linux-kernel - [PATCH 14/31] sparc32/io-unit: handle page-less SG entries

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Date:	Wed, 12 Aug 2015 09:05:33 +0200
From:	Christoph Hellwig <hch@....de>
To:	torvalds@...ux-foundation.org, axboe@...nel.dk
Cc:	dan.j.williams@...el.com, vgupta@...opsys.com,
	hskinnemoen@...il.com, egtvedt@...fundet.no, realmz6@...il.com,
	dhowells@...hat.com, monstr@...str.eu, x86@...nel.org,
	dwmw2@...radead.org, alex.williamson@...hat.com,
	grundler@...isc-linux.org, linux-kernel@...r.kernel.org,
	linux-arch@...r.kernel.org, linux-alpha@...r.kernel.org,
	linux-ia64@...r.kernel.org, linux-metag@...r.kernel.org,
	linux-mips@...ux-mips.org, linux-parisc@...r.kernel.org,
	linuxppc-dev@...ts.ozlabs.org, linux-s390@...r.kernel.org,
	sparclinux@...r.kernel.org, linux-xtensa@...ux-xtensa.org,
	linux-nvdimm@...1.01.org, linux-media@...r.kernel.org
Subject: [PATCH 14/31] sparc32/io-unit: handle page-less SG entries

For the iommu offset we just need and offset into the page.  Calculate
that using the physical address instead of using the virtual address
so that we don't require a virtual mapping.

Signed-off-by: Christoph Hellwig <hch@....de>
---
 arch/sparc/mm/io-unit.c | 23 ++++++++++++-----------
 1 file changed, 12 insertions(+), 11 deletions(-)

diff --git a/arch/sparc/mm/io-unit.c b/arch/sparc/mm/io-unit.c
index f311bf2..82f97ae 100644
--- a/arch/sparc/mm/io-unit.c
+++ b/arch/sparc/mm/io-unit.c
@@ -91,13 +91,14 @@ static int __init iounit_init(void)
 subsys_initcall(iounit_init);
 
 /* One has to hold iounit->lock to call this */
-static unsigned long iounit_get_area(struct iounit_struct *iounit, unsigned long vaddr, int size)
+static dma_addr_t iounit_get_area(struct iounit_struct *iounit,
+		unsigned long paddr, int size)
 {
 	int i, j, k, npages;
-	unsigned long rotor, scan, limit;
+	unsigned long rotor, scan, limit, dma_addr;
 	iopte_t iopte;
 
-        npages = ((vaddr & ~PAGE_MASK) + size + (PAGE_SIZE-1)) >> PAGE_SHIFT;
+        npages = ((paddr & ~PAGE_MASK) + size + (PAGE_SIZE-1)) >> PAGE_SHIFT;
 
 	/* A tiny bit of magic ingredience :) */
 	switch (npages) {
@@ -106,7 +107,7 @@ static unsigned long iounit_get_area(struct iounit_struct *iounit, unsigned long
 	default: i = 0x0213; break;
 	}
 	
-	IOD(("iounit_get_area(%08lx,%d[%d])=", vaddr, size, npages));
+	IOD(("iounit_get_area(%08lx,%d[%d])=", paddr, size, npages));
 	
 next:	j = (i & 15);
 	rotor = iounit->rotor[j - 1];
@@ -121,7 +122,7 @@ nexti:	scan = find_next_zero_bit(iounit->bmap, limit, scan);
 		}
 		i >>= 4;
 		if (!(i & 15))
-			panic("iounit_get_area: Couldn't find free iopte slots for (%08lx,%d)\n", vaddr, size);
+			panic("iounit_get_area: Couldn't find free iopte slots for (%08lx,%d)\n", paddr, size);
 		goto next;
 	}
 	for (k = 1, scan++; k < npages; k++)
@@ -129,14 +130,14 @@ nexti:	scan = find_next_zero_bit(iounit->bmap, limit, scan);
 			goto nexti;
 	iounit->rotor[j - 1] = (scan < limit) ? scan : iounit->limit[j - 1];
 	scan -= npages;
-	iopte = MKIOPTE(__pa(vaddr & PAGE_MASK));
-	vaddr = IOUNIT_DMA_BASE + (scan << PAGE_SHIFT) + (vaddr & ~PAGE_MASK);
+	iopte = MKIOPTE(paddr & PAGE_MASK);
+	dma_addr = IOUNIT_DMA_BASE + (scan << PAGE_SHIFT) + (paddr & ~PAGE_MASK);
 	for (k = 0; k < npages; k++, iopte = __iopte(iopte_val(iopte) + 0x100), scan++) {
 		set_bit(scan, iounit->bmap);
 		sbus_writel(iopte, &iounit->page_table[scan]);
 	}
-	IOD(("%08lx\n", vaddr));
-	return vaddr;
+	IOD(("%08lx\n", dma_addr));
+	return dma_addr;
 }
 
 static __u32 iounit_get_scsi_one(struct device *dev, char *vaddr, unsigned long len)
@@ -145,7 +146,7 @@ static __u32 iounit_get_scsi_one(struct device *dev, char *vaddr, unsigned long
 	unsigned long ret, flags;
 	
 	spin_lock_irqsave(&iounit->lock, flags);
-	ret = iounit_get_area(iounit, (unsigned long)vaddr, len);
+	ret = iounit_get_area(iounit, virt_to_phys(vaddr), len);
 	spin_unlock_irqrestore(&iounit->lock, flags);
 	return ret;
 }
@@ -159,7 +160,7 @@ static void iounit_get_scsi_sgl(struct device *dev, struct scatterlist *sg, int
 	spin_lock_irqsave(&iounit->lock, flags);
 	while (sz != 0) {
 		--sz;
-		sg->dma_address = iounit_get_area(iounit, (unsigned long) sg_virt(sg), sg->length);
+		sg->dma_address = iounit_get_area(iounit, sg_phys(sg), sg->length);
 		sg->dma_length = sg->length;
 		sg = sg_next(sg);
 	}
-- 
1.9.1

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