lib: utils/irqchip: Add FDT based driver for IMSIC

We add simple FDT irqchip driver for IMSIC so that generic platform
(and other FDT based platforms) can utilize common IMIC library.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>

lib/utils/irqchip/fdt_irqchip_imsic.c

@@ -0,0 +1,106 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2021 Western Digital Corporation or its affiliates.
+ * Copyright (c) 2022 Ventana Micro Systems Inc.
+ *
+ * Authors:
+ *   Anup Patel <anup.patel@wdc.com>
+ */
+
+#include <libfdt.h>
+#include <sbi/riscv_asm.h>
+#include <sbi/sbi_error.h>
+#include <sbi/sbi_hartmask.h>
+#include <sbi_utils/fdt/fdt_helper.h>
+#include <sbi_utils/irqchip/fdt_irqchip.h>
+#include <sbi_utils/irqchip/imsic.h>
+
+#define IMSIC_MAX_NR			16
+
+static unsigned long imsic_count = 0;
+static struct imsic_data imsic[IMSIC_MAX_NR];
+
+static int irqchip_imsic_update_hartid_table(void *fdt, int nodeoff,
+					     struct imsic_data *id)
+{
+	const fdt32_t *val;
+	u32 phandle, hwirq, hartid;
+	int i, err, count, cpu_offset, cpu_intc_offset;
+
+	val = fdt_getprop(fdt, nodeoff, "interrupts-extended", &count);
+	if (!val || count < sizeof(fdt32_t))
+		return SBI_EINVAL;
+	count = count / sizeof(fdt32_t);
+
+	for (i = 0; i < count; i += 2) {
+		phandle = fdt32_to_cpu(val[i]);
+		hwirq = fdt32_to_cpu(val[i + 1]);
+
+		cpu_intc_offset = fdt_node_offset_by_phandle(fdt, phandle);
+		if (cpu_intc_offset < 0)
+			continue;
+
+		cpu_offset = fdt_parent_offset(fdt, cpu_intc_offset);
+		if (cpu_intc_offset < 0)
+			continue;
+
+		err = fdt_parse_hart_id(fdt, cpu_offset, &hartid);
+		if (err)
+			return SBI_EINVAL;
+		if (SBI_HARTMASK_MAX_BITS <= hartid)
+			return SBI_EINVAL;
+
+		switch (hwirq) {
+		case IRQ_M_EXT:
+			err = imsic_map_hartid_to_data(hartid, id, i / 2);
+			if (err)
+				return err;
+			break;
+		default:
+			break;
+		}
+	}
+
+	return 0;
+}
+
+static int irqchip_imsic_cold_init(void *fdt, int nodeoff,
+				    const struct fdt_match *match)
+{
+	int rc;
+	struct imsic_data *id;
+
+	if (IMSIC_MAX_NR <= imsic_count)
+		return SBI_ENOSPC;
+	id = &imsic[imsic_count];
+
+	rc = fdt_parse_imsic_node(fdt, nodeoff, id);
+	if (rc)
+		return rc;
+	if (!id->targets_mmode)
+		return 0;
+
+	rc = irqchip_imsic_update_hartid_table(fdt, nodeoff, id);
+	if (rc)
+		return rc;
+
+	rc = imsic_cold_irqchip_init(id);
+	if (rc)
+		return rc;
+
+	imsic_count++;
+
+	return 0;
+}
+
+static const struct fdt_match irqchip_imsic_match[] = {
+	{ .compatible = "riscv,imsics" },
+	{ },
+};
+
+struct fdt_irqchip fdt_irqchip_imsic = {
+	.match_table = irqchip_imsic_match,
+	.cold_init = irqchip_imsic_cold_init,
+	.warm_init = imsic_warm_irqchip_init,
+};