diff mbox series

[U-Boot,v2,03/19] tpm: add support for TPMv2 SPI modules

Message ID 20180329074401.8691-4-miquel.raynal@bootlin.com
State Changes Requested
Delegated to: Tom Rini
Headers show
Series Introduce SPI TPM v2.0 support | expand

Commit Message

Miquel Raynal March 29, 2018, 7:43 a.m. UTC
Add the tpm_tis_spi driver that should support any TPMv2 compliant (SPI)
module.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 drivers/tpm/Kconfig       |   9 +
 drivers/tpm/Makefile      |   1 +
 drivers/tpm/tpm_tis.h     |   3 +
 drivers/tpm/tpm_tis_spi.c | 656 ++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 669 insertions(+)
 create mode 100644 drivers/tpm/tpm_tis_spi.c

Comments

Simon Glass March 29, 2018, 10:41 p.m. UTC | #1
Hi Miquel,

On 29 March 2018 at 15:43, Miquel Raynal <miquel.raynal@bootlin.com> wrote:
> Add the tpm_tis_spi driver that should support any TPMv2 compliant (SPI)
> module.
>
> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
> ---
>  drivers/tpm/Kconfig       |   9 +
>  drivers/tpm/Makefile      |   1 +
>  drivers/tpm/tpm_tis.h     |   3 +
>  drivers/tpm/tpm_tis_spi.c | 656 ++++++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 669 insertions(+)
>  create mode 100644 drivers/tpm/tpm_tis_spi.c

I think this came up in another context. Would it make sense to create
a common interface to i2c and SPI and then have a common driver?

Regards,
Simon
Miquel Raynal April 24, 2018, 1:02 p.m. UTC | #2
Hi Simon,

On Fri, 30 Mar 2018 06:41:52 +0800, Simon Glass <sjg@chromium.org>
wrote:

> Hi Miquel,
> 
> On 29 March 2018 at 15:43, Miquel Raynal <miquel.raynal@bootlin.com> wrote:
> > Add the tpm_tis_spi driver that should support any TPMv2 compliant (SPI)
> > module.
> >
> > Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
> > ---
> >  drivers/tpm/Kconfig       |   9 +
> >  drivers/tpm/Makefile      |   1 +
> >  drivers/tpm/tpm_tis.h     |   3 +
> >  drivers/tpm/tpm_tis_spi.c | 656 ++++++++++++++++++++++++++++++++++++++++++++++
> >  4 files changed, 669 insertions(+)
> >  create mode 100644 drivers/tpm/tpm_tis_spi.c  
> 
> I think this came up in another context. Would it make sense to create
> a common interface to i2c and SPI and then have a common driver?

I hesitated to do it (even started to write down some common code), and
finally there was not so much of it, I was not sure if it would bring
something more than obfuscation so I chose not to add an extra layer as
I had currently only one SPI chip and no I2C chip to check the
architecture. Maybe the question should be asked again when someone
will want I2C support.

Regards,
Miquèl
diff mbox series

Patch

diff --git a/drivers/tpm/Kconfig b/drivers/tpm/Kconfig
index a98570ee77..cc57008b6a 100644
--- a/drivers/tpm/Kconfig
+++ b/drivers/tpm/Kconfig
@@ -46,6 +46,15 @@  config TPM_TIS_I2C_BURST_LIMITATION_LEN
 	help
 	  Use this to set the burst limitation length
 
