| /* SPDX-License-Identifier: GPL-2.0-only */ |
| |
| /* Based on Linux Kernel TPM driver */ |
| |
| /* |
| * cr50 is a TPM 2.0 capable device that requires special |
| * handling for the I2C interface. |
| * |
| * - Use an interrupt for transaction status instead of hardcoded delays |
| * - Must use write+wait+read read protocol |
| * - All 4 bytes of status register must be read/written at once |
| * - Burst count max is 63 bytes, and burst count behaves |
| * slightly differently than other I2C TPMs |
| * - When reading from FIFO the full burstcnt must be read |
| * instead of just reading header and determining the remainder |
| */ |
| |
| #include <commonlib/endian.h> |
| #include <commonlib/helpers.h> |
| #include <console/console.h> |
| #include <delay.h> |
| #include <device/i2c_simple.h> |
| #include <drivers/tpm/cr50.h> |
| #include <endian.h> |
| #include <security/tpm/tis.h> |
| #include <string.h> |
| #include <types.h> |
| #include <timer.h> |
| |
| #include "tpm.h" |
| |
| #define CR50_MAX_BUFSIZE 63 |
| #define CR50_TIMEOUT_INIT_MS 30000 /* Very long timeout for TPM init */ |
| #define CR50_TIMEOUT_LONG_MS 2000 /* Long timeout while waiting for TPM */ |
| #define CR50_TIMEOUT_SHORT_MS 2 /* Short timeout during transactions */ |
| #define CR50_DID_VID 0x00281ae0L |
| #define TI50_DID_VID 0x504a6666L |
| |
| struct tpm_inf_dev { |
| int bus; |
| int locality; |
| unsigned int addr; |
| uint8_t buf[CR50_MAX_BUFSIZE + sizeof(uint8_t)]; |
| }; |
| |
| static struct tpm_inf_dev tpm_dev; |
| |
| /* |
| * cr50_i2c_read() - read from TPM register |
| * |
| * @addr: register address to read from |
| * @buffer: provided by caller |
| * @len: number of bytes to read |
| * |
| * 1) send register address byte 'addr' to the TPM |
| * 2) wait for TPM to indicate it is ready |
| * 3) read 'len' bytes of TPM response into the provided 'buffer' |
| * |
| * Return -1 on error, 0 on success. |
| */ |
| static int cr50_i2c_read(uint8_t addr, uint8_t *buffer, size_t len) |
| { |
| if (tpm_dev.addr == 0) |
| return -1; |
| |
| /* Clear interrupt before starting transaction */ |
| cr50_plat_irq_status(); |
| |
| /* Send the register address byte to the TPM */ |
| if (i2c_write_raw(tpm_dev.bus, tpm_dev.addr, &addr, 1)) { |
| printk(BIOS_ERR, "%s: Address write failed\n", __func__); |
| return -1; |
| } |
| |
| /* Wait for TPM to be ready with response data */ |
| if (cr50_wait_tpm_ready() != CB_SUCCESS) |
| return -1; |
| |
| /* Read response data from the TPM */ |
| if (i2c_read_raw(tpm_dev.bus, tpm_dev.addr, buffer, len)) { |
| printk(BIOS_ERR, "%s: Read response failed\n", __func__); |
| return -1; |
| } |
| |
| return 0; |
| } |
| |
| /* |
| * cr50_i2c_write() - write to TPM register |
| * |
| * @addr: register address to write to |
| * @buffer: data to write |
| * @len: number of bytes to write |
| * |
| * 1) prepend the provided address to the provided data |
| * 2) send the address+data to the TPM |
| * 3) wait for TPM to indicate it is done writing |
| * |
| * Returns -1 on error, 0 on success. |
| */ |
| static int cr50_i2c_write(uint8_t addr, const uint8_t *buffer, size_t len) |
| { |
| if (tpm_dev.addr == 0) |
| return -1; |
| if (len > CR50_MAX_BUFSIZE) |
| return -1; |
| |
| /* Prepend the 'register address' to the buffer */ |
| tpm_dev.buf[0] = addr; |
| memcpy(tpm_dev.buf + 1, buffer, len); |
| |
| /* Clear interrupt before starting transaction */ |
| cr50_plat_irq_status(); |
| |
