// SPDX-License-Identifier: GPL-2.0
/*
 * Author:
 * Miquel Raynal <miquel.raynal@bootlin.com>
 *
 * Description:
 * SPI-level driver for TCG/TIS TPM (trusted platform module).
 * Specifications at www.trustedcomputinggroup.org
 *
 * This device driver implements the TPM interface as defined in
 * the TCG SPI protocol stack version 2.0.
 *
 * It is based on the U-Boot driver tpm_tis_infineon_i2c.c.
 */

#include <common.h>
#include <dm.h>
#include <fdtdec.h>
#include <log.h>
#include <spi.h>
#include <tpm-v2.h>
#include <linux/bitops.h>
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/compiler.h>
#include <linux/types.h>
#include <linux/unaligned/be_byteshift.h>
#include <asm-generic/gpio.h>

#include "tpm_tis.h"
#include "tpm_internal.h"

#define MAX_SPI_FRAMESIZE 64

/* Number of wait states to wait for */
#define TPM_WAIT_STATES 100

/**
 * struct tpm_tis_chip_data - Non-discoverable TPM information
 *
 * @pcr_count:          Number of PCR per bank
 * @pcr_select_min:     Size in octets of the pcrSelect array
 */
struct tpm_tis_chip_data {
        unsigned int pcr_count;
        unsigned int pcr_select_min;
        unsigned int time_before_first_cmd_ms;
};

/**
 * tpm_tis_spi_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_spi_xfer(struct udevice *dev, u32 addr, const u8 *out,
                            u8 *in, u16 len)
{
        struct spi_slave *slave = dev_get_parent_priv(dev);
        int transfer_len, ret;
        u8 tx_buf[MAX_SPI_FRAMESIZE];
        u8 rx_buf[MAX_SPI_FRAMESIZE];

        if (in && out) {
                log(LOGC_NONE, LOGL_ERR, "%s: can't do full duplex\n",
                    __func__);
                return -EINVAL;
        }

        ret = spi_claim_bus(slave);
        if (ret < 0) {
                log(LOGC_NONE, LOGL_ERR, "%s: could not claim bus\n", __func__);
                return ret;
        }

        while (len) {
                /* Request */
                transfer_len = min_t(u16, len, MAX_SPI_FRAMESIZE);
                tx_buf[0] = (in ? BIT(7) : 0) | (transfer_len - 1);
                tx_buf[1] = 0xD4;
                tx_buf[2] = addr >> 8;
                tx_buf[3] = addr;

                ret = spi_xfer(slave, 4 * 8, tx_buf, rx_buf, SPI_XFER_BEGIN);
                if (ret < 0) {
                        log(LOGC_NONE, LOGL_ERR,
                            "%s: spi request transfer failed (err: %d)\n",
                            __func__, ret);
                        goto release_bus;
                }

                /* Wait state */
                if (!(rx_buf[3] & 0x1)) {
                        int i;

                        for (i = 0; i < TPM_WAIT_STATES; i++) {
                                ret = spi_xfer(slave, 1 * 8, NULL, rx_buf, 0);
                                if (ret) {
                                        log(LOGC_NONE, LOGL_ERR,
                                            "%s: wait state failed: %d\n",
                                            __func__, ret);
                                        goto release_bus;
                                }

                                if (rx_buf[0] & 0x1)
                                        break;
                        }

                        if (i == TPM_WAIT_STATES) {
                                log(LOGC_NONE, LOGL_ERR,
                                    "%s: timeout on wait state\n", __func__);
                                ret = -ETIMEDOUT;
                                goto release_bus;
                        }
                }

                /* Read/Write */
                if (out) {
                        memcpy(tx_buf, out, transfer_len);
                        out += transfer_len;
                }

                ret = spi_xfer(slave, transfer_len * 8,
                               out ? tx_buf : NULL,
                               in ? rx_buf : NULL,
                               SPI_XFER_END);
                if (ret) {
                        log(LOGC_NONE, LOGL_ERR,
                            "%s: spi read transfer failed (err: %d)\n",
                            __func__, ret);
                        goto release_bus;
                }

                if (in) {
                        memcpy(in, rx_buf, transfer_len);
                        in += transfer_len;
                }

                len -= transfer_len;
        }

release_bus:
        /* If an error occurred, release the chip by deasserting the CS */
        if (ret < 0)
                spi_xfer(slave, 0, NULL, NULL, SPI_XFER_END);

        spi_release_bus(slave);

        return ret;
}

static int tpm_tis_spi_read(struct udevice *dev, u32 addr, u16 len, u8 *in)
{
        return tpm_tis_spi_xfer(dev, addr, NULL, in, len);
}

static int tpm_tis_spi_read32(struct udevice *dev, u32 addr, u32 *result)
{
        __le32 result_le;
        int ret;

