hw/arm/armsse: Introduce SSE subsystem version property

We model Arm "Subsystems for Embedded" SoC subsystems using generic
code which is split into various sub-devices which are configurable
by QOM properties to handle the behaviour differences between the SSE
subsystems we implement.  Currently the only sub-device which needs
to change is the IOTKIT_SYSCTL device, and we do this with a mix of
properties that directly specify divergent behaviours (eg
CPUWAIT_RST) and passing it the SYS_VERSION register value as a way
for it to distinguish IoTKit from SSE-200.

The "pass SYS_VERSION" approach is already a bit hacky, since the
IOTKIT_SYSCTL device has to know that the different part of the
register value happens to be bits [31:28].  For SSE-300 this register
is renamed SOC_IDENTITY and has a different format entirely, all of
whose fields can be configured by the SoC integrator when they
integrate the SSE into their SoC, and so "pass SYS_VERSION" breaks
down completely.

Switch to using a simple integer property representing an
internal-to-QEMU enumeration of the SSE flavour.  For the moment we
only need this in IOTKIT_SYSCTL, but as we add SSE-300 support a few
of the other devices will also need to know.

We define and permit a value for the SSE-300 so we can start using
it in subsequent commits which add SSE-300 support.

The now-redundant is_sse200 flag in IoTKitSysCtl will be removed
in the following commit.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
I didn't use a full-on qdev/QOM 'enum' property here because that
requires messing with the QAPI schema, which seems like overkill for
this entirely-internal-to-the-implementation bit of information
passing.

4 files changed, 58 insertions, 10 deletions

diff --git a/hw/arm/armsse.c b/hw/arm/armsse.c
index fa155b7202..f509f59d4a 100644
--- a/hw/arm/armsse.c
+++ b/hw/arm/armsse.c
@@ -19,6 +19,7 @@
 #include "migration/vmstate.h"
 #include "hw/registerfields.h"
 #include "hw/arm/armsse.h"
+#include "hw/arm/armsse-version.h"
 #include "hw/arm/boot.h"
 #include "hw/irq.h"
 #include "hw/qdev-clock.h"
@@ -31,6 +32,7 @@ typedef enum SysConfigFormat {
 
 struct ARMSSEInfo {
     const char *name;
+    uint32_t sse_version;
     int sram_banks;
     int num_cpus;
     uint32_t sys_version;
@@ -71,6 +73,7 @@ static Property armsse_properties[] = {
 static const ARMSSEInfo armsse_variants[] = {
     {
         .name = TYPE_IOTKIT,
+        .sse_version = ARMSSE_IOTKIT,
         .sram_banks = 1,
         .num_cpus = 1,
         .sys_version = 0x41743,
@@ -85,6 +88,7 @@ static const ARMSSEInfo armsse_variants[] = {
     },
     {
         .name = TYPE_SSE200,
+        .sse_version = ARMSSE_SSE200,
         .sram_banks = 4,
         .num_cpus = 2,
         .sys_version = 0x22041743,
@@ -951,8 +955,8 @@ static void armsse_realize(DeviceState *dev, Error **errp)
     /* System information registers */
     sysbus_mmio_map(SYS_BUS_DEVICE(&s->sysinfo), 0, 0x40020000);
     /* System control registers */
-    object_property_set_int(OBJECT(&s->sysctl), "SYS_VERSION",
-                            info->sys_version, &error_abort);
+    object_property_set_int(OBJECT(&s->sysctl), "sse-version",
+                            info->sse_version, &error_abort);
     object_property_set_int(OBJECT(&s->sysctl), "CPUWAIT_RST",
                             info->cpuwait_rst, &error_abort);
     object_property_set_int(OBJECT(&s->sysctl), "INITSVTOR0_RST",
diff --git a/hw/misc/iotkit-sysctl.c b/hw/misc/iotkit-sysctl.c
index 222511c4b0..34b37fe882 100644
--- a/hw/misc/iotkit-sysctl.c
+++ b/hw/misc/iotkit-sysctl.c
@@ -28,6 +28,7 @@
 #include "hw/registerfields.h"
 #include "hw/misc/iotkit-sysctl.h"
 #include "hw/qdev-properties.h"
+#include "hw/arm/armsse-version.h"
 #include "target/arm/arm-powerctl.h"
 #include "target/arm/cpu.h"
 
