// SPDX-License-Identifier: GPL-2.0-only
/*
 * AMD Cryptographic Coprocessor (CCP) driver
 *
 * Copyright (C) 2013,2019 Advanced Micro Devices, Inc.
 *
 * Author: Tom Lendacky <thomas.lendacky@amd.com>
 * Author: Gary R Hook <gary.hook@amd.com>
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/kthread.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/spinlock.h>
#include <linux/spinlock_types.h>
#include <linux/types.h>
#include <linux/mutex.h>
#include <linux/delay.h>
#include <linux/hw_random.h>
#include <linux/cpu.h>
#include <linux/atomic.h>
#ifdef CONFIG_X86
#include <asm/cpu_device_id.h>
#endif
#include <linux/ccp.h>

#include "ccp-dev.h"

#define MAX_CCPS 32

/* Limit CCP use to a specifed number of queues per device */
static unsigned int nqueues = 0;
module_param(nqueues, uint, 0444);
MODULE_PARM_DESC(nqueues, "Number of queues per CCP (minimum 1; default: all available)");

/* Limit the maximum number of configured CCPs */
static atomic_t dev_count = ATOMIC_INIT(0);
static unsigned int max_devs = MAX_CCPS;
module_param(max_devs, uint, 0444);
MODULE_PARM_DESC(max_devs, "Maximum number of CCPs to enable (default: all; 0 disables all CCPs)");

struct ccp_tasklet_data {
        struct completion completion;
        struct ccp_cmd *cmd;
};

/* Human-readable error strings */
#define CCP_MAX_ERROR_CODE      64
static char *ccp_error_codes[] = {
        "",
        "ILLEGAL_ENGINE",
        "ILLEGAL_KEY_ID",
        "ILLEGAL_FUNCTION_TYPE",
        "ILLEGAL_FUNCTION_MODE",
        "ILLEGAL_FUNCTION_ENCRYPT",
        "ILLEGAL_FUNCTION_SIZE",
        "Zlib_MISSING_INIT_EOM",
        "ILLEGAL_FUNCTION_RSVD",
        "ILLEGAL_BUFFER_LENGTH",
        "VLSB_FAULT",
        "ILLEGAL_MEM_ADDR",
        "ILLEGAL_MEM_SEL",
        "ILLEGAL_CONTEXT_ID",
        "ILLEGAL_KEY_ADDR",
        "0xF Reserved",
        "Zlib_ILLEGAL_MULTI_QUEUE",
        "Zlib_ILLEGAL_JOBID_CHANGE",
        "CMD_TIMEOUT",
        "IDMA0_AXI_SLVERR",
        "IDMA0_AXI_DECERR",
        "0x15 Reserved",
        "IDMA1_AXI_SLAVE_FAULT",
        "IDMA1_AIXI_DECERR",
        "0x18 Reserved",
        "ZLIBVHB_AXI_SLVERR",
        "ZLIBVHB_AXI_DECERR",
        "0x1B Reserved",
        "ZLIB_UNEXPECTED_EOM",
        "ZLIB_EXTRA_DATA",
        "ZLIB_BTYPE",
        "ZLIB_UNDEFINED_SYMBOL",
        "ZLIB_UNDEFINED_DISTANCE_S",
        "ZLIB_CODE_LENGTH_SYMBOL",
        "ZLIB _VHB_ILLEGAL_FETCH",
        "ZLIB_UNCOMPRESSED_LEN",
        "ZLIB_LIMIT_REACHED",
        "ZLIB_CHECKSUM_MISMATCH0",
        "ODMA0_AXI_SLVERR",
        "ODMA0_AXI_DECERR",
        "0x28 Reserved",
        "ODMA1_AXI_SLVERR",
        "ODMA1_AXI_DECERR",
};

void ccp_log_error(struct ccp_device *d, unsigned int e)
{
        if (WARN_ON(e >= CCP_MAX_ERROR_CODE))
                return;

        if (e < ARRAY_SIZE(ccp_error_codes))
                dev_err(d->dev, "CCP error %d: %s\n", e, ccp_error_codes[e]);
        else
                dev_err(d->dev, "CCP error %d: Unknown Error\n", e);
}

