arch/mips/sgi-ip27/ip27-hubio.c

   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
  19 static 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  **/
  30 unsigned 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  */
  85 static 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  **/
 137 static 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  */
 175 void 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 }