[PATCH 1/2] riscv: Add stimecmp save and restore

[Nick Hu]

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 at sifive.com>
---
 arch/riscv/include/asm/suspend.h |  4 ++++
 arch/riscv/kernel/suspend.c      | 13 +++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/arch/riscv/include/asm/suspend.h b/arch/riscv/include/asm/suspend.h
index 4ffb022b097f..ffaac2efabb5 100644
--- a/arch/riscv/include/asm/suspend.h
+++ b/arch/riscv/include/asm/suspend.h
@@ -16,6 +16,10 @@ struct suspend_context {
 	unsigned long envcfg;
 	unsigned long tvec;
 	unsigned long ie;
+#if __riscv_xlen < 64
+	unsigned long stimecmph;
+#endif
+	unsigned long stimecmp;
 #ifdef CONFIG_MMU
 	unsigned long satp;
 #endif
diff --git a/arch/riscv/kernel/suspend.c b/arch/riscv/kernel/suspend.c
index c8cec0cc5833..3afd86e1abf7 100644
--- a/arch/riscv/kernel/suspend.c
+++ b/arch/riscv/kernel/suspend.c
@@ -19,6 +19,12 @@ void suspend_save_csrs(struct suspend_context *context)
 	context->tvec = csr_read(CSR_TVEC);
 	context->ie = csr_read(CSR_IE);
 
+	if (riscv_has_extension_unlikely(RISCV_ISA_EXT_SSTC)) {
+		context->stimecmp = csr_read(CSR_STIMECMP);
+#if __riscv_xlen < 64
+		context->stimecmph = csr_read(CSR_STIMECMPH);
+#endif
+	}
 	/*
 	 * No need to save/restore IP CSR (i.e. MIP or SIP) because:
 	 *
@@ -42,6 +48,13 @@ void suspend_restore_csrs(struct suspend_context *context)
 	csr_write(CSR_TVEC, context->tvec);
 	csr_write(CSR_IE, context->ie);
 
+	if (riscv_has_extension_unlikely(RISCV_ISA_EXT_SSTC)) {
+		csr_write(CSR_STIMECMP, context->stimecmp);
+#if __riscv_xlen < 64
+		csr_write(CSR_STIMECMPH, context->stimecmph);
+#endif
+	}
+
 #ifdef CONFIG_MMU
 	csr_write(CSR_SATP, context->satp);
 #endif
-- 
2.34.1