]> git.kernelconcepts.de Git - karo-tx-uboot.git/commitdiff
tpm: st33zp24: Add tpm st33zp24 spi support
authorChristophe Ricard <christophe.ricard@gmail.com>
Thu, 21 Jan 2016 22:27:14 +0000 (23:27 +0100)
committerSimon Glass <sjg@chromium.org>
Fri, 29 Jan 2016 04:01:22 +0000 (21:01 -0700)
Add support for TPM ST33ZP24 spi.

The ST33ZP24 does have a spi interface.
The transport protocol is proprietary.

For spi we are relying only on DM_SPI.

Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Christophe Ricard <christophe-h.ricard@st.com>
README
drivers/tpm/Kconfig
drivers/tpm/Makefile
drivers/tpm/tpm_tis_st33zp24_spi.c [new file with mode: 0644]

diff --git a/README b/README
index ec73a4e5d9186a0c9eb10e7c7d5bd2eb7c82fbc0..c7c9e0a9e3e1a3cf11beb16a671778bafe3751cb 100644 (file)
--- a/README
+++ b/README
@@ -1430,6 +1430,10 @@ The following options need to be configured:
                        Support for STMicroelectronics ST33ZP24 I2C devices.
                        Requires TPM_ST33ZP24 and I2C.
 
+                       CONFIG_TPM_ST33ZP24_SPI
+                       Support for STMicroelectronics ST33ZP24 SPI devices.
+                       Requires TPM_ST33ZP24 and SPI.
+
                CONFIG_TPM_ATMEL_TWI
                Support for Atmel TWI TPM device. Requires I2C support.
 
index 9432160667637bcef4f7e9069ec2dbb1ae07cadd..9a7b7f535fbbb07ab9aa79c1301a1c7235444133 100644 (file)
@@ -73,4 +73,13 @@ config TPM_ST33ZP24_I2C
          to the device using the standard TPM Interface Specification (TIS)
          protocol
 
+config TPM_ST33ZP24_SPI
+       bool "STMicroelectronics ST33ZP24 SPI TPM"
+       depends on TPM && DM_SPI
+       ---help---
+         This driver supports STMicroelectronics TPM 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
+
 endmenu
index cb066d78d0485870ad7a5f1dfd59c42b7c6f718b..c42a93f267cf7026267c653650a45ca1ff1d3014 100644 (file)
@@ -10,3 +10,4 @@ obj-$(CONFIG_TPM_TIS_INFINEON) += tpm_tis_infineon.o
 obj-$(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
+obj-$(CONFIG_TPM_ST33ZP24_SPI) += tpm_tis_st33zp24_spi.o
diff --git a/drivers/tpm/tpm_tis_st33zp24_spi.c b/drivers/tpm/tpm_tis_st33zp24_spi.c
new file mode 100644 (file)
index 0000000..417bbf1
--- /dev/null
@@ -0,0 +1,672 @@
+/*
+ * STMicroelectronics TPM ST33ZP24 SPI UBOOT driver
+ *
+ * Copyright (C) 2016 STMicroelectronics
+ *
+ * Description: Device driver for ST33ZP24 SPI TPM TCG.
+ *
+ * This device driver implements the TPM interface as defined in
+ * the TCG TPM Interface Spec version 1.21, revision 1.0 and the
+ * STMicroelectronics Protocol Stack Specification version 1.2.0.
