Implement support for TPM via SPI interface. The SPI bus master
is provided by PowerNV SPI device which is an SSI peripheral.
It can uses the tpm_emulator driver backend with the external
swtpm.

Signed-off-by: dan tan <dantan@linux.ibm.com>
---

v3:
- moved variable tis_addr from TPMStateSPI struct to local
- added the VM suspend/resume support:
  - added vmstate_tpm_tis_spi declaration
  - added tpm_tis_spi_pre_save() function
- fixed trace formatting string

v4:
- git commit amend only

v5:
- removed DEFINE_PROP_UINT32("irq", TPMStateSPI, tpm_state.irq_num, 0)
  from tpm_tis_spi_properties
- In tpm.rst document, under section 'The QEMU TPM emulator device',
  moved the 'PowerNV machine' section to immeidately below 'pSeriese
  machine'.

v6:
- amend commit description
- amend hw/tpm/tpm_tis_spi.c prolog to reflect the generic nature
  of the implementation
- remove irrelevant define of IBM_PONQ
- correct the function names to comply with the convention of
  beginning with tpm_tis_spi_xxxx()

v7:
- Reduce SPI wait states to improve performace.
  Although the real SPI buses have four wait states to accomodate
  the timing of various slave devices, there is no need to emulate
  that for this behavior model.

v8:
- no change
- re-package the email to comply with the convention.
---
 docs/specs/tpm.rst   |  15 ++
 include/sysemu/tpm.h |   3 +
 hw/tpm/tpm_tis_spi.c | 359 +++++++++++++++++++++++++++++++++++++++++++
 hw/tpm/Kconfig       |   6 +
 hw/tpm/meson.build   |   1 +
 hw/tpm/trace-events  |   7 +
 6 files changed, 391 insertions(+)
 create mode 100644 hw/tpm/tpm_tis_spi.c

diff --git a/docs/specs/tpm.rst b/docs/specs/tpm.rst
index 1ad36ad709..d92e7eed6f 100644
--- a/docs/specs/tpm.rst
+++ b/docs/specs/tpm.rst
@@ -24,6 +24,7 @@ QEMU files related to TPM TIS interface:
  - ``hw/tpm/tpm_tis_isa.c``
  - ``hw/tpm/tpm_tis_sysbus.c``
  - ``hw/tpm/tpm_tis_i2c.c``
+ - ``hw/tpm/tpm_tis_spi.c``
  - ``hw/tpm/tpm_tis.h``
 
 Both an ISA device and a sysbus device are available. The former is
@@ -33,6 +34,9 @@ Arm virt machine.
 An I2C device support is also provided which can be instantiated in the Arm
 based emulation machines. This device only supports the TPM 2 protocol.
 
+A Serial Peripheral Interface (SPI) device support has been added to the
+PowerNV emulation machines. This device only supports the TPM 2 protocol.
+
 CRB interface
 -------------
 
@@ -339,6 +343,17 @@ In case a pSeries machine is emulated, use the following command line:
     -device virtio-blk-pci,bus=pci.0,addr=0x3,drive=drive-virtio-disk0,id=virtio-disk0 \
     -drive file=test.img,format=raw,if=none,id=drive-virtio-disk0
 
+In case a PowerNV machine is emulated and you want to use a TPM device
+attached to SPI bus, use the following command line (SPI bus master is
+provided by PowerNV SPI device):
+
+.. code-block:: console
+
+  qemu-system-ppc64 -m 2G -machine powernv10 -nographic \
+    -chardev socket,id=chrtpm,path=/tmp/mytpm1/swtpm-sock \
+    -tpmdev emulator,id=tpm0,chardev=chrtpm \
+    -device tpm-tis-spi,tpmdev=tpm0,bus=pnv-spi-bus.4
+
 In case an Arm virt machine is emulated, use the following command line:
 
