[PATCH v5 2/3] hw/acpi: add indication for i8042 in IA-PC boot flags of the FADT table

[Ani Sinha <ani@anisinha.ca>]

From: Liav Albani <liavalb@gmail.com>

This can allow the guest OS to determine more easily if i8042 controller
is present in the system or not, so it doesn't need to do probing of the
controller, but just initialize it immediately, before enumerating the
ACPI AML namespace.

This change only applies to the x86/q35 machine type, as it uses FACP
ACPI table with revision higher than 1, which should implement at least
ACPI 2.0 features within the table, hence it can also set the IA-PC boot
flags register according to the ACPI 2.0 specification.

Signed-off-by: Liav Albani <liavalb@gmail.com>
Signed-off-by: Ani Sinha <ani@anisinha.ca>
---
 hw/acpi/aml-build.c         | 8 +++++++-
 hw/i386/acpi-build.c        | 8 ++++++++
 include/hw/acpi/acpi-defs.h | 1 +
 include/hw/input/i8042.h    | 6 ++++++
 4 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/hw/acpi/aml-build.c b/hw/acpi/aml-build.c
index 8966e16320..1773cf55f1 100644
--- a/hw/acpi/aml-build.c
+++ b/hw/acpi/aml-build.c
@@ -2152,7 +2152,13 @@ void build_fadt(GArray *tbl, BIOSLinker *linker, const AcpiFadtData *f,
     build_append_int_noprefix(tbl, 0, 1); /* DAY_ALRM */
     build_append_int_noprefix(tbl, 0, 1); /* MON_ALRM */
     build_append_int_noprefix(tbl, f->rtc_century, 1); /* CENTURY */
-    build_append_int_noprefix(tbl, 0, 2); /* IAPC_BOOT_ARCH */
+    /* IAPC_BOOT_ARCH */
+    if (f->rev == 1) {
+        build_append_int_noprefix(tbl, 0, 2);
+    } else {
+        /* since ACPI v2.0 */
+        build_append_int_noprefix(tbl, f->iapc_boot_arch, 2);
+    }
     build_append_int_noprefix(tbl, 0, 1); /* Reserved */
     build_append_int_noprefix(tbl, f->flags, 4); /* Flags */
 
diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index ebd47aa26f..28ca75fb50 100644
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -38,6 +38,7 @@
 #include "hw/nvram/fw_cfg.h"
 #include "hw/acpi/bios-linker-loader.h"
 #include "hw/isa/isa.h"
+#include "hw/input/i8042.h"
 #include "hw/block/fdc.h"
 #include "hw/acpi/memory_hotplug.h"
 #include "sysemu/tpm.h"
@@ -192,6 +193,13 @@ static void init_common_fadt_data(MachineState *ms, Object *o,
             .address = object_property_get_uint(o, ACPI_PM_PROP_GPE0_BLK, NULL)
         },
     };
+
+    /*
+     * ACPI v2, Table 5-10 - Fixed ACPI Description Table Boot Architecture
+     * Flags, bit offset 1 - 8042.
+     */
+    fadt.iapc_boot_arch = i8042_present() ? 0x1 << 1 : 0x0;
+
     *data = fadt;
 }
 
diff --git a/include/hw/acpi/acpi-defs.h b/include/hw/acpi/acpi-defs.h
index c97e8633ad..2b42e4192b 100644
--- a/include/hw/acpi/acpi-defs.h
+++ b/include/hw/acpi/acpi-defs.h
@@ -77,6 +77,7 @@ typedef struct AcpiFadtData {
     uint16_t plvl2_lat;        /* P_LVL2_LAT */
     uint16_t plvl3_lat;        /* P_LVL3_LAT */
     uint16_t arm_boot_arch;    /* ARM_BOOT_ARCH */
+    uint16_t iapc_boot_arch;   /* IAPC_BOOT_ARCH */
     uint8_t minor_ver;         /* FADT Minor Version */
 
     /*
diff --git a/include/hw/input/i8042.h b/include/hw/input/i8042.h
index 1d90432dae..c739f30be8 100644
--- a/include/hw/input/i8042.h
+++ b/include/hw/input/i8042.h
@@ -23,4 +23,10 @@ void i8042_mm_init(qemu_irq kbd_irq, qemu_irq mouse_irq,
 void i8042_isa_mouse_fake_event(ISAKBDState *isa);
 void i8042_setup_a20_line(ISADevice *dev, qemu_irq a20_out);
 
+static inline bool i8042_present(void)
+{
+    bool amb = false;
+    return object_resolve_path_type("", TYPE_I8042, &amb) || amb;
+}
+
 #endif /* HW_INPUT_I8042_H */
-- 
2.25.1