/*
 * STMicroelectronics TPM I2C 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/i2c.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_DUMMY_BYTE                  0xAA

struct st33zp24_i2c_phy {
        struct i2c_client *client;
        u8 buf[TPM_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,
};

#ifdef CONFIG_OF
static int st33zp24_i2c_of_request_resources(struct st33zp24_i2c_phy *phy)
{
        struct device_node *pp;
        struct i2c_client *client = phy->client;
        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;
}
#else
static int st33zp24_i2c_of_request_resources(struct st33zp24_i2c_phy *phy)
{
        return -ENODEV;
}
#endif

static int st33zp24_i2c_request_resources(struct i2c_client *client,
                                          struct st33zp24_i2c_phy *phy)
{
        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(phy);
                if (ret)
                        return ret;
        } else if (pdata) {
                ret = st33zp24_i2c_request_resources(client, phy);
                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);

        return st33zp24_remove(chip);
}

static const struct i2c_device_id st33zp24_i2c_id[] = {
        {TPM_ST33_I2C, 0},
        {}
};
MODULE_DEVICE_TABLE(i2c, st33zp24_i2c_id);

#ifdef CONFIG_OF
static const struct of_device_id of_st33zp24_i2c_match[] = {
        { .compatible = "st,st33zp24-i2c", },
        {}
};
MODULE_DEVICE_TABLE(of, of_st33zp24_i2c_match);
#endif

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),
        },
        .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");