drivers/char/tpm/tpm_tis_spi_main.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2015 Infineon Technologies AG
   4  * Copyright (C) 2016 STMicroelectronics SAS
   5  *
   6  * Authors:
   7  * Peter Huewe <peter.huewe@infineon.com>
   8  * Christophe Ricard <christophe-h.ricard@st.com>
   9  *
  10  * Maintained by: <tpmdd-devel@lists.sourceforge.net>
  11  *
  12  * Device driver for TCG/TCPA TPM (trusted platform module).
  13  * Specifications at www.trustedcomputinggroup.org
  14  *
  15  * This device driver implements the TPM interface as defined in
  16  * the TCG TPM Interface Spec version 1.3, revision 27 via _raw/native
  17  * SPI access_.
  18  *
  19  * It is based on the original tpm_tis device driver from Leendert van
  20  * Dorn and Kyleen Hall and Jarko Sakkinnen.
  21  */
  22
  23 #include <linux/acpi.h>
  24 #include <linux/completion.h>
  25 #include <linux/init.h>
  26 #include <linux/interrupt.h>
  27 #include <linux/kernel.h>
  28 #include <linux/module.h>
  29 #include <linux/slab.h>
  30
  31 #include <linux/of_device.h>
  32 #include <linux/spi/spi.h>
  33 #include <linux/tpm.h>
  34
  35 #include "tpm.h"
  36 #include "tpm_tis_core.h"
  37 #include "tpm_tis_spi.h"
  38
  39 #define MAX_SPI_FRAMESIZE 64
  40
  41 /*
  42  * TCG SPI flow control is documented in section 6.4 of the spec[1]. In short,
  43  * keep trying to read from the device until MISO goes high indicating the
  44  * wait state has ended.
  45  *
  46  * [1] https://trustedcomputinggroup.org/resource/pc-client-platform-tpm-profile-ptp-specification/
  47  */
  48 static int tpm_tis_spi_flow_control(struct tpm_tis_spi_phy *phy,
  49                                     struct spi_transfer *spi_xfer)
  50 {
  51         struct spi_message m;
  52         int ret, i;
  53
  54         if ((phy->iobuf[3] & 0x01) == 0) {
  55                 // handle SPI wait states
  56                 for (i = 0; i < TPM_RETRY; i++) {
  57                         spi_xfer->len = 1;
  58                         spi_message_init(&m);
  59                         spi_message_add_tail(spi_xfer, &m);
  60                         ret = spi_sync_locked(phy->spi_device, &m);
  61                         if (ret < 0)
  62                                 return ret;
  63                         if (phy->iobuf[0] & 0x01)
  64                                 break;
  65                 }
  66
  67                 if (i == TPM_RETRY)
  68                         return -ETIMEDOUT;
  69         }
  70
  71         return 0;
  72 }
  73
  74 int tpm_tis_spi_transfer(struct tpm_tis_data *data, u32 addr, u16 len,
  75                          u8 *in, const u8 *out)
  76 {
  77         struct tpm_tis_spi_phy *phy = to_tpm_tis_spi_phy(data);
  78         int ret = 0;
  79         struct spi_message m;
  80         struct spi_transfer spi_xfer;
  81         u8 transfer_len;
  82
  83         spi_bus_lock(phy->spi_device->master);
  84
  85         while (len) {
  86                 transfer_len = min_t(u16, len, MAX_SPI_FRAMESIZE);
  87
  88                 phy->iobuf[0] = (in ? 0x80 : 0) | (transfer_len - 1);
  89                 phy->iobuf[1] = 0xd4;
  90                 phy->iobuf[2] = addr >> 8;
  91                 phy->iobuf[3] = addr;
  92
  93                 memset(&spi_xfer, 0, sizeof(spi_xfer));
  94                 spi_xfer.tx_buf = phy->iobuf;
  95                 spi_xfer.rx_buf = phy->iobuf;
  96                 spi_xfer.len = 4;
  97                 spi_xfer.cs_change = 1;
  98
  99                 spi_message_init(&m);
 100                 spi_message_add_tail(&spi_xfer, &m);
 101                 ret = spi_sync_locked(phy->spi_device, &m);
 102                 if (ret < 0)
 103                         goto exit;
 104
 105                 /* Flow control transfers are receive only */
 106                 spi_xfer.tx_buf = NULL;
 107                 ret = phy->flow_control(phy, &spi_xfer);
 108                 if (ret < 0)
 109                         goto exit;
 110
 111                 spi_xfer.cs_change = 0;
 112                 spi_xfer.len = transfer_len;
 113                 spi_xfer.delay.value = 5;
 114                 spi_xfer.delay.unit = SPI_DELAY_UNIT_USECS;
 115
 116                 if (out) {
 117                         spi_xfer.tx_buf = phy->iobuf;
 118                         spi_xfer.rx_buf = NULL;
 119                         memcpy(phy->iobuf, out, transfer_len);
 120                         out += transfer_len;
 121                 }
 122
 123                 spi_message_init(&m);
 124                 spi_message_add_tail(&spi_xfer, &m);
 125                 reinit_completion(&phy->ready);
 126                 ret = spi_sync_locked(phy->spi_device, &m);
 127                 if (ret < 0)
 128                         goto exit;
 129
 130                 if (in) {
 131                         memcpy(in, phy->iobuf, transfer_len);