/* List of CCPs, CCP count, read-write access lock, and access functions
 *
 * Lock structure: get ccp_unit_lock for reading whenever we need to
 * examine the CCP list. While holding it for reading we can acquire
 * the RR lock to update the round-robin next-CCP pointer. The unit lock
 * must be acquired before the RR lock.
 *
 * If the unit-lock is acquired for writing, we have total control over
 * the list, so there's no value in getting the RR lock.
 */
static DEFINE_RWLOCK(ccp_unit_lock);
static LIST_HEAD(ccp_units);

/* Round-robin counter */
static DEFINE_SPINLOCK(ccp_rr_lock);
static struct ccp_device *ccp_rr;

/**
 * ccp_add_device - add a CCP device to the list
 *
 * @ccp: ccp_device struct pointer
 *
 * Put this CCP on the unit list, which makes it available
 * for use.
 *
 * Returns zero if a CCP device is present, -ENODEV otherwise.
 */
void ccp_add_device(struct ccp_device *ccp)
{
        unsigned long flags;

        write_lock_irqsave(&ccp_unit_lock, flags);
        list_add_tail(&ccp->entry, &ccp_units);
        if (!ccp_rr)
                /* We already have the list lock (we're first) so this
                 * pointer can't change on us. Set its initial value.
                 */
                ccp_rr = ccp;
        write_unlock_irqrestore(&ccp_unit_lock, flags);
}

/**
 * ccp_del_device - remove a CCP device from the list
 *
 * @ccp: ccp_device struct pointer
 *
 * Remove this unit from the list of devices. If the next device
 * up for use is this one, adjust the pointer. If this is the last
 * device, NULL the pointer.
 */
void ccp_del_device(struct ccp_device *ccp)
{
        unsigned long flags;

        write_lock_irqsave(&ccp_unit_lock, flags);
        if (ccp_rr == ccp) {
                /* ccp_unit_lock is read/write; any read access
                 * will be suspended while we make changes to the
                 * list and RR pointer.
                 */
                if (list_is_last(&ccp_rr->entry, &ccp_units))
                        ccp_rr = list_first_entry(&ccp_units, struct ccp_device,
                                                  entry);
                else
                        ccp_rr = list_next_entry(ccp_rr, entry);
        }
        list_del(&ccp->entry);
        if (list_empty(&ccp_units))
                ccp_rr = NULL;
        write_unlock_irqrestore(&ccp_unit_lock, flags);
}



int ccp_register_rng(struct ccp_device *ccp)
{
        int ret = 0;

        dev_dbg(ccp->dev, "Registering RNG...\n");
        /* Register an RNG */
        ccp->hwrng.name = ccp->rngname;
        ccp->hwrng.read = ccp_trng_read;
        ret = hwrng_register(&ccp->hwrng);
        if (ret)
                dev_err(ccp->dev, "error registering hwrng (%d)\n", ret);

        return ret;
}

void ccp_unregister_rng(struct ccp_device *ccp)
{
        if (ccp->hwrng.name)
                hwrng_unregister(&ccp->hwrng);
}

static struct ccp_device *ccp_get_device(void)
{
        unsigned long flags;
        struct ccp_device *dp = NULL;

        /* We round-robin through the unit list.
         * The (ccp_rr) pointer refers to the next unit to use.
         */
        read_lock_irqsave(&ccp_unit_lock, flags);
        if (!list_empty(&ccp_units)) {
                spin_lock(&ccp_rr_lock);
                dp = ccp_rr;
                if (list_is_last(&ccp_rr->entry, &ccp_units))
                        ccp_rr = list_first_entry(&ccp_units, struct ccp_device,
                                                  entry);
                else
                        ccp_rr = list_next_entry(ccp_rr, entry);
                spin_unlock(&ccp_rr_lock);
        }
        read_unlock_irqrestore(&ccp_unit_lock, flags);

        return dp;
}

/**
 * ccp_present - check if a CCP device is present
 *
 * Returns zero if a CCP device is present, -ENODEV otherwise.
 */
int ccp_present(void)
{
        unsigned long flags;
        int ret;

        read_lock_irqsave(&ccp_unit_lock, flags);
        ret = list_empty(&ccp_units);
        read_unlock_irqrestore(&ccp_unit_lock, flags);

        return ret ? -ENODEV : 0;
}
EXPORT_SYMBOL_GPL(ccp_present);

