[PATCH 2/3] TPM TIS: 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>
---
V2:

Incorporated Stephen's comments.

- Removed checksum enable and checksum get registers.
- Added checksum calculation function which can be called from
  i2c layer.
---
 hw/tpm/tpm_tis.h        |  3 +++
 hw/tpm/tpm_tis_common.c | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 35 insertions(+)

diff --git a/hw/tpm/tpm_tis.h b/hw/tpm/tpm_tis.h
index f6b5872ba6..6f29a508dd 100644
--- a/hw/tpm/tpm_tis.h
+++ b/hw/tpm/tpm_tis.h
@@ -86,5 +86,8 @@ 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);
+uint16_t tpm_tis_get_checksum(TPMState *s);
 
 #endif /* TPM_TPM_TIS_H */
diff --git a/hw/tpm/tpm_tis_common.c b/hw/tpm/tpm_tis_common.c
index 503be2a541..b1acde74cb 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"
@@ -447,6 +449,27 @@ 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);
+}
+
+/*
+ * Calculate current data buffer checksum
+ */
+uint16_t tpm_tis_get_checksum(TPMState *s)
+{
+    uint16_t val = 0xffff;
+
+    val = cpu_to_be16(crc_ccitt(0, s->buffer, s->rw_offset));
+
+    return val;
+}
+
 /*
  * Write a value to a register of the TIS interface
  * See specs pages 33-63 for description of the registers
@@ -767,6 +790,15 @@ 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,
-- 
2.37.2