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Re: [PATCH 2/3] Add support for TPM devices over I2C bus


From: Stefan Berger
Subject: Re: [PATCH 2/3] Add support for TPM devices over I2C bus
Date: Tue, 21 Mar 2023 19:54:37 -0400
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.7.1



On 3/21/23 01:30, Ninad Palsule wrote:
Qemu already supports devices attached to ISA and sysbus. This drop adds
support for the I2C bus attached TPM devices.

This commit includes changes for the common code.
- Added support for the new checksum registers which are required for
   the I2C support. The checksum calculation is handled in the qemu
   common code.
- Added wrapper function for read and write data so that I2C code can
   call it without MMIO interface.

Signed-off-by: Ninad Palsule <ninad@linux.ibm.com>
---
  hw/tpm/tpm_tis.h        |  2 ++
  hw/tpm/tpm_tis_common.c | 33 +++++++++++++++++++++++++++++++++
  include/hw/acpi/tpm.h   |  2 ++
  3 files changed, 37 insertions(+)

diff --git a/hw/tpm/tpm_tis.h b/hw/tpm/tpm_tis.h
index f6b5872ba6..16b7baddd8 100644
--- a/hw/tpm/tpm_tis.h
+++ b/hw/tpm/tpm_tis.h
@@ -86,5 +86,7 @@ int tpm_tis_pre_save(TPMState *s);
  void tpm_tis_reset(TPMState *s);
  enum TPMVersion tpm_tis_get_tpm_version(TPMState *s);
  void tpm_tis_request_completed(TPMState *s, int ret);
+uint32_t tpm_tis_read_data(TPMState *s, hwaddr addr, unsigned size);
+void tpm_tis_write_data(TPMState *s, hwaddr addr, uint64_t val, uint32_t size);
#endif /* TPM_TPM_TIS_H */
diff --git a/hw/tpm/tpm_tis_common.c b/hw/tpm/tpm_tis_common.c
index 503be2a541..3c82f63179 100644
--- a/hw/tpm/tpm_tis_common.c
+++ b/hw/tpm/tpm_tis_common.c
@@ -26,6 +26,8 @@
  #include "hw/irq.h"
  #include "hw/isa/isa.h"
  #include "qapi/error.h"
+#include "qemu/bswap.h"
+#include "qemu/crc-ccitt.h"
  #include "qemu/module.h"
#include "hw/acpi/tpm.h"
@@ -422,6 +424,9 @@ static uint64_t tpm_tis_mmio_read(void *opaque, hwaddr addr,
              shift = 0; /* no more adjustments */
          }
          break;
+    case TPM_TIS_REG_DATA_CSUM_GET:
+        val = bswap16(crc_ccitt(0, s->buffer, s->rw_offset));

Should this not rather be cpu_to_be16() so that it would also work on a big 
endian host (assuming you tested this on a little e endian host)?

+        break;
      case TPM_TIS_REG_INTERFACE_ID:
          val = s->loc[locty].iface_id;
          break;
@@ -447,6 +452,15 @@ static uint64_t tpm_tis_mmio_read(void *opaque, hwaddr 
addr,
      return val;
  }
+/*
+ * A wrapper read function so that it can be directly called without
+ * mmio.
+ */
+uint32_t tpm_tis_read_data(TPMState *s, hwaddr addr, unsigned size)
+{
+    return tpm_tis_mmio_read(s, addr, size);
+}
+
  /*
   * Write a value to a register of the TIS interface
   * See specs pages 33-63 for description of the registers
@@ -600,6 +614,15 @@ static void tpm_tis_mmio_write(void *opaque, hwaddr addr,
      case TPM_TIS_REG_INT_VECTOR:
          /* hard wired -- ignore */
          break;
+    case TPM_TIS_REG_DATA_CSUM_ENABLE:
+        /*
+         * Checksum implemented by common code so no need to set
+         * any flags.
+         */
+        break;
+    case TPM_TIS_REG_DATA_CSUM_GET:
+        /* This is readonly register so ignore */
+        break;
      case TPM_TIS_REG_INT_STATUS:
          if (s->active_locty != locty) {
              break;
@@ -703,6 +726,7 @@ static void tpm_tis_mmio_write(void *opaque, hwaddr addr,
          break;
      case TPM_TIS_REG_DATA_FIFO:
      case TPM_TIS_REG_DATA_XFIFO ... TPM_TIS_REG_DATA_XFIFO_END:
+

you can remove this one

          /* data fifo */
          if (s->active_locty != locty) {
              break;
@@ -767,6 +791,15 @@ static void tpm_tis_mmio_write(void *opaque, hwaddr addr,
      }
  }
+/*
+ * A wrapper write function so that it can be directly called without
+ * mmio.
+ */
+void tpm_tis_write_data(TPMState *s, hwaddr addr, uint64_t val, uint32_t size)
+{
+    tpm_tis_mmio_write(s, addr, val, size);
+}'
+
  const MemoryRegionOps tpm_tis_memory_ops = {
      .read = tpm_tis_mmio_read,
      .write = tpm_tis_mmio_write,
diff --git a/include/hw/acpi/tpm.h b/include/hw/acpi/tpm.h
index 559ba6906c..db12c002f4 100644
--- a/include/hw/acpi/tpm.h
+++ b/include/hw/acpi/tpm.h
@@ -40,6 +40,8 @@
  #define TPM_TIS_REG_STS                   0x18
  #define TPM_TIS_REG_DATA_FIFO             0x24
  #define TPM_TIS_REG_INTERFACE_ID          0x30
+#define TPM_TIS_REG_DATA_CSUM_ENABLE      0x40
+#define TPM_TIS_REG_DATA_CSUM_GET         0x44
  #define TPM_TIS_REG_DATA_XFIFO            0x80
  #define TPM_TIS_REG_DATA_XFIFO_END        0xbc
  #define TPM_TIS_REG_DID_VID               0xf00

Looks good.



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