hw/fsi: Aspeed APB2OPB & On-chip peripheral bus

This is a part of patchset where IBM's Flexible Service Interface is
introduced.

An APB-to-OPB bridge enabling access to the OPB from the ARM core in
the AST2600. Hardware limitations prevent the OPB from being directly
mapped into APB, so all accesses are indirect through the bridge.

The On-Chip Peripheral Bus (OPB): A low-speed bus typically found in
POWER processors. This now makes an appearance in the ASPEED SoC due
to tight integration of the FSI master IP with the OPB, mainly the
existence of an MMIO-mapping of the CFAM address straight onto a
sub-region of the OPB address space.

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Signed-off-by: Ninad Palsule <ninad@linux.ibm.com>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
[ clg: - moved FSIMasterState under AspeedAPB2OPBState
       - modified fsi_opb_fsi_master_address() and
         fsi_opb_opb2fsi_address()
       - instroduced fsi_aspeed_apb2opb_init()
       - reworked fsi_aspeed_apb2opb_realize()
       - removed FSIMasterState object and fsi_opb_realize()
       - simplified OPBus
       - introduced fsi_aspeed_apb2opb_rw to fix endianness issue ]
Signed-off-by: Cédric Le Goater <clg@kaod.org>

4 files changed, 375 insertions, 0 deletions

diff --git a/hw/fsi/Kconfig b/hw/fsi/Kconfig
index 9c34a41..9cee657 100644
--- a/hw/fsi/Kconfig
+++ b/hw/fsi/Kconfig
@@ -1,2 +1,7 @@
+config FSI_APB2OPB_ASPEED
+    bool
+    depends on ASPEED_SOC
+    select FSI
+
 config FSI
     bool
diff --git a/hw/fsi/aspeed_apb2opb.c b/hw/fsi/aspeed_apb2opb.c
new file mode 100644
index 0000000..ea50718
--- /dev/null
+++ b/hw/fsi/aspeed_apb2opb.c
@@ -0,0 +1,367 @@
+/*
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ * Copyright (C) 2024 IBM Corp.
+ *
+ * ASPEED APB-OPB FSI interface
+ * IBM On-chip Peripheral Bus
+ */
+
+#include "qemu/osdep.h"
+#include "qemu/log.h"
+#include "qom/object.h"
+#include "qapi/error.h"
+#include "trace.h"
+
+#include "hw/fsi/aspeed_apb2opb.h"
+#include "hw/qdev-core.h"
+
+#define TO_REG(x) (x >> 2)
+
+#define APB2OPB_VERSION                    TO_REG(0x00)
+#define APB2OPB_TRIGGER                    TO_REG(0x04)
+
+#define APB2OPB_CONTROL                    TO_REG(0x08)
+#define   APB2OPB_CONTROL_OFF              BE_GENMASK(31, 13)
+
+#define APB2OPB_OPB2FSI                    TO_REG(0x0c)
+#define   APB2OPB_OPB2FSI_OFF              BE_GENMASK(31, 22)
+
+#define APB2OPB_OPB0_SEL                   TO_REG(0x10)
+#define APB2OPB_OPB1_SEL                   TO_REG(0x28)
+#define   APB2OPB_OPB_SEL_EN               BIT(0)
+
+#define APB2OPB_OPB0_MODE                  TO_REG(0x14)
+#define APB2OPB_OPB1_MODE                  TO_REG(0x2c)
+#define   APB2OPB_OPB_MODE_RD              BIT(0)
+
+#define APB2OPB_OPB0_XFER                  TO_REG(0x18)
+#define APB2OPB_OPB1_XFER                  TO_REG(0x30)
+#define   APB2OPB_OPB_XFER_FULL            BIT(1)
