arch/mips/kernel/mips-cm.c

/*
 * Copyright (C) 2013 Imagination Technologies
 * Author: Paul Burton <paul.burton@imgtec.com>
 *
 * 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.
 */

#include <linux/errno.h>

#include <asm/mips-cm.h>
#include <asm/mipsregs.h>

void __iomem *mips_cm_base;
void __iomem *mips_cm_l2sync_base;

phys_addr_t __mips_cm_phys_base(void)
{
	u32 config3 = read_c0_config3();
	u32 cmgcr;

	/* Check the CMGCRBase register is implemented */
	if (!(config3 & MIPS_CONF3_CMGCR))
		return 0;

	/* Read the address from CMGCRBase */
	cmgcr = read_c0_cmgcrbase();
	return (cmgcr & MIPS_CMGCRF_BASE) << (36 - 32);
}

phys_addr_t mips_cm_phys_base(void)
	__attribute__((weak, alias("__mips_cm_phys_base")));

phys_addr_t __mips_cm_l2sync_phys_base(void)
{
	u32 base_reg;

	/*
	 * If the L2-only sync region is already enabled then leave it at it's
	 * current location.
	 */
	base_reg = read_gcr_l2_only_sync_base();
	if (base_reg & CM_GCR_L2_ONLY_SYNC_BASE_SYNCEN_MSK)
		return base_reg & CM_GCR_L2_ONLY_SYNC_BASE_SYNCBASE_MSK;

	/* Default to following the CM */
	return mips_cm_phys_base() + MIPS_CM_GCR_SIZE;
}

phys_addr_t mips_cm_l2sync_phys_base(void)
	__attribute__((weak, alias("__mips_cm_l2sync_phys_base")));

static void mips_cm_probe_l2sync(void)
{
	unsigned major_rev;
	phys_addr_t addr;

	/* L2-only sync was introduced with CM major revision 6 */
	major_rev = (read_gcr_rev() & CM_GCR_REV_MAJOR_MSK) >>
		CM_GCR_REV_MAJOR_SHF;
	if (major_rev < 6)
		return;

	/* Find a location for the L2 sync region */
	addr = mips_cm_l2sync_phys_base();
	BUG_ON((addr & CM_GCR_L2_ONLY_SYNC_BASE_SYNCBASE_MSK) != addr);
	if (!addr)
		return;

	/* Set the region base address & enable it */
	write_gcr_l2_only_sync_base(addr | CM_GCR_L2_ONLY_SYNC_BASE_SYNCEN_MSK);

	/* Map the region */
	mips_cm_l2sync_base = ioremap_nocache(addr, MIPS_CM_L2SYNC_SIZE);
}

int mips_cm_probe(void)
{
	phys_addr_t addr;
	u32 base_reg;

	/*
	 * No need to probe again if we have already been
	 * here before.
	 */
	if (mips_cm_base)
		return 0;

	addr = mips_cm_phys_base();
	BUG_ON((addr & CM_GCR_BASE_GCRBASE_MSK) != addr);
	if (!addr)
		return -ENODEV;

	mips_cm_base = ioremap_nocache(addr, MIPS_CM_GCR_SIZE);
	if (!mips_cm_base)
		return -ENXIO;

	/* sanity check that we're looking at a CM */
	base_reg = read_gcr_base();
	if ((base_reg & CM_GCR_BASE_GCRBASE_MSK) != addr) {
		pr_err("GCRs appear to have been moved (expected them at 0x%08lx)!\n",
		       (unsigned long)addr);
		mips_cm_base = NULL;
		return -ENODEV;
	}

	/* set default target to memory */
	base_reg &= ~CM_GCR_BASE_CMDEFTGT_MSK;
	base_reg |= CM_GCR_BASE_CMDEFTGT_MEM;
	write_gcr_base(base_reg);

	/* disable CM regions */
	write_gcr_reg0_base(CM_GCR_REGn_BASE_BASEADDR_MSK);
	write_gcr_reg0_mask(CM_GCR_REGn_MASK_ADDRMASK_MSK);
	write_gcr_reg1_base(CM_GCR_REGn_BASE_BASEADDR_MSK);
	write_gcr_reg1_mask(CM_GCR_REGn_MASK_ADDRMASK_MSK);
	write_gcr_reg2_base(CM_GCR_REGn_BASE_BASEADDR_MSK);
	write_gcr_reg2_mask(CM_GCR_REGn_MASK_ADDRMASK_MSK);
	write_gcr_reg3_base(CM_GCR_REGn_BASE_BASEADDR_MSK);
	write_gcr_reg3_mask(CM_GCR_REGn_MASK_ADDRMASK_MSK);

	/* probe for an L2-only sync region */
	mips_cm_probe_l2sync();

	return 0;
}