[PATCH V4 0/3] doc: falcon: riscv: Falcon Mode boot on RISC-V

[PATCH V4 0/3] doc: falcon: riscv: Falcon Mode boot on RISC-V

[Randolph]

Changes in v4:
- remove "Function that a board must implement" section in
  falcon.rst
- fix compile error when config LOAD_FIT_OPENSBI_OS_BOOT
  not enabled.

Changes in v3:
- Change by suggestions in falcon.rst 
- Move the board-related code to arch-specific code,
  its the issue when enabling LOAD_FIT_OPENSBI_OS_BOOT
- Add SPL_PAYLOAD_ARGS_ADDR to defconfig.
  This is the address that SPL copies into defconfig.

Randolph (3):
  doc: falcon: riscv: Falcon Mode boot on RISC-V
  spl: riscv: falcon: move fdt blob to specified address
  configs: andes: add the fdt blob copy address for SPL

 board/AndesTech/ae350/ae350.c           |  25 ----
 common/spl/Kconfig                      |   2 +-
 common/spl/spl_opensbi.c                |  15 +++
 configs/ae350_rv32_falcon_defconfig     |   1 +
 configs/ae350_rv32_falcon_xip_defconfig |   1 +
 configs/ae350_rv64_falcon_defconfig     |   1 +
 configs/ae350_rv64_falcon_xip_defconfig |   1 +
 doc/develop/falcon.rst                  | 158 ++++++++++++++++++++++++
 8 files changed, 178 insertions(+), 26 deletions(-)

-- 
2.34.1

[PATCH V4 1/3] doc: falcon: riscv: Falcon Mode boot on RISC-V

[Randolph]

Add documentation to introduce the Falcon Mode on RISC-V.
In this mode, the boot sequence is SPL -> OpenSBI -> Linux kernel.

Signed-off-by: Randolph <randolph@andestech.com>
---
 doc/develop/falcon.rst | 158 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 158 insertions(+)

diff --git a/doc/develop/falcon.rst b/doc/develop/falcon.rst
index 8a46c0efa1..244b4ccb5c 100644
--- a/doc/develop/falcon.rst
+++ b/doc/develop/falcon.rst
@@ -256,3 +256,161 @@ the following command:
 Falcon Mode was presented at the RMLL 2012. Slides are available at:
 
