/*
 * 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),
};