tpm: provide means of shutting down comms layer while in reset

Currently the Cr50 code resets TPM communications layer at a certain
point during TPM reset process.

It turns out that this is not sufficient - the comms layer keeps
receiving and trying to invoke TPM layer, which does not mesh well
with TPM reset.

Let's provide two callbacks for each comms layer - to shut it down and
to bring it back up. We shut down the comms when starting TPM reset
and bring them back up when reset is completed.

BRANCH=cr50
BUG=b:68012381
TEST=ran AP firmware test suite on both SPI and I2C based devices.

Change-Id: I7caf4a09b9a5c6e5fc6bfe60eae1c0d64ab24904
Signed-off-by: Vadim Bendebury <vbendeb@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/754502
Reviewed-by: Randall Spangler <rspangler@chromium.org>
Reviewed-by: Mary Ruthven <mruthven@chromium.org>
(cherry picked from commit 3919001a390f593ba8e022f223bf1e43b7dbc0a2)
Reviewed-on: https://chromium-review.googlesource.com/766076

2 files changed, 25 insertions, 9 deletions

diff --git a/common/i2cs_tpm.c b/common/i2cs_tpm.c
index 42089681dd..4518eddbb9 100644
--- a/common/i2cs_tpm.c
+++ b/common/i2cs_tpm.c
@@ -211,7 +211,12 @@ static void wr_complete_handler(void *i2cs_data, size_t i2cs_data_size)
 	gpio_set_level(GPIO_INT_AP_L, 1);
 }
 
-static void i2cs_tpm_enable(void)
+static void i2cs_if_stop(void)
+{
+	i2cs_register_write_complete_handler(NULL);
+}
+
+static void i2cs_if_start(void)
 {
 	i2cs_register_write_complete_handler(wr_complete_handler);
 }
@@ -221,7 +226,7 @@ static void i2cs_if_register(void)
 	if (!board_tpm_uses_i2c())
 		return;
 
-	tpm_register_interface(i2cs_tpm_enable);
+	tpm_register_interface(i2cs_if_start, i2cs_if_stop);
 	i2cs_fifo_adjust_count = 0;
 	i2cs_write_error_count = 0;
 }
diff --git a/common/tpm_registers.c b/common/tpm_registers.c
index 46d2b7fdf1..71f0fb4a28 100644
--- a/common/tpm_registers.c
+++ b/common/tpm_registers.c
@@ -536,10 +536,13 @@ void tpm_register_get(uint32_t regaddr, uint8_t *dest, uint32_t data_size)
 	CPRINTF("\n");
 }
 
-static __preserved interface_restart_func if_restart;
-void tpm_register_interface(interface_restart_func interface_restart)
+static __preserved interface_control_func if_start;
+static __preserved interface_control_func if_stop;
+void tpm_register_interface(interface_control_func interface_start,
+			    interface_control_func interface_stop)
 {
-	if_restart = interface_restart;
+	if_start = interface_start;
+	if_stop = interface_stop;
 }
 
 static void tpm_init(void)
@@ -615,10 +618,6 @@ static void tpm_init(void)
 
 		_plat__SetNvAvail();
 	}
-
-	/* Reinitialize TPM interface unless in chip factory mode. */
-	if (!chip_factory_mode())
-		if_restart();
 }
 
 size_t tpm_get_burst_size(void)
@@ -812,6 +811,10 @@ void tpm_reinstate_nvmem_commits(void)
 
 static void tpm_reset_now(int wipe_first)
 {
+	/* TPM is not running in factory mode. */
+	if (!chip_factory_mode())
+		if_stop();
+
 	/* This is more related to TPM task activity than TPM transactions */
 	cprints(CC_TASK, "%s(%d)", __func__, wipe_first);
 
@@ -866,6 +869,14 @@ static void tpm_reset_now(int wipe_first)
 	hook_call_deferred(&reinstate_nvmem_commits_data, 3 * SECOND);
 
 	reset_in_progress = 0;
+
+	/*
+	 * In chip factory mode SPI idle byte sent on MISO is used for
+	 * progress reporting. TPM flow control messes it up, do not start TPM
+	 * in factory mode.
+	 */
+	if (!chip_factory_mode())
+		if_start();
 }
 
 void tpm_task(void)