[RFC PATCH 4/6] HACK: hw/i386/pc: Add Aspeed i2c controller + MCTP with ACPI tables

[Jonathan Cameron]

CXL devices provide a standard Fabric Management API - FM-API.
See CXL specification r3.0 from https://www.computeexpresslink.org
In many real setups that will be used by a separate host from the
one actually using the CXL devices (BMC or similar) but it is
helpful to be able to use the main CXL emulation and the
Fabric Management emulation on a single host.  This 'hack' enables
that (with minor kernel driver changes).

There are many many things wrong with how this is done but for
now it enables use of this aspeed controller with ACPI FW
on an x86 host.  That is useful for testing MCTP over I2C.

If anyone has either:
1) Docs for an I2C controller with MCTP support that might actually
   appear on an x86 host.
2) A nice solution for how wrap this up in a device whilst minimising
   kernel changes.
3) A guide / reference example to how to do the interrupt 'right'
   (I'm an ARM focused developer so got lost in the x86 interrupt
    stuff).
then let me know.

For now this works and I will carry it out of tree on
gitlab.com/jic23/qemu.

DSDT blob - as this is a hack I haven't included test updates

Scope (_SB)
{
    Device (MCTP)
    {
        Name (_HID, "PRP0001")  // _HID: Hardware ID
        Name (_DSD, Package (0x02)  // _DSD: Device-Specific Data
        {
            ToUUID ("daffd814-6eba-4d8c-8a91-bc9bbf4aa301") /* Device 
Properties for _DSD */,
            Package (0x03)
            {
                Package (0x02)
                {
                    "compatible",
                    "aspeed,ast2600-i2c-bus"
                },

                Package (0x02)
                {
                    "bus-frequency",
                    0x00061A80
                },

                Package (0x02)
                {
                    "mctp-controller",
                    One
                }
            }
        })
        Name (_CRS, ResourceTemplate ()  // _CRS: Current Resource Settings
        {
            QWordMemory (ResourceProducer, PosDecode, MinFixed, MaxFixed, 
NonCacheable, ReadWrite,
                0x0000000000000000, // Granularity
                0x00000004800FC080, // Range Minimum
                0x00000004800FC0FF, // Range Maximum
                0x0000000000000000, // Translation Offset
                0x0000000000000080, // Length
                ,, , AddressRangeMemory, TypeStatic)
            Interrupt (ResourceConsumer, Level, ActiveHigh, Shared, ,, )
            {
                0x00000007,
            }
        })
    }

    Device (MCTS)
    {
        Name (_HID, "PRP0001")  // _HID: Hardware ID
        Name (_CRS, ResourceTemplate ()  // _CRS: Current Resource Settings
        {
            I2cSerialBusV2 (0x0050, DeviceInitiated, 0x000186A0,
                AddressingMode7Bit, "\\_SB.MCTP",
                0x00, ResourceProducer, , Exclusive,
                )
        })
        Name (_DSD, Package (0x02)  // _DSD: Device-Specific Data
        {
            ToUUID ("daffd814-6eba-4d8c-8a91-bc9bbf4aa301") /* Device 
Properties for _DSD */,
            Package (0x01)
            {
                Package (0x02)
                {
                    "compatible",
                     "mctp-i2c-controller"
                }
            }
        })
    }
}

To add devices to the bus use something like:
 -device i2c_mctp_cxl_switch,bus=aspeed.i2c.bus.0,address=4,target=us0

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
---
 include/hw/i386/pc.h |  1 +
 hw/i386/acpi-build.c | 65 ++++++++++++++++++++++++++++++++++++++++++++
 hw/i386/pc.c         | 20 +++++++++++++-
 hw/i386/Kconfig      |  1 +
 4 files changed, 86 insertions(+), 1 deletion(-)

diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
index c661e9cc80..2050dabc5f 100644
--- a/include/hw/i386/pc.h
+++ b/include/hw/i386/pc.h
@@ -56,6 +56,7 @@ typedef struct PCMachineState {
 
     SGXEPCState sgx_epc;
     CXLState cxl_devices_state;
+    hwaddr i2c_base;
 } PCMachineState;
 
 #define PC_MACHINE_ACPI_DEVICE_PROP "acpi-device"
diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index d0c8e8f045..511a637114 100644
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -1424,6 +1424,68 @@ static void build_acpi0017(Aml *table)
     aml_append(table, scope);
 }
 
