linux/arch/mips/sgi-ip27/ip27-hubio.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Copyright (C) 1992-1997, 2000-2003 Silicon Graphics, Inc.
   4 * Copyright (C) 2004 Christoph Hellwig.
   5 *
   6 * Support functions for the HUB ASIC - mostly PIO mapping related.
   7 */
   8
   9#include <linux/bitops.h>
  10#include <linux/string.h>
  11#include <linux/mmzone.h>
  12#include <asm/sn/addrs.h>
  13#include <asm/sn/arch.h>
  14#include <asm/sn/agent.h>
  15#include <asm/sn/io.h>
  16#include <asm/xtalk/xtalk.h>
  17
  18
  19static int force_fire_and_forget = 1;
  20
  21/**
  22 * hub_pio_map  -  establish a HUB PIO mapping
  23 *
  24 * @hub:        hub to perform PIO mapping on
  25 * @widget:     widget ID to perform PIO mapping for
  26 * @xtalk_addr: xtalk_address that needs to be mapped
  27 * @size:       size of the PIO mapping
  28 *
  29 **/
  30unsigned long hub_pio_map(nasid_t nasid, xwidgetnum_t widget,
  31                          unsigned long xtalk_addr, size_t size)
  32{
  33        unsigned i;
  34
  35        /* use small-window mapping if possible */
  36        if ((xtalk_addr % SWIN_SIZE) + size <= SWIN_SIZE)
  37                return NODE_SWIN_BASE(nasid, widget) + (xtalk_addr % SWIN_SIZE);
  38
  39        if ((xtalk_addr % BWIN_SIZE) + size > BWIN_SIZE) {
  40                printk(KERN_WARNING "PIO mapping at hub %d widget %d addr 0x%lx"
  41                                " too big (%ld)\n",
  42                                nasid, widget, xtalk_addr, size);
  43                return 0;
  44        }
  45
  46        xtalk_addr &= ~(BWIN_SIZE-1);
  47        for (i = 0; i < HUB_NUM_BIG_WINDOW; i++) {
  48                if (test_and_set_bit(i, hub_data(nasid)->h_bigwin_used))
  49                        continue;
  50
  51                /*
  52                 * The code below does a PIO write to setup an ITTE entry.
  53                 *
  54                 * We need to prevent other CPUs from seeing our updated
  55                 * memory shadow of the ITTE (in the piomap) until the ITTE
  56                 * entry is actually set up; otherwise, another CPU might
  57                 * attempt a PIO prematurely.
  58                 *
  59                 * Also, the only way we can know that an entry has been
  60                 * received  by the hub and can be used by future PIO reads/
  61                 * writes is by reading back the ITTE entry after writing it.
  62                 *
  63                 * For these two reasons, we PIO read back the ITTE entry
  64                 * after we write it.
  65                 */
  66                IIO_ITTE_PUT(nasid, i, HUB_PIO_MAP_TO_MEM, widget, xtalk_addr);
  67                __raw_readq(IIO_ITTE_GET(nasid, i));
  68
  69                return NODE_BWIN_BASE(nasid, widget) + (xtalk_addr % BWIN_SIZE);
  70        }
  71
  72        printk(KERN_WARNING "unable to establish PIO mapping for at"
  73                        " hub %d widget %d addr 0x%lx\n",
  74                        nasid, widget, xtalk_addr);
  75        return 0;
  76}
  77
  78
  79/*
  80 * hub_setup_prb(nasid, prbnum, credits, conveyor)
  81 *
  82 *      Put a PRB into fire-and-forget mode if conveyor isn't set.  Otherwise,
  83 *      put it into conveyor belt mode with the specified number of credits.
  84 */
  85static void hub_setup_prb(nasid_t nasid, int prbnum, int credits)
  86{
  87        union iprb_u prb;
  88        int prb_offset;
  89
  90        /*
  91         * Get the current register value.
  92         */
  93        prb_offset = IIO_IOPRB(prbnum);
  94        prb.iprb_regval = REMOTE_HUB_L(nasid, prb_offset);
  95
  96        /*
  97         * Clear out some fields.
  98         */
  99        prb.iprb_ovflow = 1;
 100        prb.iprb_bnakctr = 0;
 101        prb.iprb_anakctr = 0;
 102
 103        /*
 104         * Enable or disable fire-and-forget mode.
 105         */
 106        prb.iprb_ff = force_fire_and_forget ? 1 : 0;
 107
 108        /*
 109         * Set the appropriate number of PIO credits for the widget.
 110         */
 111        prb.iprb_xtalkctr = credits;
 112
 113        /*
 114         * Store the new value to the register.
 115         */
 116        REMOTE_HUB_S(nasid, prb_offset, prb.iprb_regval);
 117}
 118
 119/**
 120 * hub_set_piomode  -  set pio mode for a given hub
 121 *
 122 * @nasid:      physical node ID for the hub in question
 123 *
 124 * Put the hub into either "PIO conveyor belt" mode or "fire-and-forget" mode.
 125 * To do this, we have to make absolutely sure that no PIOs are in progress
 126 * so we turn off access to all widgets for the duration of the function.
 127 *
 128 * XXX - This code should really check what kind of widget we're talking
 129 * to.  Bridges can only handle three requests, but XG will do more.
 130 * How many can crossbow handle to widget 0?  We're assuming 1.
 131 *
 132 * XXX - There is a bug in the crossbow that link reset PIOs do not
 133 * return write responses.  The easiest solution to this problem is to
 134 * leave widget 0 (xbow) in fire-and-forget mode at all times.  This
 135 * only affects pio's to xbow registers, which should be rare.
 136 **/
 137static void hub_set_piomode(nasid_t nasid)
 138{
 139        u64 ii_iowa;
 140        union hubii_wcr_u ii_wcr;
 141        unsigned i;
 142
 143        ii_iowa = REMOTE_HUB_L(nasid, IIO_OUTWIDGET_ACCESS);
 144        REMOTE_HUB_S(nasid, IIO_OUTWIDGET_ACCESS, 0);
 145
 146        ii_wcr.wcr_reg_value = REMOTE_HUB_L(nasid, IIO_WCR);
 147
 148        if (ii_wcr.iwcr_dir_con) {
 149                /*
 150                 * Assume a bridge here.
 151                 */
 152                hub_setup_prb(nasid, 0, 3);
 153        } else {
 154                /*
 155                 * Assume a crossbow here.
 156                 */
 157                hub_setup_prb(nasid, 0, 1);
 158        }
 159
 160        /*
 161         * XXX - Here's where we should take the widget type into
 162         * when account assigning credits.
 163         */
 164        for (i = HUB_WIDGET_ID_MIN; i <= HUB_WIDGET_ID_MAX; i++)
 165                hub_setup_prb(nasid, i, 3);
 166
 167        REMOTE_HUB_S(nasid, IIO_OUTWIDGET_ACCESS, ii_iowa);
 168}
 169
 170/*
 171 * hub_pio_init  -  PIO-related hub initialization
 172 *
 173 * @hub:        hubinfo structure for our hub
 174 */
 175void hub_pio_init(nasid_t nasid)
 176{
 177        unsigned i;
 178
 179        /* initialize big window piomaps for this hub */
 180        bitmap_zero(hub_data(nasid)->h_bigwin_used, HUB_NUM_BIG_WINDOW);
 181        for (i = 0; i < HUB_NUM_BIG_WINDOW; i++)
 182                IIO_ITTE_DISABLE(nasid, i);
 183
 184        hub_set_piomode(nasid);
 185}
 186