Commit graph

43 commits

Author SHA1 Message Date
Rick Chen
dda00ae4ef riscv: ax25: Andes specific cache shall only support in M-mode
Limit the cache configuration only can be supported in M mode.
It can not be manipulated in S mode.

Signed-off-by: Rick Chen <rick@andestech.com>
Cc: Greentime Hu <greentime@andestech.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
2019-04-08 09:45:08 +08:00
Rick Chen
8848474c5e riscv: ax25: Add platform-specific Kconfig options
Add ax25 RISC-V platform-specific Kconfig options,
to include CPU and timer drivers. Also disable
ATCPIT100 SoC timer and replace by PLMT.

Signed-off-by: Rick Chen <rick@andestech.com>
Cc: Greentime Hu <greentime@andestech.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
2019-04-08 09:45:08 +08:00
Lukas Auer
8ac39e2974 riscv: hang if relocation of secondary harts fails
Print an error message and hang if smp_call_function() returns an error,
indicating that relocation of the secondary harts has failed.

Signed-off-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Anup Patel <anup.patel@wdc.com>
2019-04-08 09:44:26 +08:00
Lukas Auer
e043240252 riscv: do not rely on hart ID passed by previous boot stage
RISC-V U-Boot expects the hart ID to be passed to it via register a0 by
the previous boot stage. Machine mode firmware such as BBL and OpenSBI
do this when starting their payload (U-Boot) in supervisor mode. If
U-Boot is running in machine mode, this task must be handled by the boot
ROM. Explicitly populate register a0 with the hart ID from the mhartid
CSR to avoid possible problems on RISC-V processors with a boot ROM that
does not handle this task.

Suggested-by: Rick Chen <rick@andestech.com>
Signed-off-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
Reviewed-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Rick Chen <rick@andestech.com>
Tested-by: Rick Chen <rick@andestech.com>
2019-04-08 09:44:26 +08:00
Lukas Auer
3dea63c844 riscv: add support for multi-hart systems
On RISC-V, all harts boot independently. To be able to run on a
multi-hart system, U-Boot must be extended with the functionality to
manage all harts in the system. All harts entering U-Boot are registered
in the available_harts mask stored in global data. A hart lottery system
as used in the Linux kernel selects the hart U-Boot runs on. All other
harts are halted. U-Boot can delegate functions to them using
smp_call_function().

Every hart has a valid pointer to the global data structure and a 8KiB
stack by default. The stack size is set with CONFIG_STACK_SIZE_SHIFT.

Signed-off-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
Reviewed-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>
2019-04-08 09:44:26 +08:00
Lukas Auer
1446b26f76 riscv: save hart ID in register tp instead of s0
The hart ID passed by the previous boot stage is currently stored in
register s0. If we divert the control flow inside a function, which is
required as part of multi-hart support, the function epilog may not be
called, clobbering register s0. Save the hart ID in the unallocatable
register tp instead to protect the hart ID.

Signed-off-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Rick Chen <rick@andestech.com>
Reviewed-by: Anup Patel <anup.patel@wdc.com>
2019-04-08 09:44:26 +08:00
Lukas Auer
2503ccc55f riscv: delay initialization of caches and debug UART
Move the initialization of the caches and the debug UART until after
board_init_f_init_reserve. This is in preparation for SMP support, where
code prior to this point will be executed by all harts. This ensures
that initialization will only be performed once on the main hart running
U-Boot.

Signed-off-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
Reviewed-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
2019-04-08 09:44:26 +08:00
Anup Patel
26f4fd1cb4 riscv: generic: Ensure that U-Boot runs within 4GB for 64bit systems
On 64bit systems, the DRAM top can be easily beyond 4GB and U-Boot
DMA mapping APIs will generate DMA addresses beyond 4GB. This
breaks DMA programming in 32bit DMA capable devices (such as
Cadence MACB ethernet). For example, If DRAM is more then 2GB
on QEMU sifive_u machine then Cadence MACB ethernet stops working
for U-Boot because it is a 32bit DMA capable device.

