/*
   * Copyright (C) 2011 Infineon Technologies
   *
   * Authors:
   * Peter Huewe <huewe.external@infineon.com>
   *
   * Description:
   * Device driver for TCG/TCPA TPM (trusted platform module).
   * Specifications at www.trustedcomputinggroup.org
   *
   * This device driver implements the TPM interface as defined in
   * the TCG TPM Interface Spec version 1.2, revision 1.0 and the
   * Infineon I2C Protocol Stack Specification v0.20.
   *
   * It is based on the Linux kernel driver tpm.c from Leendert van
   * Dorn, Dave Safford, Reiner Sailer, and Kyleen Hall.
   *
   * Version: 2.1.1
   *

   * SPDX-License-Identifier:	GPL-2.0

   */
  
  #include <common.h>

  #include <dm.h>

  #include <fdtdec.h>

  #include <i2c.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;

  enum i2c_chip_type {
  	SLB9635,
  	SLB9645,
  	UNKNOWN,
  };
  
  /* expected value for DIDVID register */
  #define TPM_TIS_I2C_DID_VID_9635 0x000b15d1L
  #define TPM_TIS_I2C_DID_VID_9645 0x001a15d1L

  static const char * const chip_name[] = {
  	[SLB9635] = "slb9635tt",
  	[SLB9645] = "slb9645tt",
  	[UNKNOWN] = "unknown/fallback to slb9635",
  };

  #define	TPM_ACCESS(l)			(0x0000 | ((l) << 4))
  #define	TPM_STS(l)			(0x0001 | ((l) << 4))
  #define	TPM_DATA_FIFO(l)		(0x0005 | ((l) << 4))
  #define	TPM_DID_VID(l)			(0x0006 | ((l) << 4))

  /*

   * tpm_tis_i2c_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_i2c_read(struct udevice *dev, u8 addr, u8 *buffer,
  			    size_t len)

  {

  	struct tpm_chip *chip = dev_get_priv(dev);

  	int rc;
  	int count;

  	uint32_t addrbuf = addr;

  	if ((chip->chip_type == SLB9635) || (chip->chip_type == UNKNOWN)) {

  		/* slb9635 protocol should work in both cases */
  		for (count = 0; count < MAX_COUNT; count++) {

  			rc = dm_i2c_write(dev, 0, (uchar *)&addrbuf, 1);

  			if (rc == 0)

  				break;  /* Success, break to skip sleep */

  			udelay(SLEEP_DURATION_US);

  		}

  		if (rc)

  			return rc;

  
  		/* After the TPM has successfully received the register address
  		 * it needs some time, thus we're sleeping here again, before
  		 * retrieving the data
  		 */
  		for (count = 0; count < MAX_COUNT; count++) {

  			udelay(SLEEP_DURATION_US);

  			rc = dm_i2c_read(dev, 0, buffer, len);

  			if (rc == 0)
  				break;  /* success, break to skip sleep */
  		}
  	} else {

  		/*
  		 * Use a combined read for newer chips.
  		 * Unfortunately the smbus functions are not suitable due to

  		 * the 32 byte limit of the smbus.

  		 * Retries should usually not be needed, but are kept just to

  		 * be safe on the safe side.
  		 */
  		for (count = 0; count < MAX_COUNT; count++) {

  			rc = dm_i2c_read(dev, addr, buffer, len);

  			if (rc == 0)
  				break;  /* break here to skip sleep */

  			udelay(SLEEP_DURATION_US);

  		}

  	}

  	/* Take care of 'guard time' */

  	udelay(SLEEP_DURATION_US);

  	if (rc)

  		return rc;

  
  	return 0;
  }

  static int tpm_tis_i2c_write_generic(struct udevice *dev, u8 addr,
  				     const u8 *buffer, size_t len,

  				     unsigned int sleep_time_us, u8 max_count)

