/*
 * Copyright (C) 2014 Intel Corporation
 *
 * Authors:
 * Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
 *
 * Maintained by: <tpmdd-devel@lists.sourceforge.net>
 *
 * This device driver implements the TPM interface as defined in
 * the TCG CRB 2.0 TPM specification.
 *
 * 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; version 2
 * of the License.
 */

#include <linux/acpi.h>
#include <linux/highmem.h>
#include <linux/rculist.h>
#include <linux/module.h>
#include <linux/pm_runtime.h>
#ifdef CONFIG_ARM64
#include <linux/arm-smccc.h>
#endif
#include "tpm.h"

#define ACPI_SIG_TPM2 "TPM2"

static const guid_t crb_acpi_start_guid =
        GUID_INIT(0x6BBF6CAB, 0x5463, 0x4714,
                  0xB7, 0xCD, 0xF0, 0x20, 0x3C, 0x03, 0x68, 0xD4);

enum crb_defaults {
        CRB_ACPI_START_REVISION_ID = 1,
        CRB_ACPI_START_INDEX = 1,
};

enum crb_loc_ctrl {
        CRB_LOC_CTRL_REQUEST_ACCESS     = BIT(0),
        CRB_LOC_CTRL_RELINQUISH         = BIT(1),
};

enum crb_loc_state {
        CRB_LOC_STATE_LOC_ASSIGNED      = BIT(1),
        CRB_LOC_STATE_TPM_REG_VALID_STS = BIT(7),
};

enum crb_ctrl_req {
        CRB_CTRL_REQ_CMD_READY  = BIT(0),
        CRB_CTRL_REQ_GO_IDLE    = BIT(1),
};

enum crb_ctrl_sts {
        CRB_CTRL_STS_ERROR      = BIT(0),
        CRB_CTRL_STS_TPM_IDLE   = BIT(1),
};

enum crb_start {
        CRB_START_INVOKE        = BIT(0),
};

enum crb_cancel {
        CRB_CANCEL_INVOKE       = BIT(0),
};

struct crb_regs_head {
        u32 loc_state;
        u32 reserved1;
        u32 loc_ctrl;
        u32 loc_sts;
        u8 reserved2[32];
        u64 intf_id;
        u64 ctrl_ext;
} __packed;

struct crb_regs_tail {
        u32 ctrl_req;
        u32 ctrl_sts;
        u32 ctrl_cancel;
        u32 ctrl_start;
        u32 ctrl_int_enable;
        u32 ctrl_int_sts;
        u32 ctrl_cmd_size;
        u32 ctrl_cmd_pa_low;
        u32 ctrl_cmd_pa_high;
        u32 ctrl_rsp_size;
        u64 ctrl_rsp_pa;
} __packed;

enum crb_status {
        CRB_DRV_STS_COMPLETE    = BIT(0),
};

enum crb_flags {
        CRB_FL_ACPI_START       = BIT(0),
        CRB_FL_CRB_START        = BIT(1),
        CRB_FL_CRB_SMC_START    = BIT(2),
};

struct crb_priv {
        unsigned int flags;
        void __iomem *iobase;
        struct crb_regs_head __iomem *regs_h;
        struct crb_regs_tail __iomem *regs_t;
        u8 __iomem *cmd;
        u8 __iomem *rsp;
        u32 cmd_size;
        u32 smc_func_id;
};

struct tpm2_crb_smc {
        u32 interrupt;
        u8 interrupt_flags;
        u8 op_flags;
        u16 reserved2;
        u32 smc_func_id;
};

/**
 * crb_go_idle - request tpm crb device to go the idle state
 *
 * @dev:  crb device
 * @priv: crb private data
 *
 * Write CRB_CTRL_REQ_GO_IDLE to TPM_CRB_CTRL_REQ
 * The device should respond within TIMEOUT_C by clearing the bit.
 * Anyhow, we do not wait here as a consequent CMD_READY request
 * will be handled correctly even if idle was not completed.
 *
 * The function does nothing for devices with ACPI-start method.
 *
 * Return: 0 always
 */
static int __maybe_unused crb_go_idle(struct device *dev, struct crb_priv *priv)
{
        if ((priv->flags & CRB_FL_ACPI_START) ||
            (priv->flags & CRB_FL_CRB_SMC_START))
                return 0;

        iowrite32(CRB_CTRL_REQ_GO_IDLE, &priv->regs_t->ctrl_req);
        /* we don't really care when this settles */

        return 0;
}

static bool crb_wait_for_reg_32(u32 __iomem *reg, u32 mask, u32 value,
                                unsigned long timeout)
{
        ktime_t start;
        ktime_t stop;