+ *
+ * SPDX-License-Identifier:    GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <fdtdec.h>
+#include <spi.h>
+#include <tpm.h>
+#include <errno.h>
+#include <linux/types.h>
+#include <asm/unaligned.h>
+#include <linux/compat.h>
+
+#include "tpm_tis.h"
+#include "tpm_internal.h"
+
+#define TPM_ACCESS                     0x0
+#define TPM_STS                                0x18
+#define TPM_DATA_FIFO                  0x24
+
+#define LOCALITY0                      0
+
+#define TPM_DATA_FIFO                          0x24
+#define TPM_INTF_CAPABILITY                    0x14
+
+#define TPM_DUMMY_BYTE                         0x00
+#define TPM_WRITE_DIRECTION                    0x80
+
+#define MAX_SPI_LATENCY                                15
+#define LOCALITY0                              0
+
+#define ST33ZP24_OK                                    0x5A
+#define ST33ZP24_UNDEFINED_ERR                         0x80
+#define ST33ZP24_BADLOCALITY                           0x81
+#define ST33ZP24_TISREGISTER_UKNOWN                    0x82
+#define ST33ZP24_LOCALITY_NOT_ACTIVATED                        0x83
+#define ST33ZP24_HASH_END_BEFORE_HASH_START            0x84
+#define ST33ZP24_BAD_COMMAND_ORDER                     0x85
+#define ST33ZP24_INCORECT_RECEIVED_LENGTH              0x86
+#define ST33ZP24_TPM_FIFO_OVERFLOW                     0x89
+#define ST33ZP24_UNEXPECTED_READ_FIFO                  0x8A
+#define ST33ZP24_UNEXPECTED_WRITE_FIFO                 0x8B
+#define ST33ZP24_CMDRDY_SET_WHEN_PROCESSING_HASH_END   0x90
+#define ST33ZP24_DUMMY_BYTES                           0x00
+
+/*
+ * TPM command can be up to 2048 byte, A TPM response can be up to
+ * 1024 byte.
+ * Between command and response, there are latency byte (up to 15
+ * usually on st33zp24 2 are enough).
+ *
+ * Overall when sending a command and expecting an answer we need if
+ * worst case:
+ * 2048 (for the TPM command) + 1024 (for the TPM answer).  We need
+ * some latency byte before the answer is available (max 15).
+ * We have 2048 + 1024 + 15.
+ */
+#define ST33ZP24_SPI_BUFFER_SIZE (TPM_BUFSIZE + (TPM_BUFSIZE / 2) +\
+                                 MAX_SPI_LATENCY)
+
+struct st33zp24_spi_phy {
+       int latency;
+
+       u8 tx_buf[ST33ZP24_SPI_BUFFER_SIZE];
+       u8 rx_buf[ST33ZP24_SPI_BUFFER_SIZE];
+};
+
+static int st33zp24_spi_status_to_errno(u8 code)
+{
+       switch (code) {
+       case ST33ZP24_OK:
+               return 0;
+       case ST33ZP24_UNDEFINED_ERR:
+       case ST33ZP24_BADLOCALITY:
+       case ST33ZP24_TISREGISTER_UKNOWN:
+       case ST33ZP24_LOCALITY_NOT_ACTIVATED:
+       case ST33ZP24_HASH_END_BEFORE_HASH_START:
+       case ST33ZP24_BAD_COMMAND_ORDER:
+       case ST33ZP24_UNEXPECTED_READ_FIFO:
+       case ST33ZP24_UNEXPECTED_WRITE_FIFO:
+       case ST33ZP24_CMDRDY_SET_WHEN_PROCESSING_HASH_END:
+               return -EPROTO;
+       case ST33ZP24_INCORECT_RECEIVED_LENGTH:
+       case ST33ZP24_TPM_FIFO_OVERFLOW:
+               return -EMSGSIZE;
+       case ST33ZP24_DUMMY_BYTES:
+               return -ENOSYS;
+       }
+       return code;
+}
+
+/*
+ * st33zp24_spi_send
+ * Send byte to TPM register according to the ST33ZP24 SPI protocol.
+ * @param: tpm, the chip description
+ * @param: tpm_register, the tpm tis register where the data should be written
+ * @param: tpm_data, the tpm_data to write inside the tpm_register
+ * @param: tpm_size, The length of the data
+ * @return: should be zero if success else a negative error code.
+ */
+static int st33zp24_spi_write(struct udevice *dev, u8 tpm_register,
+                             const u8 *tpm_data, size_t tpm_size)
+{
+       int total_length = 0, ret;
+       struct spi_slave *slave = dev_get_parent_priv(dev);
+       struct st33zp24_spi_phy *phy = dev_get_platdata(dev);
+
+       u8 *tx_buf = (u8 *)phy->tx_buf;
+       u8 *rx_buf = phy->rx_buf;
+
+       tx_buf[total_length++] = TPM_WRITE_DIRECTION | LOCALITY0;
+       tx_buf[total_length++] = tpm_register;
+
+       if (tpm_size > 0 && tpm_register == TPM_DATA_FIFO) {
+               tx_buf[total_length++] = tpm_size >> 8;
+               tx_buf[total_length++] = tpm_size;
+       }
+       memcpy(tx_buf + total_length, tpm_data, tpm_size);
+       total_length += tpm_size;
+
+       memset(tx_buf + total_length, TPM_DUMMY_BYTE, phy->latency);
+
+       total_length += phy->latency;
+
+       ret = spi_claim_bus(slave);
+       if (ret < 0)
+               return ret;
+
+       ret = spi_xfer(slave, total_length * 8, tx_buf, rx_buf,
+                      SPI_XFER_BEGIN | SPI_XFER_END);
+       if (ret < 0)
+               return ret;
+
+       spi_release_bus(slave);
+
+       if (ret == 0)
+               ret = rx_buf[total_length - 1];
+
+       return st33zp24_spi_status_to_errno(ret);
+}
+
+/*
+ * spi_st33zp24_spi_read8_reg
+ * Recv byte from the TIS register according to the ST33ZP24 SPI protocol.
