RISC-V: Use SBI SRST extension when available

The SBI SRST extension provides a standard way to poweroff and
reboot the system irrespective to whether Linux RISC-V S-mode
is running natively (HS-mode) or inside Guest/VM (VS-mode).

The SBI SRST extension is available in the SBI v0.3 specification.
(Refer, https://github.com/riscv/riscv-sbi-doc/releases/tag/v0.3.0-rc1)

This patch extends Linux RISC-V SBI implementation to detect
and use SBI SRST extension.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

1 files changed, 24 insertions, 0 deletions

diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h
index 0d42693cb65e..289621da4a2a 100644
--- a/arch/riscv/include/asm/sbi.h
+++ b/arch/riscv/include/asm/sbi.h
@@ -27,6 +27,7 @@ enum sbi_ext_id {
 	SBI_EXT_IPI = 0x735049,
 	SBI_EXT_RFENCE = 0x52464E43,
 	SBI_EXT_HSM = 0x48534D,
+	SBI_EXT_SRST = 0x53525354,
 };
 
 enum sbi_ext_base_fid {
@@ -70,6 +71,21 @@ enum sbi_hsm_hart_status {
 	SBI_HSM_HART_STATUS_STOP_PENDING,
 };
 
+enum sbi_ext_srst_fid {
+	SBI_EXT_SRST_RESET = 0,
+};
+
+enum sbi_srst_reset_type {
+	SBI_SRST_RESET_TYPE_SHUTDOWN = 0,
+	SBI_SRST_RESET_TYPE_COLD_REBOOT,
+	SBI_SRST_RESET_TYPE_WARM_REBOOT,
+};
+
+enum sbi_srst_reset_reason {
+	SBI_SRST_RESET_REASON_NONE = 0,
+	SBI_SRST_RESET_REASON_SYS_FAILURE,
+};
+
 #define SBI_SPEC_VERSION_DEFAULT	0x1
 #define SBI_SPEC_VERSION_MAJOR_SHIFT	24
 #define SBI_SPEC_VERSION_MAJOR_MASK	0x7f
@@ -148,6 +164,14 @@ static inline unsigned long sbi_minor_version(void)
 	return sbi_spec_version & SBI_SPEC_VERSION_MINOR_MASK;
 }
 
+/* Make SBI version */
+static inline unsigned long sbi_mk_version(unsigned long major,
+					    unsigned long minor)
+{
+	return ((major & SBI_SPEC_VERSION_MAJOR_MASK) <<
+		SBI_SPEC_VERSION_MAJOR_SHIFT) | minor;
+}
+
 int sbi_err_map_linux_errno(int err);
 #else /* CONFIG_RISCV_SBI */
 static inline int sbi_remote_fence_i(const unsigned long *hart_mask) { return -1; }