// SPDX-License-Identifier: GPL-2.0
/* Copyright (C) 2012-2019 ARM Limited (or its affiliates). */

#include <linux/kernel.h>
#include <linux/fips.h>
#include <linux/notifier.h>

#include "cc_driver.h"
#include "cc_fips.h"

static void fips_dsr(unsigned long devarg);

struct cc_fips_handle {
        struct tasklet_struct tasklet;
        struct notifier_block nb;
        struct cc_drvdata *drvdata;
};

/* The function called once at driver entry point to check
 * whether TEE FIPS error occurred.
 */
static bool cc_get_tee_fips_status(struct cc_drvdata *drvdata)
{
        u32 reg;

        reg = cc_ioread(drvdata, CC_REG(GPR_HOST));
        /* Did the TEE report status? */
        if (reg & CC_FIPS_SYNC_TEE_STATUS)
                /* Yes. Is it OK? */
                return (reg & CC_FIPS_SYNC_MODULE_OK);

        /* No. It's either not in use or will be reported later */
        return true;
}

/*
 * This function should push the FIPS REE library status towards the TEE library
 * by writing the error state to HOST_GPR0 register.
 */
void cc_set_ree_fips_status(struct cc_drvdata *drvdata, bool status)
{
        int val = CC_FIPS_SYNC_REE_STATUS;

        if (drvdata->hw_rev < CC_HW_REV_712)
                return;

        val |= (status ? CC_FIPS_SYNC_MODULE_OK : CC_FIPS_SYNC_MODULE_ERROR);

        cc_iowrite(drvdata, CC_REG(HOST_GPR0), val);
}

/* Push REE side FIPS test failure to TEE side */
static int cc_ree_fips_failure(struct notifier_block *nb, unsigned long unused1,
                               void *unused2)
{
        struct cc_fips_handle *fips_h =
                                container_of(nb, struct cc_fips_handle, nb);
        struct cc_drvdata *drvdata = fips_h->drvdata;
        struct device *dev = drvdata_to_dev(drvdata);

        cc_set_ree_fips_status(drvdata, false);
        dev_info(dev, "Notifying TEE of FIPS test failure...\n");

        return NOTIFY_OK;
}

void cc_fips_fini(struct cc_drvdata *drvdata)
{
        struct cc_fips_handle *fips_h = drvdata->fips_handle;

        if (drvdata->hw_rev < CC_HW_REV_712 || !fips_h)
                return;

        atomic_notifier_chain_unregister(&fips_fail_notif_chain, &fips_h->nb);

        /* Kill tasklet */
        tasklet_kill(&fips_h->tasklet);
        drvdata->fips_handle = NULL;
}

void fips_handler(struct cc_drvdata *drvdata)
{
        struct cc_fips_handle *fips_handle_ptr = drvdata->fips_handle;

        if (drvdata->hw_rev < CC_HW_REV_712)
                return;

        tasklet_schedule(&fips_handle_ptr->tasklet);
}

static inline void tee_fips_error(struct device *dev)
{
        if (fips_enabled)
                panic("ccree: TEE reported cryptographic error in fips mode!\n");
        else
                dev_err(dev, "TEE reported error!\n");
}

/*
 * This function check if cryptocell tee fips error occurred
 * and in such case triggers system error
 */
void cc_tee_handle_fips_error(struct cc_drvdata *p_drvdata)
{
        struct device *dev = drvdata_to_dev(p_drvdata);

        if (!cc_get_tee_fips_status(p_drvdata))
                tee_fips_error(dev);
}

/* Deferred service handler, run as interrupt-fired tasklet */
static void fips_dsr(unsigned long devarg)
{
        struct cc_drvdata *drvdata = (struct cc_drvdata *)devarg;
        u32 irq, val;

        irq = (drvdata->irq & (CC_GPR0_IRQ_MASK));

        if (irq) {
                cc_tee_handle_fips_error(drvdata);
        }

        /* after verifying that there is nothing to do,
         * unmask AXI completion interrupt.
         */
        val = (CC_REG(HOST_IMR) & ~irq);
        cc_iowrite(drvdata, CC_REG(HOST_IMR), val);
}

/* The function called once at driver entry point .*/
int cc_fips_init(struct cc_drvdata *p_drvdata)
{
        struct cc_fips_handle *fips_h;
        struct device *dev = drvdata_to_dev(p_drvdata);

        if (p_drvdata->hw_rev < CC_HW_REV_712)
                return 0;

        fips_h = devm_kzalloc(dev, sizeof(*fips_h), GFP_KERNEL);
        if (!fips_h)
                return -ENOMEM;

        p_drvdata->fips_handle = fips_h;

        dev_dbg(dev, "Initializing fips tasklet\n");
        tasklet_init(&fips_h->tasklet, fips_dsr, (unsigned long)p_drvdata);
        fips_h->drvdata = p_drvdata;
        fips_h->nb.notifier_call = cc_ree_fips_failure;
        atomic_notifier_chain_register(&fips_fail_notif_chain, &fips_h->nb);

        cc_tee_handle_fips_error(p_drvdata);

        return 0;
}