tpm: Extend common APIs to support TPM TIS I2C

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.

The TPM TIS I2C spec describes in the table in section "Interface Locality
Usage per Register" that the TPM_INT_ENABLE and TPM_INT_STATUS registers
must be writable for any locality even if the locality is not the active
locality. Therefore, remove the checks whether the writing locality is the
active locality for these registers.

Signed-off-by: Ninad Palsule <ninad@linux.ibm.com>
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Tested-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Tested-by: Joel Stanley <joel@jms.id.au>
Message-id: 20230414220754.1191476-3-ninadpalsule@us.ibm.com

2 files changed, 31 insertions, 8 deletions

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..c07c179dbc 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"
@@ -448,6 +450,23 @@ static uint64_t tpm_tis_mmio_read(void *opaque, hwaddr addr,
 }
 
 /*
+ * 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)
+{
+    return bswap16(crc_ccitt(0, s->buffer, s->rw_offset));
+}
+
+/*
  * Write a value to a register of the TIS interface
  * See specs pages 33-63 for description of the registers
  */
@@ -588,10 +607,6 @@ static void tpm_tis_mmio_write(void *opaque, hwaddr addr,
 
         break;
     case TPM_TIS_REG_INT_ENABLE:
-        if (s->active_locty != locty) {
-            break;
-        }
-
         s->loc[locty].inte &= mask;
         s->loc[locty].inte |= (val & (TPM_TIS_INT_ENABLED |
                                         TPM_TIS_INT_POLARITY_MASK |
@@ -601,10 +616,6 @@ static void tpm_tis_mmio_write(void *opaque, hwaddr addr,
         /* hard wired -- ignore */
         break;
     case TPM_TIS_REG_INT_STATUS:
-        if (s->active_locty != locty) {
-            break;
-        }
-
         /* clearing of interrupt flags */
         if (((val & TPM_TIS_INTERRUPTS_SUPPORTED)) &&
             (s->loc[locty].ints & TPM_TIS_INTERRUPTS_SUPPORTED)) {
@@ -767,6 +778,15 @@ 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,