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/config.h>
   9 #include <linux/module.h>
  10 #include <linux/kernel.h>
  11 #include <linux/slab.h>
  12 #include <linux/device.h>
  13 #include <linux/mm.h>
  14 #include <asm/io.h>
  15 #include <asm/scatterlist.h>
  16 #include <linux/dma-mapping.h>
  17 #include <linux/dmapool.h>
  18
  19
  20 #ifdef CONFIG_USB_DEBUG
  21         #define DEBUG
  22 #else
  23         #undef DEBUG
  24 #endif
  25
  26 #include <linux/usb.h>
  27 #include "hcd.h"
  28
  29
  30 /*
  31  * DMA-Coherent Buffers
  32  */
  33
  34 /* FIXME tune these based on pool statistics ... */
  35 static const size_t     pool_max [HCD_BUFFER_POOLS] = {
  36         /* platforms without dma-friendly caches might need to
  37          * prevent cacheline sharing...
  38          */
  39         32,
  40         128,
  41         512,
  42         PAGE_SIZE / 2
  43         /* bigger --> allocate pages */
  44 };
  45
  46
  47 /* SETUP primitives */
  48
  49 /**
  50  * hcd_buffer_create - initialize buffer pools
  51  * @hcd: the bus whose buffer pools are to be initialized
  52  * Context: !in_interrupt()
  53  *
  54  * Call this as part of initializing a host controller that uses the dma
  55  * memory allocators.  It initializes some pools of dma-coherent memory that
  56  * will be shared by all drivers using that controller, or returns a negative
  57  * errno value on error.
  58  *
  59  * Call hcd_buffer_destroy() to clean up after using those pools.
  60  */
  61 int hcd_buffer_create (struct usb_hcd *hcd)
  62 {
  63         char            name [16];
  64         int             i, size;
  65
  66         for (i = 0; i < HCD_BUFFER_POOLS; i++) {
  67                 if (!(size = pool_max [i]))
  68                         continue;
  69                 snprintf (name, sizeof name, "buffer-%d", size);
  70                 hcd->pool [i] = dma_pool_create (name, hcd->self.controller,
  71                                 size, size, 0);
  72                 if (!hcd->pool [i]) {
  73                         hcd_buffer_destroy (hcd);
  74                         return -ENOMEM;
  75                 }
  76         }
  77         return 0;
  78 }
  79
  80
  81 /**
  82  * hcd_buffer_destroy - deallocate buffer pools
  83  * @hcd: the bus whose buffer pools are to be destroyed
  84  * Context: !in_interrupt()
  85  *
  86  * This frees the buffer pools created by hcd_buffer_create().
  87  */
  88 void hcd_buffer_destroy (struct usb_hcd *hcd)
  89 {
  90         int             i;
  91
  92         for (i = 0; i < HCD_BUFFER_POOLS; i++) {
  93                 struct dma_pool         *pool = hcd->pool [i];
  94                 if (pool) {
  95                         dma_pool_destroy (pool);
  96                         hcd->pool[i] = NULL;
  97                 }
  98         }
  99 }
 100
 101
 102 /* sometimes alloc/free could use kmalloc with SLAB_DMA, for
 103  * better sharing and to leverage mm/slab.c intelligence.
 104  */
 105
 106 void *hcd_buffer_alloc (
 107         struct usb_bus          *bus,
 108         size_t                  size,
 109         gfp_t                   mem_flags,
 110         dma_addr_t              *dma
 111 )
 112 {
 113         struct usb_hcd          *hcd = bus->hcpriv;
 114         int                     i;
 115
 116         /* some USB hosts just use PIO */
 117         if (!bus->controller->dma_mask) {
 118                 *dma = ~(dma_addr_t) 0;
 119                 return kmalloc (size, mem_flags);
 120         }
 121
 122         for (i = 0; i < HCD_BUFFER_POOLS; i++) {
 123                 if (size <= pool_max [i])
 124                         return dma_pool_alloc (hcd->pool [i], mem_flags, dma);
 125         }
 126         return dma_alloc_coherent (hcd->self.controller, size, dma, 0);
 127 }
 128
 129 void hcd_buffer_free (
 130         struct usb_bus          *bus,
 131         size_t                  size,
 132         void                    *addr,
 133         dma_addr_t              dma
 134 )
 135 {
 136         struct usb_hcd          *hcd = bus->hcpriv;
 137         int                     i;
 138
 139         if (!addr)
 140                 return;
 141
 142         if (!bus->controller->dma_mask) {
 143                 kfree (addr);
 144                 return;
 145         }
 146
 147         for (i = 0; i < HCD_BUFFER_POOLS; i++) {
 148                 if (size <= pool_max [i]) {
 149                         dma_pool_free (hcd->pool [i], addr, dma);
 150                         return;
 151                 }
 152         }
 153         dma_free_coherent (hcd->self.controller, size, addr, dma);
 154 }