[PATCH v3 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.

---
V3:
Incorporated review comments from Cedric and Stefan.

- Pass locality to the checksum calculation function and cleanup
- Moved I2C related definations in the acpi/tpm.h
---
 hw/tpm/tpm_tis.h        |  3 +++
 hw/tpm/tpm_tis_common.c | 32 ++++++++++++++++++++++++++++++++
 include/hw/acpi/tpm.h   | 28 ++++++++++++++++++++++++++++
 3 files changed, 63 insertions(+)

diff --git a/hw/tpm/tpm_tis.h b/hw/tpm/tpm_tis.h
index f6b5872ba6..784898ce34 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, uint8_t locty);
 
 #endif /* TPM_TPM_TIS_H */
diff --git a/hw/tpm/tpm_tis_common.c b/hw/tpm/tpm_tis_common.c
index 503be2a541..84f3e2259f 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, uint8_t locty)
+{
+    if (TPM_TIS_IS_VALID_LOCTY(locty) && (s->active_locty == locty)) {
+        return cpu_to_be16(crc_ccitt(0, s->buffer, s->rw_offset));
+    } else {
+        return 0;
+    }
+}
+
 /*
  * 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,
diff --git a/include/hw/acpi/tpm.h b/include/hw/acpi/tpm.h
index 559ba6906c..82430605c7 100644
--- a/include/hw/acpi/tpm.h
+++ b/include/hw/acpi/tpm.h
@@ -93,6 +93,7 @@
 #define TPM_TIS_CAP_DATA_TRANSFER_64B    (3 << 9)
 #define TPM_TIS_CAP_DATA_TRANSFER_LEGACY (0 << 9)
 #define TPM_TIS_CAP_BURST_COUNT_DYNAMIC  (0 << 8)
+#define TPM_TIS_CAP_BURST_COUNT_STATIC   (1 << 8)
 #define TPM_TIS_CAP_INTERRUPT_LOW_LEVEL  (1 << 4) /* support is mandatory */
 #define TPM_TIS_CAPABILITIES_SUPPORTED1_3 \
     (TPM_TIS_CAP_INTERRUPT_LOW_LEVEL | \
@@ -209,6 +210,33 @@ REG32(CRB_DATA_BUFFER, 0x80)
 #define TPM_PPI_FUNC_ALLOWED_USR_NOT_REQ (4 << 0)
 #define TPM_PPI_FUNC_MASK                (7 << 0)
 
+/* TPM TIS I2C registers */
+#define TPM_TIS_I2C_REG_LOC_SEL          0x00
+#define TPM_TIS_I2C_REG_ACCESS           0x04
+#define TPM_TIS_I2C_REG_INT_ENABLE       0x08
+#define TPM_TIS_I2C_REG_INT_CAPABILITY   0x14
+#define TPM_TIS_I2C_REG_STS              0x18
+#define TPM_TIS_I2C_REG_DATA_FIFO        0x24
+#define TPM_TIS_I2C_REG_INTF_CAPABILITY  0x30
+#define TPM_TIS_I2C_REG_I2C_DEV_ADDRESS  0x38
+#define TPM_TIS_I2C_REG_DATA_CSUM_ENABLE 0x40
+#define TPM_TIS_I2C_REG_DATA_CSUM_GET    0x44
+#define TPM_TIS_I2C_REG_DID_VID          0x48
+#define TPM_TIS_I2C_REG_RID              0x4c
+#define TPM_TIS_I2C_REG_UNKNOWN          0xff
+
+/* I2C specific interface capabilities */
+#define TPM_I2C_CAP_INTERFACE_TYPE     (0x2 << 0)       /* FIFO interface */
+#define TPM_I2C_CAP_INTERFACE_VER      (0x0 << 4)       /* TCG I2C intf 1.0 */
+#define TPM_I2C_CAP_TPM2_FAMILY        (0x1 << 7)       /* TPM 2.0 family. */
+#define TPM_I2C_CAP_DEV_ADDR_CHANGE    (0x0 << 27)      /* No dev addr chng */
+#define TPM_I2C_CAP_BURST_COUNT_STATIC (0x1 << 29)      /* Burst count static */
+#define TPM_I2C_CAP_LOCALITY_CAP       (0x1 << 25)      /* 0-5 locality */
+#define TPM_I2C_CAP_BUS_SPEED          (3   << 21)      /* std and fast mode */
+
+/* TPM_STS mask for read bits 31:26 must be zero */
+#define TPM_I2C_STS_READ_MASK          0x03ffffff
+
 void tpm_build_ppi_acpi(TPMIf *tpm, Aml *dev);
 
 #endif /* CONFIG_TPM */
-- 
2.37.2