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