[PATCH v9 44/45] pci-bridge/cxl_downstream: Add a CXL switch downstream port

[Jonathan Cameron <Jonathan.Cameron@huawei.com>]

Emulation of a simple CXL Switch downstream port.
The Device ID has been allocated for this use.

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
---
 hw/cxl/cxl-host.c              |  43 +++++-
 hw/pci-bridge/cxl_downstream.c | 244 +++++++++++++++++++++++++++++++++
 hw/pci-bridge/meson.build      |   2 +-
 3 files changed, 286 insertions(+), 3 deletions(-)

diff --git a/hw/cxl/cxl-host.c b/hw/cxl/cxl-host.c
index 469b3c4ced..317f5a37ca 100644
--- a/hw/cxl/cxl-host.c
+++ b/hw/cxl/cxl-host.c
@@ -130,8 +130,9 @@ static bool cxl_hdm_find_target(uint32_t *cache_mem, hwaddr addr,
 
 static PCIDevice *cxl_cfmws_find_device(CXLFixedWindow *fw, hwaddr addr)
 {
-    CXLComponentState *hb_cstate;
+    CXLComponentState *hb_cstate, *usp_cstate;
     PCIHostState *hb;
+    CXLUpstreamPort *usp;
     int rb_index;
     uint32_t *cache_mem;
     uint8_t target;
@@ -165,8 +166,46 @@ static PCIDevice *cxl_cfmws_find_device(CXLFixedWindow *fw, hwaddr addr)
     }
 
     d = pci_bridge_get_sec_bus(PCI_BRIDGE(rp))->devices[0];
+    if (!d) {
+        return NULL;
+    }
+
+    if (object_dynamic_cast(OBJECT(d), TYPE_CXL_TYPE3)) {
+        return d;
+    }
+
+    /*
+     * Could also be a switch.  Note only one level of switching currently
+     * supported.
+     */
+    if (!object_dynamic_cast(OBJECT(d), TYPE_CXL_USP)) {
+        return NULL;
+    }
+    usp = CXL_USP(d);
+
+    usp_cstate = cxl_usp_to_cstate(usp);
+    if (!usp_cstate) {
+        return NULL;
+    }
+
+    cache_mem = usp_cstate->crb.cache_mem_registers;
+
+    target_found = cxl_hdm_find_target(cache_mem, addr, &target);
+    if (!target_found) {
+        return NULL;
+    }
+
+    d = pcie_find_port_by_pn(&PCI_BRIDGE(d)->sec_bus, target);
+    if (!d) {
+        return NULL;
+    }
+
+    d = pci_bridge_get_sec_bus(PCI_BRIDGE(d))->devices[0];
+    if (!d) {
+        return NULL;
+    }
 
-    if (!d || !object_dynamic_cast(OBJECT(d), TYPE_CXL_TYPE3)) {
+    if (!object_dynamic_cast(OBJECT(d), TYPE_CXL_TYPE3)) {
         return NULL;
     }
 
