/* * Copyright (C) 2012,2013 Infineon Technologies * * Authors: * Peter Huewe * * Device driver for TCG/TCPA TPM (trusted platform module). * Specifications at www.trustedcomputinggroup.org * * This device driver implements the TPM interface as defined in * the TCG TPM Interface Spec version 1.2, revision 1.0 and the * Infineon I2C Protocol Stack Specification v0.20. * * It is based on the original tpm_tis device driver from Leendert van * Dorn and Kyleen Hall. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License as * published by the Free Software Foundation, version 2 of the * License. * * */ #include #include #include #include "tpm.h" /* max. buffer size supported by our TPM */ #define TPM_BUFSIZE 1260 /* max. number of iterations after I2C NAK */ #define MAX_COUNT 3 #define SLEEP_DURATION_LOW 55 #define SLEEP_DURATION_HI 65 /* max. number of iterations after I2C NAK for 'long' commands * we need this especially for sending TPM_READY, since the cleanup after the * transtion to the ready state may take some time, but it is unpredictable * how long it will take. */ #define MAX_COUNT_LONG 50 #define SLEEP_DURATION_LONG_LOW 200 #define SLEEP_DURATION_LONG_HI 220 /* After sending TPM_READY to 'reset' the TPM we have to sleep even longer */ #define SLEEP_DURATION_RESET_LOW 2400 #define SLEEP_DURATION_RESET_HI 2600 /* we want to use usleep_range instead of msleep for the 5ms TPM_TIMEOUT */ #define TPM_TIMEOUT_US_LOW (TPM_TIMEOUT * 1000) #define TPM_TIMEOUT_US_HI (TPM_TIMEOUT_US_LOW + 2000) /* expected value for DIDVID register */ #define TPM_TIS_I2C_DID_VID_9635 0xd1150b00L #define TPM_TIS_I2C_DID_VID_9645 0x001a15d1L enum i2c_chip_type { SLB9635, SLB9645, UNKNOWN, }; /* Structure to store I2C TPM specific stuff */ struct tpm_inf_dev { struct i2c_client *client; u8 buf[TPM_BUFSIZE + sizeof(u8)]; /* max. buffer size + addr */ struct tpm_chip *chip; enum i2c_chip_type chip_type; }; static struct tpm_inf_dev tpm_dev; /* * iic_tpm_read() - read from TPM register * @addr: register address to read from * @buffer: provided by caller * @len: number of bytes to read * * Read len bytes from TPM register and put them into * buffer (little-endian format, i.e. first byte is put into buffer[0]). * * NOTE: TPM is big-endian for multi-byte values. Multi-byte * values have to be swapped. * * NOTE: We can't unfortunately use the combined read/write functions * provided by the i2c core as the TPM currently does not support the * repeated start condition and due to it's special requirements. * The i2c_smbus* functions do not work for this chip. * * Return -EIO on error, 0 on success. */ static int iic_tpm_read(u8 addr, u8 *buffer, size_t len) { struct i2c_msg msg1 = { .addr = tpm_dev.client->addr, .len = 1, .buf = &addr }; struct i2c_msg msg2 = { .addr = tpm_dev.client->addr, .flags = I2C_M_RD, .len = len, .buf = buffer }; struct i2c_msg msgs[] = {msg1, msg2}; int rc = 0; int count; /* Lock the adapter for the duration of the whole sequence. */ if (!tpm_dev.client->adapter->algo->master_xfer) return -EOPNOTSUPP; i2c_lock_adapter(tpm_dev.client->adapter); if (tpm_dev.chip_type == SLB9645) { /* use a combined read for newer chips * unfortunately the smbus functions are not suitable due to * the 32 byte limit of the smbus. * retries should usually not be needed, but are kept just to * be on the safe side. */ for (count = 0; count < MAX_COUNT; count++) { rc = __i2c_transfer(tpm_dev.client->adapter, msgs, 2); if (rc > 0) break; /* break here to skip sleep */ usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI); } } else { /* slb9635 protocol should work in all cases */ for (count = 0; count < MAX_COUNT; count++) { rc = __i2c_transfer(tpm_dev.client->adapter, &msg1, 1); if (rc > 0) break; /* break here to skip sleep */ usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI); } if (rc <= 0) goto out; /* After the TPM has successfully received the register address * it needs some time, thus we're sleeping here again, before * retrieving the data */ for (count = 0; count < MAX_COUNT; count++) { usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI); rc = __i2c_transfer(tpm_dev.client->adapter, &msg2, 1); if (rc > 0) break; } } out: i2c_unlock_adapter(tpm_dev.client->adapter); /* take care of 'guard time' */ usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI); /* __i2c_transfer returns the number of successfully transferred * messages. * So rc should be greater than 0 here otherwise we have an error. */ if (rc <= 0) return -EIO; return 0; } static int iic_tpm_write_generic(u8 addr, u8 *buffer, size_t len, unsigned int sleep_low, unsigned int sleep_hi, u8 max_count) { int rc = -EIO; int count; struct i2c_msg msg1 = { .addr = tpm_dev.client->addr, .len = len + 1, .buf = tpm_dev.buf }; if (len > TPM_BUFSIZE) return -EINVAL; if (!tpm_dev.client->adapter->algo->master_xfer) return -EOPNOTSUPP; i2c_lock_adapter(tpm_dev.client->adapter); /* prepend the 'register address' to the buffer */ tpm_dev.buf[0] = addr; memcpy(&(tpm_dev.buf[1]), buffer, len); /* * NOTE: We have to use these special mechanisms here and unfortunately * cannot rely on the standard behavior of i2c_transfer. * Even for newer chips the smbus functions are not * suitable due to the 32 byte limit of the smbus. */ for (count = 0; count < max_count; count++) { rc = __i2c_transfer(tpm_dev.client->adapter, &msg1, 1); if (rc > 0) break; usleep_range(sleep_low, sleep_hi); } i2c_unlock_adapter(tpm_dev.client->adapter); /* take care of 'guard time' */ usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI); /* __i2c_transfer returns the number of successfully transferred * messages. * So rc should be greater than 0 here otherwise we have an error. */ if (rc <= 0) return -EIO; return 0; } /* * iic_tpm_write() - write to TPM register * @addr: register address to write to * @buffer: containing data to be written * @len: number of bytes to write * * Write len bytes from provided buffer to TPM register (little * endian format, i.e. buffer[0] is written as first byte). * * NOTE: TPM is big-endian for multi-byte values. Multi-byte * values have to be swapped. * * NOTE: use this function instead of the iic_tpm_write_generic function. * * Return -EIO on error, 0 on success */ static int iic_tpm_write(u8 addr, u8 *buffer, size_t len) { return iic_tpm_write_generic(addr, buffer, len, SLEEP_DURATION_LOW, SLEEP_DURATION_HI, MAX_COUNT); } /* * This function is needed especially for the cleanup situation after * sending TPM_READY * */ static int iic_tpm_write_long(u8 addr, u8 *buffer, size_t len) { return iic_tpm_write_generic(addr, buffer, len, SLEEP_DURATION_LONG_LOW, SLEEP_DURATION_LONG_HI, MAX_COUNT_LONG); } enum tis_access { TPM_ACCESS_VALID = 0x80, TPM_ACCESS_ACTIVE_LOCALITY = 0x20, TPM_ACCESS_REQUEST_PENDING = 0x04, TPM_ACCESS_REQUEST_USE = 0x02, }; enum tis_status { TPM_STS_VALID = 0x80, TPM_STS_COMMAND_READY = 0x40, TPM_STS_GO = 0x20, TPM_STS_DATA_AVAIL = 0x10, TPM_STS_DATA_EXPECT = 0x08, }; enum tis_defaults { TIS_SHORT_TIMEOUT = 750, /* ms */ TIS_LONG_TIMEOUT = 2000, /* 2 sec */ }; #define TPM_ACCESS(l) (0x0000 | ((l) << 4)) #define TPM_STS(l) (0x0001 | ((l) << 4)) #define TPM_DATA_FIFO(l) (0x0005 | ((l) << 4)) #define TPM_DID_VID(l) (0x0006 | ((l) << 4)) static int check_locality(struct tpm_chip *chip, int loc) { u8 buf; int rc; rc = iic_tpm_read(TPM_ACCESS(loc), &buf, 1); if (rc < 0) return rc; if ((buf & (TPM_ACCESS_ACTIVE_LOCALITY | TPM_ACCESS_VALID)) == (TPM_ACCESS_ACTIVE_LOCALITY | TPM_ACCESS_VALID)) { chip->vendor.locality = loc; return loc; } return -EIO; } /* implementation similar to tpm_tis */ static void release_locality(struct tpm_chip *chip, int loc, int force) { u8 buf; if (iic_tpm_read(TPM_ACCESS(loc), &buf, 1) < 0) return; if (force || (buf & (TPM_ACCESS_REQUEST_PENDING | TPM_ACCESS_VALID)) == (TPM_ACCESS_REQUEST_PENDING | TPM_ACCESS_VALID)) { buf = TPM_ACCESS_ACTIVE_LOCALITY; iic_tpm_write(TPM_ACCESS(loc), &buf, 1); } } static int request_locality(struct tpm_chip *chip, int loc) { unsigned long stop; u8 buf = TPM_ACCESS_REQUEST_USE; if (check_locality(chip, loc) >= 0) return loc; iic_tpm_write(TPM_ACCESS(loc), &buf, 1); /* wait for burstcount */ stop = jiffies + chip->vendor.timeout_a; do { if (check_locality(chip, loc) >= 0) return loc; usleep_range(TPM_TIMEOUT_US_LOW, TPM_TIMEOUT_US_HI); } while (time_before(jiffies, stop)); return -ETIME; } static u8 tpm_tis_i2c_status(struct tpm_chip *chip) { /* NOTE: since I2C read may fail, return 0 in this case --> time-out */ u8 buf = 0xFF; u8 i = 0; do { if (iic_tpm_read(TPM_STS(chip->vendor.locality), &buf, 1) < 0) return 0; i++; /* if locallity is set STS should not be 0xFF */ } while ((buf == 0xFF) && i < 10); return buf; } static void tpm_tis_i2c_ready(struct tpm_chip *chip) { /* this causes the current command to be aborted */ u8 buf = TPM_STS_COMMAND_READY; iic_tpm_write_long(TPM_STS(chip->vendor.locality), &buf, 1); } static ssize_t get_burstcount(struct tpm_chip *chip) { unsigned long stop; ssize_t burstcnt; u8 buf[3]; /* wait for burstcount */ /* which timeout value, spec has 2 answers (c & d) */ stop = jiffies + chip->vendor.timeout_d; do { /* Note: STS is little endian */ if (iic_tpm_read(TPM_STS(chip->vendor.locality)+1, buf, 3) < 0) burstcnt = 0; else burstcnt = (buf[2] << 16) + (buf[1] << 8) + buf[0]; if (burstcnt) return burstcnt; usleep_range(TPM_TIMEOUT_US_LOW, TPM_TIMEOUT_US_HI); } while (time_before(jiffies, stop)); return -EBUSY; } static int wait_for_stat(struct tpm_chip *chip, u8 mask, unsigned long timeout, int *status) { unsigned long stop; /* check current status */ *status = tpm_tis_i2c_status(chip); if ((*status != 0xFF) && (*status & mask) == mask) return 0; stop = jiffies + timeout; do { /* since we just checked the status, give the TPM some time */ usleep_range(TPM_TIMEOUT_US_LOW, TPM_TIMEOUT_US_HI); *status = tpm_tis_i2c_status(chip); if ((*status & mask) == mask) return 0; } while (time_before(jiffies, stop)); return -ETIME; } static int recv_data(struct tpm_chip *chip, u8 *buf, size_t count) { size_t size = 0; ssize_t burstcnt; u8 retries = 0; int rc; while (size < count) { burstcnt = get_burstcount(chip); /* burstcnt < 0 = TPM is busy */ if (burstcnt < 0) return