+ * @param: tpm, the chip description
+ * @param: tpm_loc, the locality to read register from
+ * @param: tpm_register, the tpm tis register where the data should be read
+ * @param: tpm_data, the TPM response
+ * @param: tpm_size, tpm TPM response size to read.
+ * @return: should be zero if success else a negative error code.
+ */
+static u8 st33zp24_spi_read8_reg(struct udevice *dev, u8 tpm_register,
+                                u8 *tpm_data, size_t tpm_size)
+{
+       int total_length = 0, ret;
+       struct spi_slave *slave = dev_get_parent_priv(dev);
+       struct st33zp24_spi_phy *phy = dev_get_platdata(dev);
+
+       u8 *tx_buf = (u8 *)phy->tx_buf;
+       u8 *rx_buf = phy->rx_buf;
+
+       /* Pre-Header */
+       tx_buf[total_length++] = LOCALITY0;
+       tx_buf[total_length++] = tpm_register;
+
+       memset(&tx_buf[total_length], TPM_DUMMY_BYTE,
+              phy->latency + tpm_size);
+       total_length += phy->latency + tpm_size;
+
+       ret = spi_claim_bus(slave);
+       if (ret < 0)
+               return 0;
+
+       ret = spi_xfer(slave, total_length * 8, tx_buf, rx_buf,
+                      SPI_XFER_BEGIN | SPI_XFER_END);
+       if (ret < 0)
+               return 0;
+
+       spi_release_bus(slave);
+
+       if (tpm_size > 0 && ret == 0) {
+               ret = rx_buf[total_length - tpm_size - 1];
+               memcpy(tpm_data, rx_buf + total_length - tpm_size, tpm_size);
+       }
+       return ret;
+}
+
+/*
+ * st33zp24_spi_recv
+ * Recv byte from the TIS register according to the ST33ZP24 SPI protocol.
+ * @param: phy_id, the phy description
+ * @param: tpm_register, the tpm tis register where the data should be read
+ * @param: tpm_data, the TPM response
+ * @param: tpm_size, tpm TPM response size to read.
+ * @return: number of byte read successfully: should be one if success.
+ */
+static int st33zp24_spi_read(struct udevice *dev, u8 tpm_register,
+                            u8 *tpm_data, size_t tpm_size)
+{
+       int ret;
+
+       ret = st33zp24_spi_read8_reg(dev, tpm_register, tpm_data, tpm_size);
+       if (!st33zp24_spi_status_to_errno(ret))
+               return tpm_size;
+
+       return ret;
+}
+
+static int st33zp24_spi_evaluate_latency(struct udevice *dev)
+{
+       int latency = 1, status = 0;
+       u8 data = 0;
+       struct st33zp24_spi_phy *phy = dev_get_platdata(dev);
+
+       while (!status && latency < MAX_SPI_LATENCY) {
+               phy->latency = latency;
+               status = st33zp24_spi_read8_reg(dev, TPM_INTF_CAPABILITY,
+                                               &data, 1);
+               latency++;
+       }
+       if (status < 0)
+               return status;
+       if (latency == MAX_SPI_LATENCY)
+               return -ENODEV;
+
+       return latency - 1;
+}
+
+/*
+ * st33zp24_spi_release_locality release the active locality
+ * @param: chip, the tpm chip description.