+config TPM_TIS_SPI
+	bool "Enable support for TPMv2 SPI chips"
+	depends on TPM && DM_SPI
+	help
+	  This driver supports TPMv2 devices connected on the SPI bus.
+	  The usual TPM operations and the 'tpm' command can be used to talk
+	  to the device using the standard TPM Interface Specification (TIS)
+	  protocol
+
 config TPM_TIS_LPC
 	bool "Enable support for Infineon SLB9635/45 TPMs on LPC"
 	depends on TPM && X86
diff --git a/drivers/tpm/Makefile b/drivers/tpm/Makefile
index 5a19a58f43..a753b24230 100644
--- a/drivers/tpm/Makefile
+++ b/drivers/tpm/Makefile
@@ -7,6 +7,7 @@  obj-$(CONFIG_TPM) += tpm-uclass.o
 
 obj-$(CONFIG_TPM_ATMEL_TWI) += tpm_atmel_twi.o
 obj-$(CONFIG_TPM_TIS_INFINEON_I2C) += tpm_tis_infineon_i2c.o
+obj-$(CONFIG_TPM_TIS_SPI) += tpm_tis_spi.o
 obj-$(CONFIG_TPM_TIS_LPC) += tpm_tis_lpc.o
 obj-$(CONFIG_TPM_TIS_SANDBOX) += tpm_tis_sandbox.o
 obj-$(CONFIG_TPM_ST33ZP24_I2C) += tpm_tis_st33zp24_i2c.o
diff --git a/drivers/tpm/tpm_tis.h b/drivers/tpm/tpm_tis.h
index 2b81f3be50..1f4b0c24bd 100644
--- a/drivers/tpm/tpm_tis.h
+++ b/drivers/tpm/tpm_tis.h
@@ -37,6 +37,9 @@  enum tpm_timeout {
 #define TPM_RSP_SIZE_BYTE	2
 #define TPM_RSP_RC_BYTE		6
 
