linux-kernel - [PATCH RFC 2/6] MIPS: Allow platforms to override mapping/unmapping coherent

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Date:   Tue, 23 Jan 2018 17:47:02 -0800
From:   Florian Fainelli <f.fainelli@...il.com>
To:     linux-mips@...ux-mips.org
Cc:     Florian Fainelli <florian.fainelli@...adcom.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Ralf Baechle <ralf@...ux-mips.org>,
        Kevin Cernekee <cernekee@...il.com>,
        James Hogan <jhogan@...nel.org>,
        Paul Burton <paul.burton@...s.com>,
        Matt Redfearn <matt.redfearn@...s.com>,
        "Maciej W. Rozycki" <macro@...s.com>,
        Huacai Chen <chenhc@...ote.com>,
        Kate Stewart <kstewart@...uxfoundation.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Marcin Nowakowski <marcin.nowakowski@...s.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Ingo Molnar <mingo@...nel.org>,
        David Howells <dhowells@...hat.com>,
        Kees Cook <keescook@...omium.org>,
        Thomas Meyer <thomas@...3r.de>,
        "Bryan O'Donoghue" <pure.logic@...us-software.ie>,
        Robin Murphy <robin.murphy@....com>,
        Michal Hocko <mhocko@...e.com>,
        Lucas Stach <l.stach@...gutronix.de>,
        Vladimir Murzin <vladimir.murzin@....com>,
        Bart Van Assche <bart.vanassche@...disk.com>,
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH RFC 2/6] MIPS: Allow platforms to override mapping/unmapping coherent

From: Florian Fainelli <florian.fainelli@...adcom.com>

In preparation for allowing support for Broadcom's eXtended Kseg0/1
feature, allow platforms to override how coherent DMA mappings are done
by providing plat_map_coherent() and plat_unmap_coherent() hooks, which
default to the current implementation with CAC/UNCAC unless changed.

Signed-off-by: Florian Fainelli <f.fainelli@...il.com>
---
 arch/mips/include/asm/mach-generic/dma-coherence.h | 16 ++++++++++++++++
 arch/mips/mm/dma-default.c                         | 10 +++++++---
 2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/arch/mips/include/asm/mach-generic/dma-coherence.h b/arch/mips/include/asm/mach-generic/dma-coherence.h
index e6e7dfa15801..42a1546e7d10 100644
--- a/arch/mips/include/asm/mach-generic/dma-coherence.h
+++ b/arch/mips/include/asm/mach-generic/dma-coherence.h
@@ -98,4 +98,20 @@ static inline phys_addr_t dma_to_phys(struct device *dev, dma_addr_t daddr)
 #endif
 #endif /* CONFIG_SWIOTLB */
 
+#ifndef plat_map_coherent
+static inline int plat_map_coherent(dma_addr_t handle, void *cac_va, size_t size,
+				    void **uncac_va, gfp_t gfp)
+{
+	*uncac_va = UNCAC_ADDR(cac_va);
+	return 0;
+}
+#endif
+
+#ifndef plat_unmap_coherent
+static inline void *plat_unmap_coherent(void *addr)
+{
+	return CAC_ADDR(addr);
+}
+#endif
+
 #endif /* __ASM_MACH_GENERIC_DMA_COHERENCE_H */
diff --git a/arch/mips/mm/dma-default.c b/arch/mips/mm/dma-default.c
index e3e94d05f0fd..f82f00dcc841 100644
--- a/arch/mips/mm/dma-default.c
+++ b/arch/mips/mm/dma-default.c
@@ -151,7 +151,11 @@ static void *mips_dma_alloc_coherent(struct device *dev, size_t size,
 	if (!(attrs & DMA_ATTR_NON_CONSISTENT) &&
 	    !plat_device_is_coherent(dev)) {
 		dma_cache_wback_inv((unsigned long) ret, size);
-		ret = UNCAC_ADDR(ret);
+		if (plat_map_coherent(*dma_handle, ret, PFN_ALIGN(size),
+				      &ret, gfp)) {
+			free_pages((unsigned long)ret, size);
+			ret = NULL;
+		}
 	}
 
 	return ret;
@@ -167,7 +171,7 @@ static void mips_dma_free_coherent(struct device *dev, size_t size, void *vaddr,
 	plat_unmap_dma_mem(dev, dma_handle, size, DMA_BIDIRECTIONAL);
 
 	if (!(attrs & DMA_ATTR_NON_CONSISTENT) && !plat_device_is_coherent(dev))
-		addr = CAC_ADDR(addr);
+		addr = (unsigned long)plat_unmap_coherent(vaddr);
 
 	page = virt_to_page((void *) addr);
 
@@ -187,7 +191,7 @@ static int mips_dma_mmap(struct device *dev, struct vm_area_struct *vma,
 	int ret = -ENXIO;
 
 	if (!plat_device_is_coherent(dev))
-		addr = CAC_ADDR(addr);
+		addr = (unsigned long)plat_unmap_coherent((void *)addr);
 
 	pfn = page_to_pfn(virt_to_page((void *)addr));
 
-- 
2.7.4