  {

  	struct tpm_chip_priv *priv = dev_get_uclass_priv(dev);
  	struct tpm_chip *chip = dev_get_priv(dev);

  	int rc = 0;
  	int count;

  	if (chip->chip_type == SLB9635) {
  		/* Prepare send buffer to include the address */
  		priv->buf[0] = addr;
  		memcpy(&(priv->buf[1]), buffer, len);
  		buffer = priv->buf;
  		len++;
  		addr = 0;
  	}

  	for (count = 0; count < max_count; count++) {

  		rc = dm_i2c_write(dev, addr, buffer, len);

  		if (rc == 0)

  			break;  /* Success, break to skip sleep */

  		udelay(sleep_time_us);

  	}

  	/* take care of 'guard time' */

  	udelay(sleep_time_us);

  	if (rc)

  		return rc;

  
  	return 0;
  }
  
  /*

   * tpm_tis_i2c_write() - write to TPM register

   * @addr: register address to write to
   * @buffer: containing data to be written
   * @len: number of bytes to write
   *
   * Write len bytes from provided buffer to TPM register (little
   * endian format, i.e. buffer[0] is written as first byte).
   *
   * NOTE: TPM is big-endian for multi-byte values. Multi-byte
   * values have to be swapped.
   *

   * NOTE: use this function instead of the tpm_tis_i2c_write_generic function.

   *
   * Return -EIO on error, 0 on success
   */

  static int tpm_tis_i2c_write(struct udevice *dev, u8 addr, const u8 *buffer,
  			     size_t len)

  {

  	return tpm_tis_i2c_write_generic(dev, addr, buffer, len,
  					 SLEEP_DURATION_US, MAX_COUNT);

  }
  
  /*
   * This function is needed especially for the cleanup situation after
   * sending TPM_READY

   */

  static int tpm_tis_i2c_write_long(struct udevice *dev, u8 addr, u8 *buffer,
  				  size_t len)

  {

  	return tpm_tis_i2c_write_generic(dev, addr, buffer, len,

  					 SLEEP_DURATION_LONG_US,
  					 MAX_COUNT_LONG);

  }

  static int tpm_tis_i2c_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 rc;

  	rc = tpm_tis_i2c_read(dev, TPM_ACCESS(loc), &buf, 1);

  	if (rc < 0)
  		return rc;

  	if ((buf & mask) == mask) {

  		chip->locality = loc;

  		return loc;
  	}

  	return -ENOENT;

  }

  static void tpm_tis_i2c_release_locality(struct udevice *dev, int loc,

  					 int force)

  {

  	const u8 mask = TPM_ACCESS_REQUEST_PENDING | TPM_ACCESS_VALID;

  	u8 buf;

  	if (tpm_tis_i2c_read(dev, TPM_ACCESS(loc), &buf, 1) < 0)

  		return;

  	if (force || (buf & mask) == mask) {

  		buf = TPM_ACCESS_ACTIVE_LOCALITY;

  		tpm_tis_i2c_write(dev, TPM_ACCESS(loc), &buf, 1);

  	}
  }

  static int tpm_tis_i2c_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 rc;

  	rc = tpm_tis_i2c_check_locality(dev, loc);
  	if (rc >= 0) {
  		debug("%s: Already have locality
  ", __func__);

  		return loc;  /* We already have the locality */

  	} else if (rc != -ENOENT) {
  		debug("%s: Failed to get locality: %d
  ", __func__, rc);
  		return rc;
  	}

  	rc = tpm_tis_i2c_write(dev, TPM_ACCESS(loc), &buf, 1);
  	if (rc) {
  		debug("%s: Failed to write to TPM: %d
  ", __func__, rc);

  		return rc;

  	}

  	/* Wait for burstcount */

  	start = get_timer(0);

  	stop = chip->timeout_a;

  	do {

  		rc = tpm_tis_i2c_check_locality(dev, loc);
  		if (rc >= 0) {
  			debug("%s: Have locality
  ", __func__);

  			return loc;

  		} else if (rc != -ENOENT) {
  			debug("%s: Failed to get locality: %d
  ", __func__, rc);
  			return rc;
  		}

  		mdelay(TPM_TIMEOUT_MS);

  	} while (get_timer(start) < stop);

  	debug("%s: Timeout getting locality: %d
  ", __func__, rc);

  	return rc;

  }

  static u8 tpm_tis_i2c_status(struct udevice *dev)

