Add a callback interface, harts_early_init() to perform proprietary or
customized CRSs configuration for each hart. harts_early_init() is placed
after stack of harts are initialized and before main boot hart is picked up.
Several conditions should be aware of or avoided are listed:
- cannot access gd
At the moment, gd hasn't initialized yet.
- all operations in harts_early_init() should only affect core itself
For example, the operations for board level should be moved to mach_xxx()
or board_init_xxx() functions instead.
- Common resource need protection if multicore
Since all harts might enter harts_early_init() in parallel, common
resource need a mechanism to handle race condition.
- A reference implementation is added in ./arch/riscv/cpu/cpu.c
The implementation is declared with '__weak' and can be overridden.
Changelogs:
v7
- remove M-mode check in [v6 1/2]
- remove 'arch' from title of patch
- add Reviewed-by
v6
- revised the description in both of commit message and comment [1/2]
- moved the implementation of harts_early_init() in [2/2] from
board/sifive/unmatched/spl.c to arch/riscv/cpu/fu740/spl.c. and revised
commit message
v5
- rename riscv_hart_early_init to harts_early_init
- rephrase dummy for harts_early_init() to callback but keep current
comments not specific for customizing CSRs only.
- Fix nit in [2/2] and add reviewed-by
v4
- Revising the comments for riscv_hart_early_init() in [1/2]
- Remove unnecessary braces and add reviewed-by in [2/2]
Green Wan (2):
riscv: cpu: Add callback to init each core
riscv: cpu: fu740: clear feature disable CSR
arch/riscv/cpu/cpu.c | 11 +++++++++++
arch/riscv/cpu/fu740/spl.c | 15 +++++++++++++++
arch/riscv/cpu/start.S | 6 ++++++
3 files changed, 32 insertions(+)
--
2.31.0