+ */
+static void st33zp24_spi_release_locality(struct udevice *dev)
+{
+       u8 data = TPM_ACCESS_ACTIVE_LOCALITY;
+
+       st33zp24_spi_write(dev, TPM_ACCESS, &data, 1);
+}
+
+/*
+ * st33zp24_spi_check_locality if the locality is active
+ * @param: chip, the tpm chip description
+ * @return: the active locality or -EACCES.
+ */
+static int st33zp24_spi_check_locality(struct udevice *dev)
+{
+       u8 data;
+       u8 status;
+       struct tpm_chip *chip = dev_get_priv(dev);
+
+       status = st33zp24_spi_read(dev, TPM_ACCESS, &data, 1);
+       if (status && (data &
+               (TPM_ACCESS_ACTIVE_LOCALITY | TPM_ACCESS_VALID)) ==
+               (TPM_ACCESS_ACTIVE_LOCALITY | TPM_ACCESS_VALID))
+               return chip->locality;
+
+       return -EACCES;
+}
+
+/*
+ * st33zp24_spi_request_locality request the TPM locality
+ * @param: chip, the chip description
+ * @return: the active locality or negative value.
+ */
+static int st33zp24_spi_request_locality(struct udevice *dev)
+{
+       unsigned long start, stop;
+       long ret;
+       u8 data;
+       struct tpm_chip *chip = dev_get_priv(dev);
+
+       if (st33zp24_spi_check_locality(dev) == chip->locality)
+               return chip->locality;
+
+       data = TPM_ACCESS_REQUEST_USE;
+       ret = st33zp24_spi_write(dev, TPM_ACCESS, &data, 1);
+       if (ret < 0)
+               return ret;
+
+       /* wait for locality activated */
+       start = get_timer(0);
+       stop = chip->timeout_a;
+       do {
+               if (st33zp24_spi_check_locality(dev) >= 0)
+                       return chip->locality;
+               udelay(TPM_TIMEOUT_MS * 1000);
+       } while  (get_timer(start) < stop);
+
+       return -EACCES;
+}
+
+/*
+ * st33zp24_spi_status return the TPM_STS register
+ * @param: chip, the tpm chip description
+ * @return: the TPM_STS register value.
+ */
+static u8 st33zp24_spi_status(struct udevice *dev)
+{
+       u8 data;
+
+       st33zp24_spi_read(dev, TPM_STS, &data, 1);
+       return data;
+}
+
+/*
+ * st33zp24_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 st33zp24_spi_get_burstcount(struct udevice *dev)
+{
+       struct tpm_chip *chip = dev_get_priv(dev);
+       unsigned long start, stop;
+       int burstcnt, status;
+       u8 tpm_reg, temp;
+
+       /* wait for burstcount */
+       start = get_timer(0);
+       stop = chip->timeout_d;
+       do {
+               tpm_reg = TPM_STS + 1;
+               status = st33zp24_spi_read(dev, tpm_reg, &temp, 1);
+               if (status < 0)
+                       return -EBUSY;
+
+               tpm_reg = TPM_STS + 2;
+               burstcnt = temp;
+               status = st33zp24_spi_read(dev, tpm_reg, &temp, 1);
+               if (status < 0)
+                       return -EBUSY;
+
+               burstcnt |= temp << 8;
+               if (burstcnt)
+                       return burstcnt;
+               udelay(TIS_SHORT_TIMEOUT_MS * 1000);
+       } while (get_timer(start) < stop);
+
+       return -EBUSY;
+}
+
+/*
+ * st33zp24_spi_cancel, cancel the current command execution or
+ * set STS to COMMAND READY.
+ * @param: chip, tpm_chip description.
+ */
+static void st33zp24_spi_cancel(struct udevice *dev)
+{
+       u8 data;
+
+       data = TPM_STS_COMMAND_READY;
+       st33zp24_spi_write(dev, TPM_STS, &data, 1);
+}
+
+/*
+ * st33zp24_spi_wait_for_stat wait for a TPM_STS value
+ * @param: chip, the tpm chip description
+ * @param: mask, the value mask to wait
+ * @param: timeout, the timeout
+ * @param: status,
+ * @return: the tpm status, 0 if success, -ETIME if timeout is reached.