+/* Number of xfer retries */
+#define TPM_XFER_RETRY		10
+
 struct tpm_chip {
 	int is_open;
 	int locality;
diff --git a/drivers/tpm/tpm_tis_spi.c b/drivers/tpm/tpm_tis_spi.c
new file mode 100644
index 0000000000..17f6cfa85c
--- /dev/null
+++ b/drivers/tpm/tpm_tis_spi.c
@@ -0,0 +1,656 @@ 
+/*
+ * Author:
+ * Miquel Raynal <miquel.raynal@bootlin.com>
+ *
+ * Description:
+ * SPI-level driver for TCG/TIS TPM (trusted platform module).
+ * Specifications at www.trustedcomputinggroup.org
+ *
+ * This device driver implements the TPM interface as defined in
+ * the TCG SPI protocol stack version 2.0.
+ *
+ * It is based on the U-Boot driver tpm_tis_infineon_i2c.c.
+ *
+ * SPDX-License-Identifier:	GPL-2.0
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <fdtdec.h>
+#include <spi.h>
+#include <tpm.h>
+#include <linux/errno.h>
+#include <linux/compiler.h>
+#include <linux/types.h>
+#include <linux/unaligned/be_byteshift.h>
+
+#include "tpm_tis.h"
+#include "tpm_internal.h"
+
+DECLARE_GLOBAL_DATA_PTR;
+
+#define TPM_ACCESS(l)			(0x0000 | ((l) << 12))
+#define TPM_INT_ENABLE(l)               (0x0008 | ((l) << 12))
+#define TPM_STS(l)			(0x0018 | ((l) << 12))
+#define TPM_DATA_FIFO(l)		(0x0024 | ((l) << 12))
+#define TPM_DID_VID(l)			(0x0F00 | ((l) << 12))
+#define TPM_RID(l)			(0x0F04 | ((l) << 12))
+
+#define MAX_SPI_FRAMESIZE 64
+
+/*
+ * tpm_tis_spi_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.
+ *
+ * Return -EIO on error, 0 on success.
+ */
+static int tpm_tis_spi_xfer(struct udevice *dev, u32 addr, const u8 *out,
+			    u8 *in, u16 len)
+{
+	struct spi_slave *slave = dev_get_parent_priv(dev);
+	int transfer_len, ret;
+	u8 tx_buf[MAX_SPI_FRAMESIZE];
+	u8 rx_buf[MAX_SPI_FRAMESIZE];
+
+	if (in && out) {
+		debug("%s: cannot do full duplex\n", __func__);
+		return -EINVAL;
+	}
+
+	ret = spi_claim_bus(slave);
+	if (ret < 0) {
+		debug("%s: could not claim bus\n", __func__);
+		return ret;
+	}
+
+	while (len) {
+		/* Request */
+		transfer_len = min_t(u16, len, MAX_SPI_FRAMESIZE);
+		tx_buf[0] = (in ? BIT(7) : 0) | (transfer_len - 1);
+		tx_buf[1] = 0xD4;
+		tx_buf[2] = addr >> 8;
+		tx_buf[3] = addr;
+
+		ret = spi_xfer(slave, 4 * 8, tx_buf, rx_buf, SPI_XFER_BEGIN);
+		if (ret < 0) {
+			debug("%s: spi request transfer failed (err: %d)\n",
+			      __func__, ret);
+			goto release_bus;
+		}
+
+		/* Wait state */
+		if (!(rx_buf[3] & 0x1)) {
+			int i;
+
+			rx_buf[0] = 0;
+			for (i = 0; i < TPM_XFER_RETRY; i++) {
+				ret = spi_xfer(slave, 1 * 8, NULL, rx_buf, 0);
+				if (ret < 0) {
+					debug("%s: wait state failed: %d\n",
+					      __func__, ret);
+					goto release_bus;
+				}
+
+				if (rx_buf[0] & 0x1)
+					break;
+			}
+
+			if (i == TPM_RETRY) {
+				debug("%s: timeout on wait state\n", __func__);
+				ret = -ETIMEDOUT;
+				goto release_bus;
+			}
+		}
+
+		/* Read/Write */
+		if (out) {
+			memcpy(tx_buf, out, transfer_len);
+			out += transfer_len;
+		}
+
+		ret = spi_xfer(slave, transfer_len * 8,
+			       out ? tx_buf : NULL,
+			       in ? rx_buf : NULL,
