Message-Id: <459A948D.76E4.0078.0@novell.com>
Date:	Tue, 02 Jan 2007 16:21:17 +0000
From:	"Jan Beulich" <jbeulich@...ell.com>
To:	<linux-ia64@...r.kernel.org>, <patches@...-64.org>
Cc:	"Muli Ben-Yehuda" <muli@...ibm.com>,
	<xen-devel@...ts.xensource.com>, <linux-kernel@...r.kernel.org>
Subject: [PATCH 4/4] swiotlb abstraction (e.g. for Xen)

This patch adds abstraction so that the file can be used by environments other
than IA64 and EM64T, namely for Xen.

Even if this patch is considered too convoluted, I would appreciate if the
other three ones could still be considered for merging.

Signed-off-by: Jan Beulich <jbeulich@...ell.com>

Index: 2.6.20-rc3-swiotlb-bugs/include/asm-ia64/swiotlb.h
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ 2.6.20-rc3-swiotlb-bugs/include/asm-ia64/swiotlb.h	2007-01-02 16:55:32.000000000 +0100
@@ -0,0 +1,9 @@
+#ifndef _ASM_SWIOTLB_H
+#define _ASM_SWIOTLB_H 1
+
+#include <asm/machvec.h>
+
+#define SWIOTLB_ARCH_NEED_LATE_INIT
+#define SWIOTLB_ARCH_NEED_ALLOC
+
+#endif /* _ASM_SWIOTLB_H */
Index: 2.6.20-rc3-swiotlb-bugs/include/asm-x86_64/swiotlb.h
===================================================================
--- 2.6.20-rc3-swiotlb-bugs.orig/include/asm-x86_64/swiotlb.h	2007-01-02 16:12:20.000000000 +0100
+++ 2.6.20-rc3-swiotlb-bugs/include/asm-x86_64/swiotlb.h	2007-01-02 16:55:32.000000000 +0100
@@ -44,6 +44,7 @@ extern void swiotlb_init(void);
 extern int swiotlb_force;
 
 #ifdef CONFIG_SWIOTLB
+#define SWIOTLB_ARCH_NEED_ALLOC
 extern int swiotlb;
 #else
 #define swiotlb 0
Index: 2.6.20-rc3-swiotlb-bugs/lib/swiotlb.c
===================================================================
--- 2.6.20-rc3-swiotlb-bugs.orig/lib/swiotlb.c	2007-01-02 16:52:51.000000000 +0100
+++ 2.6.20-rc3-swiotlb-bugs/lib/swiotlb.c	2007-01-02 17:04:38.000000000 +0100
@@ -28,6 +28,7 @@
 #include <asm/io.h>
 #include <asm/dma.h>
 #include <asm/scatterlist.h>
+#include <asm/swiotlb.h>
 
 #include <linux/init.h>
 #include <linux/bootmem.h>
@@ -35,8 +36,10 @@
 #define OFFSET(val,align) ((unsigned long)	\
 	                   ( (val) & ( (align) - 1)))
 
+#ifndef SG_ENT_VIRT_ADDRESS
 #define SG_ENT_VIRT_ADDRESS(sg)	(page_address((sg)->page) + (sg)->offset)
 #define SG_ENT_PHYS_ADDRESS(sg)	virt_to_bus(SG_ENT_VIRT_ADDRESS(sg))
+#endif
 
 /*
  * Maximum allowable number of contiguous slabs to map,
@@ -101,13 +104,25 @@ static unsigned int io_tlb_index;
  * We need to save away the original address corresponding to a mapped entry
  * for the sync operations.
  */
-static unsigned char **io_tlb_orig_addr;
+#ifndef SWIOTLB_ARCH_HAS_IO_TLB_ADDR_T
+typedef char *io_tlb_addr_t;
+#define swiotlb_orig_addr_null(buffer) (!(buffer))
+#define ptr_to_io_tlb_addr(ptr) (ptr)
+#define page_to_io_tlb_addr(pg, off) (page_address(pg) + (off))
+#define sg_to_io_tlb_addr(sg) SG_ENT_VIRT_ADDRESS(sg)
+#endif
+static io_tlb_addr_t *io_tlb_orig_addr;
 
