char/tpm/tpm_tis_spi_main.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * Copyright (C) 2015 Infineon Technologies AG
0004  * Copyright (C) 2016 STMicroelectronics SAS
0005  *
0006  * Authors:
0007  * Peter Huewe <peter.huewe@infineon.com>
0008  * Christophe Ricard <christophe-h.ricard@st.com>
0009  *
0010  * Maintained by: <tpmdd-devel@lists.sourceforge.net>
0011  *
0012  * Device driver for TCG/TCPA TPM (trusted platform module).
0013  * Specifications at www.trustedcomputinggroup.org
0014  *
0015  * This device driver implements the TPM interface as defined in
0016  * the TCG TPM Interface Spec version 1.3, revision 27 via _raw/native
0017  * SPI access_.
0018  *
0019  * It is based on the original tpm_tis device driver from Leendert van
0020  * Dorn and Kyleen Hall and Jarko Sakkinnen.
0021  */
0022
0023 #include <linux/acpi.h>
0024 #include <linux/completion.h>
0025 #include <linux/init.h>
0026 #include <linux/interrupt.h>
0027 #include <linux/kernel.h>
0028 #include <linux/module.h>
0029 #include <linux/slab.h>
0030
0031 #include <linux/of_device.h>
0032 #include <linux/spi/spi.h>
0033 #include <linux/tpm.h>
0034
0035 #include "tpm.h"
0036 #include "tpm_tis_core.h"
0037 #include "tpm_tis_spi.h"
0038
0039 #define MAX_SPI_FRAMESIZE 64
0040
0041 /*
0042  * TCG SPI flow control is documented in section 6.4 of the spec[1]. In short,
0043  * keep trying to read from the device until MISO goes high indicating the
0044  * wait state has ended.
0045  *
0046  * [1] https://trustedcomputinggroup.org/resource/pc-client-platform-tpm-profile-ptp-specification/
0047  */
0048 static int tpm_tis_spi_flow_control(struct tpm_tis_spi_phy *phy,
0049                     struct spi_transfer *spi_xfer)
0050 {
0051     struct spi_message m;
0052     int ret, i;
0053
0054     if ((phy->iobuf[3] & 0x01) == 0) {
0055         // handle SPI wait states
0056         for (i = 0; i < TPM_RETRY; i++) {
0057             spi_xfer->len = 1;
0058             spi_message_init(&m);
0059             spi_message_add_tail(spi_xfer, &m);
0060             ret = spi_sync_locked(phy->spi_device, &m);
0061             if (ret < 0)
0062                 return ret;
0063             if (phy->iobuf[0] & 0x01)
0064                 break;
0065         }
0066
0067         if (i == TPM_RETRY)
0068             return -ETIMEDOUT;
0069     }
0070
0071     return 0;
0072 }
0073
0074 int tpm_tis_spi_transfer(struct tpm_tis_data *data, u32 addr, u16 len,
0075              u8 *in, const u8 *out)
0076 {
0077     struct tpm_tis_spi_phy *phy = to_tpm_tis_spi_phy(data);
0078     int ret = 0;
0079     struct spi_message m;
0080     struct spi_transfer spi_xfer;
0081     u8 transfer_len;
0082
0083     spi_bus_lock(phy->spi_device->master);
0084
0085     while (len) {
0086         transfer_len = min_t(u16, len, MAX_SPI_FRAMESIZE);
0087
0088         phy->iobuf[0] = (in ? 0x80 : 0) | (transfer_len - 1);
0089         phy->iobuf[1] = 0xd4;
0090         phy->iobuf[2] = addr >> 8;
0091         phy->iobuf[3] = addr;
0092
0093         memset(&spi_xfer, 0, sizeof(spi_xfer));
0094         spi_xfer.tx_buf = phy->iobuf;
0095         spi_xfer.rx_buf = phy->iobuf;
0096         spi_xfer.len = 4;
0097         spi_xfer.cs_change = 1;
0098
0099         spi_message_init(&m);
0100         spi_message_add_tail(&spi_xfer, &m);
0101         ret = spi_sync_locked(phy->spi_device, &m);
0102         if (ret < 0)
0103             goto exit;
0104
0105         /* Flow control transfers are receive only */
0106         spi_xfer.tx_buf = NULL;
0107         ret = phy->flow_control(phy, &spi_xfer);
0108         if (ret < 0)
0109             goto exit;
0110
0111         spi_xfer.cs_change = 0;
0112         spi_xfer.len = transfer_len;
0113         spi_xfer.delay.value = 5;
0114         spi_xfer.delay.unit = SPI_DELAY_UNIT_USECS;
0115
0116         if (out) {
0117             spi_xfer.tx_buf = phy->iobuf;
0118             spi_xfer.rx_buf = NULL;
0119             memcpy(phy->iobuf, out, transfer_len);
0120             out += transfer_len;
0121         }
0122
0123         spi_message_init(&m);
0124         spi_message_add_tail(&spi_xfer, &m);
0125         reinit_completion(&phy->ready);
0126         ret = spi_sync_locked(phy->spi_device, &m);
0127         if (ret < 0)
0128             goto exit;
0129
0130         if (in) {
0131             memcpy(in, phy->iobuf, transfer_len);
0132             in += transfer_len;
0133         }
