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 <asm/scatterlist.h>
  15 #include <linux/dma-mapping.h>
  16 #include <linux/dmapool.h>
  17 #include <linux/usb.h>
  18 #include "hcd.h"
  19
  20
  21 /*
  22  * DMA-Coherent Buffers
  23  */
  24
  25 /* FIXME tune these based on pool statistics ... */
  26 static const size_t     pool_max [HCD_BUFFER_POOLS] = {
  27         /* platforms without dma-friendly caches might need to
  28          * prevent cacheline sharing...
  29          */
  30         32,
  31         128,
  32         512,
  33         PAGE_SIZE / 2
  34         /* bigger --> allocate pages */
  35 };
  36
  37
  38 /* SETUP primitives */
  39
  40 /**
  41  * hcd_buffer_create - initialize buffer pools
  42  * @hcd: the bus whose buffer pools are to be initialized
  43  * Context: !in_interrupt()
  44  *
  45  * Call this as part of initializing a host controller that uses the dma
  46  * memory allocators.  It initializes some pools of dma-coherent memory that
  47  * will be shared by all drivers using that controller, or returns a negative
  48  * errno value on error.
  49  *
  50  * Call hcd_buffer_destroy() to clean up after using those pools.
  51  */
  52 int hcd_buffer_create (struct usb_hcd *hcd)
  53 {
  54         char            name [16];
  55         int             i, size;
  56
  57         if (!hcd->self.controller->dma_mask)
  58                 return 0;
  59
  60         for (i = 0; i < HCD_BUFFER_POOLS; i++) {
  61                 if (!(size = pool_max [i]))
  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 SLAB_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                 *dma = ~(dma_addr_t) 0;
 113                 return kmalloc (size, mem_flags);
 114         }
 115
 116         for (i = 0; i < HCD_BUFFER_POOLS; i++) {
 117                 if (size <= pool_max [i])
 118                         return dma_pool_alloc (hcd->pool [i], mem_flags, dma);
 119         }
 120         return dma_alloc_coherent (hcd->self.controller, size, dma, 0);
 121 }
 122
 123 void hcd_buffer_free (
 124         struct usb_bus          *bus,
 125         size_t                  size,
 126         void                    *addr,
 127         dma_addr_t              dma
 128 )
 129 {
 130         struct usb_hcd          *hcd = bus_to_hcd(bus);
 131         int                     i;
 132
 133         if (!addr)
 134                 return;
 135
 136         if (!bus->controller->dma_mask) {
 137                 kfree (addr);
 138                 return;
 139         }
 140
 141         for (i = 0; i < HCD_BUFFER_POOLS; i++) {
 142                 if (size <= pool_max [i]) {
 143                         dma_pool_free (hcd->pool [i], addr, dma);
 144                         return;
 145                 }
 146         }
 147         dma_free_coherent (hcd->self.controller, size, addr, dma);
 148 }