+ */
+static int st33zp24_spi_wait_for_stat(struct udevice *dev, u8 mask,
+                                 unsigned long timeout, int *status)
+{
+       unsigned long start, stop;
+
+       /* Check current status */
+       *status = st33zp24_spi_status(dev);
+       if ((*status & mask) == mask)
+               return 0;
+
+       start = get_timer(0);
+       stop = timeout;
+       do {
+               udelay(TPM_TIMEOUT_MS * 1000);
+               *status = st33zp24_spi_status(dev);
+               if ((*status & mask) == mask)
+                       return 0;
+       } while (get_timer(start) < stop);
+
+       return -ETIME;
+}
+
+/*
+ * st33zp24_spi_recv_data receive data
+ * @param: chip, the tpm chip description
+ * @param: buf, the buffer where the data are received
+ * @param: count, the number of data to receive
+ * @return: the number of bytes read from TPM FIFO.
+ */
+static int st33zp24_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, status;
+
+       while (size < count &&
+              st33zp24_spi_wait_for_stat(dev, TPM_STS_DATA_AVAIL | TPM_STS_VALID,
+                               chip->timeout_c, &status) == 0) {
+               burstcnt = st33zp24_spi_get_burstcount(dev);
+               if (burstcnt < 0)
+                       return burstcnt;
+               len = min_t(int, burstcnt, count - size);
+               ret = st33zp24_spi_read(dev, TPM_DATA_FIFO, buf + size, len);
+               if (ret < 0)
+                       return ret;
+
+               size += len;
+       }
+       return size;
+}
+
+/*
+ * st33zp24_spi_recv received TPM response through TPM phy.
+ * @param: chip, tpm_chip description.
+ * @param: buf,        the buffer to store data.
+ * @param: count, the number of bytes that can received (sizeof buf).
+ * @return: Returns zero in case of success else -EIO.
+ */
+static int st33zp24_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 = st33zp24_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 += st33zp24_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:
+       st33zp24_spi_cancel(dev);
+       st33zp24_spi_release_locality(dev);
+
+       return size;
+}
+
+/*
+ * st33zp24_spi_send send TPM commands through TPM phy.
+ * @param: chip, tpm_chip description.
+ * @param: buf,        the buffer to send.
+ * @param: len, the number of bytes to send.
+ * @return: Returns zero in case of success else the negative error code.
+ */
+static int st33zp24_spi_send(struct udevice *dev, const u8 *buf, size_t len)
+{
+       struct tpm_chip *chip = dev_get_priv(dev);
+       u32 i, size;
+       int burstcnt, ret, status;
+       u8 data, tpm_stat;
+
+       if (!chip)
+               return -ENODEV;
+       if (len < TPM_HEADER_SIZE)
+               return -EIO;
+
+       ret = st33zp24_spi_request_locality(dev);
+       if (ret < 0)
+               return ret;
+
+       tpm_stat = st33zp24_spi_status(dev);
+       if ((tpm_stat & TPM_STS_COMMAND_READY) == 0) {
+               st33zp24_spi_cancel(dev);
+               if (st33zp24_spi_wait_for_stat(dev, TPM_STS_COMMAND_READY,
+                                              chip->timeout_b, &status) < 0) {
+                       ret = -ETIME;
+                       goto out_err;
+               }
+       }
+
+       for (i = 0; i < len - 1;) {
+               burstcnt = st33zp24_spi_get_burstcount(dev);
+               if (burstcnt < 0)
+                       return burstcnt;
+
+               size = min_t(int, len - i - 1, burstcnt);
+               ret = st33zp24_spi_write(dev, TPM_DATA_FIFO, buf + i, size);
+               if (ret < 0)
+                       goto out_err;
+
+               i += size;
+       }
+
+       tpm_stat = st33zp24_spi_status(dev);
+       if ((tpm_stat & TPM_STS_DATA_EXPECT) == 0) {
+               ret = -EIO;
+               goto out_err;
+       }
+
+       ret = st33zp24_spi_write(dev, TPM_DATA_FIFO, buf + len - 1, 1);
+       if (ret < 0)
+               goto out_err;
+
+       tpm_stat = st33zp24_spi_status(dev);
+       if ((tpm_stat & TPM_STS_DATA_EXPECT) != 0) {
+               ret = -EIO;
+               goto out_err;
+       }
+
+       data = TPM_STS_GO;
+       ret = st33zp24_spi_write(dev, TPM_STS, &data, 1);
+       if (ret < 0)
+               goto out_err;
+
+       return len;
+
+out_err:
+       st33zp24_spi_cancel(dev);
+       st33zp24_spi_release_locality(dev);
+
+       return ret;
+}
+
+static int st33zp24_spi_cleanup(struct udevice *dev)
+{
+       st33zp24_spi_cancel(dev);
+       /*
+        * The TPM needs some time to clean up here,
+        * so we sleep rather than keeping the bus busy
+        */
+       mdelay(2);
+       st33zp24_spi_release_locality(dev);
+
+       return 0;
+}
+
+static int st33zp24_spi_init(struct udevice *dev)
+{
+       struct tpm_chip *chip = dev_get_priv(dev);
+       struct st33zp24_spi_phy *phy = dev_get_platdata(dev);
+
+       chip->is_open = 1;
+
+       /* Default timeouts - these could move to the device tree */
+       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;
+
+       chip->locality = LOCALITY0;
+
+       phy->latency = st33zp24_spi_evaluate_latency(dev);
+       if (phy->latency <= 0)
+               return -ENODEV;
+
+       /*
+        * A timeout query to TPM can be placed here.