+#define   APB2OPB_OPB_XFER_HALF            BIT(0)
+
+#define APB2OPB_OPB0_ADDR                  TO_REG(0x1c)
+#define APB2OPB_OPB0_WRITE_DATA            TO_REG(0x20)
+
+#define APB2OPB_OPB1_ADDR                  TO_REG(0x34)
+#define APB2OPB_OPB1_WRITE_DATA                  TO_REG(0x38)
+
+#define APB2OPB_IRQ_STS                    TO_REG(0x48)
+#define   APB2OPB_IRQ_STS_OPB1_TX_ACK      BIT(17)
+#define   APB2OPB_IRQ_STS_OPB0_TX_ACK      BIT(16)
+
+#define APB2OPB_OPB0_WRITE_WORD_ENDIAN     TO_REG(0x4c)
+#define   APB2OPB_OPB0_WRITE_WORD_ENDIAN_BE 0x0011101b
+#define APB2OPB_OPB0_WRITE_BYTE_ENDIAN     TO_REG(0x50)
+#define   APB2OPB_OPB0_WRITE_BYTE_ENDIAN_BE 0x0c330f3f
+#define APB2OPB_OPB1_WRITE_WORD_ENDIAN     TO_REG(0x54)
+#define APB2OPB_OPB1_WRITE_BYTE_ENDIAN     TO_REG(0x58)
+#define APB2OPB_OPB0_READ_BYTE_ENDIAN      TO_REG(0x5c)
+#define APB2OPB_OPB1_READ_BYTE_ENDIAN      TO_REG(0x60)
+#define   APB2OPB_OPB0_READ_WORD_ENDIAN_BE  0x00030b1b
+
+#define APB2OPB_OPB0_READ_DATA         TO_REG(0x84)
+#define APB2OPB_OPB1_READ_DATA         TO_REG(0x90)
+
+/*
+ * The following magic values came from AST2600 data sheet
+ * The register values are defined under section "FSI controller"
+ * as initial values.
+ */
+static const uint32_t aspeed_apb2opb_reset[ASPEED_APB2OPB_NR_REGS] = {
+     [APB2OPB_VERSION]                = 0x000000a1,
+     [APB2OPB_OPB0_WRITE_WORD_ENDIAN] = 0x0044eee4,
+     [APB2OPB_OPB0_WRITE_BYTE_ENDIAN] = 0x0055aaff,
+     [APB2OPB_OPB1_WRITE_WORD_ENDIAN] = 0x00117717,
+     [APB2OPB_OPB1_WRITE_BYTE_ENDIAN] = 0xffaa5500,
+     [APB2OPB_OPB0_READ_BYTE_ENDIAN]  = 0x0044eee4,
+     [APB2OPB_OPB1_READ_BYTE_ENDIAN]  = 0x00117717
+};
+
+static void fsi_opb_fsi_master_address(FSIMasterState *fsi, hwaddr addr)
+{
+    memory_region_transaction_begin();
+    memory_region_set_address(&fsi->iomem, addr);
+    memory_region_transaction_commit();
+}
+
+static void fsi_opb_opb2fsi_address(FSIMasterState *fsi, hwaddr addr)
+{
+    memory_region_transaction_begin();
+    memory_region_set_address(&fsi->opb2fsi, addr);
+    memory_region_transaction_commit();
+}
+
+static uint64_t fsi_aspeed_apb2opb_read(void *opaque, hwaddr addr,
+                                        unsigned size)
+{
+    AspeedAPB2OPBState *s = ASPEED_APB2OPB(opaque);
+    unsigned int reg = TO_REG(addr);
+
+    trace_fsi_aspeed_apb2opb_read(addr, size);
+
+    if (reg >= ASPEED_APB2OPB_NR_REGS) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: Out of bounds read: 0x%"HWADDR_PRIx" for %u\n",
+                      __func__, addr, size);
+        return 0;
+    }
+
+    return s->regs[reg];
+}
+
+static MemTxResult fsi_aspeed_apb2opb_rw(AddressSpace *as, hwaddr addr,
+                                         MemTxAttrs attrs, uint32_t *data,
+                                         uint32_t size, bool is_write)
+{
+    MemTxResult res;
+
+    if (is_write) {
+        switch (size) {
+        case 4:
