/*	$NetBSD: drm_cache.c,v 1.19 2022/07/19 23:19:27 riastradh Exp $	*/

/*-
 * Copyright (c) 2013 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Taylor R. Campbell.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: drm_cache.c,v 1.19 2022/07/19 23:19:27 riastradh Exp $");

#include <sys/param.h>
#include <sys/types.h>
#include <sys/xcall.h>

#include <uvm/uvm_extern.h>

#include <linux/highmem.h>
#include <linux/mm_types.h>

#include <drm/drm_cache.h>

#if !defined(__arm__) && !defined(__aarch64__) && !defined(__alpha__)
#define DRM_CLFLUSH	1
#endif

#if defined(DRM_CLFLUSH)
static bool		drm_md_clflush_finegrained_p(void);
static void		drm_md_clflush_all(void);
static void		drm_md_clflush_begin(void);
static void		drm_md_clflush_commit(void);
static void		drm_md_clflush_page(struct page *);
static void		drm_md_clflush_virt_range(const void *, size_t);
#endif

void
drm_clflush_pages(struct page **pages, unsigned long npages)
{
#if defined(DRM_CLFLUSH)
	if (drm_md_clflush_finegrained_p()) {
		drm_md_clflush_begin();
		while (npages--)
			drm_md_clflush_page(pages[npages]);
		drm_md_clflush_commit();
	} else {
		drm_md_clflush_all();
	}
#endif
}

void
drm_clflush_sg(struct sg_table *sgt)
{
	drm_clflush_pages(sgt->sgl->sg_pgs, sgt->sgl->sg_npgs);
}

void
drm_clflush_virt_range(void *vaddr, unsigned long nbytes)
{
#if defined(DRM_CLFLUSH)
	if (drm_md_clflush_finegrained_p()) {
		drm_md_clflush_begin();
		drm_md_clflush_virt_range(vaddr, nbytes);
		drm_md_clflush_commit();
	} else {
		drm_md_clflush_all();
	}
#endif
}

#if defined(__i386__) || defined(__x86_64__)

#include <machine/cpufunc.h>

static bool
drm_md_clflush_finegrained_p(void)
{
	return ISSET(cpu_info_primary.ci_feat_val[0], CPUID_CLFSH);
}

static void
drm_x86_clflush_xc(void *arg0 __unused, void *arg1 __unused)
{
	wbinvd();
}

static void
drm_md_clflush_all(void)
{
	xc_wait(xc_broadcast(0, &drm_x86_clflush_xc, NULL, NULL));
}

static void
drm_md_clflush_begin(void)
{
	/* Support for CLFLUSH implies support for MFENCE.  */
	x86_mfence();
}

static void
drm_md_clflush_commit(void)
{
	x86_mfence();
}

static void
drm_md_clflush_page(struct page *page)
{
	void *const vaddr = kmap_atomic(page);

	drm_md_clflush_virt_range(vaddr, PAGE_SIZE);

	kunmap_atomic(vaddr);
}

static void
drm_md_clflush_virt_range(const void *ptr, size_t nbytes)
{
	const unsigned clflush_size = cpu_info_primary.ci_cflush_lsize;
	const vaddr_t vaddr = (vaddr_t)ptr;
	const vaddr_t start = rounddown(vaddr, clflush_size);
	const vaddr_t end = roundup(vaddr + nbytes, clflush_size);
	vaddr_t va;

	for (va = start; va < end; va += clflush_size)
		asm volatile ("clflush %0" : : "m" (*(const char *)va));
}

#elif defined(__sparc__) || defined(__sparc64__)

#ifdef __sparc64__
#include <sparc64/sparc64/cache.h>
#else
#include <sparc/sparc/cache.h>
#endif

static bool
drm_md_clflush_finegrained_p(void)
{
	return true;
}

static void
drm_md_clflush_all(void)
{
	panic("don't know how to flush entire cache on sparc64");
}

static void
drm_md_clflush_begin(void)
{
	membar_Sync();		/* unsure if needed */
}

static void
drm_md_clflush_commit(void)
{
	membar_Sync();		/* unsure if needed */
}

static void
drm_md_clflush_page(struct page *page)
{
#ifdef __sparc64__
	paddr_t pa = VM_PAGE_TO_PHYS(&page->p_vmp);

	cache_flush_phys(pa, PAGE_SIZE, 0);
#else
	void *const vaddr = kmap_atomic(page);

	cache_flush(vaddr, PAGE_SIZE);

	kunmap_atomic(vaddr);
#endif
}

static void
drm_md_clflush_virt_range(const void *ptr, size_t nbytes)
{
#ifdef __sparc64__
	/* XXX Mega-kludge -- doesn't seem to be a way to flush by vaddr.  */
	blast_dcache();
#else
	cache_flush(ptr, nbytes);
#endif
}

#elif defined(__powerpc__)

static bool
drm_md_clflush_finegrained_p(void)
{
	return true;
}

static void
drm_md_clflush_all(void)
{
	panic("don't know how to flush entire cache on powerpc");
}

static void
drm_md_clflush_begin(void)
{
}

static void
drm_md_clflush_commit(void)
{
	asm volatile ("sync" ::: "memory");
}

static void
drm_md_clflush_page(struct page *page)
{
	void *const vaddr = kmap_atomic(page);

	drm_md_clflush_virt_range(vaddr, PAGE_SIZE);

	kunmap_atomic(vaddr);
}

static void
drm_md_clflush_virt_range(const void *ptr, size_t nbytes)
{
	const unsigned dcsize = curcpu()->ci_ci.dcache_line_size;
	vaddr_t va = (vaddr_t)ptr;
	vaddr_t start = rounddown(va, dcsize);
	vaddr_t end = roundup(va + nbytes, dcsize);
	vsize_t len = end - start;
	vsize_t off;

	for (off = 0; off < len; off += dcsize)
		asm volatile ("dcbf\t%0,%1" : : "b"(start), "r"(off));
}

#endif