lib: Implement SBI v0.2

SBI v0.2 introduces a base specification which is mandatory to
implement for any SBI implementations that is not legacy.

Add support for the base extension.

Signed-off-by: Atish Patra <[email protected]>
Reviewed-by: Anup Patel <[email protected]>

2 files changed, 139 insertions, 31 deletions

diff --git a/include/sbi/sbi_ecall_interface.h b/include/sbi/sbi_ecall_interface.h
index a7564d69..cfdf9e1f 100644
--- a/include/sbi/sbi_ecall_interface.h
+++ b/include/sbi/sbi_ecall_interface.h
@@ -22,8 +22,22 @@ enum sbi_ext_id {
 	SBI_EXT_0_1_REMOTE_SFENCE_VMA = 0x6,
 	SBI_EXT_0_1_REMOTE_SFENCE_VMA_ASID = 0x7,
 	SBI_EXT_0_1_SHUTDOWN = 0x8,
+	SBI_EXT_BASE = 0x10,
 };
 
+enum sbi_ext_base_fid {
+	SBI_EXT_BASE_GET_SPEC_VERSION = 0,
+	SBI_EXT_BASE_GET_IMP_ID,
+	SBI_EXT_BASE_GET_IMP_VERSION,
+	SBI_EXT_BASE_PROBE_EXT,
+	SBI_EXT_BASE_GET_MVENDORID,
+	SBI_EXT_BASE_GET_MARCHID,
+	SBI_EXT_BASE_GET_MIMPID,
+};
+
+#define SBI_SPEC_VERSION_MAJOR_OFFSET	24
+#define SBI_SPEC_VERSION_MAJOR_MASK	0x7f
+#define SBI_SPEC_VERSION_MINOR_MASK	0xffffff
 /* clang-format on */
 
 #endif
diff --git a/lib/sbi/sbi_ecall.c b/lib/sbi/sbi_ecall.c
index b8e444f4..0a934e90 100644
--- a/lib/sbi/sbi_ecall.c
+++ b/lib/sbi/sbi_ecall.c
@@ -17,9 +17,12 @@
 #include <sbi/sbi_tlb.h>
 #include <sbi/sbi_trap.h>
 #include <sbi/sbi_hart.h>
+#include <sbi/sbi_version.h>
+#include <sbi/riscv_asm.h>
 
 #define SBI_ECALL_VERSION_MAJOR 0
-#define SBI_ECALL_VERSION_MINOR 1
+#define SBI_ECALL_VERSION_MINOR 2
+#define SBI_OPENSBI_IMPID 1
 
 u16 sbi_ecall_version_major(void)
 {
@@ -31,34 +34,95 @@ u16 sbi_ecall_version_minor(void)
 	return SBI_ECALL_VERSION_MINOR;
 }
 
