mirror of https://gitee.com/openkylin/linux.git
59 lines
1.4 KiB
C
59 lines
1.4 KiB
C
/*
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* The USB Monitor, inspired by Dave Harding's USBMon.
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*
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* mon_dma.c: Library which snoops on DMA areas.
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*
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* Copyright (C) 2005 Pete Zaitcev (zaitcev@redhat.com)
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*/
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#include <linux/kernel.h>
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#include <linux/list.h>
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#include <linux/highmem.h>
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#include <asm/page.h>
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#include <linux/usb.h> /* Only needed for declarations in usb_mon.h */
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#include "usb_mon.h"
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/*
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* PC-compatibles, are, fortunately, sufficiently cache-coherent for this.
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*/
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#if defined(__i386__) || defined(__x86_64__) /* CONFIG_ARCH_I386 doesn't exit */
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#define MON_HAS_UNMAP 1
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#define phys_to_page(phys) pfn_to_page((phys) >> PAGE_SHIFT)
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char mon_dmapeek(unsigned char *dst, dma_addr_t dma_addr, int len)
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{
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struct page *pg;
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unsigned long flags;
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unsigned char *map;
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unsigned char *ptr;
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/*
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* On i386, a DMA handle is the "physical" address of a page.
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* In other words, the bus address is equal to physical address.
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* There is no IOMMU.
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*/
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pg = phys_to_page(dma_addr);
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/*
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* We are called from hardware IRQs in case of callbacks.
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* But we can be called from softirq or process context in case
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* of submissions. In such case, we need to protect KM_IRQ0.
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*/
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local_irq_save(flags);
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map = kmap_atomic(pg, KM_IRQ0);
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ptr = map + (dma_addr & (PAGE_SIZE-1));
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memcpy(dst, ptr, len);
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kunmap_atomic(map, KM_IRQ0);
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local_irq_restore(flags);
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return 0;
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}
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#endif /* __i386__ */
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#ifndef MON_HAS_UNMAP
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char mon_dmapeek(unsigned char *dst, dma_addr_t dma_addr, int len)
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{
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return 'D';
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}
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#endif
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