// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *              GRU KERNEL MCS INSTRUCTIONS
 *
 *  Copyright (c) 2008 Silicon Graphics, Inc.  All Rights Reserved.
 */

#include <linux/kernel.h>
#include "gru.h"
#include "grulib.h"
#include "grutables.h"

/* 10 sec */
#include <linux/sync_core.h>
#include <asm/tsc.h>
#define GRU_OPERATION_TIMEOUT   ((cycles_t) tsc_khz*10*1000)
#define CLKS2NSEC(c)            ((c) * 1000000 / tsc_khz)

/* Extract the status field from a kernel handle */
#define GET_MSEG_HANDLE_STATUS(h)       (((*(unsigned long *)(h)) >> 16) & 3)

struct mcs_op_statistic mcs_op_statistics[mcsop_last];

static void update_mcs_stats(enum mcs_op op, unsigned long clks)
{
        unsigned long nsec;

        nsec = CLKS2NSEC(clks);
        atomic_long_inc(&mcs_op_statistics[op].count);
        atomic_long_add(nsec, &mcs_op_statistics[op].total);
        if (mcs_op_statistics[op].max < nsec)
                mcs_op_statistics[op].max = nsec;
}

static void start_instruction(void *h)
{
        unsigned long *w0 = h;

        wmb();          /* setting CMD/STATUS bits must be last */
        *w0 = *w0 | 0x20001;
        gru_flush_cache(h);
}

static void report_instruction_timeout(void *h)
{
        unsigned long goff = GSEGPOFF((unsigned long)h);
        char *id = "???";

        if (TYPE_IS(CCH, goff))
                id = "CCH";
        else if (TYPE_IS(TGH, goff))
                id = "TGH";
        else if (TYPE_IS(TFH, goff))
                id = "TFH";

        panic(KERN_ALERT "GRU %p (%s) is malfunctioning\n", h, id);
}

static int wait_instruction_complete(void *h, enum mcs_op opc)
{
        int status;
        unsigned long start_time = get_cycles();

        while (1) {
                cpu_relax();
                status = GET_MSEG_HANDLE_STATUS(h);
                if (status != CCHSTATUS_ACTIVE)
                        break;
                if (GRU_OPERATION_TIMEOUT < (get_cycles() - start_time)) {
                        report_instruction_timeout(h);
                        start_time = get_cycles();
                }
        }
        if (gru_options & OPT_STATS)
                update_mcs_stats(opc, get_cycles() - start_time);
        return status;
}

int cch_allocate(struct gru_context_configuration_handle *cch)
{
        int ret;

        cch->opc = CCHOP_ALLOCATE;
        start_instruction(cch);
        ret = wait_instruction_complete(cch, cchop_allocate);

        /*
         * Stop speculation into the GSEG being mapped by the previous ALLOCATE.
         * The GSEG memory does not exist until the ALLOCATE completes.
         */
        sync_core();
        return ret;
}

int cch_start(struct gru_context_configuration_handle *cch)
{
        cch->opc = CCHOP_START;
        start_instruction(cch);
        return wait_instruction_complete(cch, cchop_start);
}

int cch_interrupt(struct gru_context_configuration_handle *cch)
{
        cch->opc = CCHOP_INTERRUPT;
        start_instruction(cch);
        return wait_instruction_complete(cch, cchop_interrupt);
}

int cch_deallocate(struct gru_context_configuration_handle *cch)
{
        int ret;

        cch->opc = CCHOP_DEALLOCATE;
        start_instruction(cch);
        ret = wait_instruction_complete(cch, cchop_deallocate);

        /*
         * Stop speculation into the GSEG being unmapped by the previous
         * DEALLOCATE.
         */
        sync_core();
        return ret;
}

int cch_interrupt_sync(struct gru_context_configuration_handle
                                     *cch)
{
        cch->opc = CCHOP_INTERRUPT_SYNC;
        start_instruction(cch);
        return wait_instruction_complete(cch, cchop_interrupt_sync);
}

int tgh_invalidate(struct gru_tlb_global_handle *tgh,
                                 unsigned long vaddr, unsigned long vaddrmask,
                                 int asid, int pagesize, int global, int n,
                                 unsigned short ctxbitmap)
{
        tgh->vaddr = vaddr;
        tgh->asid = asid;
        tgh->pagesize = pagesize;
        tgh->n = n;
        tgh->global = global;
        tgh->vaddrmask = vaddrmask;
        tgh->ctxbitmap = ctxbitmap;
        tgh->opc = TGHOP_TLBINV;
        start_instruction(tgh);
        return wait_instruction_complete(tgh, tghop_invalidate);
}

int tfh_write_only(struct gru_tlb_fault_handle *tfh,
                                  unsigned long paddr, int gaa,
                                  unsigned long vaddr, int asid, int dirty,
                                  int pagesize)
{
        tfh->fillasid = asid;
        tfh->fillvaddr = vaddr;
        tfh->pfn = paddr >> GRU_PADDR_SHIFT;
        tfh->gaa = gaa;
        tfh->dirty = dirty;
        tfh->pagesize = pagesize;
        tfh->opc = TFHOP_WRITE_ONLY;
        start_instruction(tfh);
        return wait_instruction_complete(tfh, tfhop_write_only);
}

void tfh_write_restart(struct gru_tlb_fault_handle *tfh,
                                     unsigned long paddr, int gaa,
                                     unsigned long vaddr, int asid, int dirty,
                                     int pagesize)
{
        tfh->fillasid = asid;
        tfh->fillvaddr = vaddr;
        tfh->pfn = paddr >> GRU_PADDR_SHIFT;
        tfh->gaa = gaa;
        tfh->dirty = dirty;
        tfh->pagesize = pagesize;
        tfh->opc = TFHOP_WRITE_RESTART;
        start_instruction(tfh);
}

void tfh_user_polling_mode(struct gru_tlb_fault_handle *tfh)
{
        tfh->opc = TFHOP_USER_POLLING_MODE;
        start_instruction(tfh);
}

void tfh_exception(struct gru_tlb_fault_handle *tfh)
{
        tfh->opc = TFHOP_EXCEPTION;
        start_instruction(tfh);
}