diff options
Diffstat (limited to 'drivers/tpm')
| -rw-r--r-- | drivers/tpm/Kconfig | 10 | ||||
| -rw-r--r-- | drivers/tpm/Makefile | 1 | ||||
| -rw-r--r-- | drivers/tpm/cr50_i2c.c | 659 |
3 files changed, 670 insertions, 0 deletions
diff --git a/drivers/tpm/Kconfig b/drivers/tpm/Kconfig index 94629df..555a76b 100644 --- a/drivers/tpm/Kconfig +++ b/drivers/tpm/Kconfig @@ -127,6 +127,16 @@ config TPM_V2 if TPM_V2 +config TPM2_CR50_I2C + bool "Enable support for Google cr50 TPM" + depends on DM_I2C + help + Cr50 is an implementation of a TPM on Google's H1 security chip. + This uses the same open-source firmware as the Chromium OS EC. + While Cr50 has other features, its primary role is as the root of + trust for a device, It operates like a TPM and can be used with + verified boot. Cr50 is used on recent Chromebooks (since 2017). + config TPM2_TIS_SANDBOX bool "Enable sandbox TPMv2.x driver" depends on TPM_V2 && SANDBOX diff --git a/drivers/tpm/Makefile b/drivers/tpm/Makefile index 94c337b..4c866b3 100644 --- a/drivers/tpm/Makefile +++ b/drivers/tpm/Makefile @@ -10,5 +10,6 @@ obj-$(CONFIG_TPM_TIS_SANDBOX) += tpm_tis_sandbox.o obj-$(CONFIG_TPM_ST33ZP24_I2C) += tpm_tis_st33zp24_i2c.o obj-$(CONFIG_TPM_ST33ZP24_SPI) += tpm_tis_st33zp24_spi.o +obj-$(CONFIG_TPM2_CR50_I2C) += cr50_i2c.o obj-$(CONFIG_TPM2_TIS_SANDBOX) += tpm2_tis_sandbox.o obj-$(CONFIG_TPM2_TIS_SPI) += tpm2_tis_spi.o diff --git a/drivers/tpm/cr50_i2c.c b/drivers/tpm/cr50_i2c.c new file mode 100644 index 0000000..b904a7d --- /dev/null +++ b/drivers/tpm/cr50_i2c.c @@ -0,0 +1,659 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Cr50 / H1 TPM support + * + * Copyright 2018 Google LLC + */ + +#define LOG_CATEGORY UCLASS_TPM + +#include <common.h> +#include <dm.h> +#include <i2c.h> +#include <irq.h> +#include <spl.h> +#include <tpm-v2.h> +#include <asm/gpio.h> +#include <asm/io.h> +#include <asm/arch/iomap.h> +#include <asm/arch/pm.h> + +enum { + TIMEOUT_INIT_MS = 30000, /* Very long timeout for TPM init */ + TIMEOUT_LONG_US = 2 * 1000 * 1000, + TIMEOUT_SHORT_US = 2 * 1000, + TIMEOUT_NO_IRQ_US = 20 * 1000, + TIMEOUT_IRQ_US = 100 * 1000, +}; + +enum { + CR50_DID_VID = 0x00281ae0L +}; + +enum { + CR50_MAX_BUF_SIZE = 63, +}; + +struct cr50_priv { + struct gpio_desc ready_gpio; + struct irq irq; + int locality; + uint vendor; + bool use_irq; +}; + +/* Wait for interrupt to indicate TPM is ready */ +static int cr50_i2c_wait_tpm_ready(struct udevice *dev) +{ + struct cr50_priv *priv = dev_get_priv(dev); + ulong timeout, base; + int i; + + if (!priv->use_irq && !dm_gpio_is_valid(&priv->ready_gpio)) { + /* Fixed delay if interrupt not supported */ + udelay(TIMEOUT_NO_IRQ_US); + return 0; + } + + base = timer_get_us(); + timeout = base + TIMEOUT_IRQ_US; + + i = 0; + while (priv->use_irq ? !irq_read_and_clear(&priv->irq) : + !dm_gpio_get_value(&priv->ready_gpio)) { + i++; + if ((int)(timer_get_us() - timeout) >= 0) { + log_warning("Timeout\n"); + /* Use this instead of the -ETIMEDOUT used by i2c */ + return -ETIME; + } + } + log_debug("i=%d\n", i); + + return 0; +} + +/* Clear pending interrupts */ +static