0134
0135         len -= transfer_len;
0136     }
0137
0138 exit:
0139     spi_bus_unlock(phy->spi_device->master);
0140     return ret;
0141 }
0142
0143 static int tpm_tis_spi_read_bytes(struct tpm_tis_data *data, u32 addr,
0144                   u16 len, u8 *result, enum tpm_tis_io_mode io_mode)
0145 {
0146     return tpm_tis_spi_transfer(data, addr, len, result, NULL);
0147 }
0148
0149 static int tpm_tis_spi_write_bytes(struct tpm_tis_data *data, u32 addr,
0150                    u16 len, const u8 *value, enum tpm_tis_io_mode io_mode)
0151 {
0152     return tpm_tis_spi_transfer(data, addr, len, NULL, value);
0153 }
0154
0155 int tpm_tis_spi_init(struct spi_device *spi, struct tpm_tis_spi_phy *phy,
0156              int irq, const struct tpm_tis_phy_ops *phy_ops)
0157 {
0158     phy->iobuf = devm_kmalloc(&spi->dev, MAX_SPI_FRAMESIZE, GFP_KERNEL);
0159     if (!phy->iobuf)
0160         return -ENOMEM;
0161
0162     phy->spi_device = spi;
0163
0164     return tpm_tis_core_init(&spi->dev, &phy->priv, irq, phy_ops, NULL);
0165 }
0166
0167 static const struct tpm_tis_phy_ops tpm_spi_phy_ops = {
0168     .read_bytes = tpm_tis_spi_read_bytes,
0169     .write_bytes = tpm_tis_spi_write_bytes,
0170 };
0171
0172 static int tpm_tis_spi_probe(struct spi_device *dev)
0173 {
0174     struct tpm_tis_spi_phy *phy;
0175     int irq;
0176
0177     phy = devm_kzalloc(&dev->dev, sizeof(struct tpm_tis_spi_phy),
0178                GFP_KERNEL);
0179     if (!phy)
0180         return -ENOMEM;
0181
0182     phy->flow_control = tpm_tis_spi_flow_control;
0183
0184     /* If the SPI device has an IRQ then use that */
0185     if (dev->irq > 0)
0186         irq = dev->irq;
0187     else
0188         irq = -1;
0189
0190     init_completion(&phy->ready);
0191     return tpm_tis_spi_init(dev, phy, irq, &tpm_spi_phy_ops);
0192 }
0193
0194 typedef int (*tpm_tis_spi_probe_func)(struct spi_device *);
0195
0196 static int tpm_tis_spi_driver_probe(struct spi_device *spi)
0197 {
0198     const struct spi_device_id *spi_dev_id = spi_get_device_id(spi);
0199     tpm_tis_spi_probe_func probe_func;
0200
0201     probe_func = of_device_get_match_data(&spi->dev);
0202     if (!probe_func) {
0203         if (spi_dev_id) {
0204             probe_func = (tpm_tis_spi_probe_func)spi_dev_id->driver_data;
0205             if (!probe_func)
0206                 return -ENODEV;
0207         } else
0208             probe_func = tpm_tis_spi_probe;
0209     }
0210
0211     return probe_func(spi);
0212 }
0213
0214 static SIMPLE_DEV_PM_OPS(tpm_tis_pm, tpm_pm_suspend, tpm_tis_spi_resume);
0215
0216 static void tpm_tis_spi_remove(struct spi_device *dev)
0217 {
0218     struct tpm_chip *chip = spi_get_drvdata(dev);
0219
0220     tpm_chip_unregister(chip);
0221     tpm_tis_remove(chip);
0222 }
0223
0224 static const struct spi_device_id tpm_tis_spi_id[] = {
0225     { "st33htpm-spi", (unsigned long)tpm_tis_spi_probe },
0226     { "slb9670", (unsigned long)tpm_tis_spi_probe },
0227     { "tpm_tis_spi", (unsigned long)tpm_tis_spi_probe },
0228     { "tpm_tis-spi", (unsigned long)tpm_tis_spi_probe },
0229     { "cr50", (unsigned long)cr50_spi_probe },
0230     {}
0231 };
0232 MODULE_DEVICE_TABLE(spi, tpm_tis_spi_id);
0233
0234 static const struct of_device_id of_tis_spi_match[] = {
0235     { .compatible = "st,st33htpm-spi", .data = tpm_tis_spi_probe },
0236     { .compatible = "infineon,slb9670", .data = tpm_tis_spi_probe },
0237     { .compatible = "tcg,tpm_tis-spi", .data = tpm_tis_spi_probe },
0238     { .compatible = "google,cr50", .data = cr50_spi_probe },
0239     {}
0240 };
0241 MODULE_DEVICE_TABLE(of, of_tis_spi_match);
0242
0243 static const struct acpi_device_id acpi_tis_spi_match[] = {
0244     {"SMO0768", 0},
0245     {}
0246 };
0247 MODULE_DEVICE_TABLE(acpi, acpi_tis_spi_match);
0248
0249 static struct spi_driver tpm_tis_spi_driver = {
0250     .driver = {
0251         .name = "tpm_tis_spi",
0252         .pm = &tpm_tis_pm,
0253         .of_match_table = of_match_ptr(of_tis_spi_match),
0254         .acpi_match_table = ACPI_PTR(acpi_tis_spi_match),
0255         .probe_type = PROBE_PREFER_ASYNCHRONOUS,
0256     },
0257     .probe = tpm_tis_spi_driver_probe,
0258     .remove = tpm_tis_spi_remove,
0259     .id_table = tpm_tis_spi_id,
0260 };
0261 module_spi_driver(tpm_tis_spi_driver);
0262
0263 MODULE_DESCRIPTION("TPM Driver for native SPI access");
0264 MODULE_LICENSE("GPL");