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lib: sbi: Implement Sstc extension

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Recently, Sstc extension was ratified. It defines stimecmp which allows
the supervisor mode to directly update the timecmp value without the
need of the SBI call. The hardware also can inject the S-mode timer
interrupt direclty to the supervisor without going through the M-mode.
To maintain backward compatibility with the older software, SBI call
now uses stimecmp directly if the hardware supports.

Implement the Sstc extension.

Signed-off-by: Atish Patra <atishp@rivosinc.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
This commit is contained in:
Atish Patra
2022-04-25 23:29:22 -07:00
committed by Anup Patel
parent 4035ae94be
commit d62f6da062
4 changed files with 57 additions and 4 deletions
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4
include/sbi/sbi_hart.h
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@@ -30,9 +30,11 @@ enum sbi_hart_features {
SBI_HART_HAS_MENVCFG = (1 << 6),
/** HART has mstateen CSR **/
SBI_HART_HAS_SMSTATEEN = (1 << 7),
/** HART has SSTC extension implemented in hardware */
SBI_HART_HAS_SSTC = (1 << 8),
/** Last index of Hart features*/
SBI_HART_HAS_LAST_FEATURE = SBI_HART_HAS_SMSTATEEN,
SBI_HART_HAS_LAST_FEATURE = SBI_HART_HAS_SSTC,
};
struct sbi_scratch;