-int sbi_ecall_0_1_handler(u32 hartid, struct sbi_trap_regs *regs,
-			     struct sbi_scratch *scratch,
-			     struct unpriv_trap *uptrap)
+int sbi_check_extension(struct sbi_scratch *scratch, unsigned long extid,
+			unsigned long *out_val)
+{
+	/**
+	 * Each extension apart from base & 0.1, will be implemented as
+	 * platform specific feature. Thus, extension probing can be achieved
+	 * by checking the feature bits of the platform. We can create a map
+	 * between extension ID & feature and use a generic function to check
+	 * or just use a switch case for every new extension support added
+	 * TODO: Implement it.
+	 */
+
+	if ((extid >= SBI_EXT_0_1_SET_TIMER &&
+	    extid <= SBI_EXT_0_1_SHUTDOWN) || (extid == SBI_EXT_BASE))
+		*out_val = 1;
+	else
+		*out_val = 0;
+
+	return 0;
+}
+
+int sbi_ecall_base_handler(struct sbi_scratch *scratch, unsigned long extid,
+			   unsigned long funcid, unsigned long *args,
+			   unsigned long *out_val, unsigned long *out_tcause,
+			   unsigned long *out_tval)
+{
+	int ret = 0;
+
+	switch (funcid) {
+	case SBI_EXT_BASE_GET_SPEC_VERSION:
+		*out_val = (SBI_ECALL_VERSION_MAJOR <<
+			   SBI_SPEC_VERSION_MAJOR_OFFSET) &
+			   (SBI_SPEC_VERSION_MAJOR_MASK <<
+			    SBI_SPEC_VERSION_MAJOR_OFFSET);
+		*out_val = *out_val | SBI_ECALL_VERSION_MINOR;
+		break;
+	case SBI_EXT_BASE_GET_IMP_ID:
+		*out_val = SBI_OPENSBI_IMPID;
+		break;
+	case SBI_EXT_BASE_GET_IMP_VERSION:
+		*out_val = OPENSBI_VERSION;
+		break;
+	case SBI_EXT_BASE_GET_MVENDORID:
+		*out_val = csr_read(CSR_MVENDORID);
+		break;
+	case SBI_EXT_BASE_GET_MARCHID:
+		*out_val = csr_read(CSR_MARCHID);
+		break;
+	case SBI_EXT_BASE_GET_MIMPID:
+		*out_val = csr_read(CSR_MIMPID);
+		break;
+	case SBI_EXT_BASE_PROBE_EXT:
+		ret = sbi_check_extension(scratch, args[0], out_val);
+	default:
+		ret = SBI_ENOTSUPP;
+	}
+
+	return ret;
+}
+
+int sbi_ecall_0_1_handler(struct sbi_scratch *scratch, unsigned long extid,
+			   unsigned long *args, unsigned long *tval,
+			   unsigned long *tcause)
 {
 	int ret = 0;
 	struct sbi_tlb_info tlb_info;
 	u32 source_hart = sbi_current_hartid();
+	struct unpriv_trap uptrap = {0};
 
-	switch (regs->a7) {
+	switch (extid) {
 	case SBI_EXT_0_1_SET_TIMER:
 #if __riscv_xlen == 32
 		sbi_timer_event_start(scratch,
-				      (((u64)regs->a1 << 32) | (u64)regs->a0));
+				      (((u64)args[1] << 32) | (u64)args[0]));
 #else
-		sbi_timer_event_start(scratch, (u64)regs->a0);
+		sbi_timer_event_start(scratch, (u64)args[0]);
 #endif
 		break;
 	case SBI_EXT_0_1_CONSOLE_PUTCHAR:
-		sbi_putc(regs->a0);
+		sbi_putc(args[0]);
 		break;
 	case SBI_EXT_0_1_CONSOLE_GETCHAR:
-		regs->a0 = sbi_getc();
+		ret = sbi_getc();
 		break;
 	case SBI_EXT_0_1_CLEAR_IPI:
 		sbi_ipi_clear_smode(scratch);
 		break;
 	case SBI_EXT_0_1_SEND_IPI:
-		ret = sbi_ipi_send_many(scratch, uptrap, (ulong *)regs->a0,
+		ret = sbi_ipi_send_many(scratch, &uptrap, (ulong *)args[0],
 					SBI_IPI_EVENT_SOFT, NULL);
 		break;
 	case SBI_EXT_0_1_REMOTE_FENCE_I:
@@ -66,26 +130,26 @@ int sbi_ecall_0_1_handler(u32 hartid, struct sbi_trap_regs *regs,
 		tlb_info.size  = 0;
 		tlb_info.type  = SBI_ITLB_FLUSH;
 		tlb_info.shart_mask = 1UL << source_hart;
-		ret = sbi_ipi_send_many(scratch, uptrap, (ulong *)regs->a0,
+		ret = sbi_ipi_send_many(scratch, &uptrap, (ulong *)args[0],
 					SBI_IPI_EVENT_FENCE_I, &tlb_info);
 		break;
 	case SBI_EXT_0_1_REMOTE_SFENCE_VMA:
-		tlb_info.start = (unsigned long)regs->a1;
-		tlb_info.size  = (unsigned long)regs->a2;
+		tlb_info.start = (unsigned long)args[1];
+		tlb_info.size  = (unsigned long)args[2];
 		tlb_info.type  = SBI_TLB_FLUSH_VMA;
 		tlb_info.shart_mask = 1UL << source_hart;
 