 /*
  * Protect the above data structures in the map and unmap calls
  */
 static DEFINE_SPINLOCK(io_tlb_lock);
 
+#ifdef SWIOTLB_EXTRA_VARIABLES
+SWIOTLB_EXTRA_VARIABLES;
+#endif
+
+#ifndef SWIOTLB_ARCH_HAS_SETUP_IO_TLB_NPAGES
 static int __init
 setup_io_tlb_npages(char *str)
 {
@@ -122,9 +137,25 @@ setup_io_tlb_npages(char *str)
 		swiotlb_force = 1;
 	return 1;
 }
+#endif
 __setup("swiotlb=", setup_io_tlb_npages);
 /* make io_tlb_overflow tunable too? */
 
+#ifndef swiotlb_adjust_size
+#define swiotlb_adjust_size(size) ((void)0)
+#endif
+
+#ifndef swiotlb_adjust_seg
+#define swiotlb_adjust_seg(start, size) ((void)0)
+#endif
+
+#ifndef swiotlb_print_info
+#define swiotlb_print_info(bytes) \
+	printk(KERN_INFO "Placing %luMB software IO TLB between 0x%lx - " \
+	       "0x%lx\n", bytes >> 20, \
+	       virt_to_bus(io_tlb_start), virt_to_bus(io_tlb_end))
+#endif
+
 /*
  * Statically reserve bounce buffer space and initialize bounce buffer data
  * structures for the software IO TLB used to implement the DMA API.
@@ -138,6 +169,8 @@ swiotlb_init_with_default_size(size_t de
 		io_tlb_nslabs = (default_size >> IO_TLB_SHIFT);
 		io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
 	}
+	swiotlb_adjust_size(io_tlb_nslabs);
+	swiotlb_adjust_size(io_tlb_overflow);
 
 	bytes = io_tlb_nslabs << IO_TLB_SHIFT;
 
@@ -155,10 +188,14 @@ swiotlb_init_with_default_size(size_t de
 	 * between io_tlb_start and io_tlb_end.
 	 */
 	io_tlb_list = alloc_bootmem(io_tlb_nslabs * sizeof(int));
-	for (i = 0; i < io_tlb_nslabs; i++)
+	for (i = 0; i < io_tlb_nslabs; i++) {
+		if ( !(i % IO_TLB_SEGSIZE) )
+			swiotlb_adjust_seg(io_tlb_start + (i << IO_TLB_SHIFT),
+				IO_TLB_SEGSIZE << IO_TLB_SHIFT);
  		io_tlb_list[i] = IO_TLB_SEGSIZE - OFFSET(i, IO_TLB_SEGSIZE);
+ 	}
 	io_tlb_index = 0;
-	io_tlb_orig_addr = alloc_bootmem(io_tlb_nslabs * sizeof(char *));
+	io_tlb_orig_addr = alloc_bootmem(io_tlb_nslabs * sizeof(io_tlb_addr_t));
 
 	/*
 	 * Get the overflow emergency buffer
@@ -166,17 +203,21 @@ swiotlb_init_with_default_size(size_t de
 	io_tlb_overflow_buffer = alloc_bootmem_low(io_tlb_overflow);
 	if (!io_tlb_overflow_buffer)
 		panic("Cannot allocate SWIOTLB overflow buffer!\n");
+	swiotlb_adjust_seg(io_tlb_overflow_buffer, io_tlb_overflow);
 
-	printk(KERN_INFO "Placing software IO TLB between 0x%lx - 0x%lx\n",
-	       virt_to_bus(io_tlb_start), virt_to_bus(io_tlb_end));
+	swiotlb_print_info(bytes);
 }
+#ifndef __swiotlb_init_with_default_size
+#define __swiotlb_init_with_default_size swiotlb_init_with_default_size
+#endif
 
 void __init
 swiotlb_init(void)
 {
-	swiotlb_init_with_default_size(64 * (1<<20));	/* default to 64MB */
+	__swiotlb_init_with_default_size(64 * (1<<20)); /* default to 64MB */
 }
 
