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49 lines
1.6 KiB
Plaintext
49 lines
1.6 KiB
Plaintext
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The U-Boot Driver Model Project
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===============================
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TPM system analysis
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===================
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Marek Vasut <marek.vasut@gmail.com>
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2012-02-23
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I) Overview
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-----------
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There is currently only one TPM chip driver available and therefore the API
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controlling it is very much based on this. The API is very simple:
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int tis_open(void);
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int tis_close(void);
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int tis_sendrecv(const u8 *sendbuf, size_t send_size,
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u8 *recvbuf, size_t *recv_len);
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The command operating the TPM chip only provides operations to send and receive
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bytes from the chip.
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II) Approach
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------------
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The API can't be generalised too much considering there's only one TPM chip
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supported. But it's a good idea to split the tis_sendrecv() function in two
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functions. Therefore the new API will use register the TPM chip by calling:
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tpm_device_register(struct instance *i, const struct tpm_ops *ops);
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And the struct tpm_ops will contain the following members:
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struct tpm_ops {
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int (*tpm_open)(struct instance *i);
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int (*tpm_close)(struct instance *i);
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int (*tpm_send)(const uint8_t *buf, const size_t size);
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int (*tpm_recv)(uint8_t *buf, size_t *size);
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};
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The behaviour of "tpm_open()" and "tpm_close()" will basically copy the
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behaviour of "tis_open()" and "tis_close()". The "tpm_send()" will be based on
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the "tis_senddata()" and "tis_recv()" will be based on "tis_readresponse()".
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III) Analysis of in-tree drivers
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--------------------------------
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There is only one in-tree driver present, the "drivers/tpm/generic_lpc_tpm.c",
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which will be simply converted as outlined in previous chapter.
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