 .. code-block:: console
diff --git a/include/sysemu/tpm.h b/include/sysemu/tpm.h
index 1ee568b3b6..22b05110e2 100644
--- a/include/sysemu/tpm.h
+++ b/include/sysemu/tpm.h
@@ -49,6 +49,7 @@ struct TPMIfClass {
 #define TYPE_TPM_CRB                "tpm-crb"
 #define TYPE_TPM_SPAPR              "tpm-spapr"
 #define TYPE_TPM_TIS_I2C            "tpm-tis-i2c"
+#define TYPE_TPM_TIS_SPI            "tpm-tis-spi"
 
 #define TPM_IS_TIS_ISA(chr)                         \
     object_dynamic_cast(OBJECT(chr), TYPE_TPM_TIS_ISA)
@@ -60,6 +61,8 @@ struct TPMIfClass {
     object_dynamic_cast(OBJECT(chr), TYPE_TPM_SPAPR)
 #define TPM_IS_TIS_I2C(chr)                      \
     object_dynamic_cast(OBJECT(chr), TYPE_TPM_TIS_I2C)
+#define TPM_IS_TIS_SPI(chr)                      \
+    object_dynamic_cast(OBJECT(chr), TYPE_TPM_TIS_SPI)
 
 /* returns NULL unless there is exactly one TPM device */
 static inline TPMIf *tpm_find(void)
diff --git a/hw/tpm/tpm_tis_spi.c b/hw/tpm/tpm_tis_spi.c
new file mode 100644
index 0000000000..c405bf4561
--- /dev/null
+++ b/hw/tpm/tpm_tis_spi.c
@@ -0,0 +1,359 @@
+/*
+ * QEMU SPI TPM 2.0 model
+ *
+ * Copyright (c) 2024, IBM Corporation.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+#include "qemu/log.h"
+#include "hw/sysbus.h"
+#include "hw/acpi/tpm.h"
+#include "tpm_prop.h"
+#include "qemu/log.h"
+#include "trace.h"
+#include "tpm_tis.h"
+#include "hw/ssi/ssi.h"
+#include "migration/vmstate.h"
+
+typedef struct TPMStateSPI {
+    /*< private >*/
+    SSIPeripheral parent_object;
+
+    uint8_t     byte_offset;     /* byte offset in transfer */
+    uint8_t     wait_state_cnt;  /* wait state counter */
+    uint8_t     xfer_size;       /* data size of transfer */
+    uint32_t    reg_addr;        /* register address of transfer */
+
+    uint8_t     spi_state;       /* READ / WRITE / IDLE */
+#define SPI_STATE_IDLE   0
+#define SPI_STATE_WRITE  1
+#define SPI_STATE_READ   2
+
+    bool        command;
+
+    /*< public >*/
+    TPMState    tpm_state;       /* not a QOM object */
+
+} TPMStateSPI;
+
+#define CMD_BYTE_WRITE          (1 << 7)
+#define CMD_BYTE_XFER_SZ_MASK   0x1f
+#define TIS_SPI_HIGH_ADDR_BYTE  0xd4
+#define NUM_WAIT_STATES         1
+
+DECLARE_INSTANCE_CHECKER(TPMStateSPI, TPM_TIS_SPI, TYPE_TPM_TIS_SPI)
+
+static int tpm_tis_spi_pre_save(void *opaque)
+{
+    TPMStateSPI *spist = opaque;
+
+    return tpm_tis_pre_save(&spist->tpm_state);
+}
+
+static const VMStateDescription vmstate_tpm_tis_spi = {
+     .name = "tpm-tis-spi",
+     .version_id = 0,
+     .pre_save  = tpm_tis_spi_pre_save,
+     .fields = (const VMStateField[]) {
+         VMSTATE_BUFFER(tpm_state.buffer, TPMStateSPI),
+         VMSTATE_UINT16(tpm_state.rw_offset, TPMStateSPI),
+         VMSTATE_UINT8(tpm_state.active_locty, TPMStateSPI),
+         VMSTATE_UINT8(tpm_state.aborting_locty, TPMStateSPI),
+         VMSTATE_UINT8(tpm_state.next_locty, TPMStateSPI),
+
+         VMSTATE_STRUCT_ARRAY(tpm_state.loc, TPMStateSPI,
+                              TPM_TIS_NUM_LOCALITIES, 0,
+                              vmstate_locty, TPMLocality),
+
+         /* spi specifics */
+         VMSTATE_UINT8(byte_offset, TPMStateSPI),
+         VMSTATE_UINT8(wait_state_cnt, TPMStateSPI),
+         VMSTATE_UINT8(xfer_size, TPMStateSPI),
+         VMSTATE_UINT32(reg_addr, TPMStateSPI),
+         VMSTATE_UINT8(spi_state, TPMStateSPI),
+         VMSTATE_BOOL(command, TPMStateSPI),
+
+         VMSTATE_END_OF_LIST()
+     }
+};
+
+static inline void tpm_tis_spi_clear_data(TPMStateSPI *spist)