@@ -438,10 +439,12 @@ static void iotkit_sysctl_realize(DeviceState *dev, Error **errp)
 {
     IoTKitSysCtl *s = IOTKIT_SYSCTL(dev);
 
-    /* The top 4 bits of the SYS_VERSION register tell us if we're an SSE-200 */
-    if (extract32(s->sys_version, 28, 4) == 2) {
-        s->is_sse200 = true;
+    if (!armsse_version_valid(s->sse_version)) {
+        error_setg(errp, "invalid sse-version value %d", s->sse_version);
+        return;
     }
+
+    s->is_sse200 = s->sse_version == ARMSSE_SSE200;
 }
 
 static bool sse200_needed(void *opaque)
@@ -493,7 +496,7 @@ static const VMStateDescription iotkit_sysctl_vmstate = {
 };
 
 static Property iotkit_sysctl_props[] = {
-    DEFINE_PROP_UINT32("SYS_VERSION", IoTKitSysCtl, sys_version, 0),
+    DEFINE_PROP_UINT32("sse-version", IoTKitSysCtl, sse_version, 0),
     DEFINE_PROP_UINT32("CPUWAIT_RST", IoTKitSysCtl, cpuwait_rst, 0),
     DEFINE_PROP_UINT32("INITSVTOR0_RST", IoTKitSysCtl, initsvtor0_rst,
                        0x10000000),
diff --git a/include/hw/arm/armsse-version.h b/include/hw/arm/armsse-version.h
new file mode 100644
index 0000000000..60780fa984
--- /dev/null
+++ b/include/hw/arm/armsse-version.h
@@ -0,0 +1,42 @@
+/*
+ * ARM SSE (Subsystems for Embedded): IoTKit, SSE-200
+ *
+ * Copyright (c) 2020 Linaro Limited
+ * Written by Peter Maydell
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 or
+ * (at your option) any later version.
+ */
+
+#ifndef ARMSSE_VERSION_H
+#define ARMSSE_VERSION_H
+
+
+/*
+ * Define an enumeration of the possible values of the sse-version
+ * property implemented by various sub-devices of the SSE, and
+ * a validation function that checks that a valid value has been passed.
+ * These are arbitrary QEMU-internal values (nobody should be creating
+ * the sub-devices of the SSE except for the SSE object itself), but
+ * we pick obvious numbers for the benefit of people debugging with gdb.
+ */
+enum {
+    ARMSSE_IOTKIT = 0,
+    ARMSSE_SSE200 = 200,
+    ARMSSE_SSE300 = 300,
+};
+
+static inline bool armsse_version_valid(uint32_t sse_version)
+{
+    switch (sse_version) {
+    case ARMSSE_IOTKIT:
+    case ARMSSE_SSE200:
+    case ARMSSE_SSE300:
+        return true;
+    default:
+        return false;
+    }
+}
+
+#endif
diff --git a/include/hw/misc/iotkit-sysctl.h b/include/hw/misc/iotkit-sysctl.h
index 2bc391138d..7cdafea3e2 100644
--- a/include/hw/misc/iotkit-sysctl.h
+++ b/include/hw/misc/iotkit-sysctl.h
@@ -17,9 +17,8 @@
  * "system control register" blocks.
  *
  * QEMU interface:
- *  + QOM property "SYS_VERSION": value of the SYS_VERSION register of the
- *    system information block of the SSE
- *    (used to identify whether to provide SSE-200-only registers)
+ *  + QOM property "sse-version": indicates which SSE version this is part of
+ *    (used to identify whether to provide SSE-200-only registers, etc)
  *  + sysbus MMIO region 0: the system information register bank
  *  + sysbus MMIO region 1: the system control register bank
  */
@@ -61,7 +60,7 @@ struct IoTKitSysCtl {
     uint32_t pdcm_pd_sram3_sense;
 
     /* Properties */
-    uint32_t sys_version;
+    uint32_t sse_version;
     uint32_t cpuwait_rst;
     uint32_t initsvtor0_rst;
     uint32_t initsvtor1_rst;