/**
 * ccp_version - get the version of the CCP device
 *
 * Returns the version from the first unit on the list;
 * otherwise a zero if no CCP device is present
 */
unsigned int ccp_version(void)
{
        struct ccp_device *dp;
        unsigned long flags;
        int ret = 0;

        read_lock_irqsave(&ccp_unit_lock, flags);
        if (!list_empty(&ccp_units)) {
                dp = list_first_entry(&ccp_units, struct ccp_device, entry);
                ret = dp->vdata->version;
        }
        read_unlock_irqrestore(&ccp_unit_lock, flags);

        return ret;
}
EXPORT_SYMBOL_GPL(ccp_version);

/**
 * ccp_enqueue_cmd - queue an operation for processing by the CCP
 *
 * @cmd: ccp_cmd struct to be processed
 *
 * Queue a cmd to be processed by the CCP. If queueing the cmd
 * would exceed the defined length of the cmd queue the cmd will
 * only be queued if the CCP_CMD_MAY_BACKLOG flag is set and will
 * result in a return code of -EBUSY.
 *
 * The callback routine specified in the ccp_cmd struct will be
 * called to notify the caller of completion (if the cmd was not
 * backlogged) or advancement out of the backlog. If the cmd has
 * advanced out of the backlog the "err" value of the callback
 * will be -EINPROGRESS. Any other "err" value during callback is
 * the result of the operation.
 *
 * The cmd has been successfully queued if:
 *   the return code is -EINPROGRESS or
 *   the return code is -EBUSY and CCP_CMD_MAY_BACKLOG flag is set
 */
int ccp_enqueue_cmd(struct ccp_cmd *cmd)
{
        struct ccp_device *ccp;
        unsigned long flags;
        unsigned int i;
        int ret;

        /* Some commands might need to be sent to a specific device */
        ccp = cmd->ccp ? cmd->ccp : ccp_get_device();

        if (!ccp)
                return -ENODEV;

        /* Caller must supply a callback routine */
        if (!cmd->callback)
                return -EINVAL;

        cmd->ccp = ccp;

        spin_lock_irqsave(&ccp->cmd_lock, flags);

        i = ccp->cmd_q_count;

        if (ccp->cmd_count >= MAX_CMD_QLEN) {
                if (cmd->flags & CCP_CMD_MAY_BACKLOG) {
                        ret = -EBUSY;
                        list_add_tail(&cmd->entry, &ccp->backlog);
                } else {
                        ret = -ENOSPC;
                }
        } else {
                ret = -EINPROGRESS;
                ccp->cmd_count++;
                list_add_tail(&cmd->entry, &ccp->cmd);

                /* Find an idle queue */
                if (!ccp->suspending) {
                        for (i = 0; i < ccp->cmd_q_count; i++) {
                                if (ccp->cmd_q[i].active)
                                        continue;

                                break;
                        }
                }
        }

        spin_unlock_irqrestore(&ccp->cmd_lock, flags);

        /* If we found an idle queue, wake it up */
        if (i < ccp->cmd_q_count)
                wake_up_process(ccp->cmd_q[i].kthread);

        return ret;
}
EXPORT_SYMBOL_GPL(ccp_enqueue_cmd);

static void ccp_do_cmd_backlog(struct work_struct *work)
{
        struct ccp_cmd *cmd = container_of(work, struct ccp_cmd, work);
        struct ccp_device *ccp = cmd->ccp;
        unsigned long flags;
        unsigned int i;

        cmd->callback(cmd->data, -EINPROGRESS);

        spin_lock_irqsave(&ccp->cmd_lock, flags);

        ccp->cmd_count++;
        list_add_tail(&cmd->entry, &ccp->cmd);

        /* Find an idle queue */
        for (i = 0; i < ccp->cmd_q_count; i++) {
                if (ccp->cmd_q[i].active)
                        continue;

                break;
        }

        spin_unlock_irqrestore(&ccp->cmd_lock, flags);