+{
+    spist->spi_state = SPI_STATE_IDLE;
+    spist->byte_offset = 0;
+    spist->wait_state_cnt = 0;
+    spist->xfer_size = 0;
+    spist->reg_addr = 0;
+
+    return;
+}
+
+/* Callback from TPM to indicate that response is copied */
+static void tpm_tis_spi_request_completed(TPMIf *ti, int ret)
+{
+    TPMStateSPI *spist = TPM_TIS_SPI(ti);
+    TPMState *s = &spist->tpm_state;
+
+    /* Inform the common code. */
+    tpm_tis_request_completed(s, ret);
+}
+
+static enum TPMVersion tpm_tis_spi_get_tpm_version(TPMIf *ti)
+{
+    TPMStateSPI *spist = TPM_TIS_SPI(ti);
+    TPMState *s = &spist->tpm_state;
+
+    return tpm_tis_get_tpm_version(s);
+}
+
+/*
+ * TCG PC Client Platform TPM Profile Specification for TPM 2.0 ver 1.05 rev 14
+ *
+ * For system Software, the TPM has a 64-bit address of 0x0000_0000_FED4_xxxx.
+ * On SPI, the chipset passes the least significant 24 bits to the TPM.
+ * The upper bytes will be used by the chipset to select the TPM’s SPI CS#
+ * signal. Table 9 shows the locality based on the 16 least significant address
+ * bits and assume that either the LPC TPM sync or SPI TPM CS# is used.
+ *
+ */
+static void tpm_tis_spi_write(TPMStateSPI *spist, uint32_t addr, uint8_t val)
+{
+    TPMState *tpm_st = &spist->tpm_state;
+
+    trace_tpm_tis_spi_write(addr, val);
+    tpm_tis_write_data(tpm_st, addr, val, 1);
+}
+
+static uint8_t tpm_tis_spi_read(TPMStateSPI *spist, uint32_t addr)
+{
+    TPMState *tpm_st = &spist->tpm_state;
+    uint8_t data;
+
+    data = tpm_tis_read_data(tpm_st, addr, 1);
+    trace_tpm_tis_spi_read(addr, data);
+    return data;
+}
+
+static Property tpm_tis_spi_properties[] = {
+    DEFINE_PROP_TPMBE("tpmdev", TPMStateSPI, tpm_state.be_driver),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
+static void tpm_tis_spi_reset(DeviceState *dev)
+{
+    TPMStateSPI *spist = TPM_TIS_SPI(dev);
+    TPMState *s = &spist->tpm_state;
+
+    tpm_tis_spi_clear_data(spist);
+    return tpm_tis_reset(s);
+}
+
+static uint32_t tpm_tis_spi_transfer(SSIPeripheral *ss, uint32_t tx)
+{
+    TPMStateSPI *spist = TPM_TIS_SPI(ss);
+    uint32_t rx = 0;
+    uint8_t byte;       /* reversed byte value */
+    uint8_t offset = 0; /* offset of byte in payload */
+    uint8_t index;      /* index of data byte in transfer */
+    uint32_t tis_addr;  /* tis address including locty */
+
+    /* new transfer or not */
+    if (spist->command) {   /* new transfer start */
+        if (spist->spi_state != SPI_STATE_IDLE) {
+            qemu_log_mask(LOG_GUEST_ERROR, "unexpected new transfer\n");
+        }
+        spist->byte_offset = 0;
+        spist->wait_state_cnt = 0;
+    }
+    /*
+     * Explanation of wait_state:
+     * The original TPM model did not have wait state or "flow control" support
+     * built in.  If you wanted to read a TPM register through SPI you sent
+     * the first byte with the read/write bit and size, then three address bytes
+     * and any additional bytes after that were don't care bytes for reads and
+     * the model would begin returning byte data to the SPI reader from the
+     * register address provided.  In the real world this would mean that a
+     * TPM device had only the time between the 31st clock and the 32nd clock
+     * to fetch the register data that it had to provide to SPI MISO starting
+     * with the 32nd clock.
+     *
+     * In reality the TPM begins introducing a wait state at the 31st clock
+     * by holding MISO low.  This is how it controls the "flow" of the
