[RFC PATCH 1/7] lib: utils: fdt_helper: add fdt_has_isa_extension() helper

[Yu-Chien Peter Lin]

Add a helper function to search for a given ISA string in
`riscv,isa-extensions` or `riscv,isa` properties within
the FDT.

Signed-off-by: Yu-Chien Peter Lin <peter.lin at sifive.com>
---
 include/sbi_utils/fdt/fdt_helper.h |  2 ++
 lib/utils/fdt/fdt_helper.c         | 35 ++++++++++++++++++++++++++++++
 2 files changed, 37 insertions(+)

diff --git a/include/sbi_utils/fdt/fdt_helper.h b/include/sbi_utils/fdt/fdt_helper.h
index 24ad1a94..8aa216c7 100644
--- a/include/sbi_utils/fdt/fdt_helper.h
+++ b/include/sbi_utils/fdt/fdt_helper.h
@@ -56,6 +56,8 @@ int fdt_parse_timebase_frequency(const void *fdt, unsigned long *freq);
 
 int fdt_parse_isa_extensions(const void *fdt, unsigned long *hart_exts);
 
+bool fdt_has_isa_extension(const void *fdt, const char *ext);
+
 int fdt_parse_gaisler_uart_node(const void *fdt, int nodeoffset,
 				struct platform_uart_data *uart);
 
diff --git a/lib/utils/fdt/fdt_helper.c b/lib/utils/fdt/fdt_helper.c
index b0b18b1c..de72f34a 100644
--- a/lib/utils/fdt/fdt_helper.c
+++ b/lib/utils/fdt/fdt_helper.c
@@ -447,6 +447,41 @@ int fdt_parse_isa_extensions(const void *fdt, unsigned long *hart_exts)
 	return 0;
 }
 
+bool fdt_has_isa_extension(const void *fdt, const char *ext)
+{
+	const struct sbi_hart_ext_data *ext_data = NULL;
+	DECLARE_BITMAP(hart_exts, SBI_HART_EXT_MAX);
+	int rc, i;
+
+	if (!fdt || !ext)
+		return false;
+
+	for (i = 0; i < SBI_HART_EXT_MAX; i++) {
+		if (!sbi_strncmp(sbi_hart_ext[i].name, ext,
+	                         sbi_strlen(ext))) {
+			ext_data = &sbi_hart_ext[i];
+			break;
+		}
+	}
+
+	if (!ext_data) {
+		sbi_printf("%s: extension %s not found in sbi_hart_ext[]\n",
+			   __func__, ext);
+		return false;
+	}
+
+	bitmap_zero(hart_exts, SBI_HART_EXT_MAX);
+
+	rc = fdt_parse_isa_extensions(fdt, hart_exts);
+	if (rc) {
+		sbi_printf("%s: failed to parse isa extensions\n",
+			   __func__);
+		return false;
+	}
+
+	return bitmap_test(hart_exts, ext_data->id);
+}
+
 static int fdt_parse_uart_node_common(const void *fdt, int nodeoffset,
 				      struct platform_uart_data *uart,
 				      unsigned long default_freq,
-- 
2.48.0