/*
   * STMicroelectronics TPM SPI Linux driver for TPM ST33ZP24
   * Copyright (C) 2009 - 2015  STMicroelectronics
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation; either version 2 of the License, or
   * (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, see <http://www.gnu.org/licenses/>.
   */
  
  #include <linux/module.h>
  #include <linux/spi/spi.h>
  #include <linux/gpio.h>
  #include <linux/of_irq.h>
  #include <linux/of_gpio.h>
  #include <linux/tpm.h>
  #include <linux/platform_data/st33zp24.h>
  
  #include "st33zp24.h"
  
  #define TPM_DATA_FIFO           0x24
  #define TPM_INTF_CAPABILITY     0x14
  
  #define TPM_DUMMY_BYTE		0x00
  
  #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 {
  	struct spi_device *spi_device;
  	struct spi_transfer spi_xfer;
  	u8 tx_buf[ST33ZP24_SPI_BUFFER_SIZE];
  	u8 rx_buf[ST33ZP24_SPI_BUFFER_SIZE];
  
  	int io_lpcpd;
  	int latency;
  };
  
  static int st33zp24_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 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 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_send(void *phy_id, u8 tpm_register, u8 *tpm_data,
  			     int tpm_size)
  {
  	u8 data = 0;
  	int total_length = 0, nbr_dummy_bytes = 0, ret = 0;
  	struct st33zp24_spi_phy *phy = phy_id;
  	struct spi_device *dev = phy->spi_device;
  	u8 *tx_buf = (u8 *)phy->spi_xfer.tx_buf;
  	u8 *rx_buf = phy->spi_xfer.rx_buf;
  
  	/* Pre-Header */
  	data = TPM_WRITE_DIRECTION | LOCALITY0;
  	memcpy(tx_buf + total_length, &data, sizeof(data));
  	total_length++;
  	data = tpm_register;
  	memcpy(tx_buf + total_length, &data, sizeof(data));
  	total_length++;
  
  	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;
  
  	nbr_dummy_bytes = phy->latency;
  	memset(&tx_buf[total_length], TPM_DUMMY_BYTE, nbr_dummy_bytes);
  
  	phy->spi_xfer.len = total_length + nbr_dummy_bytes;
  
  	ret = spi_sync_transfer(dev, &phy->spi_xfer, 1);
  	if (ret == 0)
  		ret = rx_buf[total_length + nbr_dummy_bytes - 1];
  
  	return st33zp24_status_to_errno(ret);
  } /* st33zp24_spi_send() */
  
  /*
   * read8_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: should be zero if success else a negative error code.
   */
  static int read8_reg(void *phy_id, u8 tpm_register, u8 *tpm_data, int tpm_size)
  {
  	u8 data = 0;
  	int total_length = 0, nbr_dummy_bytes, ret;
  	struct st33zp24_spi_phy *phy = phy_id;
  	struct spi_device *dev = phy->spi_device;
  	u8 *tx_buf = (u8 *)phy->spi_xfer.tx_buf;
  	u8 *rx_buf = phy->spi_xfer.rx_buf;
  
  	/* Pre-Header */
  	data = LOCALITY0;
  	memcpy(tx_buf + total_length, &data, sizeof(data));
  	total_length++;
  	data = tpm_register;
  	memcpy(tx_buf + total_length, &data, sizeof(data));
  	total_length++;
  
  	nbr_dummy_bytes = phy->latency;
  	memset(&tx_buf[total_length], TPM_DUMMY_BYTE,
  	       nbr_dummy_bytes + tpm_size);
  
  	phy->spi_xfer.len = total_length + nbr_dummy_bytes + tpm_size;
  
  	/* header + status byte + size of the data + status byte */
  	ret = spi_sync_transfer(dev, &phy->spi_xfer, 1);
  	if (tpm_size > 0 && ret == 0) {
  		ret = rx_buf[total_length + nbr_dummy_bytes - 1];
  
  		memcpy(tpm_data, rx_buf + total_length + nbr_dummy_bytes,
  		       tpm_size);
  	}
  
  	return ret;
  } /* read8_reg() */
  
  /*
   * 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_recv(void *phy_id, u8 tpm_register, u8 *tpm_data,
  			     int tpm_size)
  {
  	int ret;
  
  	ret = read8_reg(phy_id, tpm_register, tpm_data, tpm_size);
  	if (!st33zp24_status_to_errno(ret))
  		return tpm_size;
  	return ret;
  } /* st33zp24_spi_recv() */
  
  static int evaluate_latency(void *phy_id)
  {
  	struct st33zp24_spi_phy *phy = phy_id;
  	int latency = 1, status = 0;
  	u8 data = 0;
  
  	while (!status && latency < MAX_SPI_LATENCY) {
  		phy->latency = latency;
  		status = read8_reg(phy_id, TPM_INTF_CAPABILITY, &data, 1);
  		latency++;
  	}
  	return latency - 1;
  } /* evaluate_latency() */
  
  static const struct st33zp24_phy_ops spi_phy_ops = {
  	.send = st33zp24_spi_send,
  	.recv = st33zp24_spi_recv,
  };
  
  #ifdef CONFIG_OF
  static int tpm_stm_spi_of_request_resources(struct st33zp24_spi_phy *phy)
  {
  	struct device_node *pp;
  	struct spi_device *dev = phy->spi_device;
  	int gpio;
  	int ret;
  
  	pp = dev->dev.of_node;
  	if (!pp) {
  		dev_err(&dev->dev, "No platform data
  ");
  		return -ENODEV;
  	}
  