  {

  	struct tpm_chip *chip = dev_get_priv(dev);

  	/* NOTE: Since i2c read may fail, return 0 in this case --> time-out */

  	u8 buf;

  	if (tpm_tis_i2c_read(dev, TPM_STS(chip->locality), &buf, 1) < 0)

  		return 0;
  	else
  		return buf;
  }

  static int tpm_tis_i2c_ready(struct udevice *dev)

  {

  	struct tpm_chip *chip = dev_get_priv(dev);

  	int rc;

  	/* This causes the current command to be aborted */

  	u8 buf = TPM_STS_COMMAND_READY;

  	debug("%s
  ", __func__);

  	rc = tpm_tis_i2c_write_long(dev, TPM_STS(chip->locality), &buf, 1);

  	if (rc)
  		debug("%s: rc=%d
  ", __func__, rc);

  
  	return rc;

  }

  static ssize_t tpm_tis_i2c_get_burstcount(struct udevice *dev)

  {

  	struct tpm_chip *chip = dev_get_priv(dev);

  	unsigned long start, stop;
  	ssize_t burstcnt;

  	u8 addr, buf[3];

  	/* Wait for burstcount */
  	/* XXX: Which timeout value? Spec has 2 answers (c & d) */

  	start = get_timer(0);

  	stop = chip->timeout_d;

  	do {
  		/* Note: STS is little endian */

  		addr = TPM_STS(chip->locality) + 1;

  		if (tpm_tis_i2c_read(dev, addr, buf, 3) < 0)

  			burstcnt = 0;
  		else
  			burstcnt = (buf[2] << 16) + (buf[1] << 8) + buf[0];
  
  		if (burstcnt)
  			return burstcnt;

  		mdelay(TPM_TIMEOUT_MS);

  	} while (get_timer(start) < stop);
  
  	return -EBUSY;
  }

  static int tpm_tis_i2c_wait_for_stat(struct udevice *dev, u8 mask,

  				     unsigned long timeout, int *status)

  {
  	unsigned long start, stop;

  	/* Check current status */

  	*status = tpm_tis_i2c_status(dev);

  	if ((*status & mask) == mask)
  		return 0;
  
  	start = get_timer(0);
  	stop = timeout;
  	do {

  		mdelay(TPM_TIMEOUT_MS);

  		*status = tpm_tis_i2c_status(dev);

  		if ((*status & mask) == mask)
  			return 0;

  	} while (get_timer(start) < stop);

  	return -ETIMEDOUT;

  }

  static int tpm_tis_i2c_recv_data(struct udevice *dev, u8 *buf, size_t count)

  {

  	struct tpm_chip *chip = dev_get_priv(dev);

  	size_t size = 0;
  	ssize_t burstcnt;
  	int rc;
  
  	while (size < count) {

  		burstcnt = tpm_tis_i2c_get_burstcount(dev);

  		/* burstcount < 0 -> tpm is busy */

  		if (burstcnt < 0)
  			return burstcnt;

  		/* Limit received data to max left */

  		if (burstcnt > (count - size))
  			burstcnt = count - size;

  		rc = tpm_tis_i2c_read(dev, TPM_DATA_FIFO(chip->locality),
  				      &(buf[size]), burstcnt);

  		if (rc == 0)
  			size += burstcnt;
  	}
  
  	return size;
  }

  static int tpm_tis_i2c_recv(struct udevice *dev, u8 *buf, size_t count)

  {

  	struct tpm_chip *chip = dev_get_priv(dev);

  	int size = 0;

  	int status;
  	unsigned int expected;

  	int rc;

  	status = tpm_tis_i2c_status(dev);
  	if (status == TPM_STS_COMMAND_READY)
  		return -EINTR;
  	if ((status & (TPM_STS_DATA_AVAIL | TPM_STS_VALID)) !=
  	    (TPM_STS_DATA_AVAIL | TPM_STS_VALID))
  		return -EAGAIN;
  
  	debug("...got it;
  ");

