[PATCH 00/10] Kendryte k210 SoC boards support

[Damien Le Moal <damien.lemoal@wdc.com>]

This series adds support to boot nommu Linux on Kendryte K210 SoC based
boards. This is all based on initial work done by Christoph Hellwig.

The first 2 patches fix riscv gitignore and a potential nommu
compilation error. These patches are not specific to the Kendryte
support.

Patch 3 adds unaligned load/store trap handlers for M-mode.

Patch 4 enables a builtin DTB to allow passing a device tree to the
kernel when the board bootchain is enabled to pass one.

Patch 5 introduces an early SoC initialization enabling very early
hardware initialization not possible with device tree entries pointing
to drivers. This is used in patch 6 which introduces a sysctl driver for
the K210 SoC. The early SoC initialization is used to enable the
additional 2MB of SRAM normally reserved to the SoC AI chip.

Patch 7 to 9 add necessary Kconfig changes, a defconfig and a generic
device tree suitable for many K210 boards.

Finally, patch 10 adds compilation of a bootable image file (bin file)
that can be used to flash the board ROM.

This series was tested on the Kendryte KD233 development board, the
Sipeed MAIX dan dock board and the Sipeed MAIXDUINO board. The userspace
used was built using a modified buildroot tree for the toolchain part
and an unmodified busybox tree for the initramfs image (embedded in the
kernel as a cpio file). The folowwing github project contains the
modified buildroot tree:

https://github.com/damien-lemoal/riscv64-nommu-buildroot

This is based on work from Christoph Hellwig, with additional changes
and updates to the latest upstream versions for buildroot and uClibc.

Precompiled versions of the toolchain (gcc 9.2) and initramfs file tree
and cpio file can be found in this project under the directory:

buildroot/riscv64-uclibc-nommu/

Flashing the file arch/riscv/boot/loader.bin to a board can be done
using the Sipeed kflash.py tool with the command:

kflash.py/kflash.py -p /dev/ttyUSB0 -b 1500000 -t loader.bin

The kflash.py tool can be found here:

https://github.com/sipeed/kflash.py

For reference, using the Sipeed MAIXDUINO board, here is the boot
output:

[INFO] Rebooting... 
--- forcing DTR inactive
--- forcing RTS inactive
--- Miniterm on /dev/ttyUSB0  115200,8,N,1 ---
--- Quit: Ctrl+] | Menu: Ctrl+T | Help: Ctrl+T followed by Ctrl+H ---
[    0.000000] Linux version 5.6.0-rc1-00011-ga2b5be1c4374 (damien@yyy) (gcc version 8.2.0 (Buildroot 2018.11-rc2-00003-ga0787e9)) #610 SMP Wed Feb 12 18:53:50 JST 2020
[    0.000000] earlycon: sifive0 at MMIO 0x0000000038000000 (options '')
[    0.000000] printk: bootconsole [sifive0] enabled
[    0.000000] initrd not found or empty - disabling initrd
[    0.000000] Zone ranges:
[    0.000000]   DMA32    [mem 0x0000000080000000-0x00000000807fffff]
[    0.000000]   Normal   empty
[    0.000000] Movable zone start for each node
[    0.000000] Early memory node ranges
[    0.000000]   node   0: [mem 0x0000000080000000-0x00000000807fffff]
[    0.000000] Initmem setup node 0 [mem 0x0000000080000000-0x00000000807fffff]
[    0.000000] elf_hwcap is 0x112d
[    0.000000] percpu: max_distance=0x18000 too large for vmalloc space 0x0
[    0.000000] percpu: Embedded 12 pages/cpu s18272 r0 d30880 u49152
[    0.000000] Built 1 zonelists, mobility grouping off.  Total pages: 2020
[    0.000000] Kernel command line: earlycon console=ttySIF0
[    0.000000] Dentry cache hash table entries: 1024 (order: 1, 8192 bytes, linear)
[    0.000000] Inode-cache hash table entries: 512 (order: 0, 4096 bytes, linear)
[    0.000000] Sorting __ex_table...
[    0.000000] mem auto-init: stack:off, heap alloc:off, heap free:off
[    0.000000] Memory: 6328K/8192K available (924K kernel code, 110K rwdata, 164K rodata, 321K init, 91K bss, 1864K reserved, 0K cma-reserved)
[    0.000000] rcu: Hierarchical RCU implementation.
[    0.000000] rcu: RCU calculated value of scheduler-enlistment delay is 25 jiffies.
[    0.000000] NR_IRQS: 0, nr_irqs: 0, preallocated irqs: 0
[    0.000000] plic: mapped 65 interrupts with 2 handlers for 4 contexts.
[    0.000000] riscv_timer_init_dt: Registering clocksource cpuid [0] hartid [0]
[    0.000000] clocksource: riscv_clocksource: mask: 0xffffffffffffffff max_cycles: 0x3990be68b, max_idle_ns: 881590404272 ns
[    0.000014] sched_clock: 64 bits at 7MHz, resolution 128ns, wraps every 4398046511054ns
[    0.008232] Console: colour dummy device 80x25
[    0.012474] Calibrating delay loop (skipped), value calculated using timer frequency.. 15.60 BogoMIPS (lpj=31200)
[    0.022678] pid_max: default: 4096 minimum: 301
[    0.027288] Mount-cache hash table entries: 512 (order: 0, 4096 bytes, linear)
[    0.034414] Mountpoint-cache hash table entries: 512 (order: 0, 4096 bytes, linear)
[    0.044796] rcu: Hierarchical SRCU implementation.
[    0.049602] smp: Bringing up secondary CPUs ...
[    0.054746] smp: Brought up 1 node, 2 CPUs
[    0.059093] devtmpfs: initialized
[    0.065523] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 7645041785100000 ns
[    0.074544] futex hash table entries: 16 (order: -2, 1024 bytes, linear)
[    0.082512] Kendryte K210 SoC sysctl
[    0.096010] clocksource: Switched to clocksource riscv_clocksource
[    0.178581] workingset: timestamp_bits=62 max_order=11 bucket_order=0
[    0.185846] 38000000.serial: ttySIF0 at MMIO 0x38000000 (irq = 1, base_baud = 0) is a SiFive UART v0
[    0.194344] printk: console [ttySIF0] enabled
[    0.194344] printk: console [ttySIF0] enabled
[    0.202929] printk: bootconsole [sifive0] disabled
[    0.202929] printk: bootconsole [sifive0] disabled
[    0.214853] random: get_random_bytes called from 0x0000000080055178 with crng_init=0
[    0.223606] devtmpfs: mounted
[    0.226861] Freeing unused kernel memory: 320K
[    0.230574] This architecture does not have kernel memory protection.
[    0.236987] Run /sbin/init as init process
[    0.241181] Run /etc/init as init process
[    0.245178] Run /bin/init as init process