| /* Send write request buffer with address */ |
| if (i2c_write_raw(tpm_dev.bus, tpm_dev.addr, tpm_dev.buf, len + 1)) { |
| printk(BIOS_ERR, "%s: Error writing to TPM\n", __func__); |
| return -1; |
| } |
| |
| /* Wait for TPM to be ready */ |
| return cr50_wait_tpm_ready() == CB_SUCCESS ? 0 : -1; |
| } |
| |
| /* |
| * Cr50 processes reset requests asynchronously and conceivably could be busy |
| * executing a long command and not reacting to the reset pulse for a while. |
| * |
| * This function will make sure that the AP does not proceed with boot until |
| * TPM finished reset processing. |
| */ |
| static int process_reset(void) |
| { |
| struct stopwatch sw; |
| int rc = 0; |
| uint8_t access; |
| |
| /* |
| * Locality is released by TPM reset. |
| * |
| * If locality is taken at this point, this could be due to the fact |
| * that the TPM is performing a long operation and has not processed |
| * reset request yet. We'll wait up to CR50_TIMEOUT_INIT_MS and see if |
| * it releases locality when reset is processed. |
| */ |
| stopwatch_init_msecs_expire(&sw, CR50_TIMEOUT_INIT_MS); |
| do { |
| const uint8_t mask = |
| TPM_ACCESS_VALID | TPM_ACCESS_ACTIVE_LOCALITY; |
| |
| rc = cr50_i2c_read(TPM_ACCESS(0), |
| &access, sizeof(access)); |
| if (rc || ((access & mask) == mask)) { |
| /* |
| * Don't bombard the chip with traffic, let it keep |
| * processing the command. |
| */ |
| mdelay(2); |
| continue; |
| } |
| |
| printk(BIOS_INFO, "TPM ready after %lld ms\n", |
| stopwatch_duration_msecs(&sw)); |
| |
| return 0; |
| } while (!stopwatch_expired(&sw)); |
| |
| if (rc) |
| printk(BIOS_ERR, "Failed to read TPM\n"); |
| else |
| printk(BIOS_ERR, |
| "TPM failed to reset after %lld ms, status: %#x\n", |
| stopwatch_duration_msecs(&sw), access); |
| |
| return -1; |
| } |
| |
| /* |
| * Locality could be already claimed (if this is a later coreboot stage and |
| * the RO did not release it), or not yet claimed, if this is verstage or the |
| * older RO did release it. |
| */ |
| static int claim_locality(void) |
| { |
| uint8_t access; |
| const uint8_t mask = TPM_ACCESS_VALID | TPM_ACCESS_ACTIVE_LOCALITY; |
| |
| if (cr50_i2c_read(TPM_ACCESS(0), &access, sizeof(access))) |
| return -1; |
| |
| if ((access & mask) == mask) { |
| printk(BIOS_INFO, "Locality already claimed\n"); |
| return 0; |
| } |
| |
| access = TPM_ACCESS_REQUEST_USE; |
| if (cr50_i2c_write(TPM_ACCESS(0), |
| &access, sizeof(access))) |
| return -1; |
| |
| if (cr50_i2c_read(TPM_ACCESS(0), &access, sizeof(access))) |
| return -1; |
| |
| if ((access & mask) != mask) { |
| printk(BIOS_INFO, "Failed to claim locality.\n"); |
| return -1; |
| } |
| |
| return 0; |
| } |
| |
| /* cr50 requires all 4 bytes of status register to be read */ |
| static uint8_t cr50_i2c_tis_status(void) |
| { |
| uint8_t buf[4]; |
| if (cr50_i2c_read(TPM_STS(tpm_dev.locality), buf, sizeof(buf)) < 0) { |
| printk(BIOS_ERR, "%s: Failed to read status\n", __func__); |
| return 0; |
| } |
| return buf[0]; |
| } |
| |
| /* cr50 requires all 4 bytes of status register to be written */ |
| static void cr50_i2c_tis_ready(void) |
| { |
| uint8_t buf[4] = { TPM_STS_COMMAND_READY }; |
| cr50_i2c_write(TPM_STS(tpm_dev.locality), buf, sizeof(buf)); |
| mdelay(CR50_TIMEOUT_SHORT_MS); |
| } |
| |
| /* cr50 uses bytes 3:2 of status register for burst count and |
| * all 4 bytes must be read */ |
| static int cr50_i2c_wait_burststs(uint8_t mask, size_t *burst, int *status) |
| { |
| uint8_t buf[4]; |