diff --git a/hw/pci-bridge/cxl_downstream.c b/hw/pci-bridge/cxl_downstream.c
new file mode 100644
index 0000000000..641593203e
--- /dev/null
+++ b/hw/pci-bridge/cxl_downstream.c
@@ -0,0 +1,244 @@
+/*
+ * Emulated CXL Switch Downstream Port
+ *
+ * Copyright (c) 2022 Huawei Technologies.
+ *
+ * Based on xio31130_downstream.c
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+#include "qemu/log.h"
+#include "hw/pci/msi.h"
+#include "hw/pci/pcie.h"
+#include "hw/pci/pcie_port.h"
+#include "qapi/error.h"
+
+typedef struct CXLDownStreamPort {
+    /*< private >*/
+    PCIESlot parent_obj;
+
+    /*< public >*/
+    CXLComponentState cxl_cstate;
+} CXLDownstreamPort;
+
+#define TYPE_CXL_DSP "cxl-downstream"
+DECLARE_INSTANCE_CHECKER(CXLDownstreamPort, CXL_DSP, TYPE_CXL_DSP)
+
+#define CXL_DOWNSTREAM_PORT_MSI_OFFSET 0x70
+#define CXL_DOWNSTREAM_PORT_MSI_NR_VECTOR 1
+#define CXL_DOWNSTREAM_PORT_EXP_OFFSET 0x90
+#define CXL_DOWNSTREAM_PORT_AER_OFFSET 0x100
+#define CXL_DOWNSTREAM_PORT_DVSEC_OFFSET        \
+    (CXL_DOWNSTREAM_PORT_AER_OFFSET + PCI_ERR_SIZEOF)
+
+static void latch_registers(CXLDownstreamPort *dsp)
+{
+    uint32_t *reg_state = dsp->cxl_cstate.crb.cache_mem_registers;
+
+    cxl_component_register_init_common(reg_state, CXL2_DOWNSTREAM_PORT);
+}
+
+/* TODO: Look at sharing this code acorss all CXL port types */
+static void cxl_dsp_dvsec_write_config(PCIDevice *dev, uint32_t addr,
+                                      uint32_t val, int len)
+{
+    CXLDownstreamPort *dsp = CXL_DSP(dev);
+    CXLComponentState *cxl_cstate = &dsp->cxl_cstate;
+
+    if (range_contains(&cxl_cstate->dvsecs[EXTENSIONS_PORT_DVSEC], addr)) {
+        uint8_t *reg = &dev->config[addr];
+        addr -= cxl_cstate->dvsecs[EXTENSIONS_PORT_DVSEC].lob;
+        if (addr == PORT_CONTROL_OFFSET) {
+            if (pci_get_word(reg) & PORT_CONTROL_UNMASK_SBR) {
+                /* unmask SBR */
+                qemu_log_mask(LOG_UNIMP, "SBR mask control is not supported\n");
+            }
+            if (pci_get_word(reg) & PORT_CONTROL_ALT_MEMID_EN) {
+                /* Alt Memory & ID Space Enable */
+                qemu_log_mask(LOG_UNIMP,
+                              "Alt Memory & ID space is not supported\n");
+
+            }
+        }
+    }
+}
+
+static void cxl_dsp_config_write(PCIDevice *d, uint32_t address,
+                                 uint32_t val, int len)
+{
+    uint16_t slt_ctl, slt_sta;
+
+    pcie_cap_slot_get(d, &slt_ctl, &slt_sta);
+    pci_bridge_write_config(d, address, val, len);
+    pcie_cap_flr_write_config(d, address, val, len);
+    pcie_cap_slot_write_config(d, slt_ctl, slt_sta, address, val, len);
+    pcie_aer_write_config(d, address, val, len);
+
+    cxl_dsp_dvsec_write_config(d, address, val, len);
+}
+
+static void cxl_dsp_reset(DeviceState *qdev)
+{
+    PCIDevice *d = PCI_DEVICE(qdev);
+    CXLDownstreamPort *dsp = CXL_DSP(qdev);
+
+    pcie_cap_deverr_reset(d);
+    pcie_cap_slot_reset(d);
+    pcie_cap_arifwd_reset(d);
+    pci_bridge_reset(qdev);
+
+    latch_registers(dsp);
+}
+
+static void build_dvsecs(CXLComponentState *cxl)
+{
+    uint8_t *dvsec;
+
+    dvsec = (uint8_t *)&(CXLDVSECPortExtensions){ 0 };
+    cxl_component_create_dvsec(cxl, EXTENSIONS_PORT_DVSEC_LENGTH,
+                               EXTENSIONS_PORT_DVSEC,
+                               EXTENSIONS_PORT_DVSEC_REVID, dvsec);
+
+    dvsec = (uint8_t *)&(CXLDVSECPortFlexBus){
+        .cap                     = 0x27, /* Cache, IO, Mem, non-MLD */
+        .ctrl                    = 0x02, /* IO always enabled */
+        .status                  = 0x26, /* same */
+        .rcvd_mod_ts_data_phase1 = 0xef, /* WTF? */
+    };
+    cxl_component_create_dvsec(cxl, PCIE_FLEXBUS_PORT_DVSEC_LENGTH_2_0,
+                               PCIE_FLEXBUS_PORT_DVSEC,
+                               PCIE_FLEXBUS_PORT_DVSEC_REVID_2_0, dvsec);
+
+    dvsec = (uint8_t *)&(CXLDVSECPortGPF){
+        .rsvd        = 0,
+        .phase1_ctrl = 1, /* 1μs timeout */
+        .phase2_ctrl = 1, /* 1μs timeout */
+    };
+    cxl_component_create_dvsec(cxl,
+                               GPF_PORT_DVSEC_LENGTH, GPF_PORT_DVSEC,
+                               GPF_PORT_DVSEC_REVID, dvsec);
+
+    dvsec = (uint8_t *)&(CXLDVSECRegisterLocator){