To handle 32bit DMA capable devices on 64bit systems, we provide
custom implementation of board_get_usable_ram_top() which ensures
that usable ram top is not more then 4GB. This in-turn ensures
that U-Boot always runs within 4GB hence DMA addresses generated
by DMA mapping APIs will be within 4GB too.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Alexander Graf <agraf@suse.de>
Reviewed-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
2019-02-27 09:12:33 +08:00
Anup Patel
fdff1f96a6 riscv: Rename cpu/qemu to cpu/generic
The QEMU CPU support under arch/riscv is pretty much generic
and works fine for SiFive Unleashed as well. In fact, there
will be quite a few RISC-V SOCs for which QEMU CPU support
will work fine.

This patch renames cpu/qemu to cpu/generic to indicate the
above fact. If there are SOC specific errata workarounds
required in cpu/generic then those can be done at runtime
in cpu/generic based on CPU vendor specific DT compatible
string.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Alexander Graf <agraf@suse.de>
Reviewed-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
2019-02-27 09:12:33 +08:00
Lukas Auer
c9056653ec riscv: move the AX25-specific implementation of flush_dcache_all
The fence instruction is used to enforce device I/O and memory ordering
constraints in RISC-V. It can not be relied on to directly affect the
data cache on every CPU.
Andes' AX25 does not have a coherence agent. Its fence instruction
flushes the data cache and is used to keep data in the system coherent.
The implementation of flush_dcache_all in lib/cache.c is therefore
specific to the AX25. Move it into the AX25-specific cache.c in
cpu/ax25/.

This also adds a missing new line between flush_dcache_all and
flush_dcache_range in lib/cache.c.

Signed-off-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
2019-01-15 09:36:31 +08:00
Bin Meng
51ab4570f3 riscv: Save boot hart id to the global data
At present the hart id passed via a0 in the U-Boot entry is saved
to s0 at the beginning but does not preserve later. Save it to the
global data structure so that it can be used later.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
Reviewed-by: Anup Patel <anup@brainfault.org>
2018-12-18 09:56:27 +08:00
Bin Meng
10753ef8fd riscv: Return to previous privilege level after trap handling
At present the trap handler returns to hardcoded M-mode/S-mode.
Change to returning to previous privilege level instead.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
Reviewed-by: Anup Patel <anup@brainfault.org>
2018-12-18 09:56:27 +08:00
Bin Meng
496262cca6 riscv: Fix context restore before returning from trap handler
sp cannot be loaded before restoring other registers.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
Reviewed-by: Anup Patel <anup@brainfault.org>
2018-12-18 09:56:27 +08:00
Bin Meng
4b3f5ed5ac riscv: Move trap handler codes to mtrap.S
Currently the M-mode trap handler codes are in start.S. For future
extension, move them to a separate file mtrap.S.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
Reviewed-by: Anup Patel <anup@brainfault.org>
2018-12-18 09:56:27 +08:00
Bin Meng
485e822346 riscv: Do some basic architecture level cpu initialization
In arch_cpu_init_dm() do some basic architecture level cpu
initialization, like FPU enable, etc.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
Reviewed-by: Anup Patel <anup@brainfault.org>
2018-12-18 09:56:27 +08:00
Bin Meng
aef59e5cc4 riscv: Update supports_extension() to use desc from cpu driver
This updates supports_extension() implementation to use the desc
string from the cpu driver whenever possible, which avoids the
reading of misa CSR for S-mode U-Boot.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
Reviewed-by: Anup Patel <anup@brainfault.org>
2018-12-18 09:56:27 +08:00
Bin Meng
3c276b2703 riscv: Remove non-DM version of print_cpuinfo()
With DM CPU driver, the non-DM version of print_cpuinfo() is no
longer needed.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
Reviewed-by: Anup Patel <anup@brainfault.org>
2018-12-18 09:56:27 +08:00
Bin Meng
39cad5bc0b riscv: Probe cpus during boot
This calls cpu_probe_all() to probe all available cpus.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
Reviewed-by: Anup Patel <anup@brainfault.org>
2018-12-18 09:56:27 +08:00
Bin Meng
84304d4866 riscv: qemu: Add platform-specific Kconfig options
Add the QEMU RISC-V platform-specific Kconfig options, to include
CPU and timer drivers.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
Reviewed-by: Anup Patel <anup@brainfault.org>
2018-12-18 09:56:27 +08:00
Bin Meng
44fe795c14 riscv: ax25: Hide the ax25-specific Kconfig option
There is no need to expose RISCV_NDS to the Kconfig menu as it is
an ax25-specific option. Introduce a dedicated Kconfig option for
the cache ops of ax25 platform and use that to guard the cache ops.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
Reviewed-by: Rick Chen <rick@andestech.com>
2018-12-18 09:56:26 +08:00
Bin Meng
27dc2c130e riscv: qemu: Create a simple-bus driver for the soc node
To enumerate devices on the /soc/ node, create a "simple-bus"
driver to match "riscv-virtio-soc".

