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 <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 ... */
  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.
  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 */
  52int 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 */
  84void 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
 102void *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
 126void 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}
 153