+     * operation. Once the data the TPM needs to return is ready it will
+     * select bit 31 + (8*N) to send back a 1 which indicates that it will
+     * now start returning data on MISO.
+     *
+     * The same wait states are applied to writes.  In either the read or write
+     * case the wait state occurs between the command+address (4 bytes) and the
+     * data (1-n bytes) sections of the SPI frame.  The code below introduces
+     * the support for a 32 bit wait state for P10.  All reads and writes
+     * through the SPI interface MUST now be aware of the need to do flow
+     * control in order to use the TPM via SPI.
+     *
+     * In conjunction with these changes there were changes made to the SPIM
+     * engine that was introduced in P10 to support the 6x op code which is
+     * used to receive wait state 0s on the MISO line until it sees the b'1'
+     * come back before continuing to read real data from the SPI device(TPM).
+     */
+
+    trace_tpm_tis_spi_transfer_data("Payload byte_offset", spist->byte_offset);
+    /* process payload data */
+    while (offset < 4) {
+        spist->command = false;
+        byte = (tx >> (24 - 8 * offset)) & 0xFF;
+        trace_tpm_tis_spi_transfer_data("Extracted byte", byte);
+        trace_tpm_tis_spi_transfer_data("Payload offset", offset);
+        switch (spist->byte_offset) {
+        case 0:    /* command byte */
+            if ((byte & CMD_BYTE_WRITE) == 0) {  /* bit-7 */
+                spist->spi_state = SPI_STATE_WRITE;
+                trace_tpm_tis_spi_transfer_event("spi write");
+            } else {
+                spist->spi_state = SPI_STATE_READ;
+                trace_tpm_tis_spi_transfer_event("spi read");
+            }
+            spist->xfer_size = (byte & CMD_BYTE_XFER_SZ_MASK) + 1;
+            trace_tpm_tis_spi_transfer_data("xfer_size", spist->xfer_size);
+            break;
+        case 1:     /* 1st address byte */
+            if (byte != TIS_SPI_HIGH_ADDR_BYTE) {
+                qemu_log_mask(LOG_GUEST_ERROR, "incorrect high address 0x%x\n",
+                              byte);
+            }
+            spist->reg_addr = byte << 16;
+            trace_tpm_tis_spi_transfer_data("first addr byte", byte);
+            trace_tpm_tis_spi_transfer_addr("reg_addr", spist->reg_addr);
+            break;
+        case 2:     /* 2nd address byte */
+            spist->reg_addr |= byte << 8;
+            trace_tpm_tis_spi_transfer_data("second addr byte", byte);
+            trace_tpm_tis_spi_transfer_addr("reg_addr", spist->reg_addr);
+            break;
+        case 3:     /* 3rd address byte */
+            spist->reg_addr |= byte;
+            trace_tpm_tis_spi_transfer_data("third addr byte", byte);
+            trace_tpm_tis_spi_transfer_addr("reg_addr", spist->reg_addr);
+            break;
+        default:    /* data bytes */
+            if (spist->wait_state_cnt < NUM_WAIT_STATES) {
+                spist->wait_state_cnt++;
+                if (spist->wait_state_cnt == NUM_WAIT_STATES) {
+                    trace_tpm_tis_spi_transfer_data("wait complete, count",
+                                                     spist->wait_state_cnt);
+                    rx = rx | (0x01 << (24 - offset * 8));
+                    return rx;
+                } else {
+                    trace_tpm_tis_spi_transfer_data("in wait state, count",
+                                                     spist->wait_state_cnt);
+                    rx = 0;
+                }
+            } else {