-		ret = sbi_ipi_send_many(scratch, uptrap, (ulong *)regs->a0,
+		ret = sbi_ipi_send_many(scratch, &uptrap, (ulong *)args[0],
 					SBI_IPI_EVENT_SFENCE_VMA, &tlb_info);
 		break;
 	case SBI_EXT_0_1_REMOTE_SFENCE_VMA_ASID:
-		tlb_info.start = (unsigned long)regs->a1;
-		tlb_info.size  = (unsigned long)regs->a2;
-		tlb_info.asid  = (unsigned long)regs->a3;
+		tlb_info.start = (unsigned long)args[1];
+		tlb_info.size  = (unsigned long)args[2];
+		tlb_info.asid  = (unsigned long)args[3];
 		tlb_info.type  = SBI_TLB_FLUSH_VMA_ASID;
 		tlb_info.shart_mask = 1UL << source_hart;
 
-		ret = sbi_ipi_send_many(scratch, uptrap, (ulong *)regs->a0,
+		ret = sbi_ipi_send_many(scratch, &uptrap, (ulong *)args[0],
 					SBI_IPI_EVENT_SFENCE_VMA_ASID,
 					&tlb_info);
 		break;
@@ -93,9 +157,13 @@ int sbi_ecall_0_1_handler(u32 hartid, struct sbi_trap_regs *regs,
 		sbi_system_shutdown(scratch, 0);
 		break;
 	default:
-		regs->a0 = SBI_ENOTSUPP;
+		ret = SBI_ENOTSUPP;
 	};
 
+	if (ret == SBI_ETRAP) {
+		*tcause = uptrap.cause;
+		*tval = uptrap.tval;
+	}
 	return ret;
 }
 
@@ -103,23 +171,49 @@ int sbi_ecall_handler(u32 hartid, ulong mcause, struct sbi_trap_regs *regs,
 		      struct sbi_scratch *scratch)
 {
 	int ret = 0;
-	struct unpriv_trap uptrap;
-	u32 extension_id = regs->a7;
+	unsigned long extension_id = regs->a7;
+	unsigned long func_id = regs->a6;
+	unsigned long out_val;
+	unsigned long out_tval;
+	unsigned long out_tcause;
+	bool is_0_1_spec = 0;
+	unsigned long args[6];
+
+	args[0] = regs->a0;
+	args[1] = regs->a1;
+	args[2] = regs->a2;
+	args[3] = regs->a3;
+	args[4] = regs->a4;
+	args[5] = regs->a5;
 
 	if (extension_id >= SBI_EXT_0_1_SET_TIMER &&
 	    extension_id <= SBI_EXT_0_1_SHUTDOWN) {
-		ret = sbi_ecall_0_1_handler(hartid, regs, scratch, &uptrap);
-	} else {
-		regs->a0 = SBI_ENOTSUPP;
-	}
+		ret = sbi_ecall_0_1_handler(scratch, extension_id, args,
+					    &out_tval, &out_tcause);
+		is_0_1_spec = 1;
+	} else if (extension_id == SBI_EXT_BASE)
+		ret = sbi_ecall_base_handler(scratch, extension_id, func_id,
+					     args, &out_val,
+					     &out_tval, &out_tcause);
+	else
+		ret = SBI_ENOTSUPP;
 
-	if (!ret) {
-		regs->mepc += 4;
-	} else if (ret == SBI_ETRAP) {
-		ret = 0;
+	if (ret == SBI_ETRAP) {
 		sbi_trap_redirect(regs, scratch, regs->mepc,
-				  uptrap.cause, uptrap.tval);
+				  out_tcause, out_tval);
+	} else {
+		/* This function should return non-zero value only in case of
+		 * fatal error. However, there is no good way to distinguish
+		 * between a fatal and non-fatal errors yet. That's why we treat
+		 * every return value except ETRAP as non-fatal and just return
+		 * accordingly for now. Once fatal errors are defined, that
+		 * case should be handled differently.
+		 */
+		regs->mepc += 4;
+		regs->a0 = ret;
+		if (!is_0_1_spec)
+			regs->a1 = out_val;
 	}
 
-	return ret;
+	return 0;
 }