+            address_space_stl_le(as, addr, *data, attrs, &res);
+            break;
+        case 2:
+            address_space_stw_le(as, addr, *data, attrs, &res);
+            break;
+        case 1:
+            address_space_stb(as, addr, *data, attrs, &res);
+            break;
+        default:
+            g_assert_not_reached();
+        }
+    } else {
+        switch (size) {
+        case 4:
+            *data = address_space_ldl_le(as, addr, attrs, &res);
+            break;
+        case 2:
+            *data = address_space_lduw_le(as, addr, attrs, &res);
+            break;
+        case 1:
+            *data = address_space_ldub(as, addr, attrs, &res);
+            break;
+        default:
+            g_assert_not_reached();
+        }
+    }
+    return res;
+}
+
+static void fsi_aspeed_apb2opb_write(void *opaque, hwaddr addr, uint64_t data,
+                                     unsigned size)
+{
+    AspeedAPB2OPBState *s = ASPEED_APB2OPB(opaque);
+    unsigned int reg = TO_REG(addr);
+
+    trace_fsi_aspeed_apb2opb_write(addr, size, data);
+
+    if (reg >= ASPEED_APB2OPB_NR_REGS) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "%s: Out of bounds write: %"HWADDR_PRIx" for %u\n",
+                      __func__, addr, size);
+        return;
+    }
+
+    switch (reg) {
+    case APB2OPB_CONTROL:
+        fsi_opb_fsi_master_address(&s->fsi[0],
+                data & APB2OPB_CONTROL_OFF);
+        break;
+    case APB2OPB_OPB2FSI:
+        fsi_opb_opb2fsi_address(&s->fsi[0],
+                data & APB2OPB_OPB2FSI_OFF);
+        break;
+    case APB2OPB_OPB0_WRITE_WORD_ENDIAN:
+        if (data != APB2OPB_OPB0_WRITE_WORD_ENDIAN_BE) {
+            qemu_log_mask(LOG_GUEST_ERROR,
+                          "%s: Bridge needs to be driven as BE (0x%x)\n",
+                          __func__, APB2OPB_OPB0_WRITE_WORD_ENDIAN_BE);
+        }
+        break;
+    case APB2OPB_OPB0_WRITE_BYTE_ENDIAN:
+        if (data != APB2OPB_OPB0_WRITE_BYTE_ENDIAN_BE) {
+            qemu_log_mask(LOG_GUEST_ERROR,
+                          "%s: Bridge needs to be driven as BE (0x%x)\n",
+                          __func__, APB2OPB_OPB0_WRITE_BYTE_ENDIAN_BE);
+        }
+        break;
+    case APB2OPB_OPB0_READ_BYTE_ENDIAN:
+        if (data != APB2OPB_OPB0_READ_WORD_ENDIAN_BE) {
+            qemu_log_mask(LOG_GUEST_ERROR,
+                          "%s: Bridge needs to be driven as BE (0x%x)\n",
+                          __func__, APB2OPB_OPB0_READ_WORD_ENDIAN_BE);
+        }
+        break;
+    case APB2OPB_TRIGGER:
+    {
+        uint32_t opb, op_mode, op_size, op_addr, op_data;
+        MemTxResult result;
+        bool is_write;
+        int index;
+        AddressSpace *as;
+
+        assert((s->regs[APB2OPB_OPB0_SEL] & APB2OPB_OPB_SEL_EN) ^
+               (s->regs[APB2OPB_OPB1_SEL] & APB2OPB_OPB_SEL_EN));
+
+        if (s->regs[APB2OPB_OPB0_SEL] & APB2OPB_OPB_SEL_EN) {
+            opb = 0;
