[PATCH v7 10/20] xen/riscv: introduce aia_init() and aia_usable()

aia_init() is going to contain all the logic related to AIA initialization.

At the moment, it only checks whether the SSAIA extension is available,
and if so, sets is_aia_usable (which  indicates more than just the
availability of the extension) to true; it also signifies that the necessary
components (to be introduced in follow-up patches) have been initialized.

Signed-off-by: Oleksii Kurochko <[email protected]>
Acked-by: Jan Beulich <[email protected]>
---
Changes in v6-7:
 - Nothing changed. Only rebase.
---
Changes in v5:
 - Update the guards in asm/aia.h according to CODING_STYLE:
   s/ASM__RISCV__AIA_H/RISCV_AIA_H.
---
Changes in v4:
 - Add Acked-by: Jan Beulich <[email protected]>
---
Changes in v3:
 - s/is_aia_usable/_aia_usable to drop the is_ prefix while avoiding
   conflict with the aia_usable() function name.
---
Changes in v2:
 - s/is_aia_available/is_aia_usable.
 - Drop return value for aia_init().
 - s/aia_available()/aia_usable().
---
---
 xen/arch/riscv/Makefile          |  1 +
 xen/arch/riscv/aia.c             | 23 +++++++++++++++++++++++
 xen/arch/riscv/include/asm/aia.h | 10 ++++++++++
 xen/arch/riscv/intc.c            |  3 +++
 4 files changed, 37 insertions(+)
 create mode 100644 xen/arch/riscv/aia.c
 create mode 100644 xen/arch/riscv/include/asm/aia.h

diff --git a/xen/arch/riscv/Makefile b/xen/arch/riscv/Makefile
index 2d24670dfc74..8e7a6370eee2 100644
--- a/xen/arch/riscv/Makefile
+++ b/xen/arch/riscv/Makefile
@@ -1,3 +1,4 @@
+obj-y += aia.o
 obj-y += aplic.o
 obj-y += cpufeature.o
 obj-y += domain.o
diff --git a/xen/arch/riscv/aia.c b/xen/arch/riscv/aia.c
new file mode 100644
index 000000000000..e31c9c2d24b6
--- /dev/null
+++ b/xen/arch/riscv/aia.c
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <xen/errno.h>
+#include <xen/init.h>
+#include <xen/sections.h>
+#include <xen/types.h>
+
+#include <asm/cpufeature.h>
+
+static bool __ro_after_init _aia_usable;
+
+bool aia_usable(void)
+{
+    return _aia_usable;
+}
+
+void __init aia_init(void)
+{
+    if ( !riscv_isa_extension_available(NULL, RISCV_ISA_EXT_ssaia) )
+        return;
+
+    _aia_usable = true;
+}
diff --git a/xen/arch/riscv/include/asm/aia.h b/xen/arch/riscv/include/asm/aia.h
new file mode 100644
index 000000000000..aaa4bf91fc75
--- /dev/null
+++ b/xen/arch/riscv/include/asm/aia.h
@@ -0,0 +1,10 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef RISCV_AIA_H
+#define RISCV_AIA_H
+
+bool aia_usable(void);
+
+void aia_init(void);
+
+#endif /* RISCV_AIA_H */
diff --git a/xen/arch/riscv/intc.c b/xen/arch/riscv/intc.c
index e63da5e22efc..2864a896b677 100644
--- a/xen/arch/riscv/intc.c
+++ b/xen/arch/riscv/intc.c
@@ -9,6 +9,7 @@
 #include <xen/lib.h>
 #include <xen/spinlock.h>
 
+#include <asm/aia.h>
 #include <asm/intc.h>
 
 static const struct intc_hw_operations *__ro_after_init intc_hw_ops;
@@ -33,6 +34,8 @@ void __init intc_init(void)
 {
     ASSERT(intc_hw_init_ops && intc_hw_init_ops->init);
 
+    aia_init();
+
     if ( intc_hw_init_ops->init() )
         panic("Failed to initialize the interrupt controller drivers\n");
 }
-- 
2.55.0