+        .rsvd         = 0,
+        .reg0_base_lo = RBI_COMPONENT_REG | CXL_COMPONENT_REG_BAR_IDX,
+        .reg0_base_hi = 0,
+    };
+    cxl_component_create_dvsec(cxl, REG_LOC_DVSEC_LENGTH, REG_LOC_DVSEC,
+                               REG_LOC_DVSEC_REVID, dvsec);
+}
+
+static void cxl_dsp_realize(PCIDevice *d, Error **errp)
+{
+    PCIEPort *p = PCIE_PORT(d);
+    PCIESlot *s = PCIE_SLOT(d);
+    CXLDownstreamPort *dsp = CXL_DSP(d);
+    CXLComponentState *cxl_cstate = &dsp->cxl_cstate;
+    ComponentRegisters *cregs = &cxl_cstate->crb;
+    MemoryRegion *component_bar = &cregs->component_registers;
+    int rc;
+
+    pci_bridge_initfn(d, TYPE_PCIE_BUS);
+    pcie_port_init_reg(d);
+
+    rc = msi_init(d, CXL_DOWNSTREAM_PORT_MSI_OFFSET,
+                  CXL_DOWNSTREAM_PORT_MSI_NR_VECTOR,
+                  true, true, errp);
+    if (rc) {
+        assert(rc == -ENOTSUP);
+        goto err_bridge;
+    }
+
+    rc = pcie_cap_init(d, CXL_DOWNSTREAM_PORT_EXP_OFFSET,
+                       PCI_EXP_TYPE_DOWNSTREAM, p->port,
+                       errp);
+    if (rc < 0) {
+        goto err_msi;
+    }
+
+    pcie_cap_flr_init(d);
+    pcie_cap_deverr_init(d);
+    pcie_cap_slot_init(d, s);
+    pcie_cap_arifwd_init(d);
+
+    pcie_chassis_create(s->chassis);
+    rc = pcie_chassis_add_slot(s);
+    if (rc < 0) {
+        error_setg(errp, "Can't add chassis slot, error %d", rc);
+        goto err_pcie_cap;
+    }
+
+    rc = pcie_aer_init(d, PCI_ERR_VER, CXL_DOWNSTREAM_PORT_AER_OFFSET,
+                       PCI_ERR_SIZEOF, errp);
+    if (rc < 0) {
+        goto err_chassis;
+    }
+
+    cxl_cstate->dvsec_offset = CXL_DOWNSTREAM_PORT_DVSEC_OFFSET;
+    cxl_cstate->pdev = d;
+    build_dvsecs(cxl_cstate);
+    cxl_component_register_block_init(OBJECT(d), cxl_cstate, TYPE_CXL_DSP);
+    pci_register_bar(d, CXL_COMPONENT_REG_BAR_IDX,
+                     PCI_BASE_ADDRESS_SPACE_MEMORY |
+                         PCI_BASE_ADDRESS_MEM_TYPE_64,
+                     component_bar);
+
+    return;
+
+ err_chassis:
+    pcie_chassis_del_slot(s);
+ err_pcie_cap:
+    pcie_cap_exit(d);
+ err_msi:
+    msi_uninit(d);
+ err_bridge:
+    pci_bridge_exitfn(d);
+}
+
+static void cxl_dsp_exitfn(PCIDevice *d)
+{
+    PCIESlot *s = PCIE_SLOT(d);
+
+    pcie_aer_exit(d);
+    pcie_chassis_del_slot(s);
+    pcie_cap_exit(d);
+    msi_uninit(d);
+    pci_bridge_exitfn(d);
+}
+
+static void cxl_dsp_class_init(ObjectClass *oc, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(oc);
+    PCIDeviceClass *k = PCI_DEVICE_CLASS(oc);
+
+    k->is_bridge = true;
+    k->config_write = cxl_dsp_config_write;
+    k->realize = cxl_dsp_realize;
+    k->exit = cxl_dsp_exitfn;
+    k->vendor_id = 0x19e5; /* Huawei */
+    k->device_id = 0xa129; /* Emulated CXL Switch Downstream Port */
+    k->revision = 0;
+    set_bit(DEVICE_CATEGORY_BRIDGE, dc->categories);
+    dc->desc = "CXL Switch Downstream Port";
+    dc->reset = cxl_dsp_reset;
+}
+
+static const TypeInfo cxl_dsp_info = {
+    .name = TYPE_CXL_DSP,
+    .instance_size = sizeof(CXLDownstreamPort),
+    .parent = TYPE_PCIE_SLOT,
+    .class_init = cxl_dsp_class_init,
+    .interfaces = (InterfaceInfo[]) {
+        { INTERFACE_PCIE_DEVICE },
+        { INTERFACE_CXL_DEVICE },
+        { }
+    },
+};
+
+static void cxl_dsp_register_type(void)
+{
+    type_register_static(&cxl_dsp_info);
+}
+
+type_init(cxl_dsp_register_type);
diff --git a/hw/pci-bridge/meson.build b/hw/pci-bridge/meson.build
index 4a8c26b5a1..53cc53314a 100644
--- a/hw/pci-bridge/meson.build
+++ b/hw/pci-bridge/meson.build
@@ -5,7 +5,7 @@ pci_ss.add(when: 'CONFIG_IOH3420', if_true: files('ioh3420.c'))
 pci_ss.add(when: 'CONFIG_PCIE_PORT', if_true: files('pcie_root_port.c', 'gen_pcie_root_port.c', 'pcie_pci_bridge.c'))
 pci_ss.add(when: 'CONFIG_PXB', if_true: files('pci_expander_bridge.c'))
 pci_ss.add(when: 'CONFIG_XIO3130', if_true: files('xio3130_upstream.c', 'xio3130_downstream.c'))
-pci_ss.add(when: 'CONFIG_CXL', if_true: files('cxl_root_port.c', 'cxl_upstream.c'))
+pci_ss.add(when: 'CONFIG_CXL', if_true: files('cxl_root_port.c', 'cxl_upstream.c', 'cxl_downstream.c'))
 
 # NewWorld PowerMac
 pci_ss.add(when: 'CONFIG_DEC_PCI', if_true: files('dec.c'))
-- 
2.32.0