drivers/tpm/tis_i2c.c

   1 /*
   2  * Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
   3  * Use of this source code is governed by a BSD-style license that can be
   4  * found in the LICENSE file.
   5  */
   6
   7 #include <config.h>
   8 #include <common.h>
   9 #include <fdtdec.h>
  10 #include <i2c.h>
  11 #include "slb9635_i2c/tpm.h"
  12
  13 DECLARE_GLOBAL_DATA_PTR;
  14
  15 /* TPM configuration */
  16 struct tpm {
  17         int i2c_bus;
  18         int slave_addr;
  19         char inited;
  20         int old_bus;
  21 } tpm;
  22
  23
  24 static int tpm_select(void)
  25 {
  26         int ret;
  27
  28         tpm.old_bus = i2c_get_bus_num();
  29         if (tpm.old_bus != tpm.i2c_bus) {
  30                 ret = i2c_set_bus_num(tpm.i2c_bus);
  31                 if (ret) {
  32                         debug("%s: Fail to set i2c bus %d\n", __func__,
  33                               tpm.i2c_bus);
  34                         return -1;
  35                 }
  36         }
  37         return 0;
  38 }
  39
  40 static int tpm_deselect(void)
  41 {
  42         int ret;
  43
  44         if (tpm.old_bus != i2c_get_bus_num()) {
  45                 ret = i2c_set_bus_num(tpm.old_bus);
  46                 if (ret) {
  47                         debug("%s: Fail to restore i2c bus %d\n",
  48                               __func__, tpm.old_bus);
  49                         return -1;
  50                 }
  51         }
  52         tpm.old_bus = -1;
  53         return 0;
  54 }
  55
  56 /**
  57  * Decode TPM configuration.
  58  *
  59  * @param dev   Returns a configuration of TPM device
  60  * @return 0 if ok, -1 on error
  61  */
  62 static int tpm_decode_config(struct tpm *dev)
  63 {
  64 #ifdef CONFIG_OF_CONTROL
  65         const void *blob = gd->fdt_blob;
  66         int node, parent;
  67         int i2c_bus;
  68
  69         node = fdtdec_next_compatible(blob, 0, COMPAT_INFINEON_SLB9635_TPM);
  70         if (node < 0) {
  71                 node = fdtdec_next_compatible(blob, 0,
  72                                               COMPAT_INFINEON_SLB9645_TPM);
  73         }
  74         if (node < 0) {
  75                 debug("%s: Node not found\n", __func__);
  76                 return -1;
  77         }
  78         parent = fdt_parent_offset(blob, node);
  79         if (parent < 0) {
  80                 debug("%s: Cannot find node parent\n", __func__);
  81                 return -1;
  82         }
  83         i2c_bus = i2c_get_bus_num_fdt(parent);
  84         if (i2c_bus < 0)
  85                 return -1;
  86         dev->i2c_bus = i2c_bus;
  87         dev->slave_addr = fdtdec_get_addr(blob, node, "reg");
  88 #else
  89         dev->i2c_bus = CONFIG_INFINEON_TPM_I2C_BUS;
  90         dev->slave_addr = CONFIG_INFINEON_TPM_I2C_ADDR;
  91 #endif
  92         return 0;
  93 }
  94
  95 int tis_init(void)
  96 {
  97         if (tpm.inited)
  98                 return 0;
  99
 100         if (tpm_decode_config(&tpm))
 101                 return -1;
 102
 103         if (tpm_select())
 104                 return -1;
 105
 106         /*
 107          * Probe TPM twice; the first probing might fail because TPM is asleep,
 108          * and the probing can wake up TPM.
 109          */
 110         if (i2c_probe(tpm.slave_addr) && i2c_probe(tpm.slave_addr)) {
 111                 debug("%s: fail to probe i2c addr 0x%x\n", __func__,
 112                       tpm.slave_addr);
 113                 return -1;
 114         }
 115
 116         tpm_deselect();
 117
 118         tpm.inited = 1;
 119
 120         return 0;
 121 }
 122
 123 int tis_open(void)
 124 {
 125         int rc;
 126
 127         if (!tpm.inited)
 128                 return -1;
 129
 130         if (tpm_select())
 131                 return -1;
 132
 133         rc = tpm_open(tpm.slave_addr);
 134
 135         tpm_deselect();
 136
 137         return rc;
 138 }
 139
 140 int tis_close(void)
 141 {
 142         if (!tpm.inited)
 143                 return -1;
 144
 145         if (tpm_select())
 146                 return -1;
 147
 148         tpm_close();
 149
 150         tpm_deselect();
 151
 152         return 0;
 153 }
 154
 155 int tis_sendrecv(const uint8_t *sendbuf, size_t sbuf_size,
 156                 uint8_t *recvbuf, size_t *rbuf_len)
 157 {
 158         int len;
 159         uint8_t buf[4096];
 160
 161         if (!tpm.inited)
 162                 return -1;
 163
 164         if (sizeof(buf) < sbuf_size)
 165                 return -1;
 166
 167         memcpy(buf, sendbuf, sbuf_size);
 168
 169         if (tpm_select())
 170                 return -1;
 171
 172         len = tpm_transmit(buf, sbuf_size);
 173
 174         tpm_deselect();
 175
 176         if (len < 10) {
 177                 *rbuf_len = 0;
 178                 return -1;
 179         }
 180
 181         memcpy(recvbuf, buf, len);
 182         *rbuf_len = len;
 183
 184         return 0;
 185 }