[PATCH v5 04/13] riscv: sbi: add SBI FWFT extension calls

Clément Léger
2025-04-17T12:36:13Z

Add FWFT extension calls. This will be ratified in SBI V3.0 hence, it is
provided as a separate commit that can be left out if needed.

Signed-off-by: Clément Léger <cleger@rivosinc.com>
---
arch/riscv/kernel/sbi.c | 20 +++++++++++++++++++-
1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/kernel/sbi.c b/arch/riscv/kernel/sbi.c
index 379981c2bb21..7b062189b184 100644
--- a/arch/riscv/kernel/sbi.c
+++ b/arch/riscv/kernel/sbi.c
@@ -299,6 +299,8 @@ static int __sbi_rfence_v02(int fid, const struct cpumask *cpu_mask,
return 0;
}

+static bool sbi_fwft_supported;
+
/**
* sbi_fwft_set() - Set a feature on the local hart
* @feature: The feature ID to be set
@@ -309,7 +311,15 @@ static int __sbi_rfence_v02(int fid, const struct cpumask *cpu_mask,
*/
int sbi_fwft_set(u32 feature, unsigned long value, unsigned long flags)
{
- return -EOPNOTSUPP;
+ struct sbiret ret;
+
+ if (!sbi_fwft_supported)
+ return -EOPNOTSUPP;
+
+ ret = sbi_ecall(SBI_EXT_FWFT, SBI_EXT_FWFT_SET,
+ feature, value, flags, 0, 0, 0);
+
+ return sbi_err_map_linux_errno(ret.error);
}

struct fwft_set_req {
@@ -348,6 +358,9 @@ int sbi_fwft_local_set_cpumask(const cpumask_t *mask, u32 feature,
.error = ATOMIC_INIT(0),
};

+ if (!sbi_fwft_supported)
+ return -EOPNOTSUPP;
+
if (feature & SBI_FWFT_GLOBAL_FEATURE_BIT)
return -EINVAL;

@@ -679,6 +692,11 @@ void __init sbi_init(void)
pr_info("SBI DBCN extension detected\n");
sbi_debug_console_available = true;
}
+ if ((sbi_spec_version >= sbi_mk_version(3, 0)) &&
+ (sbi_probe_extension(SBI_EXT_FWFT) > 0)) {
+ pr_info("SBI FWFT extension detected\n");
+ sbi_fwft_supported = true;
+ }
} else {
__sbi_set_timer = __sbi_set_timer_v01;
__sbi_send_ipi = __sbi_send_ipi_v01;