[PATCH v4 10/11] RISC-V: try new extension properties in of_early_processor_hartid()

[Conor Dooley <conor.dooley@microchip.com>]

To fully deprecate the kernel's use of "riscv,isa",
of_early_processor_hartid() needs to first try using the new properties,
before falling back to "riscv,isa".

Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
---
Changes in v3:
- Add some printouts to explain what went wrong while parsing harts,
  so that if none are found there's at least a hint before we hit a
  BUG()
---
 arch/riscv/kernel/cpu.c | 29 ++++++++++++++++++++++++++++-
 1 file changed, 28 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/kernel/cpu.c b/arch/riscv/kernel/cpu.c
index 4f1f12f34b63..28d5af21f544 100644
--- a/arch/riscv/kernel/cpu.c
+++ b/arch/riscv/kernel/cpu.c
@@ -61,8 +61,35 @@ int riscv_early_of_processor_hartid(struct device_node *node, unsigned long *har
 		return -ENODEV;
 	}
 
+	if (of_property_read_string(node, "riscv,isa-base", &isa))
+		goto old_interface;
+
+	if (IS_ENABLED(CONFIG_32BIT) && strncasecmp(isa, "rv32i", 5)) {
+		pr_warn("CPU with hartid=%lu does not support rv32i", *hart);
+		return -ENODEV;
+	}
+
+	if (IS_ENABLED(CONFIG_64BIT) && strncasecmp(isa, "rv64i", 5)) {
+		pr_warn("CPU with hartid=%lu does not support rv64i", *hart);
+		return -ENODEV;
+	}
+
+	if (!of_property_present(node, "riscv,isa-extensions"))
+		return -ENODEV;
+
+	if (of_property_match_string(node, "riscv,isa-extensions", "i") < 0 ||
+	    of_property_match_string(node, "riscv,isa-extensions", "m") < 0 ||
+	    of_property_match_string(node, "riscv,isa-extensions", "a") < 0) {
+		pr_warn("CPU with hartid=%lu does not support ima", *hart);
+		return -ENODEV;
+	}
+
+	return 0;
+
+old_interface:
 	if (of_property_read_string(node, "riscv,isa", &isa)) {
-		pr_warn("CPU with hartid=%lu has no \"riscv,isa\" property\n", *hart);
+		pr_warn("CPU with hartid=%lu has no \"riscv,isa-base\" or \"riscv,isa\" property\n",
+			*hart);
 		return -ENODEV;
 	}
 
-- 
2.40.1