        ret = tpm_tis_spi_read(dev, addr, sizeof(u32), (u8 *)&result_le);
        if (!ret)
                *result = le32_to_cpu(result_le);

        return ret;
}


static int tpm_tis_spi_write(struct udevice *dev, u32 addr, u16 len, const u8 *out)
{
        return tpm_tis_spi_xfer(dev, addr, out, NULL, len);
}

static int tpm_tis_spi_write32(struct udevice *dev, u32 addr, u32 value)
{
        __le32 value_le = cpu_to_le32(value);

        return tpm_tis_spi_write(dev, addr, sizeof(value), (u8 *)&value_le);
}

static int tpm_tis_wait_init(struct udevice *dev, int loc)
{
        struct tpm_chip *chip = dev_get_priv(dev);
        unsigned long start, stop;
        u8 status;
        int ret;

        start = get_timer(0);
        stop = chip->timeout_b;
        do {
                mdelay(TPM_TIMEOUT_MS);

                ret = tpm_tis_spi_read(dev, TPM_ACCESS(loc), 1, &status);
                if (ret)
                        break;

                if (status & TPM_ACCESS_VALID)
                        return 0;
        } while (get_timer(start) < stop);

        return -EIO;
}

static struct tpm_tis_phy_ops phy_ops = {
        .read_bytes = tpm_tis_spi_read,
        .write_bytes = tpm_tis_spi_write,
        .read32 = tpm_tis_spi_read32,
        .write32 = tpm_tis_spi_write32,
};

static int tpm_tis_spi_probe(struct udevice *dev)
{
        struct tpm_tis_chip_data *drv_data = (void *)dev_get_driver_data(dev);
        struct tpm_chip_priv *priv = dev_get_uclass_priv(dev);
        struct tpm_chip *chip = dev_get_priv(dev);
        int ret;

        /* Use the TPM v2 stack */
        priv->version = TPM_V2;

        if (CONFIG_IS_ENABLED(DM_GPIO)) {
                struct gpio_desc reset_gpio;

                ret = gpio_request_by_name(dev, "reset-gpios", 0,
                                           &reset_gpio, GPIOD_IS_OUT);
                if (ret) {
                        /* legacy reset */
                        ret = gpio_request_by_name(dev, "gpio-reset", 0,
                                                   &reset_gpio, GPIOD_IS_OUT);
                        if (ret) {
                                log(LOGC_NONE, LOGL_NOTICE,
                                    "%s: missing reset GPIO\n", __func__);
                                goto init;
                        }
                        log(LOGC_NONE, LOGL_NOTICE,
                            "%s: gpio-reset is deprecated\n", __func__);
                }
                dm_gpio_set_value(&reset_gpio, 1);
                mdelay(1);
                dm_gpio_set_value(&reset_gpio, 0);
        }
init:
        /* Ensure a minimum amount of time elapsed since reset of the TPM */
        mdelay(drv_data->time_before_first_cmd_ms);

        ret = tpm_tis_wait_init(dev, chip->locality);
        if (ret) {
                log(LOGC_DM, LOGL_ERR, "%s: no device found\n", __func__);
                return ret;
        }

        tpm_tis_ops_register(dev, &phy_ops);
        ret = tpm_tis_init(dev);
        if (ret)
                goto err;

        priv->pcr_count = drv_data->pcr_count;
        priv->pcr_select_min = drv_data->pcr_select_min;
        priv->version = TPM_V2;

        return 0;
err:
        return -EINVAL;
}

static int tpm_tis_spi_remove(struct udevice *udev)
{
        return tpm_tis_cleanup(udev);
}

static const struct tpm_ops tpm_tis_spi_ops = {
        .open           = tpm_tis_open,
        .close          = tpm_tis_close,
        .get_desc       = tpm_tis_get_desc,
        .send           = tpm_tis_send,
        .recv           = tpm_tis_recv,
        .cleanup        = tpm_tis_cleanup,
};

static const struct tpm_tis_chip_data tpm_tis_std_chip_data = {
        .pcr_count = 24,
        .pcr_select_min = 3,
        .time_before_first_cmd_ms = 30,
};

static const struct udevice_id tpm_tis_spi_ids[] = {
        {
                .compatible = "tcg,tpm_tis-spi",
                .data = (ulong)&tpm_tis_std_chip_data,
        },
        { }
};

U_BOOT_DRIVER(tpm_tis_spi) = {
        .name   = "tpm_tis_spi",
        .id     = UCLASS_TPM,
        .of_match = tpm_tis_spi_ids,
        .ops    = &tpm_tis_spi_ops,
        .probe  = tpm_tis_spi_probe,
        .remove = tpm_tis_spi_remove,
        .priv_auto      = sizeof(struct tpm_chip),
};