void cr50_i2c_clear_tpm_irq(struct udevice *dev) +{ + struct cr50_priv *priv = dev_get_priv(dev); + + if (priv->use_irq) + irq_read_and_clear(&priv->irq); +} + +/* + * cr50_i2c_read() - read from TPM register + * + * @dev: TPM chip information + * @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 0 on success. -ve on error + */ +static int cr50_i2c_read(struct udevice *dev, u8 addr, u8 *buffer, + size_t len) +{ + int ret; + + /* Clear interrupt before starting transaction */ + cr50_i2c_clear_tpm_irq(dev); + + /* Send the register address byte to the TPM */ + ret = dm_i2c_write(dev, 0, &addr, 1); + if (ret) { + log_err("Address write failed (err=%d)\n", ret); + return ret; + } + + /* Wait for TPM to be ready with response data */ + ret = cr50_i2c_wait_tpm_ready(dev); + if (ret) + return ret; + + /* Read response data frrom the TPM */ + ret = dm_i2c_read(dev, 0, buffer, len); + if (ret) { + log_err("Read response failed (err=%d)\n", ret); + return ret; + } + + return 0; +} + +/* + * cr50_i2c_write() - write to TPM register + * + * @dev: TPM chip information + * @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(struct udevice *dev, u8 addr, const u8 *buffer, + size_t len) +{ + u8 buf[len + 1]; + int ret; + + if (len > CR50_MAX_BUF_SIZE) { + log_err("Length %zd is too large\n", len); + return -E2BIG; + } + + /* Prepend the 'register address' to the buffer */ + buf[0] = addr; + memcpy(buf + 1, buffer, len); + + /* Clear interrupt before starting transaction */ + cr50_i2c_clear_tpm_irq(dev); + + /* Send write request buffer with address */ + ret = dm_i2c_write(dev, 0, buf, len + 1); + if (ret) { + log_err("Error writing to TPM (err=%d)\n", ret); + return ret; + } + + /* Wait for TPM to be ready */ + return cr50_i2c_wait_tpm_ready(dev); +} + +static inline u8 tpm_access(u8 locality) +{ + return 0x0 | (locality << 4); +} + +static inline u8 tpm_sts(u8 locality) +{ + return 0x1 | (locality << 4); +} + +static inline u8 tpm_data_fifo(u8 locality) +{ + return 0x5 | (locality << 4); +} + +static inline u8 tpm_did_vid(u8 locality) +{ + return 0x6 | (locality << 4); +} + +static int release_locality(struct udevice *dev, int force) +{ + struct cr50_priv *priv = dev_get_priv(dev); + u8 mask = TPM_ACCESS_VALID | TPM_ACCESS_REQUEST_PENDING; + u8 addr = tpm_access(priv->locality); + int ret; + u8 buf; + + ret = cr50_i2c_read(dev, addr, &buf, 1); + if (ret) + return ret; + + if (force || (buf & mask) == mask) { + buf = TPM_ACCESS_ACTIVE_LOCALITY; + cr50_i2c_write(dev, addr, &buf, 1); + } + + priv->locality = 0; + + return 0; +} + +/* cr50 requires all 4 bytes of status register to be read */ +static int cr50_i2c_status(struct udevice *dev) +{ + struct cr50_priv *priv = dev_get_priv(dev); + u8 buf[4]; + int ret; + + ret = cr50_i2c_read(dev, tpm_sts(priv->locality), buf, sizeof(buf)); + if (ret) { + log_warning("%s: Failed to read status\n", __func__); + return ret; + } + + return buf[0]; +} + +/* cr50 requires all 4 bytes of status register to be written */ +static int cr50_i2c_ready(struct udevice *dev) +{ + struct cr50_priv *priv = dev_get_priv(dev); + u8 