diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/drivers/spi/tpm/tpm.c | 40 |
1 files changed, 36 insertions, 4 deletions
diff --git a/src/drivers/spi/tpm/tpm.c b/src/drivers/spi/tpm/tpm.c index 0b5a835837..58bf842267 100644 --- a/src/drivers/spi/tpm/tpm.c +++ b/src/drivers/spi/tpm/tpm.c @@ -280,7 +280,8 @@ static int tpm2_write_reg(unsigned reg_number, const void *buffer, size_t bytes) * To read a register, start transaction, transfer data from the TPM, deassert * CS when done. * - * Returns one to indicate success, zero to indicate failure. + * Returns one to indicate success, zero to indicate failure. In case of + * failure zero out the user buffer. */ static int tpm2_read_reg(unsigned reg_number, void *buffer, size_t bytes) { @@ -368,21 +369,52 @@ static int tpm2_claim_locality(void) return 1; } +/* Device/vendor ID values of the TPM devices this driver supports. */ +static const uint32_t supported_did_vids[] = { + 0x00281ae0 /* H1 based Cr50 security chip. */ +}; + int tpm2_init(struct spi_slave *spi_if) { uint32_t did_vid, status; uint8_t cmd; + int retries; struct tpm2_info *tpm_info = car_get_var_ptr(&g_tpm_info); struct spi_slave *spi_slave = car_get_var_ptr(&g_spi_slave); memcpy(spi_slave, spi_if, sizeof(*spi_if)); /* - * It is enough to check the first register read error status to bail - * out in case of malfunctioning TPM. + * 150 ms should be enough to synchronize with the TPM even under the + * worst nested reset request conditions. In vast majority of cases + * there would be no wait at all. */ - if (!tpm2_read_reg(TPM_DID_VID_REG, &did_vid, sizeof(did_vid))) + printk(BIOS_INFO, "Probing TPM: "); + for (retries = 15; retries > 0; retries--) { + int i; + + /* In case of falure to read div_vid is set to zero. */ + tpm2_read_reg(TPM_DID_VID_REG, &did_vid, sizeof(did_vid)); + + for (i = 0; i < ARRAY_SIZE(supported_did_vids); i++) + if (did_vid == supported_did_vids[i]) + break; /* Tpm is up and ready. */ + + if (i < ARRAY_SIZE(supported_did_vids)) + break; + + /* TPM might be resetting, let's retry in a bit. */ + mdelay(10); + printk(BIOS_INFO, "."); + } + + if (!retries) { + printk(BIOS_ERR, "\n%s: Failed to connect to the TPM\n", + __func__); return -1; + } + + printk(BIOS_INFO, " done!\n"); /* Claim locality 0. */ if (!tpm2_claim_locality()) |