[PATCH v2 3/4] xen/riscv: implement basic aplic_preinit()

[Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>]

Introduce preinitialization stuff for the RISC-V Advanced Platform-Level
Interrupt Controller (APLIC) in Xen:
 - Implementing the APLIC pre-initialization function (`aplic_preinit()`),
   ensuring that only one APLIC instance is supported in S mode.
 - Initialize APLIC's correspoinding DT node.
 - Declaring the DT device match table for APLIC.
 - Setting `aplic_info.hw_version` during its declaration.
 - Declaring an APLIC device.

Since Microchip originally developed aplic.c [1], an internal discussion
with them led to the decision to use the MIT license instead of the default
GPL-2.0-only.

[1] 
https://gitlab.com/xen-project/people/olkur/xen/-/commit/7cfb4bd4748ca268142497ac5c327d2766fb342d

Signed-off-by: Romain Caritey <Romain.Caritey@xxxxxxxxxxxxx>
Signed-off-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
---
Changes in v2:
 - drop initialization of .node member to NULL of aplic_info.
 - s/initcont/initconstrel for aplic_dt_match and put initconstrel between
   type and identifier.
 - Update identation for DT_DEVICE_START(aplic, ...).
 - Update the commit message.
---
 xen/arch/riscv/Makefile           |  1 +
 xen/arch/riscv/aplic.c            | 49 +++++++++++++++++++++++++++++++
 xen/arch/riscv/include/asm/intc.h | 20 +++++++++++++
 3 files changed, 70 insertions(+)
 create mode 100644 xen/arch/riscv/aplic.c
 create mode 100644 xen/arch/riscv/include/asm/intc.h

diff --git a/xen/arch/riscv/Makefile b/xen/arch/riscv/Makefile
index 82016a957a..dd5fd25c7d 100644
--- a/xen/arch/riscv/Makefile
+++ b/xen/arch/riscv/Makefile
@@ -1,3 +1,4 @@
+obj-y += aplic.o
 obj-y += cpufeature.o
 obj-$(CONFIG_EARLY_PRINTK) += early_printk.o
 obj-y += entry.o
diff --git a/xen/arch/riscv/aplic.c b/xen/arch/riscv/aplic.c
new file mode 100644
index 0000000000..856b3bf84f
--- /dev/null
+++ b/xen/arch/riscv/aplic.c
@@ -0,0 +1,49 @@
+/* SPDX-License-Identifier: MIT */
+
+/*
+ * xen/arch/riscv/aplic.c
+ *
+ * RISC-V Advanced Platform-Level Interrupt Controller support
+ *
+ * Copyright (c) 2023-2024 Microchip.
+ * Copyright (c) 2024-2025 Vates
+ */
+
+#include <xen/errno.h>
+#include <xen/init.h>
+#include <xen/types.h>
+
+#include <asm/device.h>
+#include <asm/intc.h>
+
+static struct intc_info aplic_info = {
+    .hw_version = INTC_APLIC
+};
+
+static int __init aplic_preinit(struct dt_device_node *node, const void *dat)
+{
+    if ( aplic_info.node )
+    {
+        printk("XEN doesn't support more than one S mode APLIC\n");
+        return -ENODEV;
+    }
+
+    /* don't process if APLIC node is not for S mode */
+    if ( dt_get_property(node, "riscv,children", NULL) )
+        return -ENODEV;
+
+    aplic_info.node = node;
+
+    return 0;
+}
+
+static const struct dt_device_match __initconstrel aplic_dt_match[] =
+{
+    DT_MATCH_COMPATIBLE("riscv,aplic"),
+    { /* sentinel */ },
+};
+
+DT_DEVICE_START(aplic, "APLIC", DEVICE_INTERRUPT_CONTROLLER)
+    .dt_match = aplic_dt_match,
+    .init = aplic_preinit,
+DT_DEVICE_END
diff --git a/xen/arch/riscv/include/asm/intc.h 
b/xen/arch/riscv/include/asm/intc.h
new file mode 100644
index 0000000000..ff9bb33896
--- /dev/null
+++ b/xen/arch/riscv/include/asm/intc.h
@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: MIT */
+
+/*
+ * (c) 2023-2024 Microchip Technology Inc.
+ * (c) 2024 Vates
+ */
+
+#ifndef ASM__RISCV__INTERRUPT_CONTOLLER_H
+#define ASM__RISCV__INTERRUPT_CONTOLLER_H
+
+enum intc_version {
+    INTC_APLIC,
+};
+
+struct intc_info {
+    enum intc_version hw_version;
+    const struct dt_device_node *node;
+};
+
+#endif /* ASM__RISCV__INTERRUPT_CONTOLLER_H */
-- 
2.48.1