buf[4] = { TPM_STS_COMMAND_READY }; + int ret; + + ret = cr50_i2c_write(dev, tpm_sts(priv->locality), buf, sizeof(buf)); + if (ret) + return ret; + + udelay(TIMEOUT_SHORT_US); + + return 0; +} + +static int cr50_i2c_wait_burststs(struct udevice *dev, u8 mask, + size_t *burst, int *status) +{ + struct cr50_priv *priv = dev_get_priv(dev); + ulong timeout; + u32 buf; + + /* + * cr50 uses bytes 3:2 of status register for burst count and all 4 + * bytes must be read + */ + timeout = timer_get_us() + TIMEOUT_LONG_US; + while (timer_get_us() < timeout) { + if (cr50_i2c_read(dev, tpm_sts(priv->locality), + (u8 *)&buf, sizeof(buf)) < 0) { + udelay(TIMEOUT_SHORT_US); + continue; + } + + *status = buf & 0xff; + *burst = le16_to_cpu((buf >> 8) & 0xffff); + + if ((*status & mask) == mask && + *burst > 0 && *burst <= CR50_MAX_BUF_SIZE) + return 0; + + udelay(TIMEOUT_SHORT_US); + } + + log_warning("Timeout reading burst and status\n"); + + return -ETIMEDOUT; +} + +static int cr50_i2c_recv(struct udevice *dev, u8 *buf, size_t buf_len) +{ + struct cr50_priv *priv = dev_get_priv(dev); + size_t burstcnt, expected, current, len; + u8 addr = tpm_data_fifo(priv->locality); + u8 mask = TPM_STS_VALID | TPM_STS_DATA_AVAIL; + u32 expected_buf; + int status; + int ret; + + log_debug("%s: len=%x\n", __func__, buf_len); + if (buf_len < TPM_HEADER_SIZE) + return -E2BIG; + + ret = cr50_i2c_wait_burststs(dev, mask, &burstcnt, &status); + if (ret < 0) { + log_warning("First chunk not available\n"); + goto out_err; + } + + /* Read first chunk of burstcnt bytes */ + if (cr50_i2c_read(dev, addr, buf, burstcnt) < 0) { + log_warning("Read failed\n"); + goto out_err; + } + + /* Determine expected data in the return buffer */ + memcpy(&expected_buf, buf + TPM_CMD_COUNT_OFFSET, sizeof(expected_buf)); + expected = be32_to_cpu(expected_buf); + if (expected > buf_len) { + log_warning("Too much data: %zu > %zu\n", 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(dev, mask, &burstcnt, &status) < 0) { + log_warning("- burst failure1\n"); + goto out_err; + } + + len = min(burstcnt, expected - current); + if (cr50_i2c_read(dev, addr, buf + current, len) != 0) { + log_warning("Read failed\n"); + goto out_err; + } + + current += len; + } + + if (cr50_i2c_wait_burststs(dev, TPM_STS_VALID, &burstcnt, + &status) < 0) { + log_warning("- burst failure2\n"); + goto out_err; + } + if (status & TPM_STS_DATA_AVAIL) { + log_warning("Data still available\n"); + goto out_err; + } + + return current; + +out_err: + /* Abort current transaction if still pending */ + ret = cr50_i2c_status(dev); + if (ret < 0) + return ret; + if (ret & TPM_STS_COMMAND_READY) { + ret = cr50_i2c_ready(dev); + if (ret) + return ret; + } + + return -EIO; +} + +static int cr50_i2c_send(struct udevice *dev, const u8 *buf, size_t len) +{ + struct cr50_priv *priv = dev_get_priv(dev); + + int status; + size_t burstcnt, limit, sent = 0; + u8 tpm_go[4] = { TPM_STS_GO }; + ulong timeout; + int ret; + + log_debug("%s: len=%x\n", __func__, len); + timeout = timer_get_us() + TIMEOUT_LONG_US; + do { + ret = cr50_i2c_status(dev); + if (ret < 0) + goto