+			       SPI_XFER_END);
+		if (ret < 0) {
+			debug("%s: spi read transfer failed (err: %d)\n",
+			      __func__, ret);
+			goto release_bus;
+		}
+
+		if (in) {
+			memcpy(in, rx_buf, transfer_len);
+			in += transfer_len;
+		}
+
+		len -= transfer_len;
+	}
+
+release_bus:
+	/* If an error occurred, release the chip by deasserting the CS */
+	if (ret < 0)
+		spi_xfer(slave, 0, NULL, NULL, SPI_XFER_END);
+
+	spi_release_bus(slave);
+
+	return ret;
+}
+
+static int tpm_tis_spi_read(struct udevice *dev, u16 addr, u8 *in, u16 len)
+{
+	return tpm_tis_spi_xfer(dev, addr, NULL, in, len);
+}
+
+static __maybe_unused int tpm_tis_spi_read16(struct udevice *dev, u32 addr,
+					     u16 *result)
+{
+	__le16 result_le;
+	int ret;
+
+	ret = tpm_tis_spi_read(dev, addr, (u8 *)&result_le, sizeof(u16));
+	if (!ret)
+		*result = le16_to_cpu(result_le);
+
+	return ret;
+}
+
+static __maybe_unused int tpm_tis_spi_read32(struct udevice *dev, u32 addr,
+					     u32 *result)
+{
+	__le32 result_le;
+	int ret;
+
+	ret = tpm_tis_spi_read(dev, addr, (u8 *)&result_le, sizeof(u32));
+	if (!ret)
+		*result = le32_to_cpu(result_le);
+
+	return ret;
+}
+
+static int tpm_tis_spi_write(struct udevice *dev, u16 addr, const u8 *out,
+			     u16 len)
+{
+	return tpm_tis_spi_xfer(dev, addr, out, NULL, len);
+}
+
+static __maybe_unused int tpm_tis_spi_write32(struct udevice *dev, u32 addr,
+					      u32 value)
+{
+	__le32 value_le = cpu_to_le32(value);
+
+	return tpm_tis_spi_write(dev, addr, (const u8 *)&value_le, sizeof(u32));
+}
+
+static int tpm_tis_spi_check_locality(struct udevice *dev, int loc)
+{
+	const u8 mask = TPM_ACCESS_ACTIVE_LOCALITY | TPM_ACCESS_VALID;
+	struct tpm_chip *chip = dev_get_priv(dev);
+	u8 buf;
+	int ret;
+
+	ret = tpm_tis_spi_read(dev, TPM_ACCESS(loc), &buf, 1);
+	if (ret)
+		return ret;
+
+	if ((buf & mask) == mask) {
+		chip->locality = loc;
+		return 0;
+	}
+
+	return -ENOENT;
+}
+
+static void tpm_tis_spi_release_locality(struct udevice *dev, int loc,
+					 bool force)
+{
+	const u8 mask = TPM_ACCESS_REQUEST_PENDING | TPM_ACCESS_VALID;
+	u8 buf;
+
+	if (tpm_tis_spi_read(dev, TPM_ACCESS(loc), &buf, 1) < 0)
+		return;
+
+	if (force || (buf & mask) == mask) {
+		buf = TPM_ACCESS_ACTIVE_LOCALITY;
+		tpm_tis_spi_write(dev, TPM_ACCESS(loc), &buf, 1);
+	}
+}
+
+static int tpm_tis_spi_request_locality(struct udevice *dev, int loc)
+{
+	struct tpm_chip *chip = dev_get_priv(dev);
+	unsigned long start, stop;
+	u8 buf = TPM_ACCESS_REQUEST_USE;
+	int ret;
+
+	ret = tpm_tis_spi_check_locality(dev, loc);
+	if (!ret)
+		return 0;
+
+	if (ret != -ENOENT) {
+		debug("%s: Failed to get locality: %d\n", __func__, ret);
+		return ret;
+	}
+
+	ret = tpm_tis_spi_write(dev, TPM_ACCESS(loc), &buf, 1);
+	if (ret) {
+		debug("%s: Failed to write to TPM: %d\n", __func__, ret);
+		return ret;
+	}
+
+	start = get_timer(0);
+	stop = chip->timeout_a;
+	do {
+		ret = tpm_tis_spi_check_locality(dev, loc);
+		if (!ret)
+			return 0;
+
+		if (ret != -ENOENT) {
+			debug("%s: Failed to get locality: %d\n", __func__,
