text: // SPDX-License-Identifier: GPL-2.0-or-later
  /*
   * STMicroelectronics TPM I2C Linux driver for TPM ST33ZP24
   * Copyright (C) 2009 - 2016 STMicroelectronics
   */
  
  #include <linux/module.h>
  #include <linux/i2c.h>
  #include <linux/gpio.h>
  #include <linux/gpio/consumer.h>
  #include <linux/of_irq.h>
  #include <linux/of_gpio.h>
  #include <linux/acpi.h>
  #include <linux/tpm.h>
  #include <linux/platform_data/st33zp24.h>
  
  #include "../tpm.h"
  #include "st33zp24.h"
  
  #define TPM_DUMMY_BYTE			0xAA
  
  struct st33zp24_i2c_phy {
  	struct i2c_client *client;
  	u8 buf[ST33ZP24_BUFSIZE + 1];
  	int io_lpcpd;
  };
  
  /*
   * write8_reg
   * Send byte to the TIS register according to the ST33ZP24 I2C protocol.
   * @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: Returns negative errno, or else the number of bytes written.
   */
  static int write8_reg(void *phy_id, u8 tpm_register, u8 *tpm_data, int tpm_size)
  {
  	struct st33zp24_i2c_phy *phy = phy_id;
  
  	phy->buf[0] = tpm_register;
  	memcpy(phy->buf + 1, tpm_data, tpm_size);
  	return i2c_master_send(phy->client, phy->buf, tpm_size + 1);
  } /* write8_reg() */
  
  /*
   * read8_reg
   * Recv byte from the TIS register according to the ST33ZP24 I2C protocol.
   * @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 read8_reg(void *phy_id, u8 tpm_register, u8 *tpm_data, int tpm_size)
  {
  	struct st33zp24_i2c_phy *phy = phy_id;
  	u8 status = 0;
  	u8 data;
  
  	data = TPM_DUMMY_BYTE;
  	status = write8_reg(phy, tpm_register, &data, 1);
  	if (status == 2)
  		status = i2c_master_recv(phy->client, tpm_data, tpm_size);
  	return status;
  } /* read8_reg() */
  
  /*
   * st33zp24_i2c_send
   * Send byte to the TIS register according to the ST33ZP24 I2C 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: number of byte written successfully: should be one if success.
   */
  static int st33zp24_i2c_send(void *phy_id, u8 tpm_register, u8 *tpm_data,
  			     int tpm_size)
  {
  	return write8_reg(phy_id, tpm_register | TPM_WRITE_DIRECTION, tpm_data,
  			  tpm_size);
  }
  
  /*
   * st33zp24_i2c_recv
   * Recv byte from the TIS register according to the ST33ZP24 I2C 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_i2c_recv(void *phy_id, u8 tpm_register, u8 *tpm_data,
  			     int tpm_size)
  {
  	return read8_reg(phy_id, tpm_register, tpm_data, tpm_size);
  }
  
  static const struct st33zp24_phy_ops i2c_phy_ops = {
  	.send = st33zp24_i2c_send,
  	.recv = st33zp24_i2c_recv,
  };
  
  static const struct acpi_gpio_params lpcpd_gpios = { 1, 0, false };
  
  static const struct acpi_gpio_mapping acpi_st33zp24_gpios[] = {
  	{ "lpcpd-gpios", &lpcpd_gpios, 1 },
  	{},
  };
  
  static int st33zp24_i2c_acpi_request_resources(struct i2c_client *client)
  {
  	struct tpm_chip *chip = i2c_get_clientdata(client);
  	struct st33zp24_dev *tpm_dev = dev_get_drvdata(&chip->dev);
  	struct st33zp24_i2c_phy *phy = tpm_dev->phy_id;
  	struct gpio_desc *gpiod_lpcpd;
  	struct device *dev = &client->dev;
  	int ret;
  
  	ret = devm_acpi_dev_add_driver_gpios(dev, acpi_st33zp24_gpios);
  	if (ret)
  		return ret;
  
  	/* Get LPCPD GPIO from ACPI */
  	gpiod_lpcpd = devm_gpiod_get(dev, "lpcpd", GPIOD_OUT_HIGH);
  	if (IS_ERR(gpiod_lpcpd)) {
  		dev_err(&client->dev,
  			"Failed to retrieve lpcpd-gpios from acpi.\n");
  		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;
  	}
  
  	phy->io_lpcpd = desc_to_gpio(gpiod_lpcpd);
  
  	return 0;
  }
  
  static int st33zp24_i2c_of_request_resources(struct i2c_client *client)
  {
  	struct tpm_chip *chip = i2c_get_clientdata(client);
  	struct st33zp24_dev *tpm_dev = dev_get_drvdata(&chip->dev);
  	struct st33zp24_i2c_phy *phy = tpm_dev->phy_id;
  	struct device_node *pp;
  	int gpio;
  	int ret;
  
  	pp = client->dev.of_node;
  	if (!pp) {
  		dev_err(&client->dev, "No platform data\n");
  		return -ENODEV;
  	}
  
