release/src-rt-6.x.4708/linux/linux-2.6.36/drivers/usb/core/buffer.c

   1 /*
   2  * DMA memory management for framework level HCD code (hc_driver)
   3  *
   4  * This implementation plugs in through generic "usb_bus" level methods,
   5  * and should work with all USB controllers, regardles of bus type.
   6  */
   7
   8 #include <linux/module.h>
   9 #include <linux/kernel.h>
  10 #include <linux/slab.h>
  11 #include <linux/device.h>
  12 #include <linux/mm.h>
  13 #include <asm/io.h>
  14 #include <linux/dma-mapping.h>
  15 #include <linux/dmapool.h>
  16 #include <linux/usb.h>
  17 #include <linux/usb/hcd.h>
  18
  19
  20 /*
  21  * DMA-Coherent Buffers
  22  */
  23
  24 static const size_t     pool_max [HCD_BUFFER_POOLS] = {
  25         /* platforms without dma-friendly caches might need to
  26          * prevent cacheline sharing...
  27          */
  28         32,
  29         128,
  30         512,
  31         PAGE_SIZE / 2
  32         /* bigger --> allocate pages */
  33 };
  34
  35
  36 /* SETUP primitives */
  37
  38 /**
  39  * hcd_buffer_create - initialize buffer pools
  40  * @hcd: the bus whose buffer pools are to be initialized
  41  * Context: !in_interrupt()
  42  *
  43  * Call this as part of initializing a host controller that uses the dma
  44  * memory allocators.  It initializes some pools of dma-coherent memory that
  45  * will be shared by all drivers using that controller, or returns a negative
  46  * errno value on error.
  47  *
  48  * Call hcd_buffer_destroy() to clean up after using those pools.
  49  */
  50 int hcd_buffer_create(struct usb_hcd *hcd)
  51 {
  52         char            name[16];
  53         int             i, size;
  54
  55         if (!hcd->self.controller->dma_mask &&
  56             !(hcd->driver->flags & HCD_LOCAL_MEM))
  57                 return 0;
  58
  59         for (i = 0; i < HCD_BUFFER_POOLS; i++) {
  60                 size = pool_max[i];
  61                 if (!size)
  62                         continue;
  63                 snprintf(name, sizeof name, "buffer-%d", size);
  64                 hcd->pool[i] = dma_pool_create(name, hcd->self.controller,
  65                                 size, size, 0);
  66                 if (!hcd->pool [i]) {
  67                         hcd_buffer_destroy(hcd);
  68                         return -ENOMEM;
  69                 }
  70         }
  71         return 0;
  72 }
  73
  74
  75 /**
  76  * hcd_buffer_destroy - deallocate buffer pools
  77  * @hcd: the bus whose buffer pools are to be destroyed
  78  * Context: !in_interrupt()
  79  *
  80  * This frees the buffer pools created by hcd_buffer_create().
  81  */
  82 void hcd_buffer_destroy(struct usb_hcd *hcd)
  83 {
  84         int i;
  85
  86         for (i = 0; i < HCD_BUFFER_POOLS; i++) {
  87                 struct dma_pool *pool = hcd->pool[i];
  88                 if (pool) {
  89                         dma_pool_destroy(pool);
  90                         hcd->pool[i] = NULL;
  91                 }
  92         }
  93 }
  94
  95
  96 /* sometimes alloc/free could use kmalloc with GFP_DMA, for
  97  * better sharing and to leverage mm/slab.c intelligence.
  98  */
  99
 100 void *hcd_buffer_alloc(
 101         struct usb_bus  *bus,
 102         size_t                  size,
 103         gfp_t                   mem_flags,
 104         dma_addr_t              *dma
 105 )
 106 {
 107         struct usb_hcd          *hcd = bus_to_hcd(bus);
 108         int                     i;
 109
 110         /* some USB hosts just use PIO */
 111         if (!bus->controller->dma_mask &&
 112             !(hcd->driver->flags & HCD_LOCAL_MEM)) {
 113                 *dma = ~(dma_addr_t) 0;
 114                 return kmalloc(size, mem_flags);
 115         }
 116
 117         for (i = 0; i < HCD_BUFFER_POOLS; i++) {
 118                 if (size <= pool_max [i])
 119                         return dma_pool_alloc(hcd->pool [i], mem_flags, dma);
 120         }
 121         return dma_alloc_coherent(hcd->self.controller, size, dma, mem_flags);
 122 }
 123
 124 void hcd_buffer_free(
 125         struct usb_bus  *bus,
 126         size_t                  size,
 127         void                    *addr,
 128         dma_addr_t              dma
 129 )
 130 {
 131         struct usb_hcd          *hcd = bus_to_hcd(bus);
 132         int                     i;
 133
 134         if (!addr)
 135                 return;
 136
 137         if (!bus->controller->dma_mask &&
 138             !(hcd->driver->flags & HCD_LOCAL_MEM)) {
 139                 kfree(addr);
 140                 return;
 141         }
 142
 143         for (i = 0; i < HCD_BUFFER_POOLS; i++) {
 144                 if (size <= pool_max [i]) {
 145                         dma_pool_free(hcd->pool [i], addr, dma);
 146                         return;
 147                 }
 148         }
 149         dma_free_coherent(hcd->self.controller, size, addr, dma);
 150 }