From 653edd17ca87fe5443053bda07db8fd56b2ebb44 Mon Sep 17 00:00:00 2001
From: Florent Kermarrec <florent@enjoy-digital.fr>
Date: Thu, 11 Jun 2020 13:38:38 +0200
Subject: [PATCH] bios/boot: simplify flashboot (remove specific linux boot).

Storage in SPI Flash is generally limited and booting Linux from it is no longer very useful
since boot from SDCard is now supported. This is in the continuity of the SDCard/Ethernet
simplications to have an easier and more flexible boot scheme.
---
 litex/soc/software/bios/boot.c | 81 ++++------------------------------
 1 file changed, 8 insertions(+), 73 deletions(-)

diff --git a/litex/soc/software/bios/boot.c b/litex/soc/software/bios/boot.c
index 257aaa07..47426b62 100644
--- a/litex/soc/software/bios/boot.c
+++ b/litex/soc/software/bios/boot.c
@@ -392,16 +392,6 @@ void netboot(void)
 
 #ifdef FLASH_BOOT_ADDRESS
 
-/* On systems with external SDRAM we copy out of the SPI flash into the SDRAM
-   before running, as it is faster.  If we have no SDRAM then we have to
-   execute directly out of the SPI flash. */
-#ifdef MAIN_RAM_BASE
-#define FIRMWARE_BASE_ADDRESS MAIN_RAM_BASE
-#else
-/* Firmware code starts after (a) length and (b) CRC -- both unsigned ints */
-#define FIRMWARE_BASE_ADDRESS (FLASH_BOOT_ADDRESS + 2 * sizeof(unsigned int))
-#endif
-
 static unsigned int check_image_in_flash(unsigned int base_address)
 {
 	uint32_t length;
@@ -452,85 +442,30 @@ static int copy_image_from_flash_to_ram(unsigned int flash_address, unsigned int
 }
 #endif
 
-#ifndef KERNEL_IMAGE_RAM_OFFSET
-#define KERNEL_IMAGE_RAM_OFFSET 0x00000000
-#endif
-#ifndef ROOTFS_IMAGE_RAM_OFFSET
-#define ROOTFS_IMAGE_RAM_OFFSET 0x00800000
-#endif
-#ifndef DEVICE_TREE_IMAGE_RAM_OFFSET
-#define DEVICE_TREE_IMAGE_RAM_OFFSET 0x01000000
-#endif
-#ifndef EMULATOR_IMAGE_RAM_OFFSET
-#define EMULATOR_IMAGE_RAM_OFFSET 0x01100000
-#endif
-
-#ifndef KERNEL_IMAGE_FLASH_OFFSET
-	#define KERNEL_IMAGE_FLASH_OFFSET      0x00000000 //  0MB
-#endif
-#ifndef ROOTFS_IMAGE_FLASH_OFFSET
-	#define ROOTFS_IMAGE_FLASH_OFFSET      0x00500000 //  5MB
-#endif
-#ifndef DEVICE_TREE_IMAGE_FLASH_OFFSET
-	#define DEVICE_TREE_IMAGE_FLASH_OFFSET 0x00D00000 // 13MB
-#endif
-#ifndef EMULATOR_IMAGE_FLASH_OFFSET
-	#define EMULATOR_IMAGE_FLASH_OFFSET    0x00E00000 // 14MB
-#endif
-
 void flashboot(void)
 {
 	uint32_t length;
 	uint32_t result;
 
-#if defined(MAIN_RAM_BASE) && defined(CONFIG_CPU_TYPE_VEXRISCV) && defined(CONFIG_CPU_VARIANT_LINUX)
-
-	printf("Loading Image from flash...\n");
-	result = copy_image_from_flash_to_ram(
-		(FLASH_BOOT_ADDRESS + KERNEL_IMAGE_FLASH_OFFSET),
-		(MAIN_RAM_BASE + KERNEL_IMAGE_RAM_OFFSET));
-
-
-	if(result) {
-		printf("Loading rootfs.cpio from flash...\n");
-		result &= copy_image_from_flash_to_ram(
-			(FLASH_BOOT_ADDRESS + ROOTFS_IMAGE_FLASH_OFFSET),
-			(MAIN_RAM_BASE + ROOTFS_IMAGE_RAM_OFFSET));
-	}
-
-	if(result) {
-		printf("Loading rv32.dtb from flash...\n");
-		result &= copy_image_from_flash_to_ram(
-			(FLASH_BOOT_ADDRESS + DEVICE_TREE_IMAGE_FLASH_OFFSET),
-			(MAIN_RAM_BASE + DEVICE_TREE_IMAGE_RAM_OFFSET));
-	}
-
-	if(result) {
-		printf("Loading emulator.bin from flash...\n");
-		result &= copy_image_from_flash_to_ram(
-			(FLASH_BOOT_ADDRESS + EMULATOR_IMAGE_FLASH_OFFSET),
-			(MAIN_RAM_BASE + EMULATOR_IMAGE_RAM_OFFSET));
-	}
-
-	if(result) {
-		boot(0, 0, 0, MAIN_RAM_BASE + EMULATOR_IMAGE_RAM_OFFSET);
-		return;
-	}
-#endif
-
 	printf("Booting from flash...\n");
 	length = check_image_in_flash(FLASH_BOOT_ADDRESS);
 	if(!length)
 		return;
 
 #ifdef MAIN_RAM_BASE
+	/* When Main RAM is available, copy the code from the Flash and execute it
+	from Main RAM since faster */
 	result = copy_image_from_flash_to_ram(FLASH_BOOT_ADDRESS, MAIN_RAM_BASE);
 	if(!result)
 		return;
+	boot(0, 0, 0, MAIN_RAM_BASE);
+#else
+	/* When Main RAM is not available, execute the code directly from Flash (XIP).
+       The code starts after (a) length and (b) CRC -- both uint32_t */
+	boot(0, 0, 0, (FLASH_BOOT_ADDRESS + 2 * sizeof(uint32_t)));
 #endif
-
-	boot(0, 0, 0, FIRMWARE_BASE_ADDRESS);
 }
+
 #endif
 
 /*-----------------------------------------------------------------------*/
-- 
2.30.2