RISC-V SBI debug console extension support

[yechao-w]

【验证方法】
1）在qemu仿真器环境进行验证，qemu仿真器版本：10.0.0；
2）仿真器的内核版本以及qemu-kvm虚拟机的内核版本均为合入此补丁的内核；
3）qemu-kvm版本：10.0.0，qemu-kvm虚拟机启动参数：（内核启动参数携带earlycon=sbi），

/usr/bin/qemu-system-riscv64 \
        -nographic -enable-kvm \
        -machine virt,pflash0=pflash0,pflash1=pflash1,acpi=on,aia=aplic-imsic,accel=kvm \
        -blockdev node-name=pflash0,driver=file,read-only=on,filename="./RISCV_VIRT_CODE.fd" \
        -blockdev node-name=pflash1,driver=file,filename="./riscv_test_VARS.fd" \
        -smp 4,sockets=2,dies=1,clusters=1,cores=2,threads=1 \
        -m 4G \
        -kernel /boot/vmlinuz-6.6.101+ \
        -initrd /boot/initramfs-6.6.101+.img \
        -append "root=UUID=fce3cee6-e5eb-4694-85f3-48a369464c19 earlycon=sbi console=tty0 console=ttyS0 selinux=0 cgroup_disable=files apparmor=0" \
        -drive file="/rvck/openEuler-24.03-LTS-riscv64.qcow2",format=qcow2,id=hd0,if=none \
        -device virtio-blk-device,drive=hd0,bootindex=1 \
        -object rng-random,filename=/dev/urandom,id=rng0 \
        -device virtio-rng-device,rng=rng0 \
        -device virtio-net-pci,netdev=net1 \
        -netdev tap,id=net1,ifname=vnet1,script=no,downscript=no \
        -cpu host \
        -device qemu-xhci \
        -usb -device usb-kbd \
        -device usb-tablet \
        -chardev socket,id=qmp,path=/var/lib/libvirt/qemu/riscv-test,server=on,wait=off \
        -mon mode=control,chardev=qmp

【验证结果】
系统启动后，启动日志如下：

[root@localhost ~]# dmesg |less
[    0.000000] Linux version 6.6.101+ (root@c8_dev) (riscv64-unknown-linux-gnu-gcc (ZTE Embsys-TSP V4.07.10.10) 12.2.0, GNU ld (ZTE Embsys-TSP V4.07.10.10) 2.39) #4 SMP Fri Aug 22 05:35:52 EDT 2025
[    0.000000] SBI specification v2.0 detected
[    0.000000] SBI implementation ID=0x3 Version=0x60665
[    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 DBCN extension detected
[    0.000000] earlycon: sbi0 at I/O port 0x0 (options '')
[    0.000000] printk: bootconsole [sbi0] enabled
[    0.000000] efi: EFI v2.7 by EDK II
[    0.000000] efi: SMBIOS 3.0=0xfff43000 MEMATTR=0xf8934018 ACPI=0xff5d5000 ACPI 2.0=0xff5d5014 INITRD=0xf898cf18 RNG=0xf8932018 MEMRESERVE=0xf898cf98 
[    0.000000] random: crng init done

内核检测到 SBI spec 2.0，以及支持DBCN extension，earlycon sbi使能成功。

[oervci]

开始测试

[oervci]

check patch done. log: https://jenkins.oerv.ac.cn/job/rvck-pipeline/job/check-patch/124/consoleFull

[oervci]

Kernel build success!

[oervci]

kunit test done. log:https://jenkins.oerv.ac.cn/job/rvck-pipeline/job/kunit-test/130/consoleFull

[oervci]

Lava check fail! log: https://jenkins.oerv.ac.cn/job/rvck-pipeline/job/rvck-lava-trigger/154/consoleFull, result url: https://lava.oerv.ac.cn/results/452/0_rvck_common-test_qemu

[wangliu-iscas]

/check

[oervci]

开始测试

[oervci]

check patch done. log: https://jenkins.oerv.ac.cn/job/rvck-pipeline/job/check-patch/149/consoleFull

[oervci]

Kernel build success!

[oervci]

kunit test done. log:https://jenkins.oerv.ac.cn/job/rvck-pipeline/job/kunit-test/156/consoleFull

[oervci]

Lava check done! result url: https://lava.oerv.ac.cn/results/617/0_rvck_common-test_qemu

[sterling-teng]

补丁没有问题，进入物理机测试阶段，通过测试后将尝试合并。