/*************************************************************************/ /*!
@Title          Linux memory interface support functions
@Copyright      Copyright (c) Imagination Technologies Ltd. All Rights Reserved
@License        Dual MIT/GPLv2

The contents of this file are subject to the MIT license as set out below.

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

Alternatively, the contents of this file may be used under the terms of
the GNU General Public License Version 2 ("GPL") in which case the provisions
of GPL are applicable instead of those above.

If you wish to allow use of your version of this file only under the terms of
GPL, and not to allow others to use your version of this file under the terms
of the MIT license, indicate your decision by deleting the provisions above
and replace them with the notice and other provisions required by GPL as set
out in the file called "GPL-COPYING" included in this distribution. If you do
not delete the provisions above, a recipient may use your version of this file
under the terms of either the MIT license or GPL.

This License is also included in this distribution in the file called
"MIT-COPYING".

EXCEPT AS OTHERWISE STATED IN A NEGOTIATED AGREEMENT: (A) THE SOFTWARE IS
PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
PURPOSE AND NONINFRINGEMENT; AND (B) IN NO EVENT SHALL THE AUTHORS OR
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CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/ /**************************************************************************/

#include <linux/version.h>

#if (LINUX_VERSION_CODE < KERNEL_VERSION(2,6,38))
#ifndef AUTOCONF_INCLUDED
#include <linux/config.h>
#endif
#endif

#include <linux/spinlock.h>
#include <linux/mm.h>
#include <asm/page.h>
#include <asm/pgtable.h>

#include "img_defs.h"
#include "pvr_debug.h"
#include "mutils.h"

#if defined(SUPPORT_LINUX_X86_PAT)
#define	PAT_LINUX_X86_WC	1

#define	PAT_X86_ENTRY_BITS	8

#define	PAT_X86_BIT_PWT		1U
#define	PAT_X86_BIT_PCD		2U
#define	PAT_X86_BIT_PAT		4U
#define	PAT_X86_BIT_MASK	(PAT_X86_BIT_PAT | PAT_X86_BIT_PCD | PAT_X86_BIT_PWT)

static IMG_BOOL g_write_combining_available = IMG_FALSE;

#define	PROT_TO_PAT_INDEX(v, B) ((v & _PAGE_ ## B) ? PAT_X86_BIT_ ## B : 0)

static inline IMG_UINT
pvr_pat_index(pgprotval_t prot_val)
{
	IMG_UINT ret = 0;
	pgprotval_t val = prot_val & _PAGE_CACHE_MASK;

	ret |= PROT_TO_PAT_INDEX(val, PAT);
	ret |= PROT_TO_PAT_INDEX(val, PCD);
	ret |= PROT_TO_PAT_INDEX(val, PWT);

	return ret;
}

static inline IMG_UINT
pvr_pat_entry(u64 pat, IMG_UINT index)
{
	return (IMG_UINT)(pat >> (index * PAT_X86_ENTRY_BITS)) & PAT_X86_BIT_MASK;
}

static IMG_VOID
PVRLinuxX86PATProbe(IMG_VOID)
{
	/*
	 * cpu_has_pat indicates whether PAT support is available on the CPU,
	 * but doesn't indicate if it has been enabled.
	 */
	if (cpu_has_pat)	/* PRQA S 3335 */ /* ignore 'no function declared' */
	{
		u64 pat;
		IMG_UINT pat_index;
		IMG_UINT pat_entry;

		PVR_TRACE(("%s: PAT available", __FUNCTION__));
		/*
		 * There is no Linux API for finding out if write combining
		 * is avaialable through the PAT, so we take the direct
		 * approach, and see if the PAT MSR contains a write combining
		 * entry.
		 */
		rdmsrl(MSR_IA32_CR_PAT, pat);
		PVR_TRACE(("%s: Top 32 bits of PAT: 0x%.8x", __FUNCTION__, (IMG_UINT)(pat >> 32)));
		PVR_TRACE(("%s: Bottom 32 bits of PAT: 0x%.8x", __FUNCTION__, (IMG_UINT)(pat)));

		pat_index = pvr_pat_index(_PAGE_CACHE_WC);
		PVR_TRACE(("%s: PAT index for write combining: %u", __FUNCTION__, pat_index));

		pat_entry = pvr_pat_entry(pat, pat_index);
		PVR_TRACE(("%s: PAT entry for write combining: 0x%.2x (should be 0x%.2x)", __FUNCTION__, pat_entry, PAT_LINUX_X86_WC));

#if defined(SUPPORT_LINUX_X86_WRITECOMBINE)
		g_write_combining_available = (IMG_BOOL)(pat_entry == PAT_LINUX_X86_WC);
#endif
	}
#if defined(DEBUG)
#if defined(SUPPORT_LINUX_X86_WRITECOMBINE)
	if (g_write_combining_available)
	{
		PVR_TRACE(("%s: Write combining available via PAT", __FUNCTION__));
	}
	else
	{
		PVR_TRACE(("%s: Write combining not available", __FUNCTION__));
	}
#else	/* defined(SUPPORT_LINUX_X86_WRITECOMBINE) */
	PVR_TRACE(("%s: Write combining disabled in driver build", __FUNCTION__));
#endif	/* defined(SUPPORT_LINUX_X86_WRITECOMBINE) */
#endif	/* DEBUG */
}

pgprot_t
pvr_pgprot_writecombine(pgprot_t prot)
{
    /*
     * It would be worth checking from time to time to see if a
     * pgprot_writecombine function (or similar) is introduced on Linux for
     * x86 processors.  If so, this function, and PVRLinuxX86PATProbe can be
     * removed, and a macro used to select between pgprot_writecombine and
     * pgprot_noncached, dpending on the value for of
     * SUPPORT_LINUX_X86_WRITECOMBINE.
     */
    /* PRQA S 0481,0482 2 */ /* scalar expressions */
    return (g_write_combining_available) ?
		__pgprot((pgprot_val(prot) & ~_PAGE_CACHE_MASK) | _PAGE_CACHE_WC) : pgprot_noncached(prot);
}
#endif	/* defined(SUPPORT_LINUX_X86_PAT) */

IMG_VOID
PVRLinuxMUtilsInit(IMG_VOID)
{
#if defined(SUPPORT_LINUX_X86_PAT)
	PVRLinuxX86PATProbe();
#endif
}