+#ifdef SWIOTLB_ARCH_NEED_LATE_INIT
 /*
  * Systems with larger DMA zones (those that don't support ISA) can
  * initialize the swiotlb later using the slab allocator if needed.
@@ -234,12 +275,12 @@ swiotlb_late_init_with_default_size(size
  		io_tlb_list[i] = IO_TLB_SEGSIZE - OFFSET(i, IO_TLB_SEGSIZE);
 	io_tlb_index = 0;
 
-	io_tlb_orig_addr = (unsigned char **)__get_free_pages(GFP_KERNEL,
-	                           get_order(io_tlb_nslabs * sizeof(char *)));
+	io_tlb_orig_addr = (io_tlb_addr_t *)__get_free_pages(GFP_KERNEL,
+	                           get_order(io_tlb_nslabs * sizeof(io_tlb_addr_t)));
 	if (!io_tlb_orig_addr)
 		goto cleanup3;
 
-	memset(io_tlb_orig_addr, 0, io_tlb_nslabs * sizeof(char *));
+	memset(io_tlb_orig_addr, 0, io_tlb_nslabs * sizeof(io_tlb_addr_t));
 
 	/*
 	 * Get the overflow emergency buffer
@@ -249,19 +290,17 @@ swiotlb_late_init_with_default_size(size
 	if (!io_tlb_overflow_buffer)
 		goto cleanup4;
 
-	printk(KERN_INFO "Placing %luMB software IO TLB between 0x%lx - "
-	       "0x%lx\n", bytes >> 20,
-	       virt_to_bus(io_tlb_start), virt_to_bus(io_tlb_end));
+	swiotlb_print_info(bytes);
 
 	return 0;
 
 cleanup4:
-	free_pages((unsigned long)io_tlb_orig_addr, get_order(io_tlb_nslabs *
-	                                                      sizeof(char *)));
+	free_pages((unsigned long)io_tlb_orig_addr,
+		   get_order(io_tlb_nslabs * sizeof(io_tlb_addr_t)));
 	io_tlb_orig_addr = NULL;
 cleanup3:
-	free_pages((unsigned long)io_tlb_list, get_order(io_tlb_nslabs *
-	                                                 sizeof(int)));
+	free_pages((unsigned long)io_tlb_list,
+		   get_order(io_tlb_nslabs * sizeof(int)));
 	io_tlb_list = NULL;
 cleanup2:
 	io_tlb_end = NULL;
@@ -271,7 +310,9 @@ cleanup1:
 	io_tlb_nslabs = req_nslabs;
 	return -ENOMEM;
 }
+#endif
 
+#ifndef SWIOTLB_ARCH_HAS_NEEDS_MAPPING
 static inline int
 address_needs_mapping(struct device *hwdev, dma_addr_t addr)
 {
@@ -282,11 +323,35 @@ address_needs_mapping(struct device *hwd
 	return (addr & ~mask) != 0;
 }
 
+static inline int range_needs_mapping(const void *ptr, size_t size)
+{
+	return swiotlb_force;
+}
+
+static inline int order_needs_mapping(unsigned int order)
+{
+	return 0;
+}
+#endif
+
+static void
+__sync_single(io_tlb_addr_t buffer, char *dma_addr, size_t size, int dir)
+{
+#ifndef SWIOTLB_ARCH_HAS_SYNC_SINGLE
+	if (dir == DMA_TO_DEVICE)
+		memcpy(dma_addr, buffer, size);
+	else
+		memcpy(buffer, dma_addr, size);
+#else
+	__swiotlb_arch_sync_single(buffer, dma_addr, size, dir);
+#endif
+}
+
 /*
  * Allocates bounce buffer and returns its kernel virtual address.
  */
 static void *
-map_single(struct device *hwdev, char *buffer, size_t size, int dir)
+map_single(struct device *hwdev, io_tlb_addr_t buffer, size_t size, int dir)
 {
 	unsigned long flags;
 	char *dma_addr;
@@ -359,7 +424,7 @@ map_single(struct device *hwdev, char *b
 	 */
 	io_tlb_orig_addr[index] = buffer;
 	if (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL)
-		memcpy(dma_addr, buffer, size);
+		__sync_single(buffer, dma_addr, size, DMA_TO_DEVICE);
 
 	return dma_addr;
 }
@@ -373,17 +438,18 @@ unmap_single(struct device *hwdev, char 
 	unsigned long flags;
 	int i, count, nslots = ALIGN(size, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
 	int index = (dma_addr - io_tlb_start) >> IO_TLB_SHIFT;
-	char *buffer = io_tlb_orig_addr[index];
+	io_tlb_addr_t buffer = io_tlb_orig_addr[index];
 