        /* If we found an idle queue, wake it up */
        if (i < ccp->cmd_q_count)
                wake_up_process(ccp->cmd_q[i].kthread);
}

static struct ccp_cmd *ccp_dequeue_cmd(struct ccp_cmd_queue *cmd_q)
{
        struct ccp_device *ccp = cmd_q->ccp;
        struct ccp_cmd *cmd = NULL;
        struct ccp_cmd *backlog = NULL;
        unsigned long flags;

        spin_lock_irqsave(&ccp->cmd_lock, flags);

        cmd_q->active = 0;

        if (ccp->suspending) {
                cmd_q->suspended = 1;

                spin_unlock_irqrestore(&ccp->cmd_lock, flags);
                wake_up_interruptible(&ccp->suspend_queue);

                return NULL;
        }

        if (ccp->cmd_count) {
                cmd_q->active = 1;

                cmd = list_first_entry(&ccp->cmd, struct ccp_cmd, entry);
                list_del(&cmd->entry);

                ccp->cmd_count--;
        }

        if (!list_empty(&ccp->backlog)) {
                backlog = list_first_entry(&ccp->backlog, struct ccp_cmd,
                                           entry);
                list_del(&backlog->entry);
        }

        spin_unlock_irqrestore(&ccp->cmd_lock, flags);

        if (backlog) {
                INIT_WORK(&backlog->work, ccp_do_cmd_backlog);
                schedule_work(&backlog->work);
        }

        return cmd;
}

static void ccp_do_cmd_complete(unsigned long data)
{
        struct ccp_tasklet_data *tdata = (struct ccp_tasklet_data *)data;
        struct ccp_cmd *cmd = tdata->cmd;

        cmd->callback(cmd->data, cmd->ret);

        complete(&tdata->completion);
}

/**
 * ccp_cmd_queue_thread - create a kernel thread to manage a CCP queue
 *
 * @data: thread-specific data
 */
int ccp_cmd_queue_thread(void *data)
{
        struct ccp_cmd_queue *cmd_q = (struct ccp_cmd_queue *)data;
        struct ccp_cmd *cmd;
        struct ccp_tasklet_data tdata;
        struct tasklet_struct tasklet;

        tasklet_init(&tasklet, ccp_do_cmd_complete, (unsigned long)&tdata);

        set_current_state(TASK_INTERRUPTIBLE);
        while (!kthread_should_stop()) {
                schedule();

                set_current_state(TASK_INTERRUPTIBLE);

                cmd = ccp_dequeue_cmd(cmd_q);
                if (!cmd)
                        continue;

                __set_current_state(TASK_RUNNING);

                /* Execute the command */
                cmd->ret = ccp_run_cmd(cmd_q, cmd);

                /* Schedule the completion callback */
                tdata.cmd = cmd;
                init_completion(&tdata.completion);
                tasklet_schedule(&tasklet);
                wait_for_completion(&tdata.completion);
        }

        __set_current_state(TASK_RUNNING);

        return 0;
}

/**
 * ccp_alloc_struct - allocate and initialize the ccp_device struct
 *
 * @sp: sp_device struct of the CCP
 */
struct ccp_device *ccp_alloc_struct(struct sp_device *sp)
{
        struct device *dev = sp->dev;
        struct ccp_device *ccp;

        ccp = devm_kzalloc(dev, sizeof(*ccp), GFP_KERNEL);
        if (!ccp)
                return NULL;
        ccp->dev = dev;
        ccp->sp = sp;
        ccp->axcache = sp->axcache;

        INIT_LIST_HEAD(&ccp->cmd);
        INIT_LIST_HEAD(&ccp->backlog);

        spin_lock_init(&ccp->cmd_lock);
        mutex_init(&ccp->req_mutex);
        mutex_init(&ccp->sb_mutex);
        ccp->sb_count = KSB_COUNT;
        ccp->sb_start = 0;

        /* Initialize the wait queues */
        init_waitqueue_head(&ccp->sb_queue);
        init_waitqueue_head(&ccp->suspend_queue);

        snprintf(ccp->name, MAX_CCP_NAME_LEN, "ccp-%u", sp->ord);
        snprintf(ccp->rngname, MAX_CCP_NAME_LEN, "ccp-%u-rng", sp->ord);

        return ccp;
}

int ccp_trng_read(struct hwrng *rng, void *data, size_t max, bool wait)
{
        struct ccp_device *ccp = container_of(rng, struct ccp_device, hwrng);
        u32 trng_value;
        int len = min_t(int, sizeof(trng_value), max);