+static void acpi_dsdt_add_mctp(Aml *scope, PCMachineState *pcms)
+{
+    uint32_t interrupt = 7;
+    Aml *main_dev = aml_device("MCTP");
+    Aml *sub_dev = aml_device("MCTS");
+    Aml *dsd_pkg = aml_package(2);
+    Aml *props_pkg = aml_package(3);
+    Aml *pkg = aml_package(2);
+    Aml *crs = aml_resource_template();
+
+    aml_append(main_dev, aml_name_decl("_HID", aml_string("PRP0001")));
+
+    aml_append(pkg, aml_string("compatible"));
+    aml_append(pkg, aml_string("aspeed,ast2600-i2c-bus"));
+    aml_append(props_pkg, pkg);
+
+    pkg = aml_package(2);
+    aml_append(pkg, aml_string("bus-frequency"));
+    aml_append(pkg, aml_int(400000));
+    aml_append(props_pkg, pkg);
+
+    pkg = aml_package(2);
+    aml_append(pkg, aml_string("mctp-controller"));
+    aml_append(pkg, aml_int(1));
+    aml_append(props_pkg, pkg);
+
+    aml_append(dsd_pkg, aml_touuid("DAFFD814-6EBA-4D8C-8A91-BC9BBF4AA301"));
+    aml_append(dsd_pkg, props_pkg);
+    aml_append(main_dev, aml_name_decl("_DSD", dsd_pkg));
+
+    aml_append(crs, aml_qword_memory(AML_POS_DECODE, AML_MIN_FIXED,
+                                     AML_MAX_FIXED, AML_NON_CACHEABLE,
+                                     AML_READ_WRITE, 0, pcms->i2c_base + 0x80,
+                                     pcms->i2c_base + 0x80 + 0x80 - 1,
+                                     0, 0x80));
+    aml_append(crs,
+               aml_interrupt(AML_CONSUMER, AML_LEVEL, AML_ACTIVE_HIGH,
+                             AML_SHARED, &interrupt, 1));
+    aml_append(main_dev, aml_name_decl("_CRS", crs));
+
+    aml_append(sub_dev, aml_name_decl("_HID", aml_string("PRP0001")));
+
+    dsd_pkg = aml_package(2);
+    aml_append(dsd_pkg, aml_touuid("DAFFD814-6EBA-4D8C-8A91-BC9BBF4AA301"));
+
+    props_pkg = aml_package(1);
+
+    pkg = aml_package(2);
+    aml_append(pkg, aml_string("compatible"));
+    aml_append(pkg, aml_string("mctp-i2c-controller"));
+    aml_append(props_pkg, pkg);
+    aml_append(dsd_pkg, props_pkg);
+
+    crs = aml_resource_template();
+    aml_append(crs, aml_i2c_slv_serial_bus_device(0x50, "\\_SB.MCTP"));
+    aml_append(sub_dev, aml_name_decl("_CRS", crs));
+    aml_append(sub_dev, aml_name_decl("_DSD", dsd_pkg));
+
+    aml_append(scope, main_dev);
+    aml_append(scope, sub_dev);
+}
+
 /*
  * Precompute the crs ranges and bus numbers that will be used in PXB entries
  * in PXB SSDT.
@@ -1652,6 +1714,9 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
         build_hpet_aml(dsdt);
     }
 
+    sb_scope = aml_scope("_SB");
+    acpi_dsdt_add_mctp(sb_scope, pcms);
+    aml_append(dsdt, sb_scope);
     if (vmbus_bridge) {
         sb_scope = aml_scope("_SB");
         aml_append(sb_scope, build_vmbus_device_aml(vmbus_bridge));
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index bb62c994fa..6d77c8970e 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -95,6 +95,7 @@
 #include "hw/i386/kvm/xen_gnttab.h"
 #include "hw/i386/kvm/xen_xenstore.h"
 #include "hw/mem/memory-device.h"
+#include "hw/i2c/aspeed_i2c.h"
 #include "sysemu/replay.h"
 #include "target/i386/cpu.h"
 #include "e820_memory_layout.h"
@@ -1083,6 +1084,8 @@ void pc_memory_init(PCMachineState *pcms,
         memory_region_init(mr, OBJECT(machine), "cxl_host_reg", cxl_size);
         memory_region_add_subregion(system_memory, cxl_base, mr);
         cxl_resv_end = cxl_base + cxl_size;
+        pcms->i2c_base = cxl_resv_end - 0x4000;
+
         if (pcms->cxl_devices_state.fixed_windows) {
             hwaddr cxl_fmw_base;
             GList *it;
@@ -1166,7 +1169,7 @@ uint64_t pc_pci_hole64_start(void)
     ram_addr_t size = 0;
 
     if (pcms->cxl_devices_state.is_enabled) {
-        hole64_start = pc_get_cxl_range_end(pcms);
+        hole64_start = pc_get_cxl_range_end(pcms) + 0x4000;
     } else if (pcmc->has_reserved_memory && (ms->ram_size < ms->maxram_size)) {
         pc_get_device_memory_range(pcms, &hole64_start, &size);
         if (!pcmc->broken_reserved_end) {
@@ -1360,6 +1363,21 @@ void pc_basic_device_init(struct PCMachineState *pcms,
     /* Super I/O */
     pc_superio_init(isa_bus, create_fdctrl, pcms->i8042_enabled,
                     pcms->vmport != ON_OFF_AUTO_ON);
+
+    {
+        AspeedI2CState *aspeed_i2c;
+        struct DeviceState *dev;
+
+        dev = qdev_new("aspeed.i2c-ast2600");
+        aspeed_i2c = ASPEED_I2C(dev);
+        object_property_set_link(OBJECT(dev), "dram",
+                                 OBJECT(MACHINE(pcms)->ram), &error_fatal);
+        sysbus_realize_and_unref(SYS_BUS_DEVICE(dev), &error_fatal);
+        sysbus_mmio_map(SYS_BUS_DEVICE(dev), 0, pcms->i2c_base);
+        /* Hack ;) - Steal unused interrupt 7 */
+        sysbus_connect_irq(SYS_BUS_DEVICE(&aspeed_i2c->busses[0]), 0,
+                           x86ms->gsi[7]);
+    }
 }
 
 void pc_nic_init(PCMachineClass *pcmc, ISABus *isa_bus, PCIBus *pci_bus)
diff --git a/hw/i386/Kconfig b/hw/i386/Kconfig
index 9051083c1e..31e1958368 100644
--- a/hw/i386/Kconfig
+++ b/hw/i386/Kconfig
@@ -45,6 +45,7 @@ config PC
     select ACPI_VMGENID
     select VIRTIO_PMEM_SUPPORTED
     select VIRTIO_MEM_SUPPORTED
+    select I2C_MCTP_CXL_FMAPI
 
 config PC_PCI
     bool
-- 
2.39.2