[PATCH v3 03/17] riscv: sbi: add SBI FWFT extension calls

Clément Léger
2025-03-10T15:13:12Z

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 | 30 ++++++++++++++++++++++++++++--
1 file changed, 28 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/kernel/sbi.c b/arch/riscv/kernel/sbi.c
index 256910db1307..af8e2199e32d 100644
--- a/arch/riscv/kernel/sbi.c
+++ b/arch/riscv/kernel/sbi.c
@@ -299,9 +299,19 @@ static int __sbi_rfence_v02(int fid, const struct cpumask *cpu_mask,
return 0;
}

+static bool sbi_fwft_supported;
+
int sbi_fwft_get(u32 feature, unsigned long *value)
{
- return -EOPNOTSUPP;
+ struct sbiret ret;
+
+ if (!sbi_fwft_supported)
+ return -EOPNOTSUPP;
+
+ ret = sbi_ecall(SBI_EXT_FWFT, SBI_EXT_FWFT_GET,
+ feature, 0, 0, 0, 0, 0);
+
+ return sbi_err_map_linux_errno(ret.error);
}

/**
@@ -314,7 +324,15 @@ int sbi_fwft_get(u32 feature, unsigned long *value)
*/
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 {
@@ -389,6 +407,9 @@ static int sbi_fwft_feature_local_set(u32 feature, unsigned long value,
int sbi_fwft_all_cpus_set(u32 feature, unsigned long value, unsigned long flags,
bool revert_on_fail)
{
+ if (!sbi_fwft_supported)
+ return -EOPNOTSUPP;
+
if (feature & SBI_FWFT_GLOBAL_FEATURE_BIT)
return sbi_fwft_set(feature, value, flags);

@@ -719,6 +740,11 @@ void __init sbi_init(void)
pr_info("SBI DBCN extension detected\n");
sbi_debug_console_available = true;
}
+ if ((sbi_spec_version >= sbi_mk_version(2, 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;
--
2.47.2