        /* Locking is provided by the caller so we can update device
         * hwrng-related fields safely
         */
        trng_value = ioread32(ccp->io_regs + TRNG_OUT_REG);
        if (!trng_value) {
                /* Zero is returned if not data is available or if a
                 * bad-entropy error is present. Assume an error if
                 * we exceed TRNG_RETRIES reads of zero.
                 */
                if (ccp->hwrng_retries++ > TRNG_RETRIES)
                        return -EIO;

                return 0;
        }

        /* Reset the counter and save the rng value */
        ccp->hwrng_retries = 0;
        memcpy(data, &trng_value, len);

        return len;
}

bool ccp_queues_suspended(struct ccp_device *ccp)
{
        unsigned int suspended = 0;
        unsigned long flags;
        unsigned int i;

        spin_lock_irqsave(&ccp->cmd_lock, flags);

        for (i = 0; i < ccp->cmd_q_count; i++)
                if (ccp->cmd_q[i].suspended)
                        suspended++;

        spin_unlock_irqrestore(&ccp->cmd_lock, flags);

        return ccp->cmd_q_count == suspended;
}

void ccp_dev_suspend(struct sp_device *sp)
{
        struct ccp_device *ccp = sp->ccp_data;
        unsigned long flags;
        unsigned int i;

        /* If there's no device there's nothing to do */
        if (!ccp)
                return;

        spin_lock_irqsave(&ccp->cmd_lock, flags);

        ccp->suspending = 1;

        /* Wake all the queue kthreads to prepare for suspend */
        for (i = 0; i < ccp->cmd_q_count; i++)
                wake_up_process(ccp->cmd_q[i].kthread);

        spin_unlock_irqrestore(&ccp->cmd_lock, flags);

        /* Wait for all queue kthreads to say they're done */
        while (!ccp_queues_suspended(ccp))
                wait_event_interruptible(ccp->suspend_queue,
                                         ccp_queues_suspended(ccp));
}

void ccp_dev_resume(struct sp_device *sp)
{
        struct ccp_device *ccp = sp->ccp_data;
        unsigned long flags;
        unsigned int i;

        /* If there's no device there's nothing to do */
        if (!ccp)
                return;

        spin_lock_irqsave(&ccp->cmd_lock, flags);

        ccp->suspending = 0;

        /* Wake up all the kthreads */
        for (i = 0; i < ccp->cmd_q_count; i++) {
                ccp->cmd_q[i].suspended = 0;
                wake_up_process(ccp->cmd_q[i].kthread);
        }

        spin_unlock_irqrestore(&ccp->cmd_lock, flags);
}

int ccp_dev_init(struct sp_device *sp)
{
        struct device *dev = sp->dev;
        struct ccp_device *ccp;
        int ret;

        /*
         * Check how many we have so far, and stop after reaching
         * that number
         */
        if (atomic_inc_return(&dev_count) > max_devs)
                return 0; /* don't fail the load */

        ret = -ENOMEM;
        ccp = ccp_alloc_struct(sp);
        if (!ccp)
                goto e_err;
        sp->ccp_data = ccp;

        if (!nqueues || (nqueues > MAX_HW_QUEUES))
                ccp->max_q_count = MAX_HW_QUEUES;
        else
                ccp->max_q_count = nqueues;

        ccp->vdata = (struct ccp_vdata *)sp->dev_vdata->ccp_vdata;
        if (!ccp->vdata || !ccp->vdata->version) {
                ret = -ENODEV;
                dev_err(dev, "missing driver data\n");
                goto e_err;
        }

        ccp->use_tasklet = sp->use_tasklet;

        ccp->io_regs = sp->io_map + ccp->vdata->offset;
        if (ccp->vdata->setup)
                ccp->vdata->setup(ccp);

        ret = ccp->vdata->perform->init(ccp);
        if (ret) {
                /* A positive number means that the device cannot be initialized,
                 * but no additional message is required.
                 */
                if (ret > 0)
                        goto e_quiet;

                /* An unexpected problem occurred, and should be reported in the log */
                goto e_err;
        }

        dev_notice(dev, "ccp enabled\n");

        return 0;

e_err:
        dev_notice(dev, "ccp initialization failed\n");

e_quiet:
        sp->ccp_data = NULL;

        return ret;
}

void ccp_dev_destroy(struct sp_device *sp)
{
        struct ccp_device *ccp = sp->ccp_data;

        if (!ccp)
                return;

        ccp->vdata->perform->destroy(ccp);
}