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drivers/spi/tpm: Improve error checking

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This adds error checking in paths that previously ignored TPM
communication errors. We hit this case occasionally during "Checking
cr50 for pending updates"; previously we would go down this path and
eventually time out using MAX_STATUS_TIMEOUT, which is 2 minutes.
Now, we detect the failure and return with an error indication instead
of timing out after a long time. The root cause of the communication
error is an open issue.

BUG=b:168090038
TEST=booted on volteer, observed error handling when
	"Checking cr50 for pending updates" fails.

Signed-off-by: Caveh Jalali <caveh@chromium.org>
Change-Id: Ia8a1202000abce1857ee694b06b1478e6b045069
Reviewed-on: https://review.coreboot.org/c/coreboot/+/45232
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Jes Klinke <jbk@chromium.org>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
This commit is contained in:
Caveh Jalali
2020-09-10 01:25:29 -07:00
committed by Patrick Georgi
parent 0f651650f3
commit 8274c2926f
1 changed files with 39 additions and 17 deletions
Download Patch File Download Diff File Expand all files Collapse all files

56
src/drivers/spi/tpm/tpm.c
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@ -348,7 +348,7 @@ static int read_tpm_sts(uint32_t *status)
return tpm2_read_reg(TPM_STS_REG, status, sizeof(*status)); return tpm2_read_reg(TPM_STS_REG, status, sizeof(*status));
} }
static int write_tpm_sts(uint32_t status) static int __must_check write_tpm_sts(uint32_t status)
{ {
return tpm2_write_reg(TPM_STS_REG, &status, sizeof(status)); return tpm2_write_reg(TPM_STS_REG, &status, sizeof(status));
} }
@ -688,9 +688,9 @@ union fifo_transfer_buffer {
* Transfer requested number of bytes to or from TPM FIFO, accounting for the * Transfer requested number of bytes to or from TPM FIFO, accounting for the
* current burst count value. * current burst count value.
*/ */
static void fifo_transfer(size_t transfer_size, static int __must_check fifo_transfer(size_t transfer_size,
union fifo_transfer_buffer buffer, union fifo_transfer_buffer buffer,
enum fifo_transfer_direction direction) enum fifo_transfer_direction direction)
{ {
size_t transaction_size; size_t transaction_size;
size_t burst_count; size_t burst_count;
@ -711,18 +711,23 @@ static void fifo_transfer(size_t transfer_size,
*/ */
transaction_size = MIN(transaction_size, 64); transaction_size = MIN(transaction_size, 64);
if (direction == fifo_receive) if (direction == fifo_receive) {
tpm2_read_reg(TPM_DATA_FIFO_REG, if (!tpm2_read_reg(TPM_DATA_FIFO_REG,
buffer.rx_buffer + handled_so_far, buffer.rx_buffer + handled_so_far,
transaction_size); transaction_size))
else return 0;
tpm2_write_reg(TPM_DATA_FIFO_REG, } else {
buffer.tx_buffer + handled_so_far, if (!tpm2_write_reg(TPM_DATA_FIFO_REG,
transaction_size); buffer.tx_buffer + handled_so_far,
transaction_size))
return 0;
}
handled_so_far += transaction_size; handled_so_far += transaction_size;
} while (handled_so_far != transfer_size); } while (handled_so_far != transfer_size);
return 1;
} }
size_t tpm2_process_command(const void *tpm2_command, size_t command_size, size_t tpm2_process_command(const void *tpm2_command, size_t command_size,
@ -755,7 +760,10 @@ size_t tpm2_process_command(const void *tpm2_command, size_t command_size,
} }
/* Let the TPM know that the command is coming. */ /* Let the TPM know that the command is coming. */
write_tpm_sts(TPM_STS_COMMAND_READY); if (!write_tpm_sts(TPM_STS_COMMAND_READY)) {
printk(BIOS_ERR, "TPM_STS_COMMAND_READY failed\n");
return 0;
}
/* /*
* TPM commands and responses written to and read from the FIFO * TPM commands and responses written to and read from the FIFO
@ -769,10 +777,17 @@ size_t tpm2_process_command(const void *tpm2_command, size_t command_size,
* burst count or the maximum PDU size, whatever is smaller. * burst count or the maximum PDU size, whatever is smaller.
*/ */
fifo_buffer.tx_buffer = cmd_body; fifo_buffer.tx_buffer = cmd_body;
fifo_transfer(command_size, fifo_buffer, fifo_transmit); if (!fifo_transfer(command_size, fifo_buffer, fifo_transmit)) {
printk(BIOS_ERR, "fifo_transfer %zd command bytes failed\n",
command_size);
return 0;
}
/* Now tell the TPM it can start processing the command. */ /* Now tell the TPM it can start processing the command. */
write_tpm_sts(TPM_STS_GO); if (!write_tpm_sts(TPM_STS_GO)) {
printk(BIOS_ERR, "TPM_STS_GO failed\n");
return 0;
}
/* Now wait for it to report that the response is ready. */ /* Now wait for it to report that the response is ready. */
expected_status_bits = TPM_STS_VALID | TPM_STS_DATA_AVAIL; expected_status_bits = TPM_STS_VALID | TPM_STS_DATA_AVAIL;
@ -815,7 +830,11 @@ size_t tpm2_process_command(const void *tpm2_command, size_t command_size,
*/ */
bytes_to_go = payload_size - 1 - HEADER_SIZE; bytes_to_go = payload_size - 1 - HEADER_SIZE;
fifo_buffer.rx_buffer = rsp_body + HEADER_SIZE; fifo_buffer.rx_buffer = rsp_body + HEADER_SIZE;
fifo_transfer(bytes_to_go, fifo_buffer, fifo_receive); if (!fifo_transfer(bytes_to_go, fifo_buffer, fifo_receive)) {
printk(BIOS_ERR, "fifo_transfer %zd receive bytes failed\n",
bytes_to_go);
return 0;
}
/* Verify that there is still data to read. */ /* Verify that there is still data to read. */
read_tpm_sts(&status); read_tpm_sts(&status);
@ -840,7 +859,10 @@ size_t tpm2_process_command(const void *tpm2_command, size_t command_size,
} }
/* Move the TPM back to idle state. */ /* Move the TPM back to idle state. */
write_tpm_sts(TPM_STS_COMMAND_READY); if (!write_tpm_sts(TPM_STS_COMMAND_READY)) {
printk(BIOS_ERR, "TPM_STS_COMMAND_READY failed\n");
return 0;
}
return payload_size; return payload_size;
} }