        start = ktime_get();
        stop = ktime_add(start, ms_to_ktime(timeout));

        do {
                if ((ioread32(reg) & mask) == value)
                        return true;

                usleep_range(50, 100);
        } while (ktime_before(ktime_get(), stop));

        return false;
}

/**
 * crb_cmd_ready - request tpm crb device to enter ready state
 *
 * @dev:  crb device
 * @priv: crb private data
 *
 * Write CRB_CTRL_REQ_CMD_READY to TPM_CRB_CTRL_REQ
 * and poll till the device acknowledge it by clearing the bit.
 * The device should respond within TIMEOUT_C.
 *
 * The function does nothing for devices with ACPI-start method
 *
 * Return: 0 on success -ETIME on timeout;
 */
static int __maybe_unused crb_cmd_ready(struct device *dev,
                                        struct crb_priv *priv)
{
        if ((priv->flags & CRB_FL_ACPI_START) ||
            (priv->flags & CRB_FL_CRB_SMC_START))
                return 0;

        iowrite32(CRB_CTRL_REQ_CMD_READY, &priv->regs_t->ctrl_req);
        if (!crb_wait_for_reg_32(&priv->regs_t->ctrl_req,
                                 CRB_CTRL_REQ_CMD_READY /* mask */,
                                 0, /* value */
                                 TPM2_TIMEOUT_C)) {
                dev_warn(dev, "cmdReady timed out\n");
                return -ETIME;
        }

        return 0;
}

static int crb_request_locality(struct tpm_chip *chip, int loc)
{
        struct crb_priv *priv = dev_get_drvdata(&chip->dev);
        u32 value = CRB_LOC_STATE_LOC_ASSIGNED |
                CRB_LOC_STATE_TPM_REG_VALID_STS;

        if (!priv->regs_h)
                return 0;

        iowrite32(CRB_LOC_CTRL_REQUEST_ACCESS, &priv->regs_h->loc_ctrl);
        if (!crb_wait_for_reg_32(&priv->regs_h->loc_state, value, value,
                                 TPM2_TIMEOUT_C)) {
                dev_warn(&chip->dev, "TPM_LOC_STATE_x.requestAccess timed out\n");
                return -ETIME;
        }

        return 0;
}

static void crb_relinquish_locality(struct tpm_chip *chip, int loc)
{
        struct crb_priv *priv = dev_get_drvdata(&chip->dev);

        if (!priv->regs_h)
                return;

        iowrite32(CRB_LOC_CTRL_RELINQUISH, &priv->regs_h->loc_ctrl);
}

static u8 crb_status(struct tpm_chip *chip)
{
        struct crb_priv *priv = dev_get_drvdata(&chip->dev);
        u8 sts = 0;

        if ((ioread32(&priv->regs_t->ctrl_start) & CRB_START_INVOKE) !=
            CRB_START_INVOKE)
                sts |= CRB_DRV_STS_COMPLETE;

        return sts;
}

static int crb_recv(struct tpm_chip *chip, u8 *buf, size_t count)
{
        struct crb_priv *priv = dev_get_drvdata(&chip->dev);
        unsigned int expected;

        /* sanity check */
        if (count < 6)
                return -EIO;

        if (ioread32(&priv->regs_t->ctrl_sts) & CRB_CTRL_STS_ERROR)
                return -EIO;

        memcpy_fromio(buf, priv->rsp, 6);
        expected = be32_to_cpup((__be32 *) &buf[2]);
        if (expected > count || expected < 6)
                return -EIO;

        memcpy_fromio(&buf[6], &priv->rsp[6], expected - 6);

        return expected;
}

static int crb_do_acpi_start(struct tpm_chip *chip)
{
        union acpi_object *obj;
        int rc;

        obj = acpi_evaluate_dsm(chip->acpi_dev_handle,
                                &crb_acpi_start_guid,
                                CRB_ACPI_START_REVISION_ID,
                                CRB_ACPI_START_INDEX,
                                NULL);
        if (!obj)
                return -ENXIO;
        rc = obj->integer.value == 0 ? 0 : -ENXIO;
        ACPI_FREE(obj);
        return rc;
}