 132                         in += transfer_len;
 133                 }
 134
 135                 len -= transfer_len;
 136         }
 137
 138 exit:
 139         spi_bus_unlock(phy->spi_device->master);
 140         return ret;
 141 }
 142
 143 static int tpm_tis_spi_read_bytes(struct tpm_tis_data *data, u32 addr,
 144                                   u16 len, u8 *result, enum tpm_tis_io_mode io_mode)
 145 {
 146         return tpm_tis_spi_transfer(data, addr, len, result, NULL);
 147 }
 148
 149 static int tpm_tis_spi_write_bytes(struct tpm_tis_data *data, u32 addr,
 150                                    u16 len, const u8 *value, enum tpm_tis_io_mode io_mode)
 151 {
 152         return tpm_tis_spi_transfer(data, addr, len, NULL, value);
 153 }
 154
 155 int tpm_tis_spi_init(struct spi_device *spi, struct tpm_tis_spi_phy *phy,
 156                      int irq, const struct tpm_tis_phy_ops *phy_ops)
 157 {
 158         phy->iobuf = devm_kmalloc(&spi->dev, MAX_SPI_FRAMESIZE, GFP_KERNEL);
 159         if (!phy->iobuf)
 160                 return -ENOMEM;
 161
 162         phy->spi_device = spi;
 163
 164         return tpm_tis_core_init(&spi->dev, &phy->priv, irq, phy_ops, NULL);
 165 }
 166
 167 static const struct tpm_tis_phy_ops tpm_spi_phy_ops = {
 168         .read_bytes = tpm_tis_spi_read_bytes,
 169         .write_bytes = tpm_tis_spi_write_bytes,
 170 };
 171
 172 static int tpm_tis_spi_probe(struct spi_device *dev)
 173 {
 174         struct tpm_tis_spi_phy *phy;
 175         int irq;
 176
 177         phy = devm_kzalloc(&dev->dev, sizeof(struct tpm_tis_spi_phy),
 178                            GFP_KERNEL);
 179         if (!phy)
 180                 return -ENOMEM;
 181
 182         phy->flow_control = tpm_tis_spi_flow_control;
 183
 184         /* If the SPI device has an IRQ then use that */
 185         if (dev->irq > 0)
 186                 irq = dev->irq;
 187         else
 188                 irq = -1;
 189
 190         init_completion(&phy->ready);
 191         return tpm_tis_spi_init(dev, phy, irq, &tpm_spi_phy_ops);
 192 }
 193
 194 typedef int (*tpm_tis_spi_probe_func)(struct spi_device *);
 195
 196 static int tpm_tis_spi_driver_probe(struct spi_device *spi)
 197 {
 198         const struct spi_device_id *spi_dev_id = spi_get_device_id(spi);
 199         tpm_tis_spi_probe_func probe_func;
 200
 201         probe_func = of_device_get_match_data(&spi->dev);
 202         if (!probe_func) {
 203                 if (spi_dev_id) {
 204                         probe_func = (tpm_tis_spi_probe_func)spi_dev_id->driver_data;
 205                         if (!probe_func)
 206                                 return -ENODEV;
 207                 } else
 208                         probe_func = tpm_tis_spi_probe;
 209         }
 210
 211         return probe_func(spi);
 212 }
 213
 214 static SIMPLE_DEV_PM_OPS(tpm_tis_pm, tpm_pm_suspend, tpm_tis_spi_resume);
 215
 216 static void tpm_tis_spi_remove(struct spi_device *dev)
 217 {
 218         struct tpm_chip *chip = spi_get_drvdata(dev);
 219
 220         tpm_chip_unregister(chip);
 221         tpm_tis_remove(chip);
 222 }
 223
 224 static const struct spi_device_id tpm_tis_spi_id[] = {
 225         { "st33htpm-spi", (unsigned long)tpm_tis_spi_probe },
 226         { "slb9670", (unsigned long)tpm_tis_spi_probe },
 227         { "tpm_tis_spi", (unsigned long)tpm_tis_spi_probe },
 228         { "tpm_tis-spi", (unsigned long)tpm_tis_spi_probe },
 229         { "cr50", (unsigned long)cr50_spi_probe },
 230         {}
 231 };
 232 MODULE_DEVICE_TABLE(spi, tpm_tis_spi_id);
 233
 234 static const struct of_device_id of_tis_spi_match[] = {
 235         { .compatible = "st,st33htpm-spi", .data = tpm_tis_spi_probe },
 236         { .compatible = "infineon,slb9670", .data = tpm_tis_spi_probe },
 237         { .compatible = "tcg,tpm_tis-spi", .data = tpm_tis_spi_probe },
 238         { .compatible = "google,cr50", .data = cr50_spi_probe },
 239         {}
 240 };
 241 MODULE_DEVICE_TABLE(of, of_tis_spi_match);
 242
 243 static const struct acpi_device_id acpi_tis_spi_match[] = {
 244         {"SMO0768", 0},
 245         {}
 246 };
 247 MODULE_DEVICE_TABLE(acpi, acpi_tis_spi_match);
 248
 249 static struct spi_driver tpm_tis_spi_driver = {
 250         .driver = {
 251                 .name = "tpm_tis_spi",
 252                 .pm = &tpm_tis_pm,
 253                 .of_match_table = of_match_ptr(of_tis_spi_match),
 254                 .acpi_match_table = ACPI_PTR(acpi_tis_spi_match),
 255                 .probe_type = PROBE_PREFER_ASYNCHRONOUS,
 256         },
 257         .probe = tpm_tis_spi_driver_probe,
 258         .remove = tpm_tis_spi_remove,
 259         .id_table = tpm_tis_spi_id,
 260 };
 261 module_spi_driver(tpm_tis_spi_driver);
 262
 263 MODULE_DESCRIPTION("TPM Driver for native SPI access");
 264 MODULE_LICENSE("GPL");