[PATCH 1/5] lib: sbi: Allow specifying start mode to sbi_hsm_hart_start() API

[Anup Patel]

The sbi_scratch already has provision to specify the next stage mode
so we can leverage this to specify start mode to sbi_hsm_hart_start().

In future, this will be useful in providing SBI calls to U-mode on
embedded cores where we M-mode and U-mode but no S-mode.

Signed-off-by: Anup Patel <anup.patel at wdc.com>
---
 include/sbi/sbi_hsm.h   | 2 +-
 lib/sbi/sbi_ecall_hsm.c | 6 +++++-
 lib/sbi/sbi_hsm.c       | 6 +++++-
 3 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/include/sbi/sbi_hsm.h b/include/sbi/sbi_hsm.h
index 57d41ff..18d129b 100644
--- a/include/sbi/sbi_hsm.h
+++ b/include/sbi/sbi_hsm.h
@@ -25,7 +25,7 @@ int sbi_hsm_init(struct sbi_scratch *scratch, u32 hartid, bool cold_boot);
 void __noreturn sbi_hsm_exit(struct sbi_scratch *scratch);
 
 int sbi_hsm_hart_start(struct sbi_scratch *scratch, u32 hartid,
-		       ulong saddr, ulong priv);
+		       ulong saddr, ulong smode, ulong priv);
 int sbi_hsm_hart_stop(struct sbi_scratch *scratch, bool exitnow);
 int sbi_hsm_hart_get_state(u32 hartid);
 int sbi_hsm_hart_state_to_status(int state);
diff --git a/lib/sbi/sbi_ecall_hsm.c b/lib/sbi/sbi_ecall_hsm.c
index 028bf68..992c93a 100644
--- a/lib/sbi/sbi_ecall_hsm.c
+++ b/lib/sbi/sbi_ecall_hsm.c
@@ -19,12 +19,16 @@ static int sbi_ecall_hsm_handler(unsigned long extid, unsigned long funcid,
 				 unsigned long *args, unsigned long *out_val,
 				 struct sbi_trap_info *out_trap)
 {
+	ulong smode;
 	int ret = 0, hstate;
 	struct sbi_scratch *scratch = sbi_scratch_thishart_ptr();
 
 	switch (funcid) {
 	case SBI_EXT_HSM_HART_START:
-		ret = sbi_hsm_hart_start(scratch, args[0], args[1], args[2]);
+		smode = csr_read(CSR_MSTATUS);
+		smode = (smode & MSTATUS_MPP) >> MSTATUS_MPP_SHIFT;
+		ret = sbi_hsm_hart_start(scratch, args[0], args[1],
+					 smode, args[2]);
 		break;
 	case SBI_EXT_HSM_HART_STOP:
 		ret = sbi_hsm_hart_stop(scratch, TRUE);
diff --git a/lib/sbi/sbi_hsm.c b/lib/sbi/sbi_hsm.c
index 013647a..b430793 100644
--- a/lib/sbi/sbi_hsm.c
+++ b/lib/sbi/sbi_hsm.c
@@ -203,7 +203,7 @@ fail_exit:
 }
 
 int sbi_hsm_hart_start(struct sbi_scratch *scratch, u32 hartid,
-		       ulong saddr, ulong priv)
+		       ulong saddr, ulong smode, ulong priv)
 {
 	int rc;
 	unsigned long init_count;
@@ -212,6 +212,9 @@ int sbi_hsm_hart_start(struct sbi_scratch *scratch, u32 hartid,
 	struct sbi_hsm_data *hdata;
 	const struct sbi_platform *plat = sbi_platform_ptr(scratch);
 
+	if (smode != PRV_M && smode != PRV_S && smode != PRV_U)
+		return SBI_EINVAL;
+
 	rscratch = sbi_hartid_to_scratch(hartid);
 	if (!rscratch)
 		return SBI_EINVAL;
@@ -236,6 +239,7 @@ int sbi_hsm_hart_start(struct sbi_scratch *scratch, u32 hartid,
 	init_count = sbi_init_count(hartid);
 	rscratch->next_arg1 = priv;
 	rscratch->next_addr = saddr;
+	rscratch->next_mode = smode;
 
 	if (sbi_platform_has_hart_hotplug(plat) ||
 	   (sbi_platform_has_hart_secondary_boot(plat) && !init_count)) {
-- 
2.25.1