burstcnt; /* limit received data to max. left */ if (burstcnt > (count - size)) burstcnt = count - size; rc = iic_tpm_read(TPM_DATA_FIFO(chip->vendor.locality), &(buf[size]), burstcnt); if (rc == 0) size += burstcnt; else if (rc < 0) retries++; /* avoid endless loop in case of broken HW */ if (retries > MAX_COUNT_LONG) return -EIO; } return size; } static int tpm_tis_i2c_recv(struct tpm_chip *chip, u8 *buf, size_t count) { int size = 0; int expected, status; if (count < TPM_HEADER_SIZE) { size = -EIO; goto out; } /* read first 10 bytes, including tag, paramsize, and result */ size = recv_data(chip, buf, TPM_HEADER_SIZE); if (size < TPM_HEADER_SIZE) { dev_err(chip->pdev, "Unable to read header\n"); goto out; } expected = be32_to_cpu(*(__be32 *)(buf + 2)); if ((size_t) expected > count) { size = -EIO; goto out; } size += recv_data(chip, &buf[TPM_HEADER_SIZE], expected - TPM_HEADER_SIZE); if (size < expected) { dev_err(chip->pdev, "Unable to read remainder of result\n"); size = -ETIME; goto out; } wait_for_stat(chip, TPM_STS_VALID, chip->vendor.timeout_c, &status); if (status & TPM_STS_DATA_AVAIL) { /* retry? */ dev_err(chip->pdev, "Error left over data\n"); size = -EIO; goto out; } out: tpm_tis_i2c_ready(chip); /* The TPM needs some time to clean up here, * so we sleep rather than keeping the bus busy */ usleep_range(SLEEP_DURATION_RESET_LOW, SLEEP_DURATION_RESET_HI); release_locality(chip, chip->vendor.locality, 0); return size; } static int tpm_tis_i2c_send(struct tpm_chip *chip, u8 *buf, size_t len) { int rc, status; ssize_t burstcnt; size_t count = 0; u8 retries = 0; u8 sts = TPM_STS_GO; if (len > TPM_BUFSIZE) return -E2BIG; /* command is too long for our tpm, sorry */ if (request_locality(chip, 0) < 0) return -EBUSY; status = tpm_tis_i2c_status(chip); if ((status & TPM_STS_COMMAND_READY) == 0) { tpm_tis_i2c_ready(chip); if (wait_for_stat (chip, TPM_STS_COMMAND_READY, chip->vendor.timeout_b, &status) < 0) { rc = -ETIME; goto out_err; } } while (count < len - 1) { burstcnt = get_burstcount(chip); /* burstcnt < 0 = TPM is busy */ if (burstcnt < 0) return burstcnt; if (burstcnt > (len - 1 - count)) burstcnt = len - 1 - count; rc = iic_tpm_write(TPM_DATA_FIFO(chip->vendor.locality), &(buf[count]), burstcnt); if (rc == 0) count += burstcnt; else if (rc < 0) retries++; /* avoid endless loop in case of broken HW */ if (retries > MAX_COUNT_LONG) { rc = -EIO; goto out_err; } wait_for_stat(chip, TPM_STS_VALID, chip->vendor.timeout_c, &status); if ((status & TPM_STS_DATA_EXPECT) == 0) { rc = -EIO; goto out_err; } } /* write last byte */ iic_tpm_write(TPM_DATA_FIFO(chip->vendor.locality), &(buf[count]), 1); wait_for_stat(chip, TPM_STS_VALID, chip->vendor.timeout_c, &status); if ((status & TPM_STS_DATA_EXPECT) != 0) { rc = -EIO; goto out_err; } /* go and do it */ iic_tpm_write(TPM_STS(chip->vendor.locality), &sts, 1); return len; out_err: tpm_tis_i2c_ready(chip); /* The TPM needs some time to clean up here, * so we sleep rather than keeping the bus busy */ usleep_range(SLEEP_DURATION_RESET_LOW, SLEEP_DURATION_RESET_HI); release_locality(chip, chip->vendor.locality, 0); return rc; } static bool tpm_tis_i2c_req_canceled(struct tpm_chip *chip, u8 status) { return (status == TPM_STS_COMMAND_READY); } static const struct tpm_class_ops tpm_tis_i2c = { .status = tpm_tis_i2c_status, .recv = tpm_tis_i2c_recv, .send = tpm_tis_i2c_send, .cancel = tpm_tis_i2c_ready, .req_complete_mask = TPM_STS_DATA_AVAIL | TPM_STS_VALID, .req_complete_val = TPM_STS_DATA_AVAIL | TPM_STS_VALID, .req_canceled = tpm_tis_i2c_req_canceled, }; static int tpm_tis_i2c_init(struct device *dev) { u32 vendor; int rc = 0; struct tpm_chip *chip; chip = tpmm_chip_alloc(dev, &tpm_tis_i2c); if (IS_ERR(chip)) return PTR_ERR(chip); /* Disable interrupts */ chip->vendor.irq = 0; /* Default timeouts */ chip->vendor.timeout_a = msecs_to_jiffies(TIS_SHORT_TIMEOUT); chip->vendor.timeout_b = msecs_to_jiffies(TIS_LONG_TIMEOUT); chip->vendor.timeout_c = msecs_to_jiffies(TIS_SHORT_TIMEOUT); chip->vendor.timeout_d = msecs_to_jiffies(TIS_SHORT_TIMEOUT); if (request_locality(chip, 0) != 0) { dev_err(dev, "could not request locality\n"); rc = -ENODEV; goto out_err; } /* read four bytes from DID_VID register */ if (iic_tpm_read(TPM_DID_VID(0), (u8 *)&vendor, 4) < 0) { dev_err(dev, "could not read vendor id\n"); rc = -EIO; goto out_release; } if (vendor == TPM_TIS_I2C_DID_VID_9645) { tpm_dev.chip_type = SLB9645; } else if (vendor == TPM_TIS_I2C_DID_VID_9635) { tpm_dev.chip_type = SLB9635; } else { dev_err(dev, "vendor id did not match! ID was %08x\n", vendor); rc = -ENODEV; goto out_release; } dev_info(dev, "1.2 TPM (device-id 0x%X)\n", vendor >> 16); INIT_LIST_HEAD(&chip->vendor.list); tpm_dev.chip = chip; tpm_get_timeouts(chip); tpm_do_selftest(chip); return tpm_chip_register(chip); out_release: release_locality(chip, chip->vendor.locality, 1); tpm_dev.client = NULL; out_err: return rc; } static const struct i2c_device_id tpm_tis_i2c_table[] = { {"tpm_i2c_infineon", 0}, {"slb9635tt", 0}, {"slb9645tt", 1}, {}, }; MODULE_DEVICE_TABLE(i2c, tpm_tis_i2c_table); #ifdef CONFIG_OF static const struct of_device_id tpm_tis_i2c_of_match[] = { { .name = "tpm_i2c_infineon", .type = "tpm", .compatible = "infineon,tpm_i2c_infineon", .data = (void *)0 }, { .name = "slb9635tt", .type = "tpm", .compatible = "infineon,slb9635tt", .data = (void *)0 }, { .name = "slb9645tt", .type = "tpm", .compatible = "infineon,slb9645tt", .data = (void *)1 }, {}, }; MODULE_DEVICE_TABLE(of, tpm_tis_i2c_of_match); #endif static SIMPLE_DEV_PM_OPS(tpm_tis_i2c_ops, tpm_pm_suspend, tpm_pm_resume); static int tpm_tis_i2c_probe(struct i2c_client *client, const struct i2c_device_id *id) { int rc; struct device *dev = &(client->dev); if (tpm_dev.client != NULL) { dev_err(dev, "This driver only supports one client at a time\n"); return -EBUSY; /* We only support one client */ } if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) { dev_err(dev, "no algorithms associated to the i2c bus\n"); return -ENODEV; } tpm_dev.client = client; rc = tpm_tis_i2c_init(&client->dev); if (rc != 0) { tpm_dev.client = NULL; rc = -ENODEV; } return rc; } static int tpm_tis_i2c_remove(struct i2c_client *client) { struct tpm_chip *chip = tpm_dev.chip; tpm_chip_unregister(chip); release_locality(chip, chip->vendor.locality, 1); tpm_dev.client = NULL; return 0; } static struct i2c_driver tpm_tis_i2c_driver = { .id_table = tpm_tis_i2c_table, .probe = tpm_tis_i2c_probe, .remove = tpm_tis_i2c_remove, .driver = { .name = "tpm_i2c_infineon", .owner = THIS_MODULE, .pm = &tpm_tis_i2c_ops, .of_match_table = of_match_ptr(tpm_tis_i2c_of_match), }, }; module_i2c_driver(tpm_tis_i2c_driver); MODULE_AUTHOR("Peter Huewe "); MODULE_DESCRIPTION("TPM TIS I2C Infineon Driver"); MODULE_VERSION("2.2.0"); MODULE_LICENSE("GPL");