[PATCH v4 9/9] sunxi: binman: Add support for including SCP firmware

[Samuel Holland]

Allwinner sun50i SoCs contain an OpenRISC 1000 CPU that functions as a
System Control Processor, or SCP. ARM Trusted Firmware (ATF)
communicates with the SCP over SCPI to implement the PSCI system
suspend, shutdown and reset functionality. Currently, SCP firmware is
optional; the system will boot and run without it, but system suspend
will be unavailable.

Since all communication with the SCP is mediated by ATF, the only thing
U-Boot needs to do is load the firmware into SRAM. The SCP firmware
occupies the last 16KiB of SRAM A2, immediately following ATF.

Reviewed-by: Simon Glass <sjg at chromium.org>
Signed-off-by: Samuel Holland <samuel at sholland.org>
---
 arch/arm/dts/sunxi-u-boot.dtsi | 16 ++++++++++++-
 board/sunxi/README.sunxi64     | 43 ++++++++++++++++++++++++++++------
 2 files changed, 51 insertions(+), 8 deletions(-)

diff --git a/arch/arm/dts/sunxi-u-boot.dtsi b/arch/arm/dts/sunxi-u-boot.dtsi
index ff3fff599f4..5ab7c6c23b7 100644
--- a/arch/arm/dts/sunxi-u-boot.dtsi
+++ b/arch/arm/dts/sunxi-u-boot.dtsi
@@ -2,8 +2,10 @@
 
 #ifdef CONFIG_MACH_SUN50I_H6
 #define BL31_ADDR 0x104000
+#define  SCP_ADDR 0x114000
 #else
 #define BL31_ADDR  0x44000
+#define  SCP_ADDR  0x50000
 #endif
 
 / {
@@ -58,6 +60,18 @@
 					};
 				};
 
+				scp {
+					description = "SCP firmware";
+					type = "firmware";
+					arch = "or1k";
+					compression = "none";
+					load = <SCP_ADDR>;
+
+					scp {
+						filename = "scp.bin";
+					};
+				};
+
 				@fdt-SEQ {
 					description = "NAME";
 					type = "flat_dt";
@@ -71,7 +85,7 @@
 				@config-SEQ {
 					description = "NAME";
 					firmware = "atf";
-					loadables = "uboot";
+					loadables = "scp", "uboot";
 					fdt = "fdt-SEQ";
 				};
 			};
diff --git a/board/sunxi/README.sunxi64 b/board/sunxi/README.sunxi64
index 258921af22d..9a67e5301eb 100644
--- a/board/sunxi/README.sunxi64
+++ b/board/sunxi/README.sunxi64
@@ -14,8 +14,12 @@ Quick Start / Overview
 - Build the ARM Trusted Firmware binary (see "ARM Trusted Firmware (ATF)" below)
   $ cd /src/arm-trusted-firmware
   $ make PLAT=sun50i_a64 DEBUG=1 bl31
+- Build the SCP firmware binary (see "SCP firmware (Crust)" below)
+  $ cd /src/crust
+  $ make pine64_plus_defconfig && make -j5 scp
 - Build U-Boot (see "SPL/U-Boot" below)
   $ export BL31=/path/to/bl31.bin
+  $ export SCP=/src/crust/build/scp/scp.bin
   $ make pine64_plus_defconfig && make -j5
 - Transfer to an uSD card (see "microSD card" below)
   $ dd if=u-boot-sunxi-with-spl.bin of=/dev/sdx bs=8k seek=1
@@ -24,13 +28,17 @@ Quick Start / Overview
 Building the firmware
 =====================
 
-The Allwinner A64/H5 firmware consists of three parts: U-Boot's SPL, an
-ARM Trusted Firmware (ATF) build and the U-Boot proper.
-The SPL will load both ATF and U-Boot proper along with the right device
-tree blob (.dtb) and will pass execution to ATF (in EL3), which in turn will
-drop into the U-Boot proper (in EL2).
-As the ATF binary will become part of the U-Boot image file, you will need
-to build it first.
+The Allwinner A64/H5/H6 firmware consists of several parts: U-Boot's SPL,
+ARM Trusted Firmware (ATF), optional System Control Processor (SCP) firmware
+(e.g. Crust), and the U-Boot proper.
+
+The SPL will load all of the other firmware binaries into RAM, along with the
+right device tree blob (.dtb), and will pass execution to ATF (in EL3). If SCP
+firmware was loaded, ATF will power on the SCP and wait for it to boot.
+ATF will then drop into U-Boot proper (in EL2).
+
+As the ATF binary and SCP firmware will become part of the U-Boot image file,
+you will need to build them first.
 
  ARM Trusted Firmware (ATF)
 ----------------------------
@@ -53,6 +61,27 @@ As sometimes the ATF build process is a bit picky about the toolchain used,
 or if you can't be bothered with building ATF, there are known working
 binaries in the firmware repository[3], purely for convenience reasons.
 
+ SCP firmware (Crust)
+----------------------
+SCP firmware is responsible for implementing system suspend/resume, and (on
+boards without a PMIC) soft poweroff/on. ATF contains fallback code for CPU
+power control, so SCP firmware is optional if you don't need either of these
+features. It runs on the AR100, with is an or1k CPU, not ARM, so it needs a
+different cross toolchain.
+
+There is one SCP firmware implementation currently available, Crust:
+$ git clone https://github.com/crust-firmware/crust
+$ cd crust
+$ export CROSS_COMPILE=or1k-linux-musl-
+$ make pine64_plus_defconfig
+$ make scp
+
+The same configuration generally works on any board with the same SoC (A64, H5,
+or H6), so if there is no config for your board, use one for a similar board.
+
+Like for ATF, U-Boot finds the SCP firmware binary via an environment variable:
+$ export SCP=/src/crust/build/scp/scp.bin
+
  SPL/U-Boot
 ------------
 Both U-Boot proper and the SPL are using the 64-bit mode. As the boot ROM
-- 
2.26.2