out_err; + if (ret & TPM_STS_COMMAND_READY) + break; + + if (timer_get_us() > timeout) + goto out_err; + + ret = cr50_i2c_ready(dev); + if (ret) + goto out_err; + } while (1); + + while (len > 0) { + u8 mask = TPM_STS_VALID; + + /* Wait for data if this is not the first chunk */ + if (sent > 0) + mask |= TPM_STS_DATA_EXPECT; + + if (cr50_i2c_wait_burststs(dev, 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(dev, tpm_data_fifo(priv->locality), + &buf[sent], limit) != 0) { + log_warning("Write failed\n"); + goto out_err; + } + + sent += limit; + len -= limit; + } + + /* Ensure TPM is not expecting more data */ + if (cr50_i2c_wait_burststs(dev, TPM_STS_VALID, &burstcnt, &status) < 0) + goto out_err; + if (status & TPM_STS_DATA_EXPECT) { + log_warning("Data still expected\n"); + goto out_err; + } + + /* Start the TPM command */ + ret = cr50_i2c_write(dev, tpm_sts(priv->locality), tpm_go, + sizeof(tpm_go)); + if (ret) { + log_warning("Start command failed\n"); + goto out_err; + } + + return sent; + +out_err: + /* Abort current transaction if still pending */ + ret = cr50_i2c_status(dev); + + if (ret < 0 || (ret & TPM_STS_COMMAND_READY)) { + ret = cr50_i2c_ready(dev); + if (ret) + return ret; + } + + return -EIO; +} + +/** + * process_reset() - Wait for the Cr50 to reset + * + * 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. + * + * @dev: Cr50 device + * @return 0 if OK, -EPERM if locality could not be taken + */ +static int process_reset(struct udevice *dev) +{ + const int loc = 0; + u8 access; + ulong start; + + /* + * 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. + */ + start = get_timer(0); + do { + const u8 mask = TPM_ACCESS_VALID | TPM_ACCESS_ACTIVE_LOCALITY; + int ret; + + ret = cr50_i2c_read(dev, tpm_access(loc), + &access, sizeof(access)); + if (ret || ((access & mask) == mask)) { + /* + * Don't bombard the chip with traffic; let it keep + * processing the command. + */ + mdelay(2); + continue; + } + + log_warning("TPM ready after %ld ms\n", get_timer(start)); + + return 0; + } while (get_timer(start) < TIMEOUT_INIT_MS); + + log_warning("TPM failed to reset after %ld ms, status: %#x\n", + get_timer(start), access); + + return -EPERM; +} + +/* + * Locality could be already claimed (if this is a later U-Boot phase and the + * read-only U-Boot did not release it), or not yet claimed, if this is TPL or + * the older read-only U-Boot did release it. + */ +static int claim_locality(struct udevice *dev, int loc) +{ + const u8 mask = TPM_ACCESS_VALID | TPM_ACCESS_ACTIVE_LOCALITY; + u8 access; + int ret; + + ret = cr50_i2c_read(dev, tpm_access(loc), &access, sizeof(access)); + if (ret) + return log_msg_ret("read1", ret); + + if ((access & mask) == mask) { + log_warning("Locality already claimed\n"); + return 0; + } + + access = TPM_ACCESS_REQUEST_USE; + ret = cr50_i2c_write(dev, tpm_access(loc), &access, sizeof(access)); + if (ret) + return log_msg_ret("write", ret); + + ret = cr50_i2c_read(dev, tpm_access(loc), &access, sizeof(access)); + if (ret) + return log_msg_ret("read2", ret); + + if ((access & mask) != mask) { + log_err("Failed