  	/* Read first 10 bytes, including tag, paramsize, and result */

  	size = tpm_tis_i2c_recv_data(dev, buf, TPM_HEADER_SIZE);

  	if (size < TPM_HEADER_SIZE) {

  		debug("Unable to read header
  ");
  		return size < 0 ? size : -EIO;

  	}
  
  	expected = get_unaligned_be32(buf + TPM_RSP_SIZE_BYTE);

  	if ((size_t)expected > count || (size_t)expected < TPM_HEADER_SIZE) {

  		debug("Error size=%x, expected=%x, count=%x
  ", size, expected,

  		      count);

  		return -ENOSPC;

  	}

  	size += tpm_tis_i2c_recv_data(dev, &buf[TPM_HEADER_SIZE],

  				      expected - TPM_HEADER_SIZE);

  	if (size < expected) {

  		debug("Unable to read remainder of result
  ");
  		return -ETIMEDOUT;

  	}

  	rc = tpm_tis_i2c_wait_for_stat(dev, TPM_STS_VALID, chip->timeout_c,
  				       &status);
  	if (rc)
  		return rc;

  	if (status & TPM_STS_DATA_AVAIL) {  /* Retry? */

  		debug("Error left over data
  ");
  		return -EIO;

  	}

  	return size;
  }

  static int tpm_tis_i2c_send(struct udevice *dev, const u8 *buf, size_t len)

  {

  	struct tpm_chip *chip = dev_get_priv(dev);

  	int rc, status;

  	size_t burstcnt;

  	size_t count = 0;

  	int retry = 0;

  	u8 sts = TPM_STS_GO;

  	debug("%s: len=%d
  ", __func__, len);

  	if (len > TPM_DEV_BUFSIZE)
  		return -E2BIG;  /* Command is too long for our tpm, sorry */

  	if (tpm_tis_i2c_request_locality(dev, 0) < 0)

  		return -EBUSY;

  	status = tpm_tis_i2c_status(dev);

  	if ((status & TPM_STS_COMMAND_READY) == 0) {

  		rc = tpm_tis_i2c_ready(dev);
  		if (rc)
  			return rc;
  		rc = tpm_tis_i2c_wait_for_stat(dev, TPM_STS_COMMAND_READY,
  					       chip->timeout_b, &status);
  		if (rc)
  			return rc;

  	}

  	burstcnt = tpm_tis_i2c_get_burstcount(dev);

  	/* burstcount < 0 -> tpm is busy */
  	if (burstcnt < 0)
  		return burstcnt;

  	while (count < len) {
  		udelay(300);
  		if (burstcnt > len - count)
  			burstcnt = len - count;

  #ifdef CONFIG_TPM_TIS_I2C_BURST_LIMITATION

  		if (retry && burstcnt > CONFIG_TPM_TIS_I2C_BURST_LIMITATION_LEN)
  			burstcnt = CONFIG_TPM_TIS_I2C_BURST_LIMITATION_LEN;

  #endif /* CONFIG_TPM_TIS_I2C_BURST_LIMITATION */

  		rc = tpm_tis_i2c_write(dev, TPM_DATA_FIFO(chip->locality),
  				       &(buf[count]), burstcnt);

  		if (rc == 0)
  			count += burstcnt;

  		else {

  			debug("%s: error
  ", __func__);

  			if (retry++ > 10)
  				return -EIO;
  			rc = tpm_tis_i2c_wait_for_stat(dev, TPM_STS_VALID,

  						       chip->timeout_c,
  						       &status);

  			if (rc)

  				return rc;

  			if ((status & TPM_STS_DATA_EXPECT) == 0)
  				return -EIO;

  		}
  	}

  	/* Go and do it */

  	rc = tpm_tis_i2c_write(dev, TPM_STS(chip->locality), &sts, 1);
  	if (rc < 0)
  		return rc;
  	debug("%s: done, rc=%d
  ", __func__, rc);

  
  	return len;

  }
  
  static int tpm_tis_i2c_cleanup(struct udevice *dev)
  {
  	struct tpm_chip *chip = dev_get_priv(dev);

  	tpm_tis_i2c_ready(dev);