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
Reviewed-by: Anup Patel <anup@brainfault.org>
2018-12-18 09:56:26 +08:00
Rick Chen
48cbf62460 riscv: ax25-ae350: Pass dtb address to u-boot with a1 register
ax25-ae350 use CONFIG_OF_BOARD via a2 and CONFIG_SYS_SDRAM_BASE
to boot from ram which allow the board to override the fdt
address originally.

But after this patch
riscv: save hart ID and device tree passed by prior boot stage
It provide prior_stage_fdt_address which offer a temporary
memory address to keep the dtb address passing from loader(gdb)
to u-boot with a1.

So passing via a2 and CONFIG_SYS_SDRAM_BASE is redundant and
can be removed. And it also somehow may corrupted BBL if it
was be arranged in CONFIG_SYS_SDRAM_BASE.

In board_fdt_blob_setup()
When boting from ram:
prior_stage_fdt_address will be use to reserved dtb temporarily.

When booting from ROM:
dtb will be pre-burned in CONFIG_SYS_FDT_BASE, if it is flash base.
Or CONFIG_SYS_FDT_BASE maybe a memory map space (NOT RAM or ROM)
which is provided by HW.

Signed-off-by: Rick Chen <rick@andestech.com>
Cc: Greentime Hu <greentime@andestech.com>
2018-12-05 14:14:16 +08:00
Anup Patel
d2db2a8fa4 riscv: Add kconfig option to run U-Boot in S-mode
This patch adds kconfig option RISCV_SMODE to run U-Boot in
S-mode. When this opition is enabled we use s<xyz> CSRs instead
of m<xyz> CSRs.

It is important to note that there is no equivalent S-mode CSR
for misa and mhartid CSRs so we expect M-mode runtime firmware
(BBL or equivalent) to emulate misa and mhartid CSR read.

In-future, we will have more patches to avoid accessing misa and
mhartid CSRs from S-mode.

Signed-off-by: Anup Patel <anup@brainfault.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
2018-12-05 14:13:53 +08:00
Rick Chen
52923c6db7 riscv: cache: Implement i/dcache [status, enable, disable]
AndeStar RISC-V(V5) provide mcache_ctl register which
can configure I/D cache as enabled or disabled.

This CSR will be encapsulated by CONFIG_RISCV_NDS.
If you want to configure cache on AndeStar V5
AE350 platform. YOu can enable [*] AndeStar V5 ISA support
by make menuconfig.

This approach also provide the expansion when the
vender specific features are going to join in.

Signed-off-by: Rick Chen <rick@andestech.com>
Cc: Greentime Hu <greentime@andestech.com>
2018-11-26 13:58:01 +08:00
Lukas Auer
5d8b2e7711 riscv: save hart ID and device tree passed by prior boot stage
Store the hart ID and device tree passed by the prior boot stage (in a0
and a1) in registers s0 and s1. Replace one use of s1 in start.S to
avoid overwriting it.

The device tree is also stored in memory to make it available to U-Boot
with the configuration CONFIG_OF_PRIOR_STAGE.

Signed-off-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Rick Chen <rick@andestech.com>
2018-11-26 13:57:32 +08:00
Lukas Auer
31f9058994 riscv: do not blindly modify the mstatus CSR
The mstatus CSR includes WPRI (writes preserve values, reads ignore
values) fields and must therefore not be set to zero without preserving
these fields. It is not apparent why mstatus is set to zero here since
it is not required for U-Boot to run. Remove it.

This instruction and others encode zero as an immediate.  RISC-V has the
zero register for this purpose. Replace the immediates with the zero
register.