+                index = spist->byte_offset - 4;
+                trace_tpm_tis_spi_transfer_data("index", index);
+                trace_tpm_tis_spi_transfer_data("data byte", byte);
+                trace_tpm_tis_spi_transfer_addr("reg_addr", spist->reg_addr);
+                if (index >= spist->xfer_size) {
+                    /*
+                     * SPI SSI framework limits both rx and tx
+                     * to fixed 4-byte with each xfer
+                     */
+                    trace_tpm_tis_spi_transfer_event("index exceeds xfer_size");
+                    return rx;
+                }
+                tis_addr = spist->reg_addr + (index % 4);
+                if (spist->spi_state == SPI_STATE_WRITE) {
+                    tpm_tis_spi_write(spist, tis_addr, byte);
+                } else {
+                    byte = tpm_tis_spi_read(spist, tis_addr);
+                    rx = rx | (byte << (24 - offset * 8));
+                    trace_tpm_tis_spi_transfer_data("byte added to response",
+                                                     byte);
+                    trace_tpm_tis_spi_transfer_data("offset", offset);
+                }
+            }
+            break;
+        }
+        if ((spist->wait_state_cnt == 0) ||
+            (spist->wait_state_cnt == NUM_WAIT_STATES)) {
+            offset++;
+            spist->byte_offset++;
+        } else {
+            break;
+        }
+    }
+    return rx;
+}
+
+static int tpm_tis_spi_cs(SSIPeripheral *ss, bool select)
+{
+    TPMStateSPI *spist = TPM_TIS_SPI(ss);
+
+    if (select) {
+        spist->command = false;
+        spist->spi_state = SPI_STATE_IDLE;
+    } else {
+        spist->command = true;
+    }
+    return 0;
+}
+
+static void tpm_tis_spi_realize(SSIPeripheral *dev, Error **errp)
+{
+    TPMStateSPI *spist = TPM_TIS_SPI(dev);
+    TPMState *s = &spist->tpm_state;
+
+    if (!tpm_find()) {
+        error_setg(errp, "at most one TPM device is permitted");
+        return;
+    }
+
+    s->be_driver = qemu_find_tpm_be("tpm0");
+
+    if (!s->be_driver) {
+        error_setg(errp, "unable to find tpm backend device");
+        return;
+    }
+}
+
+static void tpm_tis_spi_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+    TPMIfClass *tc = TPM_IF_CLASS(klass);
+    SSIPeripheralClass *k = SSI_PERIPHERAL_CLASS(klass);
+
+    k->transfer = tpm_tis_spi_transfer;
+    k->realize = tpm_tis_spi_realize;
+    k->set_cs = tpm_tis_spi_cs;
+    k->cs_polarity = SSI_CS_LOW;
+
+    device_class_set_legacy_reset(dc, tpm_tis_spi_reset);
+    device_class_set_props(dc, tpm_tis_spi_properties);
+    set_bit(DEVICE_CATEGORY_MISC, dc->categories);
+
+    dc->desc = "SPI TPM";
+    dc->vmsd = &vmstate_tpm_tis_spi;
+
+    tc->model = TPM_MODEL_TPM_TIS;
+    tc->request_completed = tpm_tis_spi_request_completed;
+    tc->get_version = tpm_tis_spi_get_tpm_version;
+}
+
+static const TypeInfo tpm_tis_spi_info = {
+    .name          = TYPE_TPM_TIS_SPI,
+    .parent        = TYPE_SSI_PERIPHERAL,
+    .instance_size = sizeof(TPMStateSPI),
+    .class_init    = tpm_tis_spi_class_init,
+    .interfaces    = (InterfaceInfo[]) {
+        { TYPE_TPM_IF },
+        { }
+    }
+};
+
+static void tpm_tis_spi_register_types(void)
+{
+    type_register_static(&tpm_tis_spi_info);
+}
+
+type_init(tpm_tis_spi_register_types)
diff --git a/hw/tpm/Kconfig b/hw/tpm/Kconfig
index a46663288c..5951c225cc 100644
--- a/hw/tpm/Kconfig
+++ b/hw/tpm/Kconfig
@@ -5,6 +5,12 @@ config TPM_TIS_I2C
     select I2C
     select TPM_TIS
 
