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}