+        * Standard timeout values are used so far
+        */
+
+       return 0;
+}
+
+static int st33zp24_spi_open(struct udevice *dev)
+{
+       struct tpm_chip *chip = dev_get_priv(dev);
+       int rc;
+
+       debug("%s: start\n", __func__);
+       if (chip->is_open)
+               return -EBUSY;
+
+       rc = st33zp24_spi_init(dev);
+       if (rc < 0)
+               chip->is_open = 0;
+
+       return rc;
+}
+
+static int st33zp24_spi_close(struct udevice *dev)
+{
+       struct tpm_chip *chip = dev_get_priv(dev);
+
+       if (chip->is_open) {
+               st33zp24_spi_release_locality(dev);
+               chip->is_open = 0;
+               chip->vend_dev = 0;
+       }
+
+       return 0;
+}
+
+static int st33zp24_spi_get_desc(struct udevice *dev, char *buf, int size)
+{
+       struct tpm_chip *chip = dev_get_priv(dev);
+
+       if (size < 50)
+               return -ENOSPC;
+
+       return snprintf(buf, size, "1.2 TPM (%s, chip type %s device-id 0x%x)",
+                       chip->is_open ? "open" : "closed",
+                       dev->name,
+                       chip->vend_dev >> 16);
+}
+
+const struct tpm_ops st33zp24_spi_tpm_ops = {
+       .open = st33zp24_spi_open,
+       .close = st33zp24_spi_close,
+       .recv = st33zp24_spi_recv,
+       .send = st33zp24_spi_send,
+       .cleanup = st33zp24_spi_cleanup,
+       .get_desc = st33zp24_spi_get_desc,
+};
+
+static int st33zp24_spi_probe(struct udevice *dev)
+{
+       struct tpm_chip_priv *uc_priv = dev_get_uclass_priv(dev);
+
+       uc_priv->duration_ms[TPM_SHORT] = TIS_SHORT_TIMEOUT_MS;
+       uc_priv->duration_ms[TPM_MEDIUM] = TIS_LONG_TIMEOUT_MS;
+       uc_priv->duration_ms[TPM_LONG] = TIS_LONG_TIMEOUT_MS;
+       uc_priv->retry_time_ms = TPM_TIMEOUT_MS;
+
+       debug("ST33ZP24 SPI TPM from STMicroelectronics found\n");
+
+       return 0;
+}
+
+static int st33zp24_spi_remove(struct udevice *dev)
+{
+       st33zp24_spi_release_locality(dev);
+
+       return 0;
+}
+
+static const struct udevice_id st33zp24_spi_ids[] = {
+       { .compatible = "st,st33zp24-spi" },
+       { }
+};
+
+U_BOOT_DRIVER(st33zp24_spi_spi) = {
+       .name   = "st33zp24-spi",
+       .id     = UCLASS_TPM,
+       .of_match = of_match_ptr(st33zp24_spi_ids),
+       .probe  = st33zp24_spi_probe,
+       .remove = st33zp24_spi_remove,
+       .ops = &st33zp24_spi_tpm_ops,
+       .priv_auto_alloc_size = sizeof(struct tpm_chip),
+       .platdata_auto_alloc_size = sizeof(struct st33zp24_spi_phy),
+};