#ifdef CONFIG_ARM64
/*
 * This is a TPM Command Response Buffer start method that invokes a
 * Secure Monitor Call to requrest the firmware to execute or cancel
 * a TPM 2.0 command.
 */
static int tpm_crb_smc_start(struct device *dev, unsigned long func_id)
{
        struct arm_smccc_res res;

        arm_smccc_smc(func_id, 0, 0, 0, 0, 0, 0, 0, &res);
        if (res.a0 != 0) {
                dev_err(dev,
                        FW_BUG "tpm_crb_smc_start() returns res.a0 = 0x%lx\n",
                        res.a0);
                return -EIO;
        }

        return 0;
}
#else
static int tpm_crb_smc_start(struct device *dev, unsigned long func_id)
{
        dev_err(dev, FW_BUG "tpm_crb: incorrect start method\n");
        return -EINVAL;
}
#endif

static int crb_send(struct tpm_chip *chip, u8 *buf, size_t len)
{
        struct crb_priv *priv = dev_get_drvdata(&chip->dev);
        int rc = 0;

        /* Zero the cancel register so that the next command will not get
         * canceled.
         */
        iowrite32(0, &priv->regs_t->ctrl_cancel);

        if (len > priv->cmd_size) {
                dev_err(&chip->dev, "invalid command count value %zd %d\n",
                        len, priv->cmd_size);
                return -E2BIG;
        }

        memcpy_toio(priv->cmd, buf, len);

        /* Make sure that cmd is populated before issuing start. */
        wmb();

        if (priv->flags & CRB_FL_CRB_START)
                iowrite32(CRB_START_INVOKE, &priv->regs_t->ctrl_start);

        if (priv->flags & CRB_FL_ACPI_START)
                rc = crb_do_acpi_start(chip);

        if (priv->flags & CRB_FL_CRB_SMC_START) {
                iowrite32(CRB_START_INVOKE, &priv->regs_t->ctrl_start);
                rc = tpm_crb_smc_start(&chip->dev, priv->smc_func_id);
        }

        return rc;
}

static void crb_cancel(struct tpm_chip *chip)
{
        struct crb_priv *priv = dev_get_drvdata(&chip->dev);

        iowrite32(CRB_CANCEL_INVOKE, &priv->regs_t->ctrl_cancel);

        if ((priv->flags & CRB_FL_ACPI_START) && crb_do_acpi_start(chip))
                dev_err(&chip->dev, "ACPI Start failed\n");
}

static bool crb_req_canceled(struct tpm_chip *chip, u8 status)
{
        struct crb_priv *priv = dev_get_drvdata(&chip->dev);
        u32 cancel = ioread32(&priv->regs_t->ctrl_cancel);

        return (cancel & CRB_CANCEL_INVOKE) == CRB_CANCEL_INVOKE;
}

static const struct tpm_class_ops tpm_crb = {
        .flags = TPM_OPS_AUTO_STARTUP,
        .status = crb_status,
        .recv = crb_recv,
        .send = crb_send,
        .cancel = crb_cancel,
        .req_canceled = crb_req_canceled,
        .request_locality = crb_request_locality,
        .relinquish_locality = crb_relinquish_locality,
        .req_complete_mask = CRB_DRV_STS_COMPLETE,
        .req_complete_val = CRB_DRV_STS_COMPLETE,
};

static int crb_check_resource(struct acpi_resource *ares, void *data)
{
        struct resource *io_res = data;
        struct resource_win win;
        struct resource *res = &(win.res);

        if (acpi_dev_resource_memory(ares, res) ||
            acpi_dev_resource_address_space(ares, &win)) {
                *io_res = *res;
                io_res->name = NULL;
        }

        return 1;
}

static void __iomem *crb_map_res(struct device *dev, struct crb_priv *priv,
                                 struct resource *io_res, u64 start, u32 size)
{
        struct resource new_res = {
                .start  = start,
                .end    = start + size - 1,
                .flags  = IORESOURCE_MEM,
        };

        /* Detect a 64 bit address on a 32 bit system */
        if (start != new_res.start)
                return (void __iomem *) ERR_PTR(-EINVAL);

        if (!resource_contains(io_res, &new_res))
                return devm_ioremap_resource(dev, &new_res);

        return priv->iobase + (new_res.start - io_res->start);
}

/*
 * Work around broken BIOSs that return inconsistent values from the ACPI
 * region vs the registers. Trust the ACPI region. Such broken systems
 * probably cannot send large TPM commands since the buffer will be truncated.
 */
static u64 crb_fixup_cmd_size(struct device *dev, struct resource *io_res,
                              u64 start, u64 size)
{
        if (io_res->start > start || io_res->end < start)
                return size;

        if (start + size - 1 <= io_res->end)
                return size;

        dev_err(dev,
                FW_BUG "ACPI region does not cover the entire command/response buffer. %pr vs %llx %llx\n",
                io_res, start, size);

        return io_res->end - start + 1;
}

static int crb_map_io(struct acpi_device *device, struct crb_priv *priv,
                      struct acpi_table_tpm2 *buf)
{
        struct list_head resources;
        struct resource io_res;
        struct device *dev = &device->dev;
        u32 pa_high, pa_low;
        u64 cmd_pa;
        u32 cmd_size;
        u64 rsp_pa;
        u32 rsp_size;
        int ret;