 	/*
 	 * First, sync the memory before unmapping the entry
 	 */
-	if (buffer && ((dir == DMA_FROM_DEVICE) || (dir == DMA_BIDIRECTIONAL)))
+	if (!swiotlb_orig_addr_null(buffer)
+	    && ((dir == DMA_FROM_DEVICE) || (dir == DMA_BIDIRECTIONAL)))
 		/*
 		 * bounce... copy the data back into the original buffer * and
 		 * delete the bounce buffer.
 		 */
-		memcpy(buffer, dma_addr, size);
+		__sync_single(buffer, dma_addr, size, DMA_FROM_DEVICE);
 
 	/*
 	 * Return the buffer to the free list by setting the corresponding
@@ -416,18 +482,18 @@ sync_single(struct device *hwdev, char *
 	    int dir, int target)
 {
 	int index = (dma_addr - io_tlb_start) >> IO_TLB_SHIFT;
-	char *buffer = io_tlb_orig_addr[index];
+	io_tlb_addr_t buffer = io_tlb_orig_addr[index];
 
 	switch (target) {
 	case SYNC_FOR_CPU:
 		if (likely(dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL))
-			memcpy(buffer, dma_addr, size);
+			__sync_single(buffer, dma_addr, size, DMA_FROM_DEVICE);
 		else
 			BUG_ON(dir != DMA_TO_DEVICE);
 		break;
 	case SYNC_FOR_DEVICE:
 		if (likely(dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL))
-			memcpy(dma_addr, buffer, size);
+			__sync_single(buffer, dma_addr, size, DMA_TO_DEVICE);
 		else
 			BUG_ON(dir != DMA_FROM_DEVICE);
 		break;
@@ -436,6 +502,8 @@ sync_single(struct device *hwdev, char *
 	}
 }
 
+#ifdef SWIOTLB_ARCH_NEED_ALLOC
+
 void *
 swiotlb_alloc_coherent(struct device *hwdev, size_t size,
 		       dma_addr_t *dma_handle, gfp_t flags)
@@ -451,7 +519,10 @@ swiotlb_alloc_coherent(struct device *hw
 	 */
 	flags |= GFP_DMA;
 
-	ret = (void *)__get_free_pages(flags, order);
+	if (!order_needs_mapping(order))
+		ret = (void *)__get_free_pages(flags, order);
+	else
+		ret = NULL;
 	if (ret && address_needs_mapping(hwdev, virt_to_bus(ret))) {
 		/*
 		 * The allocated memory isn't reachable by the device.
@@ -489,6 +560,7 @@ swiotlb_alloc_coherent(struct device *hw
 	*dma_handle = dev_addr;
 	return ret;
 }
+EXPORT_SYMBOL(swiotlb_alloc_coherent);
 
 void
 swiotlb_free_coherent(struct device *hwdev, size_t size, void *vaddr,
@@ -501,6 +573,9 @@ swiotlb_free_coherent(struct device *hwd
 		/* DMA_TO_DEVICE to avoid memcpy in unmap_single */
 		swiotlb_unmap_single (hwdev, dma_handle, size, DMA_TO_DEVICE);
 }
+EXPORT_SYMBOL(swiotlb_free_coherent);
+
+#endif
 
 static void
 swiotlb_full(struct device *dev, size_t size, int dir, int do_panic)
@@ -542,13 +617,14 @@ swiotlb_map_single(struct device *hwdev,
 	 * we can safely return the device addr and not worry about bounce
 	 * buffering it.
 	 */
-	if (!address_needs_mapping(hwdev, dev_addr) && !swiotlb_force)
+	if (!range_needs_mapping(ptr, size)
+	    && !address_needs_mapping(hwdev, dev_addr))
 		return dev_addr;
 
