arch/mips/kernel/mips-mt.c

// SPDX-License-Identifier: GPL-2.0
/*
 * General MIPS MT support routines, usable in AP/SP and SMVP.
 * Copyright (C) 2005 Mips Technologies, Inc
 */

#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/export.h>
#include <linux/interrupt.h>
#include <linux/security.h>

#include <asm/cpu.h>
#include <asm/processor.h>
#include <linux/atomic.h>
#include <asm/hardirq.h>
#include <asm/mmu_context.h>
#include <asm/mipsmtregs.h>
#include <asm/r4kcache.h>
#include <asm/cacheflush.h>
#include <asm/mips_mt.h>

int vpelimit;

static int __init maxvpes(char *str)
{
	get_option(&str, &vpelimit);

	return 1;
}

__setup("maxvpes=", maxvpes);

int tclimit;

static int __init maxtcs(char *str)
{
	get_option(&str, &tclimit);

	return 1;
}

__setup("maxtcs=", maxtcs);

static int mt_opt_rpsctl = -1;
static int mt_opt_nblsu = -1;
static int mt_opt_forceconfig7;
static int mt_opt_config7 = -1;

static int __init rpsctl_set(char *str)
{
	get_option(&str, &mt_opt_rpsctl);
	return 1;
}
__setup("rpsctl=", rpsctl_set);

static int __init nblsu_set(char *str)
{
	get_option(&str, &mt_opt_nblsu);
	return 1;
}
__setup("nblsu=", nblsu_set);

static int __init config7_set(char *str)
{
	get_option(&str, &mt_opt_config7);
	mt_opt_forceconfig7 = 1;
	return 1;
}
__setup("config7=", config7_set);

static unsigned int itc_base;

static int __init set_itc_base(char *str)
{
	get_option(&str, &itc_base);
	return 1;
}

__setup("itcbase=", set_itc_base);

void mips_mt_set_cpuoptions(void)
{
	unsigned int oconfig7 = read_c0_config7();
	unsigned int nconfig7 = oconfig7;

	if (mt_opt_rpsctl >= 0) {
		printk("34K return prediction stack override set to %d.\n",
			mt_opt_rpsctl);
		if (mt_opt_rpsctl)
			nconfig7 |= (1 << 2);
		else
			nconfig7 &= ~(1 << 2);
	}
	if (mt_opt_nblsu >= 0) {
		printk("34K ALU/LSU sync override set to %d.\n", mt_opt_nblsu);
		if (mt_opt_nblsu)
			nconfig7 |= (1 << 5);
		else
			nconfig7 &= ~(1 << 5);
	}
	if (mt_opt_forceconfig7) {
		printk("CP0.Config7 forced to 0x%08x.\n", mt_opt_config7);
		nconfig7 = mt_opt_config7;
	}
	if (oconfig7 != nconfig7) {
		__asm__ __volatile("sync");
		write_c0_config7(nconfig7);
		ehb();
		printk("Config7: 0x%08x\n", read_c0_config7());
	}

	if (itc_base != 0) {
		/*
		 * Configure ITC mapping.  This code is very
		 * specific to the 34K core family, which uses
		 * a special mode bit ("ITC") in the ErrCtl
		 * register to enable access to ITC control
		 * registers via cache "tag" operations.
		 */
		unsigned long ectlval;
		unsigned long itcblkgrn;

		/* ErrCtl register is known as "ecc" to Linux */
		ectlval = read_c0_ecc();
		write_c0_ecc(ectlval | (0x1 << 26));
		ehb();
#define INDEX_0 (0x80000000)
#define INDEX_8 (0x80000008)
		/* Read "cache tag" for Dcache pseudo-index 8 */
		cache_op(Index_Load_Tag_D, INDEX_8);
		ehb();
		itcblkgrn = read_c0_dtaglo();
		itcblkgrn &= 0xfffe0000;
		/* Set for 128 byte pitch of ITC cells */
		itcblkgrn |= 0x00000c00;
		/* Stage in Tag register */
		write_c0_dtaglo(itcblkgrn);
		ehb();
		/* Write out to ITU with CACHE op */
		cache_op(Index_Store_Tag_D, INDEX_8);
		/* Now set base address, and turn ITC on with 0x1 bit */
		write_c0_dtaglo((itc_base & 0xfffffc00) | 0x1 );
		ehb();
		/* Write out to ITU with CACHE op */
		cache_op(Index_Store_Tag_D, INDEX_0);
		write_c0_ecc(ectlval);
		ehb();
		printk("Mapped %ld ITC cells starting at 0x%08x\n",
			((itcblkgrn & 0x7fe00000) >> 20), itc_base);
	}
}

const struct class mt_class = {
	.name = "mt",
};

static int __init mips_mt_init(void)
{
	return class_register(&mt_class);
}

subsys_initcall(mips_mt_init);