drivers/tpm/tpm2_tis_spi.c - github/trini/u-boot - Gitiles

 // SPDX-License-Identifier: GPL-2.0
 /*
  * 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.
  */

 #include <common.h>
 #include <dm.h>
 #include <fdtdec.h>
 #include <log.h>
 #include <spi.h>
 #include <tpm-v2.h>
 #include <linux/bitops.h>
 #include <linux/delay.h>
 #include <linux/errno.h>
 #include <linux/compiler.h>
 #include <linux/types.h>
 #include <linux/unaligned/be_byteshift.h>
 #include <asm-generic/gpio.h>

 #include "tpm_tis.h"
 #include "tpm_internal.h"

 #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

 /* Number of wait states to wait for */
 #define TPM_WAIT_STATES 100

 /**
  * struct tpm_tis_chip_data - Non-discoverable TPM information
  *
  * @pcr_count:		Number of PCR per bank
  * @pcr_select_min:	Size in octets of the pcrSelect array
  */
 struct tpm_tis_chip_data {
 	unsigned int pcr_count;
 	unsigned int pcr_select_min;
 	unsigned int time_before_first_cmd_ms;
 };

 /**
  * 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) {
 		log(LOGC_NONE, LOGL_ERR, "%s: can't do full duplex\n",
 		    __func__);
 		return -EINVAL;
 	}

 	ret = spi_claim_bus(slave);
 	if (ret < 0) {
 		log(LOGC_NONE, LOGL_ERR, "%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) {
 			log(LOGC_NONE, LOGL_ERR,
 			    "%s: spi request transfer failed (err: %d)\n",
 			    __func__, ret);
 			goto release_bus;
 		}

 		/* Wait state */
 		if (!(rx_buf[3] & 0x1)) {
 			int i;

 			for (i = 0; i < TPM_WAIT_STATES; i++) {
 				ret = spi_xfer(slave, 1 * 8, NULL, rx_buf, 0);
 				if (ret) {
 					log(LOGC_NONE, LOGL_ERR,
 					    "%s: wait state failed: %d\n",
 					    __func__, ret);
 					goto release_bus;
 				}

 				if (rx_buf[0] & 0x1)
 					break;
 			}

 			if (i == TPM_WAIT_STATES) {
 				log(LOGC_NONE, LOGL_ERR,
 				    "%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) {
 			log(LOGC_NONE, LOGL_ERR,
 			    "%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 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 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) {
 		log(LOGC_NONE, LOGL_ERR, "%s: Failed to get locality: %d\n",
 		    __func__, ret);
 		return ret;
 	}

 	ret = tpm_tis_spi_write(dev, TPM_ACCESS(loc), &buf, 1);
 	if (ret) {
 		log(LOGC_NONE, LOGL_ERR, "%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) {
 			log(LOGC_NONE, LOGL_ERR,
 			    "%s: Failed to get locality: %d\n", __func__, ret);
 			return ret;
 		}

 		mdelay(TPM_TIMEOUT_MS);
 	} while (get_timer(start) < stop);

 	log(LOGC_NONE, LOGL_ERR, "%s: Timeout getting locality: %d\n", __func__,
 	    ret);

 	return ret;
 }

 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;
 }

 static u8 tpm_tis_spi_valid_status(struct udevice *dev, u8 *status)
 {
 	struct tpm_chip *chip = dev_get_priv(dev);

 	return tpm_tis_spi_wait_for_stat(dev, TPM_STS_VALID,
 		chip->timeout_c, status);
 }

 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;
 }

 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) {
 		log(LOGC_NONE, LOGL_ERR, "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) {
 		log(LOGC_NONE, LOGL_ERR,
 		    "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) {
 			log(LOGC_NONE, LOGL_ERR,
 			    "%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)) {
 			log(LOGC_NONE, LOGL_ERR,
 			    "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_valid_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_valid_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_tis_chip_data *drv_data = (void *)dev_get_driver_data(dev);
 	struct tpm_chip_priv *priv = dev_get_uclass_priv(dev);
 	struct tpm_chip *chip = dev_get_priv(dev);
 	int ret;

