security/tpm: make tis_probe() return tpm_family

Via an out parameter. This is needed to be able to dynamically pick TSS
implementation based on the information discovered on probing.

Change-Id: I5006e0cdfef76ff79ce9e1cf280fcd5515ae01b0
Ticket: https://ticket.coreboot.org/issues/433
Signed-off-by: Sergii Dmytruk <sergii.dmytruk@3mdeb.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/69159
Reviewed-by: Martin L Roth <gaumless@gmail.com>
Reviewed-by: Jérémy Compostella <jeremy.compostella@intel.com>
Reviewed-by: Julius Werner <jwerner@chromium.org>
Reviewed-by: Christian Walter <christian.walter@9elements.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

5 files changed, 38 insertions, 6 deletions

diff --git a/src/drivers/i2c/tpm/cr50.c b/src/drivers/i2c/tpm/cr50.c
index 8462198410..b58fbc8a67 100644
--- a/src/drivers/i2c/tpm/cr50.c
+++ b/src/drivers/i2c/tpm/cr50.c
@@ -424,8 +424,11 @@ static void cr50_vendor_init(struct tpm_chip *chip)
 	chip->cancel = &cr50_i2c_tis_ready;
 }
 
-tpm_result_t tpm_vendor_probe(unsigned int bus, uint32_t addr)
+tpm_result_t tpm_vendor_probe(unsigned int bus, uint32_t addr, enum tpm_family *family)
 {
+	/* cr50 is TPM2 */
+	if (family != NULL)
+		*family = TPM_2;
 	return TPM_SUCCESS;
 }
 
diff --git a/src/drivers/i2c/tpm/tis.c b/src/drivers/i2c/tpm/tis.c
index 6cb05f0dd7..fd09240494 100644
--- a/src/drivers/i2c/tpm/tis.c
+++ b/src/drivers/i2c/tpm/tis.c
@@ -118,9 +118,9 @@ static tpm_result_t i2c_tpm_sendrecv(const uint8_t *sendbuf, size_t sbuf_size,
 	return TPM_SUCCESS;
 }
 
-tis_sendrecv_fn tis_probe(void)
+tis_sendrecv_fn tis_probe(enum tpm_family *family)
 {
-	if (tpm_vendor_probe(CONFIG_DRIVER_TPM_I2C_BUS, CONFIG_DRIVER_TPM_I2C_ADDR))
+	if (tpm_vendor_probe(CONFIG_DRIVER_TPM_I2C_BUS, CONFIG_DRIVER_TPM_I2C_ADDR, family))
 		return NULL;
 
 	if (tpm_vendor_init(&chip, CONFIG_DRIVER_TPM_I2C_BUS, CONFIG_DRIVER_TPM_I2C_ADDR))
diff --git a/src/drivers/i2c/tpm/tis_atmel.c b/src/drivers/i2c/tpm/tis_atmel.c
index 0a29049d95..a0bbf33fc4 100644
--- a/src/drivers/i2c/tpm/tis_atmel.c
+++ b/src/drivers/i2c/tpm/tis_atmel.c
@@ -107,7 +107,19 @@ static tpm_result_t i2c_tis_sendrecv(const uint8_t *sendbuf, size_t sbuf_size,
 	return TPM_SUCCESS;
 }
 
-tis_sendrecv_fn tis_probe(void)
+tis_sendrecv_fn tis_probe(enum tpm_family *family)
 {
+	/*
+	 * Can't query version or really anything as the device doesn't support
+	 * much through this interface (can't specify address on accesses).
+	 *
+	 * Hence the assumption is that whatever TPM version is enabled at
+	 * compile-time defines what the device supports. The check is written
+	 * in a way to give TPM 1 preference even if support for both versions
+	 * is compiled in.
+	 */
+	if (family != NULL)
+		*family = CONFIG(TPM1) ? TPM_1 : TPM_2;
+
 	return &i2c_tis_sendrecv;
 }
diff --git a/src/drivers/i2c/tpm/tpm.c b/src/drivers/i2c/tpm/tpm.c
index 541eb3aaa0..eb279844e8 100644
--- a/src/drivers/i2c/tpm/tpm.c
+++ b/src/drivers/i2c/tpm/tpm.c
@@ -451,13 +451,29 @@ out_err:
 
 /* Initialization of I2C TPM */
 
-tpm_result_t tpm_vendor_probe(unsigned int bus, uint32_t addr)
+tpm_result_t tpm_vendor_probe(unsigned int bus, uint32_t addr, enum tpm_family *family)
 {
 	struct stopwatch sw;
 	uint8_t buf = 0;
 	int ret;
 	long sw_run_duration = SLEEP_DURATION_PROBE_MS;
 
+	/*
+	 * Infineon "I2C Protocol Stack Specification v0.20" is supposedly a
+	 * simple adoption of the LPC TIS Protocol to the I2C Bus, but looking
+	 * at "TCG PC Client Specific TIS" doesn't confirm that and Infineon's
+	 * specification isn't publicly available.
+	 *
+	 * Because it's unknown how to access information about TPM version of
+	 * the device in this case, the assumption is that whatever TPM version
+	 * is enabled at compile-time defines what the device supports. And
+	 * since this driver doesn't appear to be used with TPM 2 devices, the
+	 * check is written in a way to give TPM 1 preference even if support
+	 * for both versions is compiled in.
+	 */
+	if (family != NULL)
+		*family = CONFIG(TPM1) ? TPM_1 : TPM_2;
+
 	tpm_dev.chip_type = UNKNOWN;
 	tpm_dev.bus = bus;
 	tpm_dev.addr = addr;
diff --git a/src/drivers/i2c/tpm/tpm.h b/src/drivers/i2c/tpm/tpm.h
index 628ad4dc69..46935e2495 100644
--- a/src/drivers/i2c/tpm/tpm.h
+++ b/src/drivers/i2c/tpm/tpm.h
@@ -12,6 +12,7 @@
 #ifndef __DRIVERS_TPM_SLB9635_I2C_TPM_H__
 #define __DRIVERS_TPM_SLB9635_I2C_TPM_H__
 
+#include <security/tpm/tis.h>
 #include <security/tpm/tss_errors.h>
 #include <stdint.h>
 
@@ -51,7 +52,7 @@ struct tpm_chip {
 
 /* ---------- Interface for TPM vendor ------------ */
 
-tpm_result_t tpm_vendor_probe(unsigned int bus, uint32_t addr);
+tpm_result_t tpm_vendor_probe(unsigned int bus, uint32_t addr, enum tpm_family *family);
 
 tpm_result_t tpm_vendor_init(struct tpm_chip *chip, unsigned int bus, uint32_t dev_addr);