lib: sbi: Add a simple external interrupt handling framework

Currently, the external interrupt handling is scattered between
sbi_init and sbi_trap. This patch moves all external interrupt
handling into a simple framework called sbi_irqchip.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Xiang W <wxjstz@126.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>

include/sbi/sbi_irqchip.h

@@ -0,0 +1,44 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2022 Ventana Micro Systems Inc.
+ *
+ * Authors:
+ *   Anup Patel <apatel@ventanamicro.com>
+ */
+
+#ifndef __SBI_IRQCHIP_H__
+#define __SBI_IRQCHIP_H__
+
+#include <sbi/sbi_types.h>
+
+struct sbi_scratch;
+struct sbi_trap_regs;
+
+/**
+ * Set external interrupt handling function
+ *
+ * This function is called by OpenSBI platform code to set a handler for
+ * external interrupts
+ *
+ * @param fn function pointer for handling external irqs
+ */
+void sbi_irqchip_set_irqfn(int (*fn)(struct sbi_trap_regs *regs));
+
+/**
+ * Process external interrupts
+ *
+ * This function is called by sbi_trap_handler() to handle external
+ * interrupts.
+ *
+ * @param regs pointer for trap registers
+ */
+int sbi_irqchip_process(struct sbi_trap_regs *regs);
+
+/** Initialize interrupt controllers */
+int sbi_irqchip_init(struct sbi_scratch *scratch, bool cold_boot);
+
+/** Exit interrupt controllers */
+void sbi_irqchip_exit(struct sbi_scratch *scratch);
+
+#endif