Signed-off-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Rick Chen <rick@andestech.com>
2018-11-26 13:57:32 +08:00
Lukas Auer
8bfa231cc6 riscv: remove unused labels in start.S
The labels nmi_vector, trap_vector and handle_reset in start.S are not
used for RISC-V. Remove them.

Signed-off-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
2018-11-26 13:57:32 +08:00
Bin Meng
c95cafd0b1 Drop CONFIG_INIT_CRITICAL
This is now deprecated and no board is using it. Drop it.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Signed-off-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
2018-11-26 13:57:31 +08:00
Lukas Auer
2a23ac6107 riscv: align mtvec on a 4-byte boundary
The machine trap-vector base address (mtvec) must be aligned on a 4-byte
boundary. Add the necessary align directive to trap_entry.

This patch also removes the global directive for trap_entry, which is
not required.

Signed-off-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
2018-11-26 13:57:31 +08:00
Lukas Auer
c55309c091 riscv: fix inconsistent use of spaces and tabs in start.S
start.S uses both tabs and spaces after instructions. Fix this by only
using tabs after instructions.

Signed-off-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Rick Chen <rick@andestech.com>
2018-11-26 13:57:31 +08:00
Bin Meng
b984ddc2dd riscv: Move do_reset() to a common place
We don't have a reset method on any RISC-V board yet. Instead of
adding the same 'unsupported' message for each CPU variant it might
make more sense to add a generic do_reset function for all CPU
variants to lib/, similar to the one for ARM (arch/arm/lib/reset.c).

Suggested-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
2018-10-03 17:48:43 +08:00
Bin Meng
510e379c49 riscv: Add QEMU virt board support
This adds QEMU RISC-V 'virt' board target support, with the hope of
helping people easily test U-Boot on RISC-V.

The QEMU virt machine models a generic RISC-V virtual machine with
support for the VirtIO standard networking and block storage devices.
It has CLINT, PLIC, 16550A UART devices in addition to VirtIO and
it also uses device-tree to pass configuration information to guest
software. It implements RISC-V privileged architecture spec v1.10.

Both 32-bit and 64-bit builds are supported. Support is pretty much
preliminary, only booting to U-Boot shell with the UART driver on
a single core. Booting Linux is not supported yet.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
2018-10-03 17:48:37 +08:00
Bin Meng
b5369c5813 riscv: Make start.S available for all targets
Currently start.S is inside arch/riscv/cpu/ax25/, but it can be
common for all RISC-V targets.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
2018-10-03 17:48:14 +08:00
Bin Meng
2fab2e9c88 riscv: Add a helper routine to print CPU information
This adds a helper routine to print CPU information. Currently
it prints all the instruction set extensions that the processor
core supports.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
2018-10-03 17:47:55 +08:00
Bin Meng
3d6015651b riscv: Fix coding style issues in the linker script
There are several coding style issues in the linker script. Fix them.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
2018-10-03 17:47:37 +08:00
Bin Meng
dfb828ed1c riscv: Move the linker script to the CPU root directory
The linker script can be shared by all RISC-V targets. Move it to
a common place.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
2018-10-03 17:47:31 +08:00
Alexander Graf
122347f366 riscv: Include bss subsections in linker script
When we build with -fdata-sections we may end up with bss subsections. Our
linker script explicitly lists only a single consecutive bss section though.

Adapt the statement to also include subsections.

Signed-off-by: Alexander Graf <agraf@suse.de>
2018-08-20 14:25:59 +02:00
Alexander Graf
7e21fbca26 efi_loader: Rename sections to allow for implicit data
Some times gcc may generate data that is then used within code that may
be part of an efi runtime section. That data could be jump tables,
constants or strings.

In order to make sure we catch these, we need to ensure that gcc emits
them into a section that we can relocate together with all the other
efi runtime bits. This only works if the -ffunction-sections and
-fdata-sections flags are passed and the efi runtime functions are
in a section that starts with ".text".

Up to now we had all efi runtime bits in sections that did not
interfere with the normal section naming scheme, but this forces
us to do so. Hence we need to move the efi_loader text/data/rodata
sections before the global *(.text*) catch-all section.