+            op_mode = s->regs[APB2OPB_OPB0_MODE];
+            op_size = s->regs[APB2OPB_OPB0_XFER];
+            op_addr = s->regs[APB2OPB_OPB0_ADDR];
+            op_data = s->regs[APB2OPB_OPB0_WRITE_DATA];
+        } else if (s->regs[APB2OPB_OPB1_SEL] & APB2OPB_OPB_SEL_EN) {
+            opb = 1;
+            op_mode = s->regs[APB2OPB_OPB1_MODE];
+            op_size = s->regs[APB2OPB_OPB1_XFER];
+            op_addr = s->regs[APB2OPB_OPB1_ADDR];
+            op_data = s->regs[APB2OPB_OPB1_WRITE_DATA];
+        } else {
+            qemu_log_mask(LOG_GUEST_ERROR,
+                          "%s: Invalid operation: 0x%"HWADDR_PRIx" for %u\n",
+                          __func__, addr, size);
+            return;
+        }
+
+        if (op_size & ~(APB2OPB_OPB_XFER_HALF | APB2OPB_OPB_XFER_FULL)) {
+            qemu_log_mask(LOG_GUEST_ERROR,
+                          "OPB transaction failed: Unrecognized access width: %d\n",
+                          op_size);
+            return;
+        }
+
+        op_size += 1;
+        is_write = !(op_mode & APB2OPB_OPB_MODE_RD);
+        index = opb ? APB2OPB_OPB1_READ_DATA : APB2OPB_OPB0_READ_DATA;
+        as = &s->opb[opb].as;
+
+        result = fsi_aspeed_apb2opb_rw(as, op_addr, MEMTXATTRS_UNSPECIFIED,
+                                       &op_data, op_size, is_write);
+        if (result != MEMTX_OK) {
+            qemu_log_mask(LOG_GUEST_ERROR, "%s: OPB %s failed @%08x\n",
+                          __func__, is_write ? "write" : "read", op_addr);
+            return;
+        }
+
+        if (!is_write) {
+            s->regs[index] = op_data;
+        }
+
+        s->regs[APB2OPB_IRQ_STS] |= opb ? APB2OPB_IRQ_STS_OPB1_TX_ACK
+            : APB2OPB_IRQ_STS_OPB0_TX_ACK;
+        break;
+    }
+    }
+
+    s->regs[reg] = data;
+}
+
+static const struct MemoryRegionOps aspeed_apb2opb_ops = {
+    .read = fsi_aspeed_apb2opb_read,
+    .write = fsi_aspeed_apb2opb_write,
+    .valid.max_access_size = 4,
+    .valid.min_access_size = 4,
+    .impl.max_access_size = 4,
+    .impl.min_access_size = 4,
+    .endianness = DEVICE_LITTLE_ENDIAN,
+};
+
+static void fsi_aspeed_apb2opb_init(Object *o)
+{
+    AspeedAPB2OPBState *s = ASPEED_APB2OPB(o);
+    int i;
+
+    for (i = 0; i < ASPEED_FSI_NUM; i++) {
+        object_initialize_child(o, "fsi-master[*]", &s->fsi[i],
+                                TYPE_FSI_MASTER);
+    }
+}
+
+static void fsi_aspeed_apb2opb_realize(DeviceState *dev, Error **errp)
+{
+    SysBusDevice *sbd = SYS_BUS_DEVICE(dev);
+    AspeedAPB2OPBState *s = ASPEED_APB2OPB(dev);
+    int i;
+
+    /*
+     * TODO: The OPBus model initializes the OPB address space in
+     * the .instance_init handler and this is problematic for test
+     * device-introspect-test. To avoid a memory corruption and a QEMU
+     * crash, qbus_init() should be called from realize(). Something to
+     * improve. Possibly, OPBus could also be removed.
