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 "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                 return 0;
  58
  59         for (i = 0; i < HCD_BUFFER_POOLS; i++) {
  60                 if (!(size = pool_max [i]))
  61                         continue;
  62                 snprintf(name, sizeof name, "buffer-%d", size);
  63                 hcd->pool[i] = dma_pool_create(name, hcd->self.controller,
  64                                 size, size, 0);
  65                 if (!hcd->pool [i]) {
  66                         hcd_buffer_destroy(hcd);
  67                         return -ENOMEM;
  68                 }
  69         }
  70         return 0;
  71 }
  72
  73
  74 /**
  75  * hcd_buffer_destroy - deallocate buffer pools
  76  * @hcd: the bus whose buffer pools are to be destroyed
  77  * Context: !in_interrupt()
  78  *
  79  * This frees the buffer pools created by hcd_buffer_create().
  80  */
  81 void hcd_buffer_destroy(struct usb_hcd *hcd)
  82 {
  83         int             i;
  84
  85         for (i = 0; i < HCD_BUFFER_POOLS; i++) {
  86                 struct dma_pool         *pool = hcd->pool[i];
  87                 if (pool) {
  88                         dma_pool_destroy(pool);
  89                         hcd->pool[i] = NULL;
  90                 }
  91         }
  92 }
  93
  94
  95 /* sometimes alloc/free could use kmalloc with GFP_DMA, for
  96  * better sharing and to leverage mm/slab.c intelligence.
  97  */
  98
  99 void *hcd_buffer_alloc(
 100         struct usb_bus  *bus,
 101         size_t                  size,
 102         gfp_t                   mem_flags,
 103         dma_addr_t              *dma
 104 )
 105 {
 106         struct usb_hcd          *hcd = bus_to_hcd(bus);
 107         int                     i;
 108
 109         /* some USB hosts just use PIO */
 110         if (!bus->controller->dma_mask) {
 111                 *dma = ~(dma_addr_t) 0;
 112                 return kmalloc(size, mem_flags);
 113         }
 114
 115         for (i = 0; i < HCD_BUFFER_POOLS; i++) {
 116                 if (size <= pool_max [i])
 117                         return dma_pool_alloc(hcd->pool [i], mem_flags, dma);
 118         }
 119         return dma_alloc_coherent(hcd->self.controller, size, dma, 0);
 120 }
 121
 122 void hcd_buffer_free(
 123         struct usb_bus  *bus,
 124         size_t                  size,
 125         void                    *addr,
 126         dma_addr_t              dma
 127 )
 128 {
 129         struct usb_hcd          *hcd = bus_to_hcd(bus);
 130         int                     i;
 131
 132         if (!addr)
 133                 return;
 134
 135         if (!bus->controller->dma_mask) {
 136                 kfree(addr);
 137                 return;
 138         }
 139
 140         for (i = 0; i < HCD_BUFFER_POOLS; i++) {
 141                 if (size <= pool_max [i]) {
 142                         dma_pool_free(hcd->pool [i], addr, dma);
 143                         return;
 144                 }
 145         }
 146         dma_free_coherent(hcd->self.controller, size, addr, dma);
 147 }