diff options
Diffstat (limited to 'libstb/drivers')
| -rw-r--r-- | libstb/drivers/tpm_i2c_nuvoton.c | 47 |
1 files changed, 43 insertions, 4 deletions
diff --git a/libstb/drivers/tpm_i2c_nuvoton.c b/libstb/drivers/tpm_i2c_nuvoton.c index ef32b79..3679dda 100644 --- a/libstb/drivers/tpm_i2c_nuvoton.c +++ b/libstb/drivers/tpm_i2c_nuvoton.c @@ -493,12 +493,46 @@ static struct tpm_driver tpm_i2c_nuvoton_driver = { static int nuvoton_tpm_quirk(void *data, struct i2c_request *req, int *rc) { struct tpm_dev *tpm_device = data; + struct dt_node *dev; + uint16_t addr; + bool found; - /* If we're doing i2cdetect on the TPM, pretent we just NACKed - * it due to errata in nuvoton firmware where if we let this - * request go through, it would steal the bus and you'd end up - * in a nice world of pain. + /* + * The nuvoton TPM firmware has a problem where a single byte read or + * zero byte write to one of its I2C addresses causes the TPM to lock + * up the bus. Once locked up the bus can only be recovered by power + * cycling the TPM. Unfortunately, we don't have the ability to + * power cycle the TPM because allowing it to be reset at runtime + * would undermine the TPM's security model (we can reset it and + * send it whatever measurements we like to unlock it's secrets). + * So the best we can do here is try avoid triggering the problem + * in the first place. + * + * For a bit of added fun the TPM also appears to check for traffic + * on a few different I2C bus addresses. It does this even when not + * configured to respond on those addresses so you can trigger the + * bug by sending traffic... somwhere. To work around this we block + * sending I2C requests on the TPM's bus unless the DT explicitly + * tells us there is a device there. */ + + /* first, check if this a known address */ + addr = req->dev_addr; + found = false; + + dt_for_each_child(req->bus->dt_node, dev) { + if (dt_prop_get_u32(dev, "reg") == addr) { + found = true; + break; + } + } + + if (!found) { + *rc = OPAL_I2C_TIMEOUT; + return 1; + } + + /* second, check if it's a bad transaction to the TPM */ if (tpm_device->bus_id == req->bus->opal_id && tpm_device->i2c_addr == req->dev_addr && ((req->op == I2C_READ && req->rw_len == 1) || @@ -517,6 +551,7 @@ void tpm_i2c_nuvoton_probe(void) struct tpm_dev *tpm_device = NULL; struct dt_node *node = NULL; struct i2c_bus *bus; + const char *name; dt_for_each_compatible(dt_root, node, "nuvoton,npct650") { if (!dt_node_is_enabled(node)) @@ -562,6 +597,10 @@ void tpm_i2c_nuvoton_probe(void) assert(bus->check_quirk == NULL); bus->check_quirk = nuvoton_tpm_quirk; bus->check_quirk_data = tpm_device; + name = dt_prop_get(node->parent, "ibm,port-name"); + + prlog(PR_NOTICE, "NUVOTON: TPM I2C workaround applied to %s\n", + name); /* * Tweak for linux. It doesn't have a driver compatible |