If the HW support the SSTC extension, we should save and restore the
stimecmp register while cpu non retention suspend.

Signed-off-by: Nick Hu <nick.hu@sifive.com>
---
 arch/riscv/include/asm/suspend.h | 1 +
 arch/riscv/kernel/suspend.c      | 6 ++++++
 2 files changed, 7 insertions(+)

diff --git a/arch/riscv/include/asm/suspend.h b/arch/riscv/include/asm/suspend.h
index 4ffb022b097f..4dfdb7134d0e 100644
--- a/arch/riscv/include/asm/suspend.h
+++ b/arch/riscv/include/asm/suspend.h
@@ -18,6 +18,7 @@ struct suspend_context {
 	unsigned long ie;
 #ifdef CONFIG_MMU
 	unsigned long satp;
+	u64 stimecmp;
 #endif
 };
 
diff --git a/arch/riscv/kernel/suspend.c b/arch/riscv/kernel/suspend.c
index c8cec0cc5833..5d9036ea6784 100644
--- a/arch/riscv/kernel/suspend.c
+++ b/arch/riscv/kernel/suspend.c
@@ -30,6 +30,9 @@ void suspend_save_csrs(struct suspend_context *context)
 	 */
 
 #ifdef CONFIG_MMU
+	if (riscv_has_extension_unlikely(RISCV_ISA_EXT_SSTC))
+		context->stimecmp = csr_read_hi_lo(CSR_STIMECMP);
+
 	context->satp = csr_read(CSR_SATP);
 #endif
 }
@@ -43,6 +46,9 @@ void suspend_restore_csrs(struct suspend_context *context)
 	csr_write(CSR_IE, context->ie);
 
 #ifdef CONFIG_MMU
+	if (riscv_has_extension_unlikely(RISCV_ISA_EXT_SSTC))
+		csr_write_hi_lo(CSR_STIMECMP, context->stimecmp);
+
 	csr_write(CSR_SATP, context->satp);
 #endif
 }
-- 
2.34.1