| struct stopwatch sw; |
| |
| stopwatch_init_msecs_expire(&sw, CR50_TIMEOUT_LONG_MS); |
| |
| while (!stopwatch_expired(&sw)) { |
| if (cr50_i2c_read(TPM_STS(tpm_dev.locality), buf, sizeof(buf)) != 0) { |
| mdelay(CR50_TIMEOUT_SHORT_MS); |
| continue; |
| } |
| |
| *status = buf[0]; |
| *burst = read_le16(&buf[1]); |
| |
| /* Check if mask matches and burst is valid */ |
| if ((*status & mask) == mask && |
| *burst > 0 && *burst <= CR50_MAX_BUFSIZE) |
| return 0; |
| |
| mdelay(CR50_TIMEOUT_SHORT_MS); |
| } |
| |
| printk(BIOS_ERR, "%s: Timeout reading burst and status\n", __func__); |
| return -1; |
| } |
| |
| static int cr50_i2c_tis_recv(uint8_t *buf, size_t buf_len) |
| { |
| size_t burstcnt, current, len, expected; |
| uint8_t addr = TPM_DATA_FIFO(tpm_dev.locality); |
| uint8_t mask = TPM_STS_VALID | TPM_STS_DATA_AVAIL; |
| int status; |
| |
| if (buf_len < TPM_HEADER_SIZE) |
| goto out_err; |
| |
| if (cr50_i2c_wait_burststs(mask, &burstcnt, &status) < 0) { |
| printk(BIOS_ERR, "%s: First chunk not available\n", __func__); |
| goto out_err; |
| } |
| |
| /* Read first chunk of burstcnt bytes */ |
| if (cr50_i2c_read(addr, buf, burstcnt) != 0) { |
| printk(BIOS_ERR, "%s: Read failed\n", __func__); |
| goto out_err; |
| } |
| |
| /* Determine expected data in the return buffer */ |
| expected = read_be32(buf + TPM_RSP_SIZE_BYTE); |
| if (expected > buf_len) { |
| printk(BIOS_ERR, "%s: Too much data: %zu > %zu\n", |
| __func__, expected, buf_len); |
| goto out_err; |
| } |
| |
| /* Now read the rest of the data */ |
| current = burstcnt; |
| while (current < expected) { |
| /* Read updated burst count and check status */ |
| if (cr50_i2c_wait_burststs(mask, &burstcnt, &status) < 0) |
| goto out_err; |
| |
| len = MIN(burstcnt, expected - current); |
| if (cr50_i2c_read(addr, buf + current, len) != 0) { |
| printk(BIOS_ERR, "%s: Read failed\n", __func__); |
| goto out_err; |
| } |
| |
| current += len; |
| } |
| |
| /* Ensure TPM is done reading data */ |
| if (cr50_i2c_wait_burststs(TPM_STS_VALID, &burstcnt, &status) < 0) |
| goto out_err; |
| if (status & TPM_STS_DATA_AVAIL) { |
| printk(BIOS_ERR, "%s: Data still available\n", __func__); |
| goto out_err; |
| } |
| |
| return current; |
| |
| out_err: |
| /* Abort current transaction if still pending */ |
| if (cr50_i2c_tis_status() & TPM_STS_COMMAND_READY) |
| cr50_i2c_tis_ready(); |
| return -1; |
| } |
| |
| static int cr50_i2c_tis_send(uint8_t *buf, size_t len) |
| { |
| int status; |
| size_t burstcnt, limit, sent = 0; |
| uint8_t tpm_go[4] = { TPM_STS_GO }; |
| struct stopwatch sw; |
| |
| stopwatch_init_msecs_expire(&sw, CR50_TIMEOUT_LONG_MS); |
| |
| /* Wait until TPM is ready for a command */ |
| while (!(cr50_i2c_tis_status() & TPM_STS_COMMAND_READY)) { |
| if (stopwatch_expired(&sw)) { |
| printk(BIOS_ERR, "%s: Command ready timeout\n", |
| __func__); |
| return -1; |
| } |
| |
| cr50_i2c_tis_ready(); |
| } |
| |
| while (len > 0) { |
| uint8_t mask = TPM_STS_VALID; |
| |
| /* Wait for data if this is not the first chunk */ |
| if (sent > 0) |
| mask |= TPM_STS_DATA_EXPECT; |
| |
| /* Read burst count and check status */ |
| if (cr50_i2c_wait_burststs(mask, &burstcnt, &status) < 0) |
| goto out_err; |
| |
| /* Use burstcnt - 1 to account for the address byte |
| * that is inserted by cr50_i2c_write() */ |
| limit = MIN(burstcnt - 1, len); |
| if (cr50_i2c_write(TPM_DATA_FIFO(tpm_dev.locality), &buf[sent], limit) != 0) { |