 http://schedule2012.rmll.info/IMG/pdf/LSM2012_UbootFalconMode_Babic.pdf
+
+Falcon Mode Boot on RISC-V
+--------------------------
+
+Introduction
+~~~~~~~~~~~~
+
+In the RISC-V environment, OpenSBI is required to enable a supervisor mode
+binary to execute certain privileged operations. The typical boot sequence on
+RISC-V is SPL -> OpenSBI -> U-Boot -> Linux kernel. SPL will load and start
+the OpenSBI initializations, then OpenSBI will bring up the next image, U-Boot
+proper. The OpenSBI binary must be prepared in advance of the U-Boot build
+process and it will be packed together with U-Boot into a file called
+u-boot.itb.
+
+The Falcon Mode on RISC-V platforms is a distinct boot sequence. Borrowing
+ideas from the U-Boot Falcon Mode on ARM, it skips the U-Boot proper phase
+in the normal boot process and allows OpenSBI to load and start the Linux
+kernel. Its boot sequence is SPL -> OpenSBI -> Linux kernel. The OpenSBI
+binary and Linux kernel binary must be prepared prior to the U-Boot build
+process and they will be packed together as a FIT image named linux.itb in
+this process.
+
+CONFIG_SPL_LOAD_FIT_OPENSBI_OS_BOOT enables the Falcon Mode boot on RISC-V.
+This configuration setting tells OpenSBI that Linux kernel is its next OS
+image and makes it load and start the kernel afterwards.
+
+Note that the Falcon Mode boot bypasses a lot of initializations by U-Boot.
+If the Linux kernel expects hardware initializations by U-Boot, make sure to
+port the relevant code to the SPL build process.
+
+Configuration
+~~~~~~~~~~~~~
+
+CONFIG_SPL_LOAD_FIT_ADDRESS
+    Specifies the address to load u-boot.itb in a normal boot. When the Falcon
+    Mode boot is enabled, it specifies the load address of linux.itb.
+
+CONFIG_SYS_TEXT_BASE
+    Specifies the address of the text section for a u-boot proper in a normal
+    boot. When the Falcon Mode boot is enabled, it specifies the text section
+    address for the Linux kernel image.
+
+CONFIG_SPL_PAYLOAD_ARGS_ADDR
+    The address in the RAM to which the FDT blob is to be moved by the SPL.
+    SPL places the FDT blob right after the kernel. As the kernel does not
+    include the BSS section in its size calculation, SPL ends up placing
+    the FDT blob within the BSS section of the kernel. This may cause the
+    FDT blob to be cleared during kernel BSS initialization. To avoid the
+    issue, be sure to move the FDT blob out of the kernel first.
+
+CONFIG_SPL_LOAD_FIT_OPENSBI_OS_BOOT
+    Activates the Falcon Mode boot on RISC-V.
+
+Example for Andes AE350 Board
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+A FDT blob is required to boot the Linux kernel from the SPL. Andes AE350
+platforms generally come with a builtin dtb. To load a custom DTB, follow
+these steps:
+
+1. Load the custom DTB to SDRAM::
+
+        => fatload mmc 0:1 0x20000000 user_custom.dtb
+
+2. Set the SPI speed::
+
+        => sf probe 0:0 50000000 0
+
+3. Erase sectors from the SPI Flash::
+
+        => sf erase 0xf0000 0x10000
+
+4. Write the FDT blob to the erased sectors of the Flash::
+
+        => sf write 0x20000000 0xf0000 0x10000
+
+Console Log of AE350 Falcon Mode Boot
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+        U-Boot SPL 2023.01-00031-g777ecdea66 (Oct 31 2023 - 18:41:36 +0800)
+        Trying to boot from RAM
+
+        OpenSBI v1.2-51-g7304e42
+           ____                    _____ ____ _____
+          / __ \                  / ____|  _ \_   _|
+         | |  | |_ __   ___ _ __ | (___ | |_) || |
+         | |  | | '_ \ / _ \ '_ \ \___ \|  _ < | |
+         | |__| | |_) |  __/ | | |____) | |_) || |_
+          \____/| .__/ \___|_| |_|_____/|____/_____|
+                | |
+                |_|
+
+        Platform Name             : andestech,ax25
+        Platform Features         : medeleg
+        Platform HART Count       : 1
+        Platform IPI Device       : andes_plicsw
+        Platform Timer Device     : andes_plmt @ 60000000Hz
+        Platform Console Device   : uart8250
+        Platform HSM Device       : andes_smu
+        Platform PMU Device       : andes_pmu
+        Platform Reboot Device    : atcwdt200
+        Platform Shutdown Device  : ---
+        Firmware Base             : 0x0
+        Firmware Size             : 196 KB
+        Runtime SBI Version       : 1.0
+
+        Domain0 Name              : root
+        Domain0 Boot HART         : 0
+        Domain0 HARTs             : 0*
+        Domain0 Region00          : 0x0000000000000000-0x000000000003ffff ()
+        Domain0 Region01          : 0x00000000e6000000-0x00000000e60fffff (I,R)
+        Domain0 Region02          : 0x00000000e6400000-0x00000000e67fffff (I)
+        Domain0 Region03          : 0x0000000000000000-0xffffffffffffffff (R,W,X)
+        Domain0 Next Address      : 0x0000000001800000
+        Domain0 Next Arg1         : 0x0000000001700000
+        Domain0 Next Mode         : S-mode
+        Domain0 SysReset          : yes
+
+        Boot HART ID              : 0
+        Boot HART Domain          : root
+        Boot HART Priv Version    : v1.11
+        Boot HART Base ISA        : rv64imafdcx
+        Boot HART ISA Extensions  : none
+        Boot HART PMP Count       : 8
+        Boot HART PMP Granularity : 4
+        Boot HART PMP Address Bits: 31
+        Boot HART MHPM Count      : 4
+        Boot HART MHPM Bits       : 64
+        Boot HART MIDELEG         : 0x0000000000000222
+        Boot HART MEDELEG         : 0x000000000000b109
+        [    0.000000] Linux version 6.1.47-09019-g0584b09ad862-dirty
+        [    0.000000] OF: fdt: Ignoring memory range 0x0 - 0x1800000
+        [    0.000000] Machine model: andestech,ax25
+        [    0.000000] earlycon: sbi0 at I/O port 0x0 (options '')
+        [    0.000000] printk: bootconsole [sbi0] enabled
+        [    0.000000] Disabled 4-level and 5-level paging
+        [    0.000000] efi: UEFI not found.
+        [    0.000000] Zone ranges:
+        [    0.000000]   DMA32    [mem 0x0000000001800000-0x000000003fffffff]
+        [    0.000000]   Normal   empty
+        [    0.000000] Movable zone start for each node
+        [    0.000000] Early memory node ranges
+        [    0.000000]   node   0: [mem 0x0000000001800000-0x000000003fffffff]
+        [    0.000000] Initmem setup node 0 [mem 0x0000000001800000-0x000000003fffffff]
+        [    0.000000] SBI specification v1.0 detected
+        [    0.000000] SBI implementation ID=0x1 Version=0x10002
+        [    0.000000] SBI TIME extension detected
+        [    0.000000] SBI IPI extension detected
+        [    0.000000] SBI RFENCE extension detected
+        [    0.000000] SBI SRST extension detected
+        [    0.000000] SBI HSM extension detected
+        [    0.000000] riscv: base ISA extensions acim
+        [    0.000000] riscv: ELF capabilities acim
+        [    0.000000] percpu: Embedded 18 pages/cpu s35000 r8192 d30536 u73728
+        [    0.000000] Built 1 zonelists, mobility grouping on.  Total pages: 252500
-- 
2.34.1

