RISC-V: Rename and move plic_find_hart_id() to arch directory

The plic_find_hart_id() can be useful to other interrupt controller
drivers (such as RISC-V local interrupt driver) so we rename this
function to riscv_of_parent_hartid() and place it in arch directory
along with riscv_of_processor_hartid().

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com>
Acked-by: Palmer Dabbelt <palmerdabbelt@google.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

arch/riscv/include/asm/processor.h

@@ -75,6 +75,7 @@ static inline void wait_for_interrupt(void)
 
 struct device_node;
 int riscv_of_processor_hartid(struct device_node *node);
+int riscv_of_parent_hartid(struct device_node *node);
 
 extern void riscv_fill_hwcap(void);
 

arch/riscv/kernel/cpu.c

@@ -44,6 +44,22 @@ int riscv_of_processor_hartid(struct device_node *node)
 	return hart;
 }
 
+/*
+ * Find hart ID of the CPU DT node under which given DT node falls.
+ *
+ * To achieve this, we walk up the DT tree until we find an active
+ * RISC-V core (HART) node and extract the cpuid from it.
+ */
+int riscv_of_parent_hartid(struct device_node *node)
+{
+	for (; node; node = node->parent) {
+		if (of_device_is_compatible(node, "riscv"))
+			return riscv_of_processor_hartid(node);
+	}
+
+	return -1;
+}
+
 #ifdef CONFIG_PROC_FS
 
 static void print_isa(struct seq_file *f, const char *isa)

drivers/irqchip/irq-sifive-plic.c

@@ -240,20 +240,6 @@ static void plic_handle_irq(struct pt_regs *regs)
 	csr_set(CSR_IE, IE_EIE);
 }
 
-/*
- * Walk up the DT tree until we find an active RISC-V core (HART) node and
- * extract the cpuid from it.
- */
-static int plic_find_hart_id(struct device_node *node)
-{
-	for (; node; node = node->parent) {
-		if (of_device_is_compatible(node, "riscv"))
-			return riscv_of_processor_hartid(node);
-	}
-
-	return -1;
-}
-
 static void plic_set_threshold(struct plic_handler *handler, u32 threshold)
 {
 	/* priority must be > threshold to trigger an interrupt */
@@ -330,7 +316,7 @@ static int __init plic_init(struct device_node *node,
 		if (parent.args[0] != RV_IRQ_EXT)
 			continue;
 
-		hartid = plic_find_hart_id(parent.np);
+		hartid = riscv_of_parent_hartid(parent.np);
 		if (hartid < 0) {
 			pr_warn("failed to parse hart ID for context %d.\n", i);
 			continue;