[PATCH 4/5] arm64: dts: rockchip: add reboot-mode node to RK3576

[Alexey Charkov]

The RK3576 boot ROM chooses its boot device order from PMU1_GRF OS_REG0
when that register holds one of its magic values: 0xef08a53c selects USB
download (maskrom) mode, 0xef085a3X selects boot mode X, overriding what
OTP or the SARADC strap would otherwise give.

OS_REG0 cannot be written ahead of a reset, as it is cleared by NPOR.
Instead TF-A takes a request from PMU0_GRF OS_REG16, forwards it to
OS_REG0 and masks the reset outputs so that it reaches the boot ROM.
That register is the one U-Boot uses for its own boot modes as well.

Describe it as a syscon-reboot-mode node, so that a reboot can carry a
request for maskrom or for a particular boot device. Under Linux, for
example:

	systemctl reboot --reboot-argument=maskrom

Requesting anything other than maskrom needs a TF-A containing commit
2a97ba20e901 ("feat(rk3576): forward any boot ROM boot mode request on
reset"); older builds ignore those requests and boot normally.

Link: https://docs.flipper.net/one/hardware/rk3576/boot-rom
Signed-off-by: Alexey Charkov <alchark at flipper.net>
---
 arch/arm64/boot/dts/rockchip/rk3576.dtsi | 36 ++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/arch/arm64/boot/dts/rockchip/rk3576.dtsi b/arch/arm64/boot/dts/rockchip/rk3576.dtsi
index e87ace5d05e6..c938dbcad712 100644
--- a/arch/arm64/boot/dts/rockchip/rk3576.dtsi
+++ b/arch/arm64/boot/dts/rockchip/rk3576.dtsi
@@ -881,6 +881,42 @@ php_grf: syscon at 26020000 {
 		pmu0_grf: syscon at 26024000 {
 			compatible = "rockchip,rk3576-pmu0-grf", "syscon", "simple-mfd";
 			reg = <0x0 0x26024000 0x0 0x1000>;
+
+			/*
+			 * OS_REG16 carries a boot mode request across a reset.
+			 * TF-A picks it up while resetting the system, forwards
+			 * it to the boot ROM through PMU1_GRF OS_REG0 and masks
+			 * the reset outputs, so that the request survives NPOR.
+			 * The modes below are listed in boot mode order, each
+			 * naming the devices the boot ROM tries in turn.
+			 */
+			reboot_mode: reboot-mode {
+				compatible = "syscon-reboot-mode";
+				offset = <0x40>;
+				mode-normal = <BOOT_NORMAL>;
+				/* 1: USB */
+				mode-maskrom = <BOOT_BROM_DOWNLOAD>;
+				/* 2: SPI NOR, SPI NAND, USB */
+				mode-spi = <0xef085a32>;
+				/* 3: SPI NOR/NAND M1, eMMC, USB */
+				mode-spi-m1 = <0xef085a33>;
+				/* 4: SPI NOR/NAND M2, eMMC, USB */
+				mode-spi-m2 = <0xef085a34>;
+				/* 5: SPI NOR, SPI NAND, UFS, USB */
+				mode-spi-ufs = <0xef085a35>;
+				/* 6: SPI NOR/NAND M1, UFS, USB */
+				mode-spi-m1-ufs = <0xef085a36>;
+				/* 7: UFS, USB */
+				mode-ufs = <0xef085a37>;
+				/* 8: UFS, SD, USB */
+				mode-ufs-sd = <0xef085a38>;
+				/* 9: every SPI iomux, eMMC, SD, USB */
+				mode-spi-all = <0xef085a39>;
+				/* 10: eMMC, SD, USB */
+				mode-emmc-sd = <0xef085a3a>;
+				/* 11: eMMC, USB */
+				mode-emmc = <0xef085a3b>;
+			};
 		};
 
 		pmu1_grf: syscon at 26026000 {

-- 
2.55.0