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

include/sbi/sbi_trap.h

@@ -205,8 +205,6 @@ struct sbi_trap_info {
 int sbi_trap_redirect(struct sbi_trap_regs *regs,
 		      struct sbi_trap_info *trap);
 
-void sbi_trap_set_external_irqfn(int (*fn)(struct sbi_trap_regs *regs));
-
 struct sbi_trap_regs *sbi_trap_handler(struct sbi_trap_regs *regs);
 
 void __noreturn sbi_trap_exit(const struct sbi_trap_regs *regs);

lib/sbi/objects.mk

@@ -32,6 +32,7 @@ libsbi-objs-y += sbi_hsm.o
 libsbi-objs-y += sbi_illegal_insn.o
 libsbi-objs-y += sbi_init.o
 libsbi-objs-y += sbi_ipi.o
+libsbi-objs-y += sbi_irqchip.o
 libsbi-objs-y += sbi_misaligned_ldst.o
 libsbi-objs-y += sbi_platform.o
 libsbi-objs-y += sbi_pmu.o

lib/sbi/sbi_init.c

@@ -18,6 +18,7 @@
 #include <sbi/sbi_hartmask.h>
 #include <sbi/sbi_hsm.h>
 #include <sbi/sbi_ipi.h>
+#include <sbi/sbi_irqchip.h>
 #include <sbi/sbi_platform.h>
 #include <sbi/sbi_pmu.h>
 #include <sbi/sbi_system.h>
@@ -270,13 +271,12 @@ static void __noreturn init_coldboot(struct sbi_scratch *scratch, u32 hartid)
 
 	sbi_boot_print_banner(scratch);
 
-	rc = sbi_platform_irqchip_init(plat, TRUE);
+	rc = sbi_irqchip_init(scratch, TRUE);
 	if (rc) {
-		sbi_printf("%s: platform irqchip init failed (error %d)\n",
+		sbi_printf("%s: irqchip init failed (error %d)\n",
 			   __func__, rc);
 		sbi_hart_hang();
 	}
-	csr_set(CSR_MIE, MIP_MEIP);
 
 	rc = sbi_ipi_init(scratch, TRUE);
 	if (rc) {
@@ -374,10 +374,9 @@ static void init_warm_startup(struct sbi_scratch *scratch, u32 hartid)
 	if (rc)
 		sbi_hart_hang();
 
-	rc = sbi_platform_irqchip_init(plat, FALSE);
+	rc = sbi_irqchip_init(scratch, FALSE);
 	if (rc)
 		sbi_hart_hang();
-	csr_set(CSR_MIE, MIP_MEIP);
 
 	rc = sbi_ipi_init(scratch, FALSE);
 	if (rc)
@@ -552,8 +551,7 @@ void __noreturn sbi_exit(struct sbi_scratch *scratch)
 
 	sbi_ipi_exit(scratch);
 
-	csr_clear(CSR_MIE, MIP_MEIP);
+	sbi_irqchip_exit(scratch);
-	sbi_platform_irqchip_exit(plat);
 
 	sbi_platform_final_exit(plat);
 

lib/sbi/sbi_irqchip.c

@@ -0,0 +1,54 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2022 Ventana Micro Systems Inc.
+ *
+ * Authors:
+ *   Anup Patel <apatel@ventanamicro.com>
+ */
+
+#include <sbi/sbi_irqchip.h>
+#include <sbi/sbi_platform.h>
+
+static int default_irqfn(struct sbi_trap_regs *regs)
+{
+	return SBI_ENODEV;
+}
+
+static int (*ext_irqfn)(struct sbi_trap_regs *regs) = default_irqfn;
+
+void sbi_irqchip_set_irqfn(int (*fn)(struct sbi_trap_regs *regs))
+{
+	if (fn)
+		ext_irqfn = fn;
+}
+
+int sbi_irqchip_process(struct sbi_trap_regs *regs)
+{
+	return ext_irqfn(regs);
+}
+
+int sbi_irqchip_init(struct sbi_scratch *scratch, bool cold_boot)
+{
+	int rc;
+	const struct sbi_platform *plat = sbi_platform_ptr(scratch);
+
+	rc = sbi_platform_irqchip_init(plat, cold_boot);
+	if (rc)
+		return rc;
+
+	if (ext_irqfn != default_irqfn)
+		csr_set(CSR_MIE, MIP_MEIP);
+
+	return 0;
+}
+
+void sbi_irqchip_exit(struct sbi_scratch *scratch)
+{
+	const struct sbi_platform *plat = sbi_platform_ptr(scratch);
+
+	if (ext_irqfn != default_irqfn)
+		csr_clear(CSR_MIE, MIP_MEIP);
+
+	sbi_platform_irqchip_exit(plat);
+}

lib/sbi/sbi_trap.c

@@ -15,6 +15,7 @@
 #include <sbi/sbi_hart.h>
 #include <sbi/sbi_illegal_insn.h>
 #include <sbi/sbi_ipi.h>
+#include <sbi/sbi_irqchip.h>
 #include <sbi/sbi_misaligned_ldst.h>
 #include <sbi/sbi_pmu.h>
 #include <sbi/sbi_scratch.h>
@@ -195,27 +196,6 @@ int sbi_trap_redirect(struct sbi_trap_regs *regs,
 	return 0;
 }
 
-static int default_irqfn(struct sbi_trap_regs *regs)
-{
-	return SBI_ENODEV;
-}
-
-static int (*ext_irqfn)(struct sbi_trap_regs *regs) = default_irqfn;
-
-/**
- * Set external irq handler 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_trap_set_external_irqfn(int (*fn)(struct sbi_trap_regs *regs))
-{
-	if (fn)
-		ext_irqfn = fn;
-}
-
 static int sbi_trap_nonaia_irq(struct sbi_trap_regs *regs, ulong mcause)
 {
 	mcause &= ~(1UL << (__riscv_xlen - 1));
@@ -227,7 +207,7 @@ static int sbi_trap_nonaia_irq(struct sbi_trap_regs *regs, ulong mcause)
 		sbi_ipi_process();
 		break;
 	case IRQ_M_EXT:
-		return ext_irqfn(regs);
+		return sbi_irqchip_process(regs);
 	default:
 		return SBI_ENOENT;
 	};
@@ -250,7 +230,7 @@ static int sbi_trap_aia_irq(struct sbi_trap_regs *regs, ulong mcause)
 			sbi_ipi_process();
 			break;
 		case IRQ_M_EXT:
-			rc = ext_irqfn(regs);
+			rc = sbi_irqchip_process(regs);
 			if (rc)
 				return rc;
 			break;

lib/utils/irqchip/imsic.c

@@ -15,8 +15,8 @@
 #include <sbi/sbi_domain.h>
 #include <sbi/sbi_hartmask.h>
 #include <sbi/sbi_ipi.h>
+#include <sbi/sbi_irqchip.h>
 #include <sbi/sbi_error.h>
-#include <sbi/sbi_trap.h>
 #include <sbi_utils/irqchip/imsic.h>
 
 #define IMSIC_MMIO_PAGE_LE		0x00
@@ -268,7 +268,7 @@ int imsic_cold_irqchip_init(struct imsic_data *imsic)
 		return SBI_EINVAL;
 
 	/* Setup external interrupt function for IMSIC */
-	sbi_trap_set_external_irqfn(imsic_external_irqfn);
+	sbi_irqchip_set_irqfn(imsic_external_irqfn);
 
 	/* Add IMSIC regions to the root domain */
 	for (i = 0; i < IMSIC_MAX_REGS && imsic->regs[i].size; i++) {