        INIT_LIST_HEAD(&resources);
        ret = acpi_dev_get_resources(device, &resources, crb_check_resource,
                                     &io_res);
        if (ret < 0)
                return ret;
        acpi_dev_free_resource_list(&resources);

        if (resource_type(&io_res) != IORESOURCE_MEM) {
                dev_err(dev, FW_BUG "TPM2 ACPI table does not define a memory resource\n");
                return -EINVAL;
        }

        priv->iobase = devm_ioremap_resource(dev, &io_res);
        if (IS_ERR(priv->iobase))
                return PTR_ERR(priv->iobase);

        /* The ACPI IO region starts at the head area and continues to include
         * the control area, as one nice sane region except for some older
         * stuff that puts the control area outside the ACPI IO region.
         */
        if (!(priv->flags & CRB_FL_ACPI_START)) {
                if (buf->control_address == io_res.start +
                    sizeof(*priv->regs_h))
                        priv->regs_h = priv->iobase;
                else
                        dev_warn(dev, FW_BUG "Bad ACPI memory layout");
        }

        priv->regs_t = crb_map_res(dev, priv, &io_res, buf->control_address,
                                   sizeof(struct crb_regs_tail));
        if (IS_ERR(priv->regs_t))
                return PTR_ERR(priv->regs_t);

        /*
         * PTT HW bug w/a: wake up the device to access
         * possibly not retained registers.
         */
        ret = crb_cmd_ready(dev, priv);
        if (ret)
                return ret;

        pa_high = ioread32(&priv->regs_t->ctrl_cmd_pa_high);
        pa_low  = ioread32(&priv->regs_t->ctrl_cmd_pa_low);
        cmd_pa = ((u64)pa_high << 32) | pa_low;
        cmd_size = crb_fixup_cmd_size(dev, &io_res, cmd_pa,
                                      ioread32(&priv->regs_t->ctrl_cmd_size));

        dev_dbg(dev, "cmd_hi = %X cmd_low = %X cmd_size %X\n",
                pa_high, pa_low, cmd_size);

        priv->cmd = crb_map_res(dev, priv, &io_res, cmd_pa, cmd_size);
        if (IS_ERR(priv->cmd)) {
                ret = PTR_ERR(priv->cmd);
                goto out;
        }

        memcpy_fromio(&rsp_pa, &priv->regs_t->ctrl_rsp_pa, 8);
        rsp_pa = le64_to_cpu(rsp_pa);
        rsp_size = crb_fixup_cmd_size(dev, &io_res, rsp_pa,
                                      ioread32(&priv->regs_t->ctrl_rsp_size));

        if (cmd_pa != rsp_pa) {
                priv->rsp = crb_map_res(dev, priv, &io_res, rsp_pa, rsp_size);
                ret = PTR_ERR_OR_ZERO(priv->rsp);
                goto out;
        }

        /* According to the PTP specification, overlapping command and response
         * buffer sizes must be identical.
         */
        if (cmd_size != rsp_size) {
                dev_err(dev, FW_BUG "overlapping command and response buffer sizes are not identical");
                ret = -EINVAL;
                goto out;
        }

        priv->rsp = priv->cmd;

out:
        if (!ret)
                priv->cmd_size = cmd_size;

        crb_go_idle(dev, priv);

        return ret;
}

static int crb_acpi_add(struct acpi_device *device)
{
        struct acpi_table_tpm2 *buf;
        struct crb_priv *priv;
        struct tpm_chip *chip;
        struct device *dev = &device->dev;
        struct tpm2_crb_smc *crb_smc;
        acpi_status status;
        u32 sm;
        int rc;

        status = acpi_get_table(ACPI_SIG_TPM2, 1,
                                (struct acpi_table_header **) &buf);
        if (ACPI_FAILURE(status) || buf->header.length < sizeof(*buf)) {
                dev_err(dev, FW_BUG "failed to get TPM2 ACPI table\n");
                return -EINVAL;
        }

        /* Should the FIFO driver handle this? */
        sm = buf->start_method;
        if (sm == ACPI_TPM2_MEMORY_MAPPED)
                return -ENODEV;

        priv = devm_kzalloc(dev, sizeof(struct crb_priv), GFP_KERNEL);
        if (!priv)
                return -ENOMEM;