+     */
+    for (i = 0; i < ASPEED_FSI_NUM; i++) {
+        qbus_init(&s->opb[i], sizeof(s->opb[i]), TYPE_OP_BUS, DEVICE(s),
+                  NULL);
+    }
+
+    sysbus_init_irq(sbd, &s->irq);
+
+    memory_region_init_io(&s->iomem, OBJECT(s), &aspeed_apb2opb_ops, s,
+                          TYPE_ASPEED_APB2OPB, 0x1000);
+    sysbus_init_mmio(sbd, &s->iomem);
+
+    for (i = 0; i < ASPEED_FSI_NUM; i++) {
+        if (!qdev_realize(DEVICE(&s->fsi[i]), BUS(&s->opb[i]), errp)) {
+            return;
+        }
+
+        memory_region_add_subregion(&s->opb[i].mr, 0x80000000,
+                &s->fsi[i].iomem);
+
+        memory_region_add_subregion(&s->opb[i].mr, 0xa0000000,
+                &s->fsi[i].opb2fsi);
+    }
+}
+
+static void fsi_aspeed_apb2opb_reset(DeviceState *dev)
+{
+    AspeedAPB2OPBState *s = ASPEED_APB2OPB(dev);
+
+    memcpy(s->regs, aspeed_apb2opb_reset, ASPEED_APB2OPB_NR_REGS);
+}
+
+static void fsi_aspeed_apb2opb_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    dc->desc = "ASPEED APB2OPB Bridge";
+    dc->realize = fsi_aspeed_apb2opb_realize;
+    dc->reset = fsi_aspeed_apb2opb_reset;
+}
+
+static const TypeInfo aspeed_apb2opb_info = {
+    .name = TYPE_ASPEED_APB2OPB,
+    .parent = TYPE_SYS_BUS_DEVICE,
+    .instance_init = fsi_aspeed_apb2opb_init,
+    .instance_size = sizeof(AspeedAPB2OPBState),
+    .class_init = fsi_aspeed_apb2opb_class_init,
+};
+
+static void aspeed_apb2opb_register_types(void)
+{
+    type_register_static(&aspeed_apb2opb_info);
+}
+
+type_init(aspeed_apb2opb_register_types);
+
+static void fsi_opb_init(Object *o)
+{
+    OPBus *opb = OP_BUS(o);
+
+    memory_region_init(&opb->mr, 0, TYPE_FSI_OPB, UINT32_MAX);
+    address_space_init(&opb->as, &opb->mr, TYPE_FSI_OPB);
+}
+
+static const TypeInfo opb_info = {
+    .name = TYPE_OP_BUS,
+    .parent = TYPE_BUS,
+    .instance_init = fsi_opb_init,
+    .instance_size = sizeof(OPBus),
+};
+
+static void fsi_opb_register_types(void)
+{
+    type_register_static(&opb_info);
+}
+
+type_init(fsi_opb_register_types);
diff --git a/hw/fsi/meson.build b/hw/fsi/meson.build
index 7803b3a..a18a076 100644
--- a/hw/fsi/meson.build
+++ b/hw/fsi/meson.build
@@ -1 +1,2 @@
 system_ss.add(when: 'CONFIG_FSI', if_true: files('lbus.c','fsi.c','cfam.c','fsi-master.c'))
+system_ss.add(when: 'CONFIG_FSI_APB2OPB_ASPEED', if_true: files('aspeed_apb2opb.c'))
diff --git a/hw/fsi/trace-events b/hw/fsi/trace-events
index bf417b6..9e286d0 100644
--- a/hw/fsi/trace-events
+++ b/hw/fsi/trace-events
@@ -9,3 +9,5 @@ fsi_cfam_unimplemented_write(uint64_t addr, uint32_t size, uint64_t data) "@0x%"
 fsi_cfam_config_write_noaddr(uint64_t addr, uint32_t size, uint64_t data) "@0x%" PRIx64 " size=%d value=0x%"PRIx64
 fsi_master_read(uint64_t addr, uint32_t size) "@0x%" PRIx64 " size=%d"
 fsi_master_write(uint64_t addr, uint32_t size, uint64_t data) "@0x%" PRIx64 " size=%d value=0x%"PRIx64
+fsi_aspeed_apb2opb_read(uint64_t addr, uint32_t size) "@0x%" PRIx64 " size=%d"
+fsi_aspeed_apb2opb_write(uint64_t addr, uint32_t size, uint64_t data) "@0x%" PRIx64 " size=%d value=0x%"PRIx64