path: root/drivers/misc/sgi-xp/xpc.h

/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (c) 2004-2008 Silicon Graphics, Inc.  All Rights Reserved.
 */


/*
 * Cross Partition Communication (XPC) structures and macros.
 */

#ifndef _DRIVERS_MISC_SGIXP_XPC_H
#define _DRIVERS_MISC_SGIXP_XPC_H


#include <linux/interrupt.h>
#include <linux/sysctl.h>
#include <linux/device.h>
#include <linux/mutex.h>
#include <linux/completion.h>
#include <asm/pgtable.h>
#include <asm/processor.h>
#include <asm/sn/bte.h>
#include <asm/sn/clksupport.h>
#include <asm/sn/addrs.h>
#include <asm/sn/mspec.h>
#include <asm/sn/shub_mmr.h>
#include "xp.h"


/*
 * XPC Version numbers consist of a major and minor number. XPC can always
 * talk to versions with same major #, and never talk to versions with a
 * different major #.
 */
#define _XPC_VERSION(_maj, _min)	(((_maj) << 4) | ((_min) & 0xf))
#define XPC_VERSION_MAJOR(_v)		((_v) >> 4)
#define XPC_VERSION_MINOR(_v)		((_v) & 0xf)


/*
 * The next macros define word or bit representations for given
 * C-brick nasid in either the SAL provided bit array representing
 * nasids in the partition/machine or the AMO_t array used for
 * inter-partition initiation communications.
 *
 * For SN2 machines, C-Bricks are alway even numbered NASIDs.  As
 * such, some space will be saved by insisting that nasid information
 * passed from SAL always be packed for C-Bricks and the
 * cross-partition interrupts use the same packing scheme.
 */
#define XPC_NASID_W_INDEX(_n)	(((_n) / 64) / 2)
#define XPC_NASID_B_INDEX(_n)	(((_n) / 2) & (64 - 1))
#define XPC_NASID_IN_ARRAY(_n, _p) ((_p)[XPC_NASID_W_INDEX(_n)] & \
				    (1UL << XPC_NASID_B_INDEX(_n)))
#define XPC_NASID_FROM_W_B(_w, _b) (((_w) * 64 + (_b)) * 2)

#define XPC_HB_DEFAULT_INTERVAL		5	/* incr HB every x secs */
#define XPC_HB_CHECK_DEFAULT_INTERVAL	20	/* check HB every x secs */

/* define the process name of HB checker and the CPU it is pinned to */
#define XPC_HB_CHECK_THREAD_NAME	"xpc_hb"
#define XPC_HB_CHECK_CPU		0

/* define the process name of the discovery thread */
#define XPC_DISCOVERY_THREAD_NAME	"xpc_discovery"


/*
 * the reserved page
 *
 *   SAL reserves one page of memory per partition for XPC. Though a full page
 *   in length (16384 bytes), its starting address is not page aligned, but it
 *   is cacheline aligned. The reserved page consists of the following:
 *
 *   reserved page header
 *
 *     The first cacheline of the reserved page contains the header
 *     (struct xpc_rsvd_page). Before SAL initialization has completed,
 *     SAL has set up the following fields of the reserved page header:
 *     SAL_signature, SAL_version, partid, and nasids_size. The other
 *     fields are set up by XPC. (xpc_rsvd_page points to the local
 *     partition's reserved page.)
 *
 *   part_nasids mask
 *   mach_nasids mask
 *
 *     SAL also sets up two bitmaps (or masks), one that reflects the actual
 *     nasids in this partition (part_nasids), and the other that reflects
 *     the actual nasids in the entire machine (mach_nasids). We're only
 *     interested in the even numbered nasids (which contain the processors
 *     and/or memory), so we only need half as many bits to represent the
 *     nasids. The part_nasids mask is located starting at the first cacheline
 *     following the reserved page header. The mach_nasids mask follows right
 *     after the part_nasids mask. The size in bytes of each mask is reflected
 *     by the reserved page header field 'nasids_size'. (Local partition's
 *     mask pointers are xpc_part_nasids and xpc_mach_nasids.)
 *
 *   vars
 *   vars part
 *
 *     Immediately following the mach_nasids mask are the XPC variables
 *     required by other partitions. First are those that are generic to all
 *     partitions (vars), followed on the next available cacheline by those
 *     which are partition specific (vars part). These are setup by XPC.
 *     (Local partition's vars pointers are xpc_vars and xpc_vars_part.)
 *
 * Note: Until vars_pa is set, the partition XPC code has not been initialized.
 */
struct xpc_rsvd_page {
	u64 SAL_signature;	/* SAL: unique signature */
	u64 SAL_version;	/* SAL: version */
	u8 partid;		/* SAL: partition ID */
	u8 version;
	u8 pad1[6];		/* align to next u64 in cacheline */
	volatile u64 vars_pa;
	struct timespec stamp;	/* time when reserved page was setup by XPC */
	u64 pad2[9];		/* align to last u64 in cacheline */
	u64 nasids_size;	/* SAL: size of each nasid mask in bytes */
};

#define XPC_RP_VERSION _XPC_VERSION(1,1) /* version 1.1 of the reserved page */

#define XPC_SUPPORTS_RP_STAMP(_version) \
			(_version >= _XPC_VERSION(1,1))

/*
 * compare stamps - the return value is:
 *
 *	< 0,	if stamp1 < stamp2
 *	= 0,	if stamp1 == stamp2
 *	> 0,	if stamp1 > stamp2
 */
static inline int
xpc_compare_stamps(struct timespec *stamp1, struct timespec *stamp2)
{
	int ret;


	if ((ret = stamp1->tv_sec - stamp2->tv_sec) == 0) {
		ret = stamp1->tv_nsec - stamp2->tv_nsec;
	}
	return ret;
}


/*
 * Define the structures by which XPC variables can be exported to other
 * partitions. (There are two: struct xpc_vars and struct xpc_vars_part)
 */

/*
 * The following structure describes the partition generic variables
 * needed by other partitions in order to properly initialize.
 *
 * struct xpc_vars version number also applies to struct xpc_vars_part.
 * Changes to either structure and/or related functionality should be
 * reflected by incrementing either the major or minor version numbers
 * of struct xpc_vars.
 */
struct xpc_vars {
	u8 version;
	u64 heartbeat