+			      ret);
+			return ret;
+		}
+
+		mdelay(TPM_TIMEOUT_MS);
+	} while (get_timer(start) < stop);
+	debug("%s: Timeout getting locality: %d\n", __func__, ret);
+
+	return ret;
+}
+
+/*
+ * tpm_tis_spi_status return the TPM_STS register
+ * @dev: the device
+ * @status: storage parameter
+ * @return: 0 on success, a negative error otherwise
+ */
+static u8 tpm_tis_spi_status(struct udevice *dev, u8 *status)
+{
+	struct tpm_chip *chip = dev_get_priv(dev);
+
+	return tpm_tis_spi_read(dev, TPM_STS(chip->locality), status, 1);
+}
+
+static int tpm_tis_spi_wait_for_stat(struct udevice *dev, u8 mask,
+				     unsigned long timeout, u8 *status)
+{
+	unsigned long start = get_timer(0);
+	unsigned long stop = timeout;
+	int ret;
+
+	do {
+		mdelay(TPM_TIMEOUT_MS);
+		ret = tpm_tis_spi_status(dev, status);
+		if (ret)
+			return ret;
+
+		if ((*status & mask) == mask)
+			return 0;
+	} while (get_timer(start) < stop);
+
+	return -ETIMEDOUT;
+}
+
+/*
+ * tpm_tis_spi_get_burstcount return the burstcount address 0x19 0x1A
+ * @param: chip, the chip description
+ * return: the burstcount or -TPM_DRIVER_ERR in case of error.
+ */
+static int tpm_tis_spi_get_burstcount(struct udevice *dev)
+{
+	struct tpm_chip *chip = dev_get_priv(dev);
+	unsigned long start, stop;
+	u32 burstcount, ret;
+
+	/* wait for burstcount */
+	start = get_timer(0);
+	stop = chip->timeout_d;
+	do {
+		ret = tpm_tis_spi_read32(dev, TPM_STS(chip->locality),
+					 &burstcount);
+		if (ret)
+			return -EBUSY;
+
+		burstcount = (burstcount >> 8) & 0xFFFF;
+		if (burstcount)
+			return burstcount;
+
+		mdelay(TPM_TIMEOUT_MS);
+	} while (get_timer(start) < stop);
+
+	return -EBUSY;
+}
+
+/*
+ * tpm_tis_spi_cancel, cancel the current command execution or
+ * set STS to COMMAND READY.
+ * @param: chip, tpm_chip description.
+ */
+static int tpm_tis_spi_cancel(struct udevice *dev)
+{
+	struct tpm_chip *chip = dev_get_priv(dev);
+	u8 data = TPM_STS_COMMAND_READY;
+
+	return tpm_tis_spi_write(dev, TPM_STS(chip->locality), &data, 1);
+}
+
+static int tpm_tis_spi_recv_data(struct udevice *dev, u8 *buf, size_t count)
+{
+	struct tpm_chip *chip = dev_get_priv(dev);
+	int size = 0, burstcnt, len, ret;
+	u8 status;
+
+	while (size < count &&
+	       tpm_tis_spi_wait_for_stat(dev,
+					 TPM_STS_DATA_AVAIL | TPM_STS_VALID,
+					 chip->timeout_c, &status) == 0) {
+		burstcnt = tpm_tis_spi_get_burstcount(dev);
+		if (burstcnt < 0)
+			return burstcnt;
+
+		len = min_t(int, burstcnt, count - size);
+		ret = tpm_tis_spi_read(dev, TPM_DATA_FIFO(chip->locality),
+				       buf + size, len);
+		if (ret < 0)
+			return ret;
+
+		size += len;
+	}
+
+	return size;
+}
+
+static int tpm_tis_spi_recv(struct udevice *dev, u8 *buf, size_t count)
+{
+	struct tpm_chip *chip = dev_get_priv(dev);
+	int size, expected;
+
+	if (!chip)
+		return -ENODEV;
+
+	if (count < TPM_HEADER_SIZE) {
+		size = -EIO;
+		goto out;
+	}
+
+	size = tpm_tis_spi_recv_data(dev, buf, TPM_HEADER_SIZE);
+	if (size < TPM_HEADER_SIZE) {
+		debug("TPM error, unable to read header\n");