  	/* Get GPIO from device tree */
  	gpio = of_get_named_gpio(pp, "lpcpd-gpios", 0);
  	if (gpio < 0) {
  		dev_err(&client->dev,
  			"Failed to retrieve lpcpd-gpios from dts.\n");
  		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(&client->dev, gpio,
  			GPIOF_OUT_INIT_HIGH, "TPM IO LPCPD");
  	if (ret) {
  		dev_err(&client->dev, "Failed to request lpcpd pin\n");
  		return -ENODEV;
  	}
  	phy->io_lpcpd = gpio;
  
  	return 0;
  }
  
  static int st33zp24_i2c_request_resources(struct i2c_client *client)
  {
  	struct tpm_chip *chip = i2c_get_clientdata(client);
  	struct st33zp24_dev *tpm_dev = dev_get_drvdata(&chip->dev);
  	struct st33zp24_i2c_phy *phy = tpm_dev->phy_id;
  	struct st33zp24_platform_data *pdata;
  	int ret;
  
  	pdata = client->dev.platform_data;
  	if (!pdata) {
  		dev_err(&client->dev, "No platform data\n");
  		return -ENODEV;
  	}
  
  	/* store for late use */
  	phy->io_lpcpd = pdata->io_lpcpd;
  
  	if (gpio_is_valid(pdata->io_lpcpd)) {
  		ret = devm_gpio_request_one(&client->dev,
  				pdata->io_lpcpd, GPIOF_OUT_INIT_HIGH,
  				"TPM IO_LPCPD");
  		if (ret) {
  			dev_err(&client->dev, "Failed to request lpcpd pin\n");
  			return ret;
  		}
  	}
  
  	return 0;
  }
  
  /*
   * st33zp24_i2c_probe initialize the TPM device
   * @param: client, the i2c_client drescription (TPM I2C description).
   * @param: id, the i2c_device_id struct.
   * @return: 0 in case of success.
   *	 -1 in other case.
   */
  static int st33zp24_i2c_probe(struct i2c_client *client,
  			      const struct i2c_device_id *id)
  {
  	int ret;
  	struct st33zp24_platform_data *pdata;
  	struct st33zp24_i2c_phy *phy;
  
  	if (!client) {
  		pr_info("%s: i2c client is NULL. Device not accessible.\n",
  			__func__);
  		return -ENODEV;
  	}
  
  	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
  		dev_info(&client->dev, "client not i2c capable\n");
  		return -ENODEV;
  	}
  
  	phy = devm_kzalloc(&client->dev, sizeof(struct st33zp24_i2c_phy),
  			   GFP_KERNEL);
  	if (!phy)
  		return -ENOMEM;
  
  	phy->client = client;
  
  	pdata = client->dev.platform_data;
  	if (!pdata && client->dev.of_node) {
  		ret = st33zp24_i2c_of_request_resources(client);
  		if (ret)
  			return ret;
  	} else if (pdata) {
  		ret = st33zp24_i2c_request_resources(client);
  		if (ret)
  			return ret;
  	} else if (ACPI_HANDLE(&client->dev)) {
  		ret = st33zp24_i2c_acpi_request_resources(client);
  		if (ret)
  			return ret;
  	}
  
  	return st33zp24_probe(phy, &i2c_phy_ops, &client->dev, client->irq,
  			      phy->io_lpcpd);
  }
  
  /*
   * st33zp24_i2c_remove remove the TPM device
   * @param: client, the i2c_client description (TPM I2C description).
   * @return: 0 in case of success.
   */
  static int st33zp24_i2c_remove(struct i2c_client *client)
  {
  	struct tpm_chip *chip = i2c_get_clientdata(client);
  	int ret;
  
  	ret = st33zp24_remove(chip);
  	if (ret)
  		return ret;
  
  	return 0;
  }
  
  static const struct i2c_device_id st33zp24_i2c_id[] = {
  	{TPM_ST33_I2C, 0},
  	{}
  };
  MODULE_DEVICE_TABLE(i2c, st33zp24_i2c_id);
  
  static const struct of_device_id of_st33zp24_i2c_match[] = {
  	{ .compatible = "st,st33zp24-i2c", },
  	{}
  };
  MODULE_DEVICE_TABLE(of, of_st33zp24_i2c_match);
  
  static const struct acpi_device_id st33zp24_i2c_acpi_match[] = {
  	{"SMO3324"},
  	{}
  };
  MODULE_DEVICE_TABLE(acpi, st33zp24_i2c_acpi_match);
  
  static SIMPLE_DEV_PM_OPS(st33zp24_i2c_ops, st33zp24_pm_suspend,
  			 st33zp24_pm_resume);
  
  static struct i2c_driver st33zp24_i2c_driver = {
  	.driver = {
  		.name = TPM_ST33_I2C,
  		.pm = &st33zp24_i2c_ops,
  		.of_match_table = of_match_ptr(of_st33zp24_i2c_match),
  		.acpi_match_table = ACPI_PTR(st33zp24_i2c_acpi_match),
  	},
  	.probe = st33zp24_i2c_probe,
  	.remove = st33zp24_i2c_remove,
  	.id_table = st33zp24_i2c_id
  };
  
  module_i2c_driver(st33zp24_i2c_driver);
  
  MODULE_AUTHOR("TPM support (TPMsupport@list.st.com)");
  MODULE_DESCRIPTION("STM TPM 1.2 I2C ST33 Driver");
  MODULE_VERSION("1.3.0");
  MODULE_LICENSE("GPL");
  