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, regardless 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.
  47  *
  48  * Call hcd_buffer_destroy() to clean up after using those pools.
  49  *
  50  * Return: 0 if successful. A negative errno value otherwise.
  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             !(hcd->driver->flags & HCD_LOCAL_MEM))
  59                 return 0;
  60
  61         for (i = 0; i < HCD_BUFFER_POOLS; i++) {
  62                 size = pool_max[i];
  63                 if (!size)
  64                         continue;
  65                 snprintf(name, sizeof name, "buffer-%d", size);
  66                 hcd->pool[i] = dma_pool_create(name, hcd->self.controller,
  67                                 size, size, 0);
  68                 if (!hcd->pool[i]) {
  69                         hcd_buffer_destroy(hcd);
  70                         return -ENOMEM;
  71                 }
  72         }
  73         return 0;
  74 }
  75
  76
  77 /**
  78  * hcd_buffer_destroy - deallocate buffer pools
  79  * @hcd: the bus whose buffer pools are to be destroyed
  80  * Context: !in_interrupt()
  81  *
  82  * This frees the buffer pools created by hcd_buffer_create().
  83  */
  84 void hcd_buffer_destroy(struct usb_hcd *hcd)
  85 {
  86         int i;
  87
  88         for (i = 0; i < HCD_BUFFER_POOLS; i++) {
  89                 struct dma_pool *pool = hcd->pool[i];
  90                 if (pool) {
  91                         dma_pool_destroy(pool);
  92                         hcd->pool[i] = NULL;
  93                 }
  94         }
  95 }
  96
  97
  98 /* sometimes alloc/free could use kmalloc with GFP_DMA, for
  99  * better sharing and to leverage mm/slab.c intelligence.
 100  */
 101
 102 void *hcd_buffer_alloc(
 103         struct usb_bus          *bus,
 104         size_t                  size,
 105         gfp_t                   mem_flags,
 106         dma_addr_t              *dma
 107 )
 108 {
 109         struct usb_hcd          *hcd = bus_to_hcd(bus);
 110         int                     i;
 111
 112         /* some USB hosts just use PIO */
 113         if (!bus->controller->dma_mask &&
 114             !(hcd->driver->flags & HCD_LOCAL_MEM)) {
 115                 *dma = ~(dma_addr_t) 0;
 116                 return kmalloc(size, mem_flags);
 117         }
 118
 119         for (i = 0; i < HCD_BUFFER_POOLS; i++) {
 120                 if (size <= pool_max[i])
 121                         return dma_pool_alloc(hcd->pool[i], mem_flags, dma);
 122         }
 123         return dma_alloc_coherent(hcd->self.controller, size, dma, mem_flags);
 124 }
 125
 126 void hcd_buffer_free(
 127         struct usb_bus          *bus,
 128         size_t                  size,
 129         void                    *addr,
 130         dma_addr_t              dma
 131 )
 132 {
 133         struct usb_hcd          *hcd = bus_to_hcd(bus);
 134         int                     i;
 135
 136         if (!addr)
 137                 return;
 138
 139         if (!bus->controller->dma_mask &&
 140             !(hcd->driver->flags & HCD_LOCAL_MEM)) {
 141                 kfree(addr);
 142                 return;
 143         }
 144
 145         for (i = 0; i < HCD_BUFFER_POOLS; i++) {
 146                 if (size <= pool_max[i]) {
 147                         dma_pool_free(hcd->pool[i], addr, dma);
 148                         return;
 149                 }
 150         }
 151         dma_free_coherent(hcd->self.controller, size, addr, dma);
 152 }