With this patch in place, we should hopefully have an easier time
to extend the efi runtime functionality in the future.

Signed-off-by: Alexander Graf <agraf@suse.de>
[agraf: Fix x86_64 breakage]
2018-07-25 14:57:44 +02:00
Rick Chen
6f4dd62f33 riscv: cpu: nx25: Rename as ax25
Andes has rearranged the product combinations.
nx25 and ax25 both are RISC-V architecture cpu core.
But ax25 has MMU unit inside, and nx25 is not.

Cpu nx25 and platform ae250 are arranged in pairs.
Cpu ax25 and platform ae350 are arranged in pairs.

This patch will rename
nx25 as ax25
ae250 as ae350
nx25-ae250 as ax25-ae350
including filename, variable, string and definition.

Then u-boot can boot linux kernel in ae350
platform reasonably.

Signed-off-by: Rick Chen <rick@andestech.com>
Signed-off-by: Rick Chen <rickchen36@gmail.com>
Cc: Greentime Hu <green.hu@gmail.com>
2018-05-29 14:45:02 +08:00
Rick Chen
6836adbe75 efi_loader: Enable RISC-V support
We have almost all pieces needed to support RISC-V UEFI binaries in place already.
The only missing piece are ELF relocations for runtime code and
data.

This patch adds respective support in the linker script and the runtime
relocation code. It also allows users to enable the EFI_LOADER configuration
switch on RISC-V platforms.

Signed-off-by: Alexander Graf <agraf@suse.de>
2018-05-29 14:43:12 +08:00
Tom Rini
83d290c56f SPDX: Convert all of our single license tags to Linux Kernel style
When U-Boot started using SPDX tags we were among the early adopters and
there weren't a lot of other examples to borrow from.  So we picked the
area of the file that usually had a full license text and replaced it
with an appropriate SPDX-License-Identifier: entry.  Since then, the
Linux Kernel has adopted SPDX tags and they place it as the very first
line in a file (except where shebangs are used, then it's second line)
and with slightly different comment styles than us.

In part due to community overlap, in part due to better tag visibility
and in part for other minor reasons, switch over to that style.

This commit changes all instances where we have a single declared
license in the tag as both the before and after are identical in tag
contents.  There's also a few places where I found we did not have a tag
and have introduced one.

Signed-off-by: Tom Rini <trini@konsulko.com>
2018-05-07 09:34:12 -04:00
Rick Chen
d58717e425 riscv: ae250: Support DT provided by the board at runtime
Enable CONFIG_OF_BOAD to support delivery dtb to u-boot
at run time instead of embedded.

There are two methods to delivery dtb.
 1 Pass from loader:
   When u-boot boot from RAM, gdb or loader can pass dtb
   via a2 to u-boot dynamically. Of course gdb or loader
   shall be in charge of dtb delivery.

 2 Configure CONFIG_SYS_FDT_BASE:
   It can be configured as RAM or ROM base statically,
   no mater u-boot boot from RAM or ROM.
   If it was configured as ROM base, dtb can be burned
   into ROM(spi flash) by spi driver.

Meanwhile remove CONFIG_SKIP_LOWLEVEL_INIT which is
useless in nx25-ae250 configuration.

Signed-off-by: Rick Chen <rick@andestech.com>
Signed-off-by: Rick Chen <rickchen36@gmail.com>
Cc: Greentime Hu <green.hu@gmail.com>
2018-03-30 13:13:56 +08:00
Rick Chen
e8e39597a3 riscv: cpu: Add nx25 to support RISC-V
Add Andes nx25 cpu core (called AndesStar V5) to support RISC-V arch

Verifications:
1. startup and relocation ok.
2. boot from rom or ram both ok.
2. timer driver ok.
3. uart driver ok
4. mmc driver ok
5. spi driver ok.
6. 32/64 bit both ok.

Detail verification message please see doc/README.ae250.

Signed-off-by: Rick Chen <rick@andestech.com>
Signed-off-by: Rick Chen <rickchen36@gmail.com>
Signed-off-by: Greentime Hu <green.hu@gmail.com>
Cc: Padmarao Begari <Padmarao.Begari@microsemi.com>
2018-01-12 08:05:12 -05:00