  	/* Get GPIO from device tree */
  	gpio = of_get_named_gpio(pp, "lpcpd-gpios", 0);
  	if (gpio < 0) {
  		dev_err(&dev->dev,
  			"Failed to retrieve lpcpd-gpios from dts.
  ");
  		phy->io_lpcpd = -1;
  		/*
  		 * lpcpd pin is not specified. This is not an issue as
  		 * power management can be also managed by TPM specific
  		 * commands. So leave with a success status code.
  		 */
  		return 0;
  	}
  	/* GPIO request and configuration */
  	ret = devm_gpio_request_one(&dev->dev, gpio,
  			GPIOF_OUT_INIT_HIGH, "TPM IO LPCPD");
  	if (ret) {
  		dev_err(&dev->dev, "Failed to request lpcpd pin
  ");
  		return -ENODEV;
  	}
  	phy->io_lpcpd = gpio;
  
  	return 0;
  }
  #else
  static int tpm_stm_spi_of_request_resources(struct st33zp24_spi_phy *phy)
  {
  	return -ENODEV;
  }
  #endif
  
  static int tpm_stm_spi_request_resources(struct spi_device *dev,
  					 struct st33zp24_spi_phy *phy)
  {
  	struct st33zp24_platform_data *pdata;
  	int ret;
  
  	pdata = dev->dev.platform_data;
  	if (!pdata) {
  		dev_err(&dev->dev, "No platform data
  ");
  		return -ENODEV;
  	}
  
  	/* store for late use */
  	phy->io_lpcpd = pdata->io_lpcpd;
  
  	if (gpio_is_valid(pdata->io_lpcpd)) {
  		ret = devm_gpio_request_one(&dev->dev,
  				pdata->io_lpcpd, GPIOF_OUT_INIT_HIGH,
  				"TPM IO_LPCPD");
  		if (ret) {
  			dev_err(&dev->dev, "%s : reset gpio_request failed
  ",
  				__FILE__);
  			return ret;
  		}
  	}
  
  	return 0;
  }
  
  /*
   * tpm_st33_spi_probe initialize the TPM device
   * @param: dev, the spi_device drescription (TPM SPI description).
   * @return: 0 in case of success.
   *	 or a negative value describing the error.
   */
  static int
  tpm_st33_spi_probe(struct spi_device *dev)
  {
  	int ret;
  	struct st33zp24_platform_data *pdata;
  	struct st33zp24_spi_phy *phy;
  
  	/* Check SPI platform functionnalities */
  	if (!dev) {
  		pr_info("%s: dev is NULL. Device is not accessible.
  ",
  			__func__);
  		return -ENODEV;
  	}
  
  	phy = devm_kzalloc(&dev->dev, sizeof(struct st33zp24_spi_phy),
  			   GFP_KERNEL);
  	if (!phy)
  		return -ENOMEM;
  
  	phy->spi_device = dev;
  	pdata = dev->dev.platform_data;
  	if (!pdata && dev->dev.of_node) {
  		ret = tpm_stm_spi_of_request_resources(phy);
  		if (ret)
  			return ret;
  	} else if (pdata) {
  		ret = tpm_stm_spi_request_resources(dev, phy);
  		if (ret)
  			return ret;
  	}
  
  	phy->spi_xfer.tx_buf = phy->tx_buf;
  	phy->spi_xfer.rx_buf = phy->rx_buf;
  
  	phy->latency = evaluate_latency(phy);
  	if (phy->latency <= 0)
  		return -ENODEV;
  
  	return st33zp24_probe(phy, &spi_phy_ops, &dev->dev, dev->irq,
  			      phy->io_lpcpd);
  }
  
  /*
   * tpm_st33_spi_remove remove the TPM device
   * @param: client, the spi_device drescription (TPM SPI description).
   * @return: 0 in case of success.
   */
  static int tpm_st33_spi_remove(struct spi_device *dev)
  {
  	struct tpm_chip *chip = spi_get_drvdata(dev);
  
  	return st33zp24_remove(chip);
  }
  
  static const struct spi_device_id st33zp24_spi_id[] = {
  	{TPM_ST33_SPI, 0},
  	{}
  };
  MODULE_DEVICE_TABLE(spi, st33zp24_spi_id);
  
  #ifdef CONFIG_OF
  static const struct of_device_id of_st33zp24_spi_match[] = {
  	{ .compatible = "st,st33zp24-spi", },
  	{}
  };
  MODULE_DEVICE_TABLE(of, of_st33zp24_spi_match);
  #endif
  
  static SIMPLE_DEV_PM_OPS(st33zp24_spi_ops, st33zp24_pm_suspend,
  			 st33zp24_pm_resume);
  
  static struct spi_driver tpm_st33_spi_driver = {
  	.driver = {
  		.name = TPM_ST33_SPI,
  		.pm = &st33zp24_spi_ops,
  		.of_match_table = of_match_ptr(of_st33zp24_spi_match),
  	},
  	.probe = tpm_st33_spi_probe,
  	.remove = tpm_st33_spi_remove,
  	.id_table = st33zp24_spi_id,
  };
  
  module_spi_driver(tpm_st33_spi_driver);
  
  MODULE_AUTHOR("TPM support (TPMsupport@list.st.com)");
  MODULE_DESCRIPTION("STM TPM 1.2 SPI ST33 Driver");
  MODULE_VERSION("1.3.0");
  MODULE_LICENSE("GPL");