[PATCH V4 2/3] spl: riscv: falcon: move fdt blob to specified address

[Randolph]

In Falcon Boot mode, the fdt blob should be move to the RAM from
kernel BSS section. To avoid being cleared by BSS initialisation.
SPL_PAYLOAD_ARGS_ADDR is the address where SPL copies.

Signed-off-by: Randolph <randolph@andestech.com>
---
 board/AndesTech/ae350/ae350.c | 25 -------------------------
 common/spl/Kconfig            |  2 +-
 common/spl/spl_opensbi.c      | 15 +++++++++++++++
 3 files changed, 16 insertions(+), 26 deletions(-)

diff --git a/board/AndesTech/ae350/ae350.c b/board/AndesTech/ae350/ae350.c
index 772c6bf1ee..36375d9def 100644
--- a/board/AndesTech/ae350/ae350.c
+++ b/board/AndesTech/ae350/ae350.c
@@ -19,8 +19,6 @@
 #include <fdtdec.h>
 #include <dm.h>
 #include <spl.h>
-#include <mapmem.h>
-#include <hang.h>
 
 DECLARE_GLOBAL_DATA_PTR;
 
@@ -28,29 +26,6 @@ DECLARE_GLOBAL_DATA_PTR;
  * Miscellaneous platform dependent initializations
  */
 
-#if CONFIG_IS_ENABLED(LOAD_FIT) || CONFIG_IS_ENABLED(LOAD_FIT_FULL)
-#define ANDES_SPL_FDT_ADDR	(CONFIG_TEXT_BASE - 0x100000)
-void spl_perform_fixups(struct spl_image_info *spl_image)
-{
-	/*
-	 * Originally, u-boot-spl will place DTB directly after the kernel,
-	 * but the size of the kernel did not include the BSS section, which
-	 * means u-boot-spl will place the DTB in the kernel BSS section
-	 * causing the DTB to be cleared by kernel BSS initializtion.
-	 * Moving DTB in front of the kernel can avoid the error.
-	 */
-	if (ANDES_SPL_FDT_ADDR < 0) {
-		printf("%s: CONFIG_TEXT_BASE needs to be larger than 0x100000\n",
-		       __func__);
-		hang();
-	}
-
-	memcpy((void *)ANDES_SPL_FDT_ADDR, spl_image->fdt_addr,
-	       fdt_totalsize(spl_image->fdt_addr));
-	spl_image->fdt_addr = map_sysmem(ANDES_SPL_FDT_ADDR, 0);
-}
-#endif
-
 int board_init(void)
 {
 	gd->bd->bi_boot_params = PHYS_SDRAM_0 + 0x400;
diff --git a/common/spl/Kconfig b/common/spl/Kconfig
index c521b02f4a..bb283d823e 100644
--- a/common/spl/Kconfig
+++ b/common/spl/Kconfig
@@ -1081,7 +1081,7 @@ config SPL_OS_BOOT
 