+		goto out;
+	}
+
+	expected = get_unaligned_be32(buf + 2);
+	if (expected > count) {
+		size = -EIO;
+		goto out;
+	}
+
+	size += tpm_tis_spi_recv_data(dev, &buf[TPM_HEADER_SIZE],
+				   expected - TPM_HEADER_SIZE);
+	if (size < expected) {
+		debug("TPM error, unable to read remaining bytes of result\n");
+		size = -EIO;
+		goto out;
+	}
+
+out:
+	tpm_tis_spi_cancel(dev);
+	tpm_tis_spi_release_locality(dev, chip->locality, false);
+
+	return size;
+}
+
+static int tpm_tis_spi_send(struct udevice *dev, const u8 *buf, size_t len)
+{
+	struct tpm_chip *chip = dev_get_priv(dev);
+	u32 i, size;
+	u8 status;
+	int burstcnt, ret;
+	u8 data;
+
+	if (!chip)
+		return -ENODEV;
+
+	if (len > TPM_DEV_BUFSIZE)
+		return -E2BIG;  /* Command is too long for our tpm, sorry */
+
+	ret = tpm_tis_spi_request_locality(dev, 0);
+	if (ret < 0)
+		return -EBUSY;
+
+	/*
+	 * Check if the TPM is ready. If not, if not, cancel the pending command
+	 * and poll on the status to be finally ready.
+	 */
+	ret = tpm_tis_spi_status(dev, &status);
+	if (ret)
+		return ret;
+
+	if (!(status & TPM_STS_COMMAND_READY)) {
+		/* Force the transition, usually this will be done at startup */
+		ret = tpm_tis_spi_cancel(dev);
+		if (ret) {
+			debug("%s: Could not cancel previous operation\n",
+			      __func__);
+			goto out_err;
+		}
+
+		ret = tpm_tis_spi_wait_for_stat(dev, TPM_STS_COMMAND_READY,
+						chip->timeout_b, &status);
+		if (ret < 0 || !(status & TPM_STS_COMMAND_READY)) {
+			debug("status %d after wait for stat returned %d\n",
+			      status, ret);
+			goto out_err;
+		}
+	}
+
+	for (i = 0; i < len - 1;) {
+		burstcnt = tpm_tis_spi_get_burstcount(dev);
+		if (burstcnt < 0)
+			return burstcnt;
+
+		size = min_t(int, len - i - 1, burstcnt);
+		ret = tpm_tis_spi_write(dev, TPM_DATA_FIFO(chip->locality),
+					buf + i, size);
+		if (ret < 0)
+			goto out_err;
+
+		i += size;
+	}
+
+	ret = tpm_tis_spi_status(dev, &status);
+	if (ret)
+		goto out_err;
+
+	if ((status & TPM_STS_DATA_EXPECT) == 0) {
+		ret = -EIO;
+		goto out_err;
+	}
+
+	ret = tpm_tis_spi_write(dev, TPM_DATA_FIFO(chip->locality),
+				buf + len - 1, 1);
+	if (ret)
+		goto out_err;
+
+	ret = tpm_tis_spi_status(dev, &status);
+	if (ret)
+		goto out_err;
+
+	if ((status & TPM_STS_DATA_EXPECT) != 0) {
+		ret = -EIO;
+		goto out_err;
+	}
+
+	data = TPM_STS_GO;
+	ret = tpm_tis_spi_write(dev, TPM_STS(chip->locality), &data, 1);
+	if (ret)
+		goto out_err;
+
+	return len;
+
+out_err:
+	tpm_tis_spi_cancel(dev);
+	tpm_tis_spi_release_locality(dev, chip->locality, false);
+
+	return ret;
+}
+
+static int tpm_tis_spi_cleanup(struct udevice *dev)
+{
+	struct tpm_chip *chip = dev_get_priv(dev);
+
+	tpm_tis_spi_cancel(dev);
+	/*
+	 * The TPM needs some time to clean up here,
+	 * so we sleep rather than keeping the bus busy
+	 */
+	mdelay(2);
+	tpm_tis_spi_release_locality(dev, chip->locality, false);
+
+	return 0;
+}
+
+static int tpm_tis_spi_open(struct udevice *dev)
+{
+	struct tpm_chip *chip = dev_get_priv(dev);
+
+	if (chip->is_open)
+		return -EBUSY;