| printk(BIOS_ERR, "%s: Write failed\n", __func__); |
| goto out_err; |
| } |
| |
| sent += limit; |
| len -= limit; |
| } |
| |
| /* Ensure TPM is not expecting more data */ |
| if (cr50_i2c_wait_burststs(TPM_STS_VALID, &burstcnt, &status) < 0) |
| goto out_err; |
| if (status & TPM_STS_DATA_EXPECT) { |
| printk(BIOS_ERR, "%s: Data still expected\n", __func__); |
| goto out_err; |
| } |
| |
| /* Start the TPM command */ |
| if (cr50_i2c_write(TPM_STS(tpm_dev.locality), tpm_go, sizeof(tpm_go)) < 0) { |
| printk(BIOS_ERR, "%s: Start command failed\n", __func__); |
| goto out_err; |
| } |
| return sent; |
| |
| out_err: |
| /* Abort current transaction if still pending */ |
| if (cr50_i2c_tis_status() & TPM_STS_COMMAND_READY) |
| cr50_i2c_tis_ready(); |
| return -1; |
| } |
| |
| static void cr50_vendor_init(struct tpm_chip *chip) |
| { |
| chip->req_complete_mask = TPM_STS_DATA_AVAIL | TPM_STS_VALID; |
| chip->req_complete_val = TPM_STS_DATA_AVAIL | TPM_STS_VALID; |
| chip->req_canceled = TPM_STS_COMMAND_READY; |
| chip->status = &cr50_i2c_tis_status; |
| chip->recv = &cr50_i2c_tis_recv; |
| chip->send = &cr50_i2c_tis_send; |
| chip->cancel = &cr50_i2c_tis_ready; |
| } |
| |
| int tpm_vendor_probe(unsigned int bus, uint32_t addr) |
| { |
| return 0; |
| } |
| |
| static int cr50_i2c_probe(uint32_t *did_vid) |
| { |
| int retries; |
| |
| /* |
| * 1s should be enough to synchronize with the TPM even under the |
| * worst nested reset request conditions. In vast majority of cases |
| * there would be no wait at all. If this probe fails, boot likely |
| * cannot proceed, so an extra long timeout is appropriate. |
| */ |
| printk(BIOS_INFO, "Probing TPM I2C: "); |
| |
| for (retries = 100; retries > 0; retries--) { |
| int rc; |
| |
| rc = cr50_i2c_read(TPM_DID_VID(0), (uint8_t *)did_vid, 4); |
| |
| /* Exit once DID and VID verified */ |
| if (!rc && (*did_vid == CR50_DID_VID || *did_vid == TI50_DID_VID)) { |
| printk(BIOS_INFO, "done! DID_VID 0x%08x\n", *did_vid); |
| return 0; |
| } |
| |
| /* TPM might be resetting, let's retry in a bit. */ |
| mdelay(10); |
| printk(BIOS_INFO, "."); |
| } |
| |
| /* |
| * I2C reads failed, or the DID and VID didn't match |
| */ |
| printk(BIOS_ERR, "DID_VID 0x%08x not recognized\n", *did_vid); |
| return -1; |
| } |
| |
| int tpm_vendor_init(struct tpm_chip *chip, unsigned int bus, uint32_t dev_addr) |
| { |
| uint32_t did_vid = 0; |
| |
| if (dev_addr == 0) { |
| printk(BIOS_ERR, "%s: missing device address\n", __func__); |
| return -1; |
| } |
| |
| tpm_dev.bus = bus; |
| tpm_dev.addr = dev_addr; |
| |
| cr50_vendor_init(chip); |
| |
| if (cr50_i2c_probe(&did_vid)) |
| return -1; |
| |
| if (ENV_SEPARATE_VERSTAGE || ENV_BOOTBLOCK) |
| if (process_reset()) |
| return -1; |
| |
| if (claim_locality()) |
| return -1; |
| |
| printk(BIOS_DEBUG, "cr50 TPM 2.0 (i2c %u:0x%02x id %#x)\n", |
| bus, dev_addr, did_vid >> 16); |
| |
| if (tpm_first_access_this_boot()) { |
| /* This is called for the side-effect of printing the version string. */ |
| cr50_get_firmware_version(NULL); |
| cr50_set_board_cfg(); |
| } |
| |
| chip->is_open = 1; |
| return 0; |
| } |
| |
| enum cb_err tis_vendor_write(unsigned int addr, const void *buffer, size_t bytes) |
| { |
| return cr50_i2c_write(addr & 0xff, buffer, bytes) ? CB_ERR : CB_SUCCESS; |
| } |
| |
| enum cb_err tis_vendor_read(unsigned int addr, void *buffer, size_t bytes) |
| { |
| return cr50_i2c_read(addr & 0xff, buffer, bytes) ? CB_ERR : CB_SUCCESS; |
| } |