        /* The reason for the extra quirk is that the PTT in 4th Gen Core CPUs
         * report only ACPI start but in practice seems to require both
         * ACPI start and CRB start.
         */
        if (sm == ACPI_TPM2_COMMAND_BUFFER || sm == ACPI_TPM2_MEMORY_MAPPED ||
            !strcmp(acpi_device_hid(device), "MSFT0101"))
                priv->flags |= CRB_FL_CRB_START;

        if (sm == ACPI_TPM2_START_METHOD ||
            sm == ACPI_TPM2_COMMAND_BUFFER_WITH_START_METHOD)
                priv->flags |= CRB_FL_ACPI_START;

        if (sm == ACPI_TPM2_COMMAND_BUFFER_WITH_ARM_SMC) {
                if (buf->header.length < (sizeof(*buf) + sizeof(*crb_smc))) {
                        dev_err(dev,
                                FW_BUG "TPM2 ACPI table has wrong size %u for start method type %d\n",
                                buf->header.length,
                                ACPI_TPM2_COMMAND_BUFFER_WITH_ARM_SMC);
                        return -EINVAL;
                }
                crb_smc = ACPI_ADD_PTR(struct tpm2_crb_smc, buf, sizeof(*buf));
                priv->smc_func_id = crb_smc->smc_func_id;
                priv->flags |= CRB_FL_CRB_SMC_START;
        }

        rc = crb_map_io(device, priv, buf);
        if (rc)
                return rc;

        chip = tpmm_chip_alloc(dev, &tpm_crb);
        if (IS_ERR(chip))
                return PTR_ERR(chip);

        dev_set_drvdata(&chip->dev, priv);
        chip->acpi_dev_handle = device->handle;
        chip->flags = TPM_CHIP_FLAG_TPM2;

        rc  = crb_cmd_ready(dev, priv);
        if (rc)
                return rc;

        pm_runtime_get_noresume(dev);
        pm_runtime_set_active(dev);
        pm_runtime_enable(dev);

        rc = tpm_chip_register(chip);
        if (rc) {
                crb_go_idle(dev, priv);
                pm_runtime_put_noidle(dev);
                pm_runtime_disable(dev);
                return rc;
        }

        pm_runtime_put(dev);

        return 0;
}

static int crb_acpi_remove(struct acpi_device *device)
{
        struct device *dev = &device->dev;
        struct tpm_chip *chip = dev_get_drvdata(dev);

        tpm_chip_unregister(chip);

        pm_runtime_disable(dev);

        return 0;
}

static int __maybe_unused crb_pm_runtime_suspend(struct device *dev)
{
        struct tpm_chip *chip = dev_get_drvdata(dev);
        struct crb_priv *priv = dev_get_drvdata(&chip->dev);

        return crb_go_idle(dev, priv);
}

static int __maybe_unused crb_pm_runtime_resume(struct device *dev)
{
        struct tpm_chip *chip = dev_get_drvdata(dev);
        struct crb_priv *priv = dev_get_drvdata(&chip->dev);

        return crb_cmd_ready(dev, priv);
}

static int __maybe_unused crb_pm_suspend(struct device *dev)
{
        int ret;

        ret = tpm_pm_suspend(dev);
        if (ret)
                return ret;

        return crb_pm_runtime_suspend(dev);
}

static int __maybe_unused crb_pm_resume(struct device *dev)
{
        int ret;

        ret = crb_pm_runtime_resume(dev);
        if (ret)
                return ret;

        return tpm_pm_resume(dev);
}

static const struct dev_pm_ops crb_pm = {
        SET_SYSTEM_SLEEP_PM_OPS(crb_pm_suspend, crb_pm_resume)
        SET_RUNTIME_PM_OPS(crb_pm_runtime_suspend, crb_pm_runtime_resume, NULL)
};

static const struct acpi_device_id crb_device_ids[] = {
        {"MSFT0101", 0},
        {"", 0},
};
MODULE_DEVICE_TABLE(acpi, crb_device_ids);

static struct acpi_driver crb_acpi_driver = {
        .name = "tpm_crb",
        .ids = crb_device_ids,
        .ops = {
                .add = crb_acpi_add,
                .remove = crb_acpi_remove,
        },
        .drv = {
                .pm = &crb_pm,
        },
};

module_acpi_driver(crb_acpi_driver);
MODULE_AUTHOR("Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>");
MODULE_DESCRIPTION("TPM2 Driver");
MODULE_VERSION("0.1");
MODULE_LICENSE("GPL");