to claim locality\n"); + return -EPERM; + } + log_info("Claimed locality %d\n", loc); + + return 0; +} + +static int cr50_i2c_get_desc(struct udevice *dev, char *buf, int size) +{ + struct dm_i2c_chip *chip = dev_get_parent_platdata(dev); + struct cr50_priv *priv = dev_get_priv(dev); + + return snprintf(buf, size, "cr50 TPM 2.0 (i2c %02x id %x) irq=%d", + chip->chip_addr, priv->vendor >> 16, priv->use_irq); +} + +static int cr50_i2c_open(struct udevice *dev) +{ + char buf[80]; + int ret; + + ret = process_reset(dev); + if (ret) + return log_msg_ret("reset", ret); + + ret = claim_locality(dev, 0); + if (ret) + return log_msg_ret("claim", ret); + + cr50_i2c_get_desc(dev, buf, sizeof(buf)); + log_debug("%s\n", buf); + + return 0; +} + +static int cr50_i2c_cleanup(struct udevice *dev) +{ + release_locality(dev, 1); + + return 0; +} + +enum { + TPM_TIMEOUT_MS = 5, + SHORT_TIMEOUT_MS = 750, + LONG_TIMEOUT_MS = 2000, +}; + +static int cr50_i2c_ofdata_to_platdata(struct udevice *dev) +{ + struct tpm_chip_priv *upriv = dev_get_uclass_priv(dev); + struct cr50_priv *priv = dev_get_priv(dev); + struct irq irq; + int ret; + + upriv->version = TPM_V2; + upriv->duration_ms[TPM_SHORT] = SHORT_TIMEOUT_MS; + upriv->duration_ms[TPM_MEDIUM] = LONG_TIMEOUT_MS; + upriv->duration_ms[TPM_LONG] = LONG_TIMEOUT_MS; + upriv->retry_time_ms = TPM_TIMEOUT_MS; + + upriv->pcr_count = 32; + upriv->pcr_select_min = 2; + + /* Optional GPIO to track when cr50 is ready */ + ret = irq_get_by_index(dev, 0, &irq); + if (!ret) { + priv->irq = irq; + priv->use_irq = true; + } else { + ret = gpio_request_by_name(dev, "ready-gpio", 0, + &priv->ready_gpio, GPIOD_IS_IN); + if (ret) { + log_warning("Cr50 does not have an ready GPIO/interrupt (err=%d)\n", + ret); + } + } + + return 0; +} + +static int cr50_i2c_probe(struct udevice *dev) +{ + struct cr50_priv *priv = dev_get_priv(dev); + u32 vendor = 0; + ulong start; + + /* + * 150ms should be enough to synchronise with the TPM even under the + * worst nested-reset-request conditions. In the vast majority of cases + * there will be no wait at all. + */ + start = get_timer(0); + while (get_timer(start) < 150) { + int ret; + + /* Exit once DID and VID verified */ + ret = cr50_i2c_read(dev, tpm_did_vid(0), (u8 *)&vendor, 4); + if (!ret && vendor == CR50_DID_VID) + break; + + /* TPM might be resetting; let's retry in a bit */ + mdelay(10); + } + if (vendor != CR50_DID_VID) { + log_debug("DID_VID %08x not recognised\n", vendor); + return log_msg_ret("vendor-id", -EXDEV); + } + priv->vendor = vendor; + + return 0; +} + +static const struct tpm_ops cr50_i2c_ops = { + .open = cr50_i2c_open, + .get_desc = cr50_i2c_get_desc, + .send = cr50_i2c_send, + .recv = cr50_i2c_recv, + .cleanup = cr50_i2c_cleanup, +}; + +static const struct udevice_id cr50_i2c_ids[] = { + { .compatible = "google,cr50" }, + { } +}; + +U_BOOT_DRIVER(cr50_i2c) = { + .name = "cr50_i2c", + .id = UCLASS_TPM, + .of_match = cr50_i2c_ids, + .ops = &cr50_i2c_ops, + .ofdata_to_platdata = cr50_i2c_ofdata_to_platdata, + .probe = cr50_i2c_probe, + .priv_auto_alloc_size = sizeof(struct cr50_priv), +}; |