+config TPM_TIS_SPI
+    bool
+    depends on TPM
+    select TPM_BACKEND
+    select TPM_TIS
+
 config TPM_TIS_ISA
     bool
     depends on TPM && ISA_BUS
diff --git a/hw/tpm/meson.build b/hw/tpm/meson.build
index 6968e60b3f..e03cfb11b9 100644
--- a/hw/tpm/meson.build
+++ b/hw/tpm/meson.build
@@ -2,6 +2,7 @@ system_ss.add(when: 'CONFIG_TPM_TIS', if_true: files('tpm_tis_common.c'))
 system_ss.add(when: 'CONFIG_TPM_TIS_ISA', if_true: files('tpm_tis_isa.c'))
 system_ss.add(when: 'CONFIG_TPM_TIS_SYSBUS', if_true: files('tpm_tis_sysbus.c'))
 system_ss.add(when: 'CONFIG_TPM_TIS_I2C', if_true: files('tpm_tis_i2c.c'))
+system_ss.add(when: 'CONFIG_TPM_TIS_SPI', if_true: files('tpm_tis_spi.c'))
 system_ss.add(when: 'CONFIG_TPM_CRB', if_true: files('tpm_crb.c'))
 system_ss.add(when: 'CONFIG_TPM_TIS', if_true: files('tpm_ppi.c'))
 system_ss.add(when: 'CONFIG_TPM_CRB', if_true: files('tpm_ppi.c'))
diff --git a/hw/tpm/trace-events b/hw/tpm/trace-events
index fa882dfefe..0324ceb6d0 100644
--- a/hw/tpm/trace-events
+++ b/hw/tpm/trace-events
@@ -42,3 +42,10 @@ tpm_tis_i2c_recv(uint8_t data) "TPM I2C read: 0x%X"
 tpm_tis_i2c_send(uint8_t data) "TPM I2C write: 0x%X"
 tpm_tis_i2c_event(const char *event) "TPM I2C event: %s"
 tpm_tis_i2c_send_reg(const char *name, int reg) "TPM I2C write register: %s(0x%X)"
+
+# tpm_tis_spi.c
+tpm_tis_spi_write(uint32_t addr, uint8_t val) "TPM SPI write - addr:0x%08X 0x%02x"
+tpm_tis_spi_read(uint32_t addr, uint8_t val) "TPM SPI read - addr:0x%08X 0x%02x"
+tpm_tis_spi_transfer_event(const char *event) "TPM SPI XFER event: %s"
+tpm_tis_spi_transfer_data(const char *name, uint8_t val) "TPM SPI XFER: %s = 0x%02x"
+tpm_tis_spi_transfer_addr(const char *name, uint32_t addr) "TPM SPI XFER: %s = 0x%08x"
-- 
2.39.5