path: root/drivers/misc/sgi-gru/grukservices.c

/*
 * SN Platform GRU Driver
 *
 *              KERNEL SERVICES THAT USE THE GRU
 *
 *  Copyright (c) 2008 Silicon Graphics, Inc.  All Rights Reserved.
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 */

#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/spinlock.h>
#include <linux/device.h>
#include <linux/miscdevice.h>
#include <linux/proc_fs.h>
#include <linux/interrupt.h>
#include <linux/uaccess.h>
#include <linux/delay.h>
#include <linux/export.h>
#include <asm/io_apic.h>
#include "gru.h"
#include "grulib.h"
#include "grutables.h"
#include "grukservices.h"
#include "gru_instructions.h"
#include <asm/uv/uv_hub.h>

/*
 * Kernel GRU Usage
 *
 * The following is an interim algorithm for management of kernel GRU
 * resources. This will likely be replaced when we better understand the
 * kernel/user requirements.
 *
 * Blade percpu resources reserved for kernel use. These resources are
 * reserved whenever the the kernel context for the blade is loaded. Note
 * that the kernel context is not guaranteed to be always available. It is
 * loaded on demand & can be stolen by a user if the user demand exceeds the
 * kernel demand. The kernel can always reload the kernel context but
 * a SLEEP may be required!!!.
 *
 * Async Overview:
 *
 * 	Each blade has one "kernel context" that owns GRU kernel resources
 * 	located on the blade. Kernel drivers use GRU resources in this context
 * 	for sending messages, zeroing memory, etc.
 *
 * 	The kernel context is dynamically loaded on demand. If it is not in
 * 	use by the kernel, the kernel context can be unloaded & given to a user.
 * 	The kernel context will be reloaded when needed. This may require that
 * 	a context be stolen from a user.
 * 		NOTE: frequent unloading/reloading of the kernel context is
 * 		expensive. We are depending on batch schedulers, cpusets, sane
 * 		drivers or some other mechanism to prevent the need for frequent
 *	 	stealing/reloading.
 *
 * 	The kernel context consists of two parts:
 * 		- 1 CB & a few DSRs that are reserved for each cpu on the blade.
 * 		  Each cpu has it's own private resources & does not share them
 * 		  with other cpus. These resources are used serially, ie,
 * 		  locked, used & unlocked  on each call to a function in
 * 		  grukservices.
 * 		  	(Now that we have dynamic loading of kernel contexts, I
 * 		  	 may rethink this & allow sharing between cpus....)
 *
 *		- Additional resources can be reserved long term & used directly
 *		  by UV drivers located in the kernel. Drivers using these GRU
 *		  resources can use asynchronous GRU instructions that send
 *		  interrupts on completion.
 *		  	- these resources must be explicitly locked/unlocked
 *		  	- locked resources prevent (obviously) the kernel
 *		  	  context from being unloaded.
 *			- drivers using these resource directly issue their own
 *			  GRU instruction and must wait/check completion.
 *
 * 		  When these resources are reserved, the caller can optionally
 * 		  associate a wait_queue with the resources and use asynchronous
 * 		  GRU instructions. When an async GRU instruction completes, the
 * 		  driver will do a wakeup on the event.
 *
 */


#define ASYNC_HAN_TO_BID(h)	((h) - 1)
#define ASYNC_BID_TO_HAN(b)	((b) + 1)
#define ASYNC_HAN_TO_BS(h)	gru_base[ASYNC_HAN_TO_BID(h)]

#define GRU_NUM_KERNEL_CBR	1
#define GRU_NUM_KERNEL_DSR_BYTES 256
#define GRU_NUM_KERNEL_DSR_CL	(GRU_NUM_KERNEL_DSR_BYTES /		\
					GRU_CACHE_LINE_BYTES)

/* GRU instruction attributes for all instructions */
#define IMA			IMA_CB_DELAY

/* GRU cacheline size is always 64 bytes - even on arches with 128 byte lines */
#define __gru_cacheline_aligned__                               \
	__attribute__((__aligned__(GRU_CACHE_LINE_BYTES)))

#define MAGIC	0x1234567887654321UL

/* Default retry count for GRU errors on kernel instructions */
#define EXCEPTION_RETRY_LIMIT	3

/* Status of message queue sections */
#define MQS_EMPTY		0
#define MQS_FULL		1
#define MQS_NOOP		2

/*----------------- RESOURCE MANAGEMENT -------------------------------------*/
/* optimized for x86_64 */
struct message_queue {
	union gru_mesqhead	head __gru_cacheline_aligned__;	/* CL 0 */
	int			qlines;				/* DW 1 */
	long 			hstatus[2];
	void 			*next __gru_cacheline_aligned__;/* CL 1 */
	void 			*limit;
	void 			*start;
	void 			*start2;
	char			data ____cacheline_aligned;	/* CL 2 */
};

/* First word in every message - used by mesq interface */
struct message_header {
	char	present;
	char	present2;
	char 	lines;
	char	fill;
};

#define HSTATUS(mq, h)	((mq) + offsetof(struct message_queue, hstatus[h]))

/*
 * Reload the blade's kernel context into a GRU chiplet. Called holding
 * the bs_kgts_sema for READ. Will steal user contexts if necessary.
 */
static void gru_load_kernel_context(struct gru_blade_state *bs, int blade_id)
{
	struct gru_state *gru;
	struct gru_thread_state *kgts;
	void *vaddr;
	int ctxnum, ncpus;

	up_read(&bs->bs_kgts_sema);
	down_write(&bs->bs_kgts_sema);

	if (!bs->bs_kgts) {
		bs->bs_kgts = gru_alloc_gts(NULL, 0, 0, 0, 0, 0);
		bs->bs_kgts->ts_user_blade_id = blade_id;
	}
	kgts = bs->bs_kgts;

	if (!kgts->ts_gru) {
		STAT(load_kernel_context);
		ncpus = uv_blade_nr_possible_cpus(blade_id);
		kgts->ts_cbr_au_count = GRU_CB_COUNT_TO_AU(
			GRU_NUM_KERNEL_CBR * ncpus + bs->bs_async_cbrs);
		kgts->ts_dsr_au_count = GRU_DS_BYTES_TO_AU(
			GRU_NUM_KERNEL_DSR_BYTES * ncpus +
				bs->bs_async_dsr_bytes);