lib: utils/fdt: Add support for parsing riscv,isa-extensions

From: Conor Dooley <[email protected]>

A new property has been added, with an extensive rationale at [1], that can be used in place of "riscv,isa" to indicate what extensions are supported by a given platform that is a list of strings rather than a single string. There are some differences between the new property, "riscv,isa-extensions" and the incumbent "riscv,isa" - chief among them for the sake of parsing being the list of strings, as opposed to a string. Another advantage is strictly defined meanings for each string in a dt-binding, rather than deriving meaning from RVI standards. This may likely to some divergence over time, but, at least for now, there's no relevant differences between the two for an M-Mode program.

Add support for the new property in OpenSBI, prioritising it, before falling back to the, now deprecated, "riscv,isa" property if it is not present.

Link https://lore.kernel.org/all/20230702-eats-scorebook-c951f170d29f at spud/ [1]

Signed-off-by Conor Dooley <[email protected]>

---
 lib/utils/fdt/fdt_helper.c | 27 +++++++++++++++++++++++----
 1 file changed, 23 insertions(+), 4 deletions(-)

lib/utils/fdt/fdt_helper.c +23 -5

index 9a945af..b7f7e07 100644
@@ -411,6 +411,18 @@ static int fdt_parse_isa_one_hart(const char *isa, unsigned long *extensions)
        return 0;
 }
 
+static void fdt_parse_isa_extensions_one_hart(const char *isa,
+                                             unsigned long *extensions,
+                                             int len)
+{
+       size_t i;
+
+       for (i = 0; i < SBI_HART_EXT_MAX; i++) {
+               if (fdt_stringlist_contains(isa, len, sbi_hart_ext[i].name))
+                       __set_bit(sbi_hart_ext[i].id, extensions);
+       }
+}
+
 static int fdt_parse_isa_all_harts(void *fdt)
 {
        u32 hartid;

@@ -434,10 +446,6 @@ static int fdt_parse_isa_all_harts(void *fdt)
                if (!fdt_node_is_enabled(fdt, cpu_offset))
                        continue;
 
-               val = fdt_getprop(fdt, cpu_offset, "riscv,isa", &len);
-               if (!val || len <= 0)
-                       return SBI_ENOENT;
-
                scratch = sbi_hartid_to_scratch(hartid);
                if (!scratch)
                        return SBI_ENOENT;

@@ -445,6 +453,17 @@ static int fdt_parse_isa_all_harts(void *fdt)
                hart_exts = sbi_scratch_offset_ptr(scratch,
                                                   fdt_isa_bitmap_offset);
 
+               val = fdt_getprop(fdt, cpu_offset, "riscv,isa-extensions", &len);
+               if (val && len > 0) {
+                       fdt_parse_isa_extensions_one_hart((const char *)val,
+                                                         hart_exts, len);
+                       continue;
+               }
+
+               val = fdt_getprop(fdt, cpu_offset, "riscv,isa", &len);
+               if (!val || len <= 0)
+                       return SBI_ENOENT;
+
                err = fdt_parse_isa_one_hart((const char *)val, hart_exts);
                if (err)
                        return err;
--

2.43.0

--
opensbi mailing list
opensbi at lists.infradead.org
http://lists.infradead.org/mailman/listinfo/opensbi