[v3,16/17] tpm: Add a driver for H1/Cr50

diff --git a/drivers/tpm/Kconfig b/drivers/tpm/Kconfig
index 94629dffd2..555a76bb1e 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 94c337b8ed..4c866b37c5 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 0000000000..b904a7d426
--- /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),
+};