 	/* Use the TPM v2 stack */
 	priv->version = TPM_V2;

 	if (CONFIG_IS_ENABLED(DM_GPIO)) {
 		struct gpio_desc reset_gpio;

 		ret = gpio_request_by_name(dev, "reset-gpios", 0,
 					   &reset_gpio, GPIOD_IS_OUT);
 		if (ret) {
 			/* legacy reset */
 			ret = gpio_request_by_name(dev, "gpio-reset", 0,
 						   &reset_gpio, GPIOD_IS_OUT);
 			if (ret) {
 				log(LOGC_NONE, LOGL_NOTICE,
 				    "%s: missing reset GPIO\n", __func__);
 				goto init;
 			}
 			log(LOGC_NONE, LOGL_NOTICE,
 			    "%s: gpio-reset is deprecated\n", __func__);
 		}
 		dm_gpio_set_value(&reset_gpio, 1);
 		mdelay(1);
 		dm_gpio_set_value(&reset_gpio, 0);
 	}
 init:
 	/* Ensure a minimum amount of time elapsed since reset of the TPM */
 	mdelay(drv_data->time_before_first_cmd_ms);

 	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;
 	priv->pcr_count = drv_data->pcr_count;
 	priv->pcr_select_min = drv_data->pcr_select_min;

 	ret = tpm_tis_wait_init(dev, chip->locality);
 	if (ret) {
 		log(LOGC_DM, LOGL_ERR, "%s: no device found\n", __func__);
 		return ret;
 	}

 	ret = tpm_tis_spi_request_locality(dev, chip->locality);
 	if (ret) {
 		log(LOGC_NONE, LOGL_ERR, "%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) {
 		log(LOGC_NONE, LOGL_ERR,
 		    "%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) {
 		log(LOGC_NONE, LOGL_ERR, "%s: could not retrieve RevisionID\n",
 		    __func__);
 		return ret;
 	}

 	log(LOGC_NONE, LOGL_ERR,
 	    "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 tpm_tis_chip_data tpm_tis_std_chip_data = {
 	.pcr_count = 24,
 	.pcr_select_min = 3,
 	.time_before_first_cmd_ms = 30,
 };

 static const struct udevice_id tpm_tis_spi_ids[] = {
 	{
 		.compatible = "tcg,tpm_tis-spi",
 		.data = (ulong)&tpm_tis_std_chip_data,
 	},
 	{ }
 };

 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	= sizeof(struct tpm_chip),
 };
	// SPDX-License-Identifier: GPL-2.0
	/*
	* 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.
	*/

	#include <common.h>
	#include <dm.h>
	#include <fdtdec.h>
	#include <log.h>
	#include <spi.h>
	#include <tpm-v2.h>
	#include <linux/bitops.h>
	#include <linux/delay.h>
	#include <linux/errno.h>
	#include <linux/compiler.h>
	#include <linux/types.h>
	#include <linux/unaligned/be_byteshift.h>
	#include <asm-generic/gpio.h>

	#include "tpm_tis.h"
	#include "tpm_internal.h"

	#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

	/* Number of wait states to wait for */
	#define TPM_WAIT_STATES 100

	/**
	* struct tpm_tis_chip_data - Non-discoverable TPM information
	*
	* @pcr_count: Number of PCR per bank
	* @pcr_select_min: Size in octets of the pcrSelect array
	*/
	struct tpm_tis_chip_data {
	unsigned int pcr_count;
	unsigned int pcr_select_min;
	unsigned int time_before_first_cmd_ms;
	};

	/**
	* 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) {
	log(LOGC_NONE, LOGL_ERR, "%s: can't do full duplex\n",
	__func__);
	return -EINVAL;
	}

	ret = spi_claim_bus(slave);
	if (ret < 0) {
	log(LOGC_NONE, LOGL_ERR, "%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) {
	log(LOGC_NONE, LOGL_ERR,
	"%s: spi request transfer failed (err: %d)\n",
	__func__, ret);
	goto release_bus;
	}

