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

[Ninad Palsule <ninad@linux.ibm.com>]

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));
+        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:
+
         /* 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
-- 
2.37.2