irqchip/riscv-imsic-state: Create separate function for DT

While populating IMSIC global structure, many fields are initialized
using DT properties. Make the code which uses DT properties as separate
function so that it is easier to add ACPI support later. No
functionality added/changed.
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Tested-by: Björn Töpel <bjorn@rivosinc.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://patch.msgid.link/20240812005929.113499-15-sunilvl@ventanamicro.comSigned-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/irqchip/irq-riscv-imsic-state.c

@@ -510,6 +510,60 @@ static int __init imsic_matrix_init(void)
 	return 0;
 }
 
+static int __init imsic_populate_global_dt(struct fwnode_handle *fwnode,
+					   struct imsic_global_config *global,
+					   u32 *nr_parent_irqs)
+{
+	int rc;
+
+	/* Find number of guest index bits in MSI address */
+	rc = of_property_read_u32(to_of_node(fwnode), "riscv,guest-index-bits",
+				  &global->guest_index_bits);
+	if (rc)
+		global->guest_index_bits = 0;
+
+	/* Find number of HART index bits */
+	rc = of_property_read_u32(to_of_node(fwnode), "riscv,hart-index-bits",
+				  &global->hart_index_bits);
+	if (rc) {
+		/* Assume default value */
+		global->hart_index_bits = __fls(*nr_parent_irqs);
+		if (BIT(global->hart_index_bits) < *nr_parent_irqs)
+			global->hart_index_bits++;
+	}
+
+	/* Find number of group index bits */
+	rc = of_property_read_u32(to_of_node(fwnode), "riscv,group-index-bits",
+				  &global->group_index_bits);
+	if (rc)
+		global->group_index_bits = 0;
+
+	/*
+	 * Find first bit position of group index.
+	 * If not specified assumed the default APLIC-IMSIC configuration.
+	 */
+	rc = of_property_read_u32(to_of_node(fwnode), "riscv,group-index-shift",
+				  &global->group_index_shift);
+	if (rc)
+		global->group_index_shift = IMSIC_MMIO_PAGE_SHIFT * 2;
+
+	/* Find number of interrupt identities */
+	rc = of_property_read_u32(to_of_node(fwnode), "riscv,num-ids",
+				  &global->nr_ids);
+	if (rc) {
+		pr_err("%pfwP: number of interrupt identities not found\n", fwnode);
+		return rc;
+	}
+
+	/* Find number of guest interrupt identities */
+	rc = of_property_read_u32(to_of_node(fwnode), "riscv,num-guest-ids",
+				  &global->nr_guest_ids);
+	if (rc)
+		global->nr_guest_ids = global->nr_ids;
+
+	return 0;
+}
+
 static int __init imsic_get_parent_hartid(struct fwnode_handle *fwnode,
 					  u32 index, unsigned long *hartid)
 {
@@ -578,50 +632,9 @@ static int __init imsic_parse_fwnode(struct fwnode_handle *fwnode,
 		return -EINVAL;
 	}
 
-	/* Find number of guest index bits in MSI address */
-	rc = of_property_read_u32(to_of_node(fwnode), "riscv,guest-index-bits",
-				  &global->guest_index_bits);
-	if (rc)
-		global->guest_index_bits = 0;
-
-	/* Find number of HART index bits */
-	rc = of_property_read_u32(to_of_node(fwnode), "riscv,hart-index-bits",
-				  &global->hart_index_bits);
-	if (rc) {
-		/* Assume default value */
-		global->hart_index_bits = __fls(*nr_parent_irqs);
-		if (BIT(global->hart_index_bits) < *nr_parent_irqs)
-			global->hart_index_bits++;
-	}
-
-	/* Find number of group index bits */
-	rc = of_property_read_u32(to_of_node(fwnode), "riscv,group-index-bits",
-				  &global->group_index_bits);
-	if (rc)
-		global->group_index_bits = 0;
-
-	/*
-	 * Find first bit position of group index.
-	 * If not specified assumed the default APLIC-IMSIC configuration.
-	 */
-	rc = of_property_read_u32(to_of_node(fwnode), "riscv,group-index-shift",
-				  &global->group_index_shift);
+	rc = imsic_populate_global_dt(fwnode, global, nr_parent_irqs);
 	if (rc)
-		global->group_index_shift = IMSIC_MMIO_PAGE_SHIFT * 2;
-
-	/* Find number of interrupt identities */
-	rc = of_property_read_u32(to_of_node(fwnode), "riscv,num-ids",
-				  &global->nr_ids);
-	if (rc) {
-		pr_err("%pfwP: number of interrupt identities not found\n", fwnode);
 		return rc;
-	}
-
-	/* Find number of guest interrupt identities */
-	rc = of_property_read_u32(to_of_node(fwnode), "riscv,num-guest-ids",
-				  &global->nr_guest_ids);
-	if (rc)
-		global->nr_guest_ids = global->nr_ids;
 
 	/* Sanity check guest index bits */
 	i = BITS_PER_LONG - IMSIC_MMIO_PAGE_SHIFT;