 config SPL_PAYLOAD_ARGS_ADDR
 	hex "Address in memory to load 'args' file for Falcon Mode to"
-	depends on SPL_OS_BOOT
+	depends on SPL_OS_BOOT || SPL_LOAD_FIT_OPENSBI_OS_BOOT
 	default 0x88000000 if ARCH_OMAP2PLUS
 	help
 	  Address in memory where the 'args' file, typically a device tree
diff --git a/common/spl/spl_opensbi.c b/common/spl/spl_opensbi.c
index 9801d38c0b..8127ebc946 100644
--- a/common/spl/spl_opensbi.c
+++ b/common/spl/spl_opensbi.c
@@ -16,6 +16,7 @@
 #include <opensbi.h>
 #include <linux/libfdt.h>
 #include <linux/printk.h>
+#include <mapmem.h>
 
 DECLARE_GLOBAL_DATA_PTR;
 
@@ -57,6 +58,20 @@ void __noreturn spl_invoke_opensbi(struct spl_image_info *spl_image)
 		hang();
 	}
 
+	/*
+	 * Originally, u-boot-spl will place DTB directly after the kernel,
+	 * but the size of the kernel did not include the BSS section, which
+	 * means u-boot-spl will place the DTB in the kernel BSS section
+	 * causing the DTB to be cleared by kernel BSS initializtion.
+	 * Moving DTB in front of the kernel can avoid the error.
+	 */
+#if CONFIG_IS_ENABLED(LOAD_FIT_OPENSBI_OS_BOOT) && \
+    CONFIG_IS_ENABLED(PAYLOAD_ARGS_ADDR)
+	memcpy((void *)CONFIG_SPL_PAYLOAD_ARGS_ADDR, spl_image->fdt_addr,
+	       fdt_totalsize(spl_image->fdt_addr));
+	spl_image->fdt_addr = map_sysmem(CONFIG_SPL_PAYLOAD_ARGS_ADDR, 0);
+#endif
+
 	/*
 	 * Find next os image in /fit-images
 	 * The next os image default is u-boot proper, once enable
-- 
2.34.1

[PATCH V4 3/3] configs: andes: add the fdt blob copy address for SPL

[Randolph]

Add the address to which the FDT blob is to be moved.

Signed-off-by: Randolph <randolph@andestech.com>
---
 configs/ae350_rv32_falcon_defconfig     | 1 +
 configs/ae350_rv32_falcon_xip_defconfig | 1 +
 configs/ae350_rv64_falcon_defconfig     | 1 +
 configs/ae350_rv64_falcon_xip_defconfig | 1 +
 4 files changed, 4 insertions(+)