	/* Wait state */
	if (!(rx_buf[3] & 0x1)) {
	int i;

	for (i = 0; i < TPM_WAIT_STATES; i++) {
	ret = spi_xfer(slave, 1 * 8, NULL, rx_buf, 0);
	if (ret) {
	log(LOGC_NONE, LOGL_ERR,
	"%s: wait state failed: %d\n",
	__func__, ret);
	goto release_bus;
	}

	if (rx_buf[0] & 0x1)
	break;
	}

	if (i == TPM_WAIT_STATES) {
	log(LOGC_NONE, LOGL_ERR,
	"%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) {
	log(LOGC_NONE, LOGL_ERR,
	"%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 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 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) {
	log(LOGC_NONE, LOGL_ERR, "%s: Failed to get locality: %d\n",
	__func__, ret);
	return ret;
	}

	ret = tpm_tis_spi_write(dev, TPM_ACCESS(loc), &buf, 1);
	if (ret) {
	log(LOGC_NONE, LOGL_ERR, "%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) {
	log(LOGC_NONE, LOGL_ERR,
	"%s: Failed to get locality: %d\n", __func__, ret);
	return ret;
	}

	mdelay(TPM_TIMEOUT_MS);
	} while (get_timer(start) < stop);

	log(LOGC_NONE, LOGL_ERR, "%s: Timeout getting locality: %d\n", __func__,
	ret);

	return ret;
	}

	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;
	}

	static u8 tpm_tis_spi_valid_status(struct udevice dev, u8 status)
	{
	struct tpm_chip *chip = dev_get_priv(dev);

	return tpm_tis_spi_wait_for_stat(dev, TPM_STS_VALID,
	chip->timeout_c, status);
	}

	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;
	}

	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) {
	log(LOGC_NONE, LOGL_ERR, "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) {
	log(LOGC_NONE, LOGL_ERR,
	"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) {
	log(LOGC_NONE, LOGL_ERR,
	"%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)) {
	log(LOGC_NONE, LOGL_ERR,
	"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_valid_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_valid_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_tis_chip_data drv_data = (void )dev_get_driver_data(dev);
	struct tpm_chip_priv *priv = dev_get_uclass_priv(dev);
	struct tpm_chip *chip = dev_get_priv(dev);
	int ret;

	/* Use the TPM v2 stack */
	priv->version = TPM_V2;

	if (CONFIG_IS_ENABLED(DM_GPIO)) {
	struct gpio_desc reset_gpio;

	ret = gpio_request_by_name(dev, "reset-gpios", 0,
	&reset_gpio, GPIOD_IS_OUT);
	if (ret) {
	/* legacy reset */
	ret = gpio_request_by_name(dev, "gpio-reset", 0,
	&reset_gpio, GPIOD_IS_OUT);
	if (ret) {
	log(LOGC_NONE, LOGL_NOTICE,
	"%s: missing reset GPIO\n", __func__);
	goto init;
	}
	log(LOGC_NONE, LOGL_NOTICE,
	"%s: gpio-reset is deprecated\n", __func__);
	}
	dm_gpio_set_value(&reset_gpio, 1);
	mdelay(1);
	dm_gpio_set_value(&reset_gpio, 0);
	}
	init:
	/* Ensure a minimum amount of time elapsed since reset of the TPM */
	mdelay(drv_data->time_before_first_cmd_ms);

	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;
	priv->pcr_count = drv_data->pcr_count;
	priv->pcr_select_min = drv_data->pcr_select_min;

	ret = tpm_tis_wait_init(dev, chip->locality);
	if (ret) {
	log(LOGC_DM, LOGL_ERR, "%s: no device found\n", __func__);
	return ret;
	}

	ret = tpm_tis_spi_request_locality(dev, chip->locality);
	if (ret) {
	log(LOGC_NONE, LOGL_ERR, "%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) {
	log(LOGC_NONE, LOGL_ERR,
	"%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) {
	log(LOGC_NONE, LOGL_ERR, "%s: could not retrieve RevisionID\n",
	__func__);
	return ret;
	}

	log(LOGC_NONE, LOGL_ERR,
	"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 tpm_tis_chip_data tpm_tis_std_chip_data = {
	.pcr_count = 24,
	.pcr_select_min = 3,
	.time_before_first_cmd_ms = 30,
	};

	static const struct udevice_id tpm_tis_spi_ids[] = {
	{
	.compatible = "tcg,tpm_tis-spi",
	.data = (ulong)&tpm_tis_std_chip_data,
	},
	{ }
	};

	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 = sizeof(struct tpm_chip),
	};