xref: /openbmc/u-boot/drivers/tpm/tpm_atmel_twi.c (revision ee7bb5be)
1 /*
2  * Copyright (C) 2013 Guntermann & Drunck, GmbH
3  *
4  * Written by Dirk Eibach <eibach@gdsys.de>
5  *
6  * SPDX-License-Identifier:	GPL-2.0+
7  */
8 
9 #include <common.h>
10 #include <dm.h>
11 #include <tpm.h>
12 #include <i2c.h>
13 #include <asm/unaligned.h>
14 
15 #include "tpm_internal.h"
16 
17 #define ATMEL_TPM_TIMEOUT_MS 5000 /* sufficient for anything but
18 				     generating/exporting keys */
19 
20 /*
21  * tpm_atmel_twi_open()
22  *
23  * Requests access to locality 0 for the caller. After all commands have been
24  * completed the caller is supposed to call tis_close().
25  *
26  * Returns 0 on success, -1 on failure.
27  */
28 static int tpm_atmel_twi_open(struct udevice *dev)
29 {
30 	return 0;
31 }
32 
33 /*
34  * tpm_atmel_twi_close()
35  *
36  * terminate the currect session with the TPM by releasing the locked
37  * locality. Returns 0 on success of -1 on failure (in case lock
38  * removal did not succeed).
39  */
40 static int tpm_atmel_twi_close(struct udevice *dev)
41 {
42 	return 0;
43 }
44 
45 /*
46  * tpm_atmel_twi_get_desc()
47  *
48  * @dev:        Device to check
49  * @buf:        Buffer to put the string
50  * @size:       Maximum size of buffer
51  * @return length of string, or -ENOSPC it no space
52  */
53 static int tpm_atmel_twi_get_desc(struct udevice *dev, char *buf, int size)
54 {
55 	return 0;
56 }
57 
58 /*
59  * tpm_atmel_twi_xfer()
60  *
61  * Send the requested data to the TPM and then try to get its response
62  *
63  * @sendbuf - buffer of the data to send
64  * @send_size size of the data to send
65  * @recvbuf - memory to save the response to
66  * @recv_len - pointer to the size of the response buffer
67  *
68  * Returns 0 on success (and places the number of response bytes at recv_len)
69  * or -1 on failure.
70  */
71 static int tpm_atmel_twi_xfer(struct udevice *dev,
72 			      const uint8_t *sendbuf, size_t send_size,
73 			      uint8_t *recvbuf, size_t *recv_len)
74 {
75 	int res;
76 	unsigned long start;
77 
78 #ifdef DEBUG
79 	memset(recvbuf, 0xcc, *recv_len);
80 	printf("send to TPM (%d bytes, recv_len=%d):\n", send_size, *recv_len);
81 	print_buffer(0, (void *)sendbuf, 1, send_size, 0);
82 #endif
83 
84 	res = i2c_write(0x29, 0, 0, (uchar *)sendbuf, send_size);
85 	if (res) {
86 		printf("i2c_write returned %d\n", res);
87 		return -1;
88 	}
89 
90 	start = get_timer(0);
91 	while ((res = i2c_read(0x29, 0, 0, recvbuf, 10))) {
92 		/* TODO Use TIS_TIMEOUT from tpm_tis_infineon.h */
93 		if (get_timer(start) > ATMEL_TPM_TIMEOUT_MS) {
94 			puts("tpm timed out\n");
95 			return -1;
96 		}
97 		udelay(100);
98 	}
99 	if (!res) {
100 		*recv_len = get_unaligned_be32(recvbuf + 2);
101 		if (*recv_len > 10)
102 			res = i2c_read(0x29, 0, 0, recvbuf, *recv_len);
103 	}
104 	if (res) {
105 		printf("i2c_read returned %d (rlen=%d)\n", res, *recv_len);
106 #ifdef DEBUG
107 		print_buffer(0, recvbuf, 1, *recv_len, 0);
108 #endif
109 	}
110 
111 #ifdef DEBUG
112 	if (!res) {
113 		printf("read from TPM (%d bytes):\n", *recv_len);
114 		print_buffer(0, recvbuf, 1, *recv_len, 0);
115 	}
116 #endif
117 
118 	return res;
119 }
120 
121 static int tpm_atmel_twi_probe(struct udevice *dev)
122 {
123 	return 0;
124 }
125 
126 static const struct udevice_id tpm_atmel_twi_ids[] = {
127 	{ .compatible = "atmel,at97sc3204t"},
128 	{ }
129 };
130 
131 static const struct tpm_ops tpm_atmel_twi_ops = {
132 	.open = tpm_atmel_twi_open,
133 	.close = tpm_atmel_twi_close,
134 	.xfer = tpm_atmel_twi_xfer,
135 	.get_desc = tpm_atmel_twi_get_desc,
136 };
137 
138 U_BOOT_DRIVER(tpm_atmel_twi) = {
139 	.name = "tpm_atmel_twi",
140 	.id = UCLASS_TPM,
141 	.of_match = tpm_atmel_twi_ids,
142 	.ops = &tpm_atmel_twi_ops,
143 	.probe = tpm_atmel_twi_probe,
144 };
145