+
+	chip->is_open = 1;
+
+	return 0;
+}
+
+static int tpm_tis_spi_close(struct udevice *dev)
+{
+	struct tpm_chip *chip = dev_get_priv(dev);
+
+	if (chip->is_open) {
+		tpm_tis_spi_release_locality(dev, chip->locality, true);
+		chip->is_open = 0;
+	}
+
+	return 0;
+}
+
+static int tpm_tis_get_desc(struct udevice *dev, char *buf, int size)
+{
+	struct tpm_chip *chip = dev_get_priv(dev);
+
+	if (size < 80)
+		return -ENOSPC;
+
+	return snprintf(buf, size,
+			"%s v2.0: VendorID 0x%04x, DeviceID 0x%04x, RevisionID 0x%02x [%s]",
+			dev->name, chip->vend_dev & 0xFFFF,
+			chip->vend_dev >> 16, chip->rid,
+			(chip->is_open ? "open" : "closed"));
+}
+
+static int tpm_tis_wait_init(struct udevice *dev, int loc)
+{
+	struct tpm_chip *chip = dev_get_priv(dev);
+	unsigned long start, stop;
+	u8 status;
+	int ret;
+
+	start = get_timer(0);
+	stop = chip->timeout_b;
+	do {
+		mdelay(TPM_TIMEOUT_MS);
+
+		ret = tpm_tis_spi_read(dev, TPM_ACCESS(loc), &status, 1);
+		if (ret)
+			break;
+
+		if (status & TPM_ACCESS_VALID)
+			return 0;
+	} while (get_timer(start) < stop);
+
+	return -EIO;
+}
+
+static int tpm_tis_spi_probe(struct udevice *dev)
+{
+	struct tpm_chip *chip = dev_get_priv(dev);
+	int ret;
+
+	chip->chip_type = dev_get_driver_data(dev);
+	chip->locality = 0;
+	chip->timeout_a = TIS_SHORT_TIMEOUT_MS;
+	chip->timeout_b = TIS_LONG_TIMEOUT_MS;
+	chip->timeout_c = TIS_SHORT_TIMEOUT_MS;
+	chip->timeout_d = TIS_SHORT_TIMEOUT_MS;
+
+	ret = tpm_tis_wait_init(dev, chip->locality);
+	if (ret) {
+		debug("%s: no device found\n", __func__);
+		return ret;
+	}
+
+	ret = tpm_tis_spi_request_locality(dev, chip->locality);
+	if (ret) {
+		debug("%s: could not request locality %d\n", __func__,
+		      chip->locality);
+		return ret;
+	}
+
+	ret = tpm_tis_spi_read32(dev, TPM_DID_VID(chip->locality),
+				 &chip->vend_dev);
+	if (ret) {
+		debug("%s: could not retrieve VendorID/DeviceID\n", __func__);
+		return ret;
+	}
+
+	ret = tpm_tis_spi_read(dev, TPM_RID(chip->locality), &chip->rid, 1);
+	if (ret) {
+		debug("%s: could not retrieve RevisionID\n", __func__);
+		return ret;
+	}
+
+	debug("SPI TPMv2.0 found (vid:%04x, did:%04x, rid:%02x)\n",
+	      chip->vend_dev & 0xFFFF, chip->vend_dev >> 16, chip->rid);
+
+	return 0;
+}
+
+static int tpm_tis_spi_remove(struct udevice *dev)
+{
+	struct tpm_chip *chip = dev_get_priv(dev);
+
+	tpm_tis_spi_release_locality(dev, chip->locality, true);
+
+	return 0;
+}
+
+static const struct tpm_ops tpm_tis_spi_ops = {
+	.open		= tpm_tis_spi_open,
+	.close		= tpm_tis_spi_close,
+	.get_desc	= tpm_tis_get_desc,
+	.send		= tpm_tis_spi_send,
+	.recv		= tpm_tis_spi_recv,
+	.cleanup	= tpm_tis_spi_cleanup,
+};
+
+static const struct udevice_id tpm_tis_spi_ids[] = {
+	{ .compatible = "st,st33tphf20-spi" },
+	{ }
+};
+
+U_BOOT_DRIVER(tpm_tis_spi) = {
+	.name   = "tpm_tis_spi",
+	.id     = UCLASS_TPM,
+	.of_match = tpm_tis_spi_ids,
+	.ops    = &tpm_tis_spi_ops,
+	.probe	= tpm_tis_spi_probe,
+	.remove	= tpm_tis_spi_remove,
+	.priv_auto_alloc_size = sizeof(struct tpm_chip),
+};