 	/*
 	 * Oh well, have to allocate and map a bounce buffer.
 	 */
-	map = map_single(hwdev, ptr, size, dir);
+	map = map_single(hwdev, ptr_to_io_tlb_addr(ptr), size, dir);
 	if (!map) {
 		swiotlb_full(hwdev, size, dir, 1);
 		map = io_tlb_overflow_buffer;
@@ -676,17 +752,16 @@ int
 swiotlb_map_sg(struct device *hwdev, struct scatterlist *sg, int nelems,
 	       int dir)
 {
-	void *addr;
 	dma_addr_t dev_addr;
 	int i;
 
 	BUG_ON(dir == DMA_NONE);
 
 	for (i = 0; i < nelems; i++, sg++) {
-		addr = SG_ENT_VIRT_ADDRESS(sg);
-		dev_addr = virt_to_bus(addr);
-		if (swiotlb_force || address_needs_mapping(hwdev, dev_addr)) {
-			void *map = map_single(hwdev, addr, sg->length, dir);
+		dev_addr = SG_ENT_PHYS_ADDRESS(sg);
+		if (range_needs_mapping(SG_ENT_VIRT_ADDRESS(sg), sg->length)
+		    || address_needs_mapping(hwdev, dev_addr)) {
+			void *map = map_single(hwdev, sg_to_io_tlb_addr(sg), sg->length, dir);
 			if (!map) {
 				/* Don't panic here, we expect map_sg users
 				   to do proper error handling. */
@@ -760,6 +835,44 @@ swiotlb_sync_sg_for_device(struct device
 	swiotlb_sync_sg(hwdev, sg, nelems, dir, SYNC_FOR_DEVICE);
 }
 
+#ifdef SWIOTLB_ARCH_NEED_MAP_PAGE
+
+dma_addr_t
+swiotlb_map_page(struct device *hwdev, struct page *page,
+		 unsigned long offset, size_t size,
+		 enum dma_data_direction direction)
+{
+	dma_addr_t dev_addr;
+	char *map;
+
+	dev_addr = page_to_bus(page) + offset;
+	if (address_needs_mapping(hwdev, dev_addr)) {
+		map = map_single(hwdev, page_to_io_tlb_addr(page, offset), size, direction);
+		if (!map) {
+			swiotlb_full(hwdev, size, direction, 1);
+			map = io_tlb_overflow_buffer;
+		}
+		dev_addr = virt_to_bus(map);
+	}
+
+	return dev_addr;
+}
+
+void
+swiotlb_unmap_page(struct device *hwdev, dma_addr_t dev_addr,
+		   size_t size, enum dma_data_direction direction)
+{
+	char *dma_addr = bus_to_virt(dev_addr);
+
+	BUG_ON(direction == DMA_NONE);
+	if (dma_addr >= io_tlb_start && dma_addr < io_tlb_end)
+		unmap_single(hwdev, dma_addr, size, direction);
+	else if (direction == DMA_FROM_DEVICE)
+		dma_mark_clean(dma_addr, size);
+}
+
+#endif
+
 int
 swiotlb_dma_mapping_error(dma_addr_t dma_addr)
 {
@@ -772,10 +885,13 @@ swiotlb_dma_mapping_error(dma_addr_t dma
  * during bus mastering, then you would pass 0x00ffffff as the mask to
  * this function.
  */
+#ifndef __swiotlb_dma_supported
+#define __swiotlb_dma_supported(hwdev, mask) (virt_to_bus(io_tlb_end - 1) <= (mask))
+#endif
 int
 swiotlb_dma_supported(struct device *hwdev, u64 mask)
 {
-	return virt_to_bus(io_tlb_end - 1) <= mask;
+	return __swiotlb_dma_supported(hwdev, mask);
 }
 
 EXPORT_SYMBOL(swiotlb_init);
@@ -790,6 +906,4 @@ EXPORT_SYMBOL_GPL(swiotlb_sync_single_ra
 EXPORT_SYMBOL(swiotlb_sync_sg_for_cpu);
 EXPORT_SYMBOL(swiotlb_sync_sg_for_device);
 EXPORT_SYMBOL(swiotlb_dma_mapping_error);
-EXPORT_SYMBOL(swiotlb_alloc_coherent);
-EXPORT_SYMBOL(swiotlb_free_coherent);
 EXPORT_SYMBOL(swiotlb_dma_supported);

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