Previously we assume only 1 UART8250 instance can be used. Now we support
multiple instances by introducing counterpart functions to putc/getc/init
which take an extra *dev parameter, and name them as uart8250_device_xyz()
The original functions without the *dev parameter will operate on the
default instance exactly the same as before, so no changes on the caller
is required.
Note: uart8250_device_init only does device initialization without the
console registration logic.
Signed-off-by: Bo Gan <ganboing@gmail.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20251218104243.562667-7-ganboing@gmail.com
Signed-off-by: Anup Patel <anup@brainfault.org>
Initial platform support for ESWIN Computing EIC7700 based on public SoC
datasheet[1] and tested on HiFive Premier P550. Vendor U-boot/Linux boots
fine, and I've tested Geekbench 6.5.0 Preview and got scores on par with
the vendor OpenSBI. System shutdown/reboot for HiFive Premier P550 and
other boards will be implemented in subsequent commits. At this point,
only SoC-level warm reset is implemented.
The files and functions are intentionally named as eic770x in many places
for future enhancements to support the 2 die version of the same SoC,
namely EIC7702, seen on DC-ROMA AI PC FML13V03 [2]. This patch set only
deals with the single die version, and the assumption is we can be either
die with id=0 or id=1, but there's only a single die in the system, or we
are only using a single die out of 2. However, the way the SoC handles 2-
die greatly affects how we configure it in a 1-die setup. EIC770X address
map has die 0/1 memory regions interleaved (see comments in eic770x.c).
If only 1 die is connected or active, it creates holes in the address map
for those regions corresponding to the remote die. When speculative-
execution or HW prefetcher touches data-cacheable regions that happen to
fall into those holes, it can trigger bus error. Specifically:
- Remote (non-existent) die L3 zero device
- Remote (non-existent) die cached memory region
- Other holes in Memory Port
To make matters worse, EIC770X doesn't have cache coherent DMA, and due
to the fact that the P550 core lacks Svpbmt, the SoC maps main memory
twice as different regions, so it can bypass cache and fetch the data
directly from memory. In address space, we have two memory regions, one
as cached, the other as uncached. Thus, we also need an extra PMP entry
to protect OpenSBI blob from the uncached window. To do this, platform
code requires single_fw_region, otherwise, we'll run out of PMP entries.
EIC770X also have several feature disable/enable CSRs accessible in M
mode. By default many core features such as speculation and HW prefetch
are disabled, and M mode software is responsible of enabling. Hence,
introduce 4 new build time tunable parameters to Kconfig, which reflects
the values get updated to those CSRs:
- ESWIN_EIC770X_FEAT0_CFG
- ESWIN_EIC770X_FEAT1_CFG
- ESWIN_EIC770X_L1_HWPF_CFG
- ESWIN_EIC770X_L2_HWPF_CFG
The default values are somewhat optimal for generic workloads. They are
dumped when running SiFive's vendor OpenSBI, and in addition, with my
own tuning to address the perf regression reported by drmpeg [3]
To build the firmware+u-boot blob, Use the following, and docs [4] for
testing it with UART boot without flashing:
make FW_TEXT_START=0x80000000 \
FW_PAYLOAD_OFFSET=0x200000 \
FW_PAYLOAD_PATH=u-boot-nodtb.bin \
FW_PAYLOAD_FDT_ADDR=0xf8000000 \
FW_FDT_PATH=u-boot.dtb
[1] https://github.com/eswincomputing/EIC7700X-SoC-Technical-Reference-Manual
[2] https://github.com/geerlingguy/sbc-reviews/issues/82
[3] https://forums.sifive.com/t/low-1-core-stream-bandwidth/7274/15
[4] https://github.com/ganboing/EIC770x-Docs/blob/main/p550/bootchain/UART-Boot.md
Signed-off-by: Bo Gan <ganboing@gmail.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20251218104243.562667-6-ganboing@gmail.com
Signed-off-by: Anup Patel <anup@brainfault.org>
By default the OpenSBI itself is covered by 2 memregions for RX/RW
sections. This is required by platforms with Smepmp to enforce
proper permissions in M mode. Note: M-mode only regions can't
have RWX permissions with Smepmp. Platforms with traditional PMPs
won't be able to benefit from it, as both regions are effectively
RWX in M mode, but usually it's harmless to so. Now we provide
these platforms with an option to disable this logic. It saves 1
PMP entry. For platforms really in short of PMPs, it does make a
difference.
Note: Platform requesting single OpenSBI memregion must be using
traditional (old) PMP. We expect the platform code to do
the right thing.
Signed-off-by: Bo Gan <ganboing@gmail.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20251218104243.562667-5-ganboing@gmail.com
Signed-off-by: Anup Patel <anup@brainfault.org>
sbi_load/store_access_handler now tries to call platform emulators
if defined. Otherwise, redirects the fault. If the platform code
returns failure, this means the H/S/U has accessed the emulated
devices in an unexpected manner, which is very likely caused by
buggy code in H/S/U. We redirect the fault, so lower privileged
level can get notified, and act accordingly. (E.g., oops in Linux)
We let the handler truly fail if the trap was originated from M mode.
In this case, something must be very wrong and we should just fail.
Signed-off-by: Bo Gan <ganboing@gmail.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
This patch allows the platform to define load/store emulators. This
enables a platform to trap-and-emulate special devices or filter
access to existing physical devices.
Signed-off-by: Bo Gan <ganboing@gmail.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
This patch abstracts out the instruction decoding part of misaligned ld/st
fault handlers, so it can be reused by ld/st access fault handlers.
Also Added lb/lbu/sb decoding. (previously unreachable by misaligned fault)
sbi_trap_emulate_load/store is now the common handler which takes a `emu`
parameter that is responsible for emulating the misaligned or access fault.
The `emu` callback is expected to fixup the fault, and based on the return
code of `emu`, sbi_trap_emulate_load/store will:
r/wlen => the fixup is successful and regs/mepc needs to be updated.
0 => the fixup is successful, but regs/mepc should be left untouched
(this is usually used if `emu` does `sbi_trap_redirect`)
-err => failed, sbi_trap_error will be called
For now, load/store access faults are blindly redirected. It will be
enhanced in the following patches.
Signed-off-by: Bo Gan <ganboing@gmail.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
This simplifies both handlers such that when the handler needs to
redirect the original trap, it's readily available.
Signed-off-by: Bo Gan <ganboing@gmail.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
sbi_trap_redirect now uses const pointer to `trap`.
This ensures the caller that we never change `trap` in sbi_trap_redirect.
Signed-off-by: Bo Gan <ganboing@gmail.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
