drivers/usb/mon/mon_dma.c

   1 /*
   2  * The USB Monitor, inspired by Dave Harding's USBMon.
   3  *
   4  * mon_dma.c: Library which snoops on DMA areas.
   5  *
   6  * Copyright (C) 2005 Pete Zaitcev (zaitcev@redhat.com)
   7  */
   8 #include <linux/kernel.h>
   9 #include <linux/list.h>
  10 #include <linux/highmem.h>
  11 #include <asm/page.h>
  12
  13 #include <linux/usb.h>  /* Only needed for declarations in usb_mon.h */
  14 #include "usb_mon.h"
  15
  16 /*
  17  * PC-compatibles, are, fortunately, sufficiently cache-coherent for this.
  18  */
  19 #if defined(__i386__) || defined(__x86_64__) /* CONFIG_ARCH_I386 doesn't exit */
  20 #define MON_HAS_UNMAP 1
  21
  22 #define phys_to_page(phys)      pfn_to_page((phys) >> PAGE_SHIFT)
  23
  24 char mon_dmapeek(unsigned char *dst, dma_addr_t dma_addr, int len)
  25 {
  26         struct page *pg;
  27         unsigned long flags;
  28         unsigned char *map;
  29         unsigned char *ptr;
  30
  31         /*
  32          * On i386, a DMA handle is the "physical" address of a page.
  33          * In other words, the bus address is equal to physical address.
  34          * There is no IOMMU.
  35          */
  36         pg = phys_to_page(dma_addr);
  37
  38         /*
  39          * We are called from hardware IRQs in case of callbacks.
  40          * But we can be called from softirq or process context in case
  41          * of submissions. In such case, we need to protect KM_IRQ0.
  42          */
  43         local_irq_save(flags);
  44         map = kmap_atomic(pg, KM_IRQ0);
  45         ptr = map + (dma_addr & (PAGE_SIZE-1));
  46         memcpy(dst, ptr, len);
  47         kunmap_atomic(map, KM_IRQ0);
  48         local_irq_restore(flags);
  49         return 0;
  50 }
  51
  52 void mon_dmapeek_vec(const struct mon_reader_bin *rp,
  53     unsigned int offset, dma_addr_t dma_addr, unsigned int length)
  54 {
  55         unsigned long flags;
  56         unsigned int step_len;
  57         struct page *pg;
  58         unsigned char *map;
  59         unsigned long page_off, page_len;
  60
  61         local_irq_save(flags);
  62         while (length) {
  63                 /* compute number of bytes we are going to copy in this page */
  64                 step_len = length;
  65                 page_off = dma_addr & (PAGE_SIZE-1);
  66                 page_len = PAGE_SIZE - page_off;
  67                 if (page_len < step_len)
  68                         step_len = page_len;
  69
  70                 /* copy data and advance pointers */
  71                 pg = phys_to_page(dma_addr);
  72                 map = kmap_atomic(pg, KM_IRQ0);
  73                 offset = mon_copy_to_buff(rp, offset, map + page_off, step_len);
  74                 kunmap_atomic(map, KM_IRQ0);
  75                 dma_addr += step_len;
  76                 length -= step_len;
  77         }
  78         local_irq_restore(flags);
  79 }
  80
  81 #endif /* __i386__ */
  82
  83 #ifndef MON_HAS_UNMAP
  84 char mon_dmapeek(unsigned char *dst, dma_addr_t dma_addr, int len)
  85 {
  86         return 'D';
  87 }
  88
  89 void mon_dmapeek_vec(const struct mon_reader_bin *rp,
  90     unsigned int offset, dma_addr_t dma_addr, unsigned int length)
  91 {
  92         ;
  93 }
  94
  95 #endif /* MON_HAS_UNMAP */