[RFC 13/21] arm/cpu: Add infra to handle generated ID register definitions

[Eric Auger <eric.auger@redhat.com>]

The known ID regs are described in a new initialization function
dubbed initialize_cpu_sysreg_properties(). That code will be
automatically generated from linux arch/arm64/tools/sysreg. For the
time being let's just describe a single id reg, CTR_EL0. In this
description we only care about non RES/RAZ fields, ie. named fields.

The registers are populated in a 3x8x8 array and their fields are
added in a sorted list.

Signed-off-by: Eric Auger <eric.auger@redhat.com>
---
 target/arm/cpu-custom.h            | 58 ++++++++++++++++++++++++++++++
 target/arm/cpu-sysreg-properties.c | 41 +++++++++++++++++++++
 target/arm/cpu64.c                 |  2 ++
 target/arm/meson.build             |  1 +
 4 files changed, 102 insertions(+)
 create mode 100644 target/arm/cpu-custom.h
 create mode 100644 target/arm/cpu-sysreg-properties.c

diff --git a/target/arm/cpu-custom.h b/target/arm/cpu-custom.h
new file mode 100644
index 0000000000..1952095bf7
--- /dev/null
+++ b/target/arm/cpu-custom.h
@@ -0,0 +1,58 @@
+#ifndef ARM_CPU_CUSTOM_H
+#define ARM_CPU_CUSTOM_H
+
+#include "qemu/osdep.h"
+#include "qemu/error-report.h"
+#include "cpu.h"
+#include "cpu-sysregs.h"
+
+typedef struct ARM64SysRegField {
+    const char *name; /* name of the field, for instance CTR_EL0_IDC */
+    int index;
+    int lower;
+    int upper;
+} ARM64SysRegField;
+
+typedef struct ARM64SysReg {
+    const char *name;   /* name of the sysreg, for instance CTR_EL0 */
+    ARMSysReg *sysreg;
+    int index;
+    GList *fields; /* list of named fields, excluding RES* */
+} ARM64SysReg;
+
+void initialize_cpu_sysreg_properties(void);
+
+/*
+ * List of exposed ID regs (automatically populated from linux
+ * arch/arm64/tools/sysreg)
+ */
+extern ARM64SysReg arm64_id_regs[NR_ID_REGS];
+
+/* Allocate a new field and insert it at the head of the @reg list */
+static inline GList *arm64_sysreg_add_field(ARM64SysReg *reg, const char *name,
+                                     uint8_t min, uint8_t max) {
+
+     ARM64SysRegField *field = g_new0(ARM64SysRegField, 1);
+
+     field->name = name;
+     field->lower = min;
+     field->upper = max;
+     field->index = reg->index;
+
+     reg->fields = g_list_append(reg->fields, field);
+     return reg->fields;
+}
+
+static inline ARM64SysReg *
+arm64_sysreg_get(int op0, int op1, int crn, int crm, int op2)
+{
+        uint64_t index = ARM_FEATURE_ID_RANGE_IDX(op0, op1, crn, crm, op2);
+        ARM64SysReg *reg = &arm64_id_regs[index];
+
+        reg->index = index;
+        reg->sysreg = g_new(ARMSysReg, 1);
+        *reg->sysreg = sys_reg(op0, op1, crn, crm, op2);
+        return reg;
+}
+
+#endif
diff --git a/target/arm/cpu-sysreg-properties.c b/target/arm/cpu-sysreg-properties.c
new file mode 100644
index 0000000000..753e7c9127
--- /dev/null
+++ b/target/arm/cpu-sysreg-properties.c
@@ -0,0 +1,41 @@
+/*
+ * QEMU ARM CPU SYSREG PROPERTIES
+ * to be generated from linux sysreg
+ *
+ * Copyright (c) 2024, Inc. 2024
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see
+ * <http://www.gnu.org/licenses/gpl-2.0.html>
+ */
+
+#include "cpu-custom.h"
+
+ARM64SysReg arm64_id_regs[NR_ID_REGS];
+
+void initialize_cpu_sysreg_properties(void)
+{
+    memset(arm64_id_regs, 0, sizeof(ARM64SysReg) * NR_ID_REGS);
+    /* CTR_EL0 */
+    ARM64SysReg *CTR_EL0 = arm64_sysreg_get(3, 3, 0, 0, 1);
+    CTR_EL0->name = "CTR_EL0";
+    arm64_sysreg_add_field(CTR_EL0, "TMinline", 32, 37);
+    arm64_sysreg_add_field(CTR_EL0, "DIC", 29, 29);
+    arm64_sysreg_add_field(CTR_EL0, "IDC", 28, 28);
+    arm64_sysreg_add_field(CTR_EL0, "CWG", 24, 27);
+    arm64_sysreg_add_field(CTR_EL0, "ERG", 20, 23);
+    arm64_sysreg_add_field(CTR_EL0, "DMinLine", 16, 19);
+    arm64_sysreg_add_field(CTR_EL0, "L1Ip", 14, 15);
+    arm64_sysreg_add_field(CTR_EL0, "IminLine", 0, 3);
+}
+
diff --git a/target/arm/cpu64.c b/target/arm/cpu64.c
index 57e73fdd38..9f20886668 100644
--- a/target/arm/cpu64.c
+++ b/target/arm/cpu64.c
@@ -34,6 +34,7 @@
 #include "internals.h"
 #include "cpu-features.h"
 #include "cpregs.h"
+#include "cpu-custom.h"
 
 void arm_cpu_sve_finalize(ARMCPU *cpu, Error **errp)
 {
@@ -844,6 +845,7 @@ static void aarch64_cpu_register_types(void)
 {
     size_t i;
 
+    initialize_cpu_sysreg_properties();
     type_register_static(&aarch64_cpu_type_info);
 
     for (i = 0; i < ARRAY_SIZE(aarch64_cpus); ++i) {
diff --git a/target/arm/meson.build b/target/arm/meson.build
index 2e10464dbb..9c7a04ee1b 100644
--- a/target/arm/meson.build
+++ b/target/arm/meson.build
@@ -14,6 +14,7 @@ arm_ss.add(when: 'CONFIG_HVF', if_true: files('hyp_gdbstub.c'))
 arm_ss.add(when: 'TARGET_AARCH64', if_true: files(
   'cpu64.c',
   'gdbstub64.c',
+  'cpu-sysreg-properties.c',
 ))
 
 arm_system_ss = ss.source_set()
-- 
2.41.0