diff --git a/configs/ae350_rv32_falcon_defconfig b/configs/ae350_rv32_falcon_defconfig
index 3f2993e371..c0837322bb 100644
--- a/configs/ae350_rv32_falcon_defconfig
+++ b/configs/ae350_rv32_falcon_defconfig
@@ -14,6 +14,7 @@ CONFIG_TARGET_ANDES_AE350=y
 CONFIG_RISCV_SMODE=y
 # CONFIG_AVAILABLE_HARTS is not set
 CONFIG_SPL_LOAD_FIT_OPENSBI_OS_BOOT=y
+CONFIG_SPL_PAYLOAD_ARGS_ADDR=0x01700000
 CONFIG_SYS_MONITOR_BASE=0x88000000
 CONFIG_FIT=y
 CONFIG_SPL_LOAD_FIT_ADDRESS=0x10000000
diff --git a/configs/ae350_rv32_falcon_xip_defconfig b/configs/ae350_rv32_falcon_xip_defconfig
index e4f4c7807c..d401e4963b 100644
--- a/configs/ae350_rv32_falcon_xip_defconfig
+++ b/configs/ae350_rv32_falcon_xip_defconfig
@@ -15,6 +15,7 @@ CONFIG_TARGET_ANDES_AE350=y
 CONFIG_RISCV_SMODE=y
 CONFIG_SPL_XIP=y
 CONFIG_SPL_LOAD_FIT_OPENSBI_OS_BOOT=y
+CONFIG_SPL_PAYLOAD_ARGS_ADDR=0x01700000
 CONFIG_SYS_MONITOR_BASE=0x88000000
 CONFIG_FIT=y
 CONFIG_SPL_LOAD_FIT_ADDRESS=0x80010000
diff --git a/configs/ae350_rv64_falcon_defconfig b/configs/ae350_rv64_falcon_defconfig
index 4fb83d8240..b4ae5f9848 100644
--- a/configs/ae350_rv64_falcon_defconfig
+++ b/configs/ae350_rv64_falcon_defconfig
@@ -14,6 +14,7 @@ CONFIG_ARCH_RV64I=y
 CONFIG_RISCV_SMODE=y
 # CONFIG_AVAILABLE_HARTS is not set
 CONFIG_SPL_LOAD_FIT_OPENSBI_OS_BOOT=y
+CONFIG_SPL_PAYLOAD_ARGS_ADDR=0x01700000
 CONFIG_SYS_MONITOR_BASE=0x88000000
 CONFIG_FIT=y
 CONFIG_SPL_LOAD_FIT_ADDRESS=0x10000000
diff --git a/configs/ae350_rv64_falcon_xip_defconfig b/configs/ae350_rv64_falcon_xip_defconfig
index 45464260ee..c7c8324d30 100644
--- a/configs/ae350_rv64_falcon_xip_defconfig
+++ b/configs/ae350_rv64_falcon_xip_defconfig
@@ -15,6 +15,7 @@ CONFIG_ARCH_RV64I=y
 CONFIG_RISCV_SMODE=y
 CONFIG_SPL_XIP=y
 CONFIG_SPL_LOAD_FIT_OPENSBI_OS_BOOT=y
+CONFIG_SPL_PAYLOAD_ARGS_ADDR=0x01700000
 CONFIG_SYS_MONITOR_BASE=0x88000000
 CONFIG_FIT=y
 CONFIG_SPL_LOAD_FIT_ADDRESS=0x80010000
-- 
2.34.1

Re: [PATCH V4 1/3] doc: falcon: riscv: Falcon Mode boot on RISC-V

[Leo Liang]

On Fri, Dec 29, 2023 at 04:32:21PM +0800, Randolph wrote:
> Add documentation to introduce the Falcon Mode on RISC-V.
> In this mode, the boot sequence is SPL -> OpenSBI -> Linux kernel.
> 
> Signed-off-by: Randolph <randolph@andestech.com>
> ---
>  doc/develop/falcon.rst | 158 +++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 158 insertions(+)

Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>

Re: [PATCH V4 2/3] spl: riscv: falcon: move fdt blob to specified address

[Leo Liang]

On Fri, Dec 29, 2023 at 04:32:22PM +0800, Randolph wrote:
> In Falcon Boot mode, the fdt blob should be move to the RAM from
> kernel BSS section. To avoid being cleared by BSS initialisation.
> SPL_PAYLOAD_ARGS_ADDR is the address where SPL copies.
> 
> Signed-off-by: Randolph <randolph@andestech.com>
> ---
>  board/AndesTech/ae350/ae350.c | 25 -------------------------
>  common/spl/Kconfig            |  2 +-
>  common/spl/spl_opensbi.c      | 15 +++++++++++++++
>  3 files changed, 16 insertions(+), 26 deletions(-)

Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>

Re: [PATCH V4 3/3] configs: andes: add the fdt blob copy address for SPL

[Leo Liang]

On Fri, Dec 29, 2023 at 04:32:23PM +0800, Randolph wrote:
> Add the address to which the FDT blob is to be moved.
> 
> Signed-off-by: Randolph <randolph@andestech.com>
> ---
>  configs/ae350_rv32_falcon_defconfig     | 1 +
>  configs/ae350_rv32_falcon_xip_defconfig | 1 +
>  configs/ae350_rv64_falcon_defconfig     | 1 +
>  configs/ae350_rv64_falcon_xip_defconfig | 1 +
>  4 files changed, 4 insertions(+)

Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>