-----------------------------
| Kendryte K210 NOMMU Linux |
-----------------------------
Mounting /proc
Starting shell


BusyBox v1.32.0.git (2020-02-12 17:51:45 JST) hush - the humble shell
Enter 'help' for a list of built-in commands.

/ # cat /proc/cpuinfo 
processor	: 0
hart		: 0
isa		: rv64imafdc

processor	: 1
hart		: 1
isa		: rv64imafdc

/ # 
/ # ls -l /
drwxrwxr-x    2 1000     1000             0 Feb 12  2020 bin
drwxr-xr-x    2 0        0                0 Jan  1 00:00 dev
drwxrwxr-x    2 1000     1000             0 Feb 12  2020 etc
dr-xr-xr-x   58 0        0                0 Jan  1 00:00 proc
drwxrwxr-x    2 1000     1000             0 Feb 12  2020 root
drwxrwxr-x    2 1000     1000             0 Feb 12  2020 sbin
drwxrwxr-x    2 1000     1000             0 Feb 12  2020 sys
drwxrwxr-x    2 1000     1000             0 Feb 12  2020 tmp
drwxrwxr-x    4 1000     1000             0 Feb 12  2020 usr
/ # 
/ # cat /proc/vmstat 
nr_free_pages 1148
...
/ #

The K210 SoC has more devices (GPIO, SD-card, LCD, etc) that likely can
be enabled and used. For this, the sysctl driver will need further
improvements as each device uses a different clock. To share the fun,
supporting these is left as an exercise for the hobbyist and hackers
interested in this SoC/boards :)

Christoph Hellwig (2):
  riscv: Add Kendryte K210 SoC support
  riscv: create a loader.bin for the kendryte kflash.py tool

Damien Le Moal (8):
  riscv: Fix gitignore
  riscv: Force flat memory model with no-mmu
  riscv: Unaligned load/store handling for M_MODE
  riscv: Add BUILTIN_DTB support
  riscv: Add SOC early init support
  riscv: Select required drivers for Kendryte SOC
  riscv: Add Kendryte K210 device tree
  riscv: Kendryte K210 default config

 arch/riscv/Kbuild                       |   1 +
 arch/riscv/Kconfig                      |  19 ++
 arch/riscv/Kconfig.socs                 |  10 +
 arch/riscv/Makefile                     |   4 +-
 arch/riscv/boot/.gitignore              |   2 +
 arch/riscv/boot/Makefile                |   3 +
 arch/riscv/boot/dts/Makefile            |   5 +
 arch/riscv/boot/dts/kendryte/Makefile   |   2 +
 arch/riscv/boot/dts/kendryte/k210.dts   |  23 ++
 arch/riscv/boot/dts/kendryte/k210.dtsi  | 123 ++++++++
 arch/riscv/configs/nommu_k210_defconfig |  68 +++++
 arch/riscv/include/asm/soc.h            |  23 ++
 arch/riscv/kernel/Makefile              |   3 +-
 arch/riscv/kernel/head.S                |   1 +
 arch/riscv/kernel/setup.c               |   6 +
 arch/riscv/kernel/soc.c                 |  28 ++
 arch/riscv/kernel/traps.c               |  27 +-
 arch/riscv/kernel/traps_misaligned.c    | 371 ++++++++++++++++++++++++
 arch/riscv/kernel/vmlinux.lds.S         |   6 +
 arch/riscv/mm/init.c                    |   4 +
 drivers/soc/Kconfig                     |   1 +
 drivers/soc/Makefile                    |   1 +
 drivers/soc/kendryte/Kconfig            |  14 +
 drivers/soc/kendryte/Makefile           |   3 +
 drivers/soc/kendryte/k210-sysctl.c      | 245 ++++++++++++++++
 25 files changed, 987 insertions(+), 6 deletions(-)
 create mode 100644 arch/riscv/boot/dts/kendryte/Makefile
 create mode 100644 arch/riscv/boot/dts/kendryte/k210.dts
 create mode 100644 arch/riscv/boot/dts/kendryte/k210.dtsi
 create mode 100644 arch/riscv/configs/nommu_k210_defconfig
 create mode 100644 arch/riscv/include/asm/soc.h
 create mode 100644 arch/riscv/kernel/soc.c
 create mode 100644 arch/riscv/kernel/traps_misaligned.c
 create mode 100644 drivers/soc/kendryte/Kconfig
 create mode 100644 drivers/soc/kendryte/Makefile
 create mode 100644 drivers/soc/kendryte/k210-sysctl.c

-- 
2.24.1