src/boot_detect.hh

@@ -1,10 +1,9 @@
 #pragma once
+#include "boot_mode_table.hh"
 #include "print.hh"
 #include <cstdint>
 #include <string_view>
 
-extern uint32_t boot_mode_table_addr[];
-
 namespace BootDetect
 {
 
@@ -55,7 +54,6 @@ constexpr std::string_view bootmethod_string(BootMethod method)
 // - boot instance = bit 31:16
 // - boot device = bit 15:0
 //
-static constexpr uint32_t BOOTROM_PARAM_ADDR = 0x2FFC0078;
 static constexpr uint32_t BOOTROM_MODE_MASK = 0x0000FFFF;
 static constexpr uint32_t BOOTROM_MODE_SHIFT = 0;
 static constexpr uint32_t BOOTROM_INSTANCE_MASK = 0xFFFF0000;
@@ -65,28 +63,6 @@ static constexpr uint32_t BOOT_TYPE_SHIFT = 4;
 static constexpr uint32_t BOOT_INSTANCE_MASK = 0x0F;
 static constexpr uint32_t BOOT_INSTANCE_SHIFT = 0;
 
-inline uint32_t read_raw_bootrom_itf()
-{
-	print("&boot_mode_table_addr = 0x", Hex{(uint32_t)boot_mode_table_addr}, "\n");
-
-	if ((uint32_t)boot_mode_table_addr == 0) {
-		print("Boot mode table address not defined in linker script. Presuming SD Card boot\n");
-		return BOOT_SDCARD << BOOTROM_MODE_SHIFT;
-	}
-
-	auto table_addr = boot_mode_table_addr[0];
-	print("boot_mode_table_addr = 0x", Hex{table_addr}, "\n");
-
-	if (table_addr == 0) {
-		print("Boot mode table was not set by startup.s. Presuming SD Card boot\n");
-		return BOOT_SDCARD << BOOTROM_MODE_SHIFT;
-	}
-
-	auto val = *reinterpret_cast<uint32_t *>(table_addr);
-	print("boot_mode value = 0x", Hex{val}, "\n");
-	return val;
-}
-
 inline BootMethod read_boot_method()
 {
 	uint32_t bootrom_itf = read_raw_bootrom_itf();

src/mp13x/boot_mode_table.hh

@@ -0,0 +1,27 @@
+#include "print.hh"
+#include <cstdint>
+
+inline uint32_t read_raw_bootrom_itf()
+{
+	// Allocated by the linker, and value is written to the address by the startup script
+	extern uint32_t boot_mode_table_addr[];
+
+	print("&boot_mode_table_addr = 0x", Hex{(uint32_t)boot_mode_table_addr}, "\n");
+
+	if ((uint32_t)boot_mode_table_addr == 0) {
+		print("Boot mode table address not defined in linker script. Presuming SD Card boot\n");
+		return 1;
+	}
+
+	auto table_addr = boot_mode_table_addr[0];
+	print("boot_mode_table_addr = 0x", Hex{table_addr}, "\n");
+
+	if (table_addr == 0) {
+		print("Boot mode table was not set by startup.s. Presuming SD Card boot\n");
+		return 1;
+	}
+
+	auto val = *reinterpret_cast<uint32_t *>(table_addr);
+	print("boot_mode value = 0x", Hex{val}, "\n");
+	return val;
+}

src/mp15x/boot_mode_table.hh

@@ -0,0 +1,8 @@
+#include <cstdint>
+
+inline uint32_t read_raw_bootrom_itf()
+{
+	static constexpr uint32_t BOOTROM_PARAM_ADDR = 0x2FFC0078;
+	auto val = *reinterpret_cast<uint32_t *>(BOOTROM_PARAM_ADDR);
+	return val;
+}

src/mp15x/startup.s

@@ -25,9 +25,6 @@ _Reset:
 Reset_Handler:
 	cpsid   if 										// Mask Interrupts
 
-	ldr r4, =boot_mode_table_addr					// Store boot info from BOOTROM
-	str r0, [r4]									// into designated address in SRAM
-
 	mrc     p15, 0, r0, c1, c0, 0					// Read System Control register (SCTLR)
 	bic     r0, r0, #(0x1 << 12) 					// Clear I bit 12 to disable I Cache
 	bic     r0, r0, #(0x1 <<  2) 					// Clear C bit  2 to disable D Cache