  	/*
  	 * The TPM needs some time to clean up here,

  	 * so we sleep rather than keeping the bus busy
  	 */

  	mdelay(2);

  	tpm_tis_i2c_release_locality(dev, chip->locality, 0);

  	return 0;

  }

  static int tpm_tis_i2c_init(struct udevice *dev)

  {

  	struct tpm_chip *chip = dev_get_priv(dev);

  	u32 vendor;

  	u32 expected_did_vid;

  	int rc;

  	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;

  	rc = tpm_tis_i2c_request_locality(dev, 0);
  	if (rc < 0)
  		return rc;

  	/* Read four bytes from DID_VID register */

  	if (tpm_tis_i2c_read(dev, TPM_DID_VID(0), (uchar *)&vendor, 4) < 0) {
  		tpm_tis_i2c_release_locality(dev, 0, 1);

  		return -EIO;

  	}

  	if (chip->chip_type == SLB9635) {

  		vendor = be32_to_cpu(vendor);
  		expected_did_vid = TPM_TIS_I2C_DID_VID_9635;
  	} else {
  		/* device id and byte order has changed for newer i2c tpms */
  		expected_did_vid = TPM_TIS_I2C_DID_VID_9645;
  	}

  	if (chip->chip_type != UNKNOWN && vendor != expected_did_vid) {

  		pr_err("Vendor id did not match! ID was %08x
  ", vendor);

  		return -ENODEV;

  	}

  	chip->vend_dev = vendor;

  	debug("1.2 TPM (chip type %s device-id 0x%X)
  ",

  	      chip_name[chip->chip_type], vendor >> 16);

  
  	/*
  	 * A timeout query to TPM can be placed here.
  	 * Standard timeout values are used so far
  	 */
  
  	return 0;

  }

  static int tpm_tis_i2c_open(struct udevice *dev)

  {

  	struct tpm_chip *chip = dev_get_priv(dev);

  	int rc;

  	debug("%s: start
  ", __func__);
  	if (chip->is_open)
  		return -EBUSY;
  	rc = tpm_tis_i2c_init(dev);

  	if (rc < 0)

  		chip->is_open = 0;

  	return rc;
  }

  static int tpm_tis_i2c_close(struct udevice *dev)

  {

  	struct tpm_chip *chip = dev_get_priv(dev);

  	if (chip->is_open) {
  		tpm_tis_i2c_release_locality(dev, chip->locality, 1);
  		chip->is_open = 0;
  		chip->vend_dev = 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 < 50)
  		return -ENOSPC;

  	return snprintf(buf, size, "1.2 TPM (%s, chip type %s device-id 0x%x)",
  			chip->is_open ? "open" : "closed",
  			chip_name[chip->chip_type],
  			chip->vend_dev >> 16);

  }

  static int tpm_tis_i2c_probe(struct udevice *dev)

  {

  	struct tpm_chip_priv *uc_priv = dev_get_uclass_priv(dev);
  	struct tpm_chip *chip = dev_get_priv(dev);

  	chip->chip_type = dev_get_driver_data(dev);

  	/* TODO: These need to be checked and tuned */
  	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;

  
  	return 0;
  }

  static const struct tpm_ops tpm_tis_i2c_ops = {
  	.open		= tpm_tis_i2c_open,
  	.close		= tpm_tis_i2c_close,
  	.get_desc	= tpm_tis_get_desc,
  	.send		= tpm_tis_i2c_send,
  	.recv		= tpm_tis_i2c_recv,
  	.cleanup	= tpm_tis_i2c_cleanup,
  };

  static const struct udevice_id tpm_tis_i2c_ids[] = {
  	{ .compatible = "infineon,slb9635tt", .data = SLB9635 },
  	{ .compatible = "infineon,slb9645tt", .data = SLB9645 },
  	{ }
  };

  U_BOOT_DRIVER(tpm_tis_i2c) = {

  	.name   = "tpm_tis_infineon",

  	.id     = UCLASS_TPM,
  	.of_match = tpm_tis_i2c_ids,
  	.ops    = &tpm_tis_i2c_ops,
  	.probe	= tpm_tis_i2c_probe,
  	.priv_auto_alloc_size = sizeof(struct tpm_chip),
  };