[PATCH v7 08/10] RISC-V: Add SBI HSM extension

[Atish Patra]

SBI specification defines HSM extension that allows to start/stop a hart
by a supervisor anytime. The specification is available at

https://github.com/riscv/riscv-sbi-doc/blob/master/riscv-sbi.adoc

Implement SBI HSM extension.

Signed-off-by: Atish Patra <atish.patra@xxxxxxx>
---
 arch/riscv/include/asm/sbi.h | 22 ++++++++++++++++
 arch/riscv/kernel/sbi.c      | 51 ++++++++++++++++++++++++++++++++++++
 2 files changed, 73 insertions(+)

diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h
index d55d8090ab5c..bed6fa26ec84 100644
--- a/arch/riscv/include/asm/sbi.h
+++ b/arch/riscv/include/asm/sbi.h
@@ -26,6 +26,7 @@ enum sbi_ext_id {
 	SBI_EXT_TIME = 0x54494D45,
 	SBI_EXT_IPI = 0x735049,
 	SBI_EXT_RFENCE = 0x52464E43,
+	SBI_EXT_HSM = 0x48534D,
 };
 
 enum sbi_ext_base_fid {
@@ -56,6 +57,12 @@ enum sbi_ext_rfence_fid {
 	SBI_EXT_RFENCE_REMOTE_HFENCE_VVMA_ASID,
 };
 
+enum sbi_ext_hsm_fid {
+	SBI_EXT_HSM_HART_START = 0,
+	SBI_EXT_HSM_HART_STOP,
+	SBI_EXT_HSM_HART_STATUS,
+};
+
 #define SBI_SPEC_VERSION_DEFAULT	0x1
 #define SBI_SPEC_VERSION_MAJOR_SHIFT	24
 #define SBI_SPEC_VERSION_MAJOR_MASK	0x7f
@@ -70,6 +77,7 @@ enum sbi_ext_rfence_fid {
 #define SBI_ERR_INVALID_ADDRESS -5
 
 extern unsigned long sbi_spec_version;
+extern bool sbi_hsm_avail;
 struct sbiret {
 	long error;
 	long value;
@@ -110,8 +118,18 @@ int sbi_remote_hfence_vvma_asid(const unsigned long *hart_mask,
 				unsigned long start,
 				unsigned long size,
 				unsigned long asid);
+int sbi_hsm_hart_start(unsigned long hartid, unsigned long saddr,
+		       unsigned long priv);
+int sbi_hsm_hart_stop(void);
+int sbi_hsm_hart_get_status(unsigned long hartid);
+
 int sbi_probe_extension(int ext);
 
+static inline bool sbi_hsm_is_available(void)
+{
+	return sbi_hsm_avail;
+}
+
 /* Check if current SBI specification version is 0.1 or not */
 static inline int sbi_spec_is_0_1(void)
 {
@@ -137,5 +155,9 @@ void sbi_clear_ipi(void);
 void sbi_send_ipi(const unsigned long *hart_mask);
 void sbi_remote_fence_i(const unsigned long *hart_mask);
 void sbi_init(void);
+static inline bool sbi_hsm_is_available(void)
+{
+	return false;
+}
 #endif /* CONFIG_RISCV_SBI */
 #endif /* _ASM_RISCV_SBI_H */
diff --git a/arch/riscv/kernel/sbi.c b/arch/riscv/kernel/sbi.c
index 3c34aba30f6f..9bdc9801784d 100644
--- a/arch/riscv/kernel/sbi.c
+++ b/arch/riscv/kernel/sbi.c
@@ -12,6 +12,8 @@
 
 /* default SBI version is 0.1 */
 unsigned long sbi_spec_version = SBI_SPEC_VERSION_DEFAULT;
+bool sbi_hsm_avail;
+
 EXPORT_SYMBOL(sbi_spec_version);
 
 static void (*__sbi_set_timer)(uint64_t stime);
@@ -496,6 +498,54 @@ static void sbi_power_off(void)
 	sbi_shutdown();
 }
 
+int sbi_hsm_hart_stop(void)
+{
+	struct sbiret ret;
+
+	ret = sbi_ecall(SBI_EXT_HSM, SBI_EXT_HSM_HART_STOP, 0, 0, 0, 0, 0, 0);
+
+	if (!ret.error)
+		return ret.value;
+	else
+		return sbi_err_map_linux_errno(ret.error);
+}
+EXPORT_SYMBOL(sbi_hsm_hart_stop);
+
+int sbi_hsm_hart_start(unsigned long hartid, unsigned long saddr,
+		       unsigned long priv)
+{
+	struct sbiret ret;
+
+	ret = sbi_ecall(SBI_EXT_HSM, SBI_EXT_HSM_HART_START,
+			      hartid, saddr, priv, 0, 0, 0);
+	if (!ret.error)
+		return ret.value;
+	else
+		return sbi_err_map_linux_errno(ret.error);
+}
+EXPORT_SYMBOL(sbi_hsm_hart_start);
+
+int sbi_hsm_hart_get_status(unsigned long hartid)
+{
+	struct sbiret ret;
+
+	ret = sbi_ecall(SBI_EXT_HSM, SBI_EXT_HSM_HART_STATUS,
+			      hartid, 0, 0, 0, 0, 0);
+	if (!ret.error)
+		return ret.value;
+	else
+		return sbi_err_map_linux_errno(ret.error);
+}
+EXPORT_SYMBOL(sbi_hsm_hart_get_status);
+
+void __init sbi_hsm_ext_init(void)
+{
+	if (sbi_probe_extension(SBI_EXT_HSM) > 0) {
+		pr_info("SBI v0.2 HSM extension detected\n");
+		sbi_hsm_avail = true;
+	}
+}
+
 int __init sbi_init(void)
 {
 	int ret;
@@ -532,5 +582,6 @@ int __init sbi_init(void)
 		__sbi_rfence	= __sbi_rfence_v01;
 	}
 
+	sbi_hsm_ext_init();
 	return 0;
 }
-- 
2.24.0