LXR linux/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 ... */
  25static 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 */
  51int 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 */
  83void 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
 101void *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
 125void 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}
 152