linux/drivers/usb/core/buffer.c
<<
>>
Prefs
   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * DMA memory management for framework level HCD code (hc_driver)
   4 *
   5 * This implementation plugs in through generic "usb_bus" level methods,
   6 * and should work with all USB controllers, regardless of bus type.
   7 *
   8 * Released under the GPLv2 only.
   9 */
  10
  11#include <linux/module.h>
  12#include <linux/kernel.h>
  13#include <linux/slab.h>
  14#include <linux/device.h>
  15#include <linux/mm.h>
  16#include <linux/io.h>
  17#include <linux/dma-mapping.h>
  18#include <linux/dmapool.h>
  19#include <linux/genalloc.h>
  20#include <linux/usb.h>
  21#include <linux/usb/hcd.h>
  22
  23
  24/*
  25 * DMA-Coherent Buffers
  26 */
  27
  28/* FIXME tune these based on pool statistics ... */
  29static size_t pool_max[HCD_BUFFER_POOLS] = {
  30        32, 128, 512, 2048,
  31};
  32
  33void __init usb_init_pool_max(void)
  34{
  35        /*
  36         * The pool_max values must never be smaller than
  37         * ARCH_KMALLOC_MINALIGN.
  38         */
  39        if (ARCH_KMALLOC_MINALIGN <= 32)
  40                ;                       /* Original value is okay */
  41        else if (ARCH_KMALLOC_MINALIGN <= 64)
  42                pool_max[0] = 64;
  43        else if (ARCH_KMALLOC_MINALIGN <= 128)
  44                pool_max[0] = 0;        /* Don't use this pool */
  45        else
  46                BUILD_BUG();            /* We don't allow this */
  47}
  48
  49/* SETUP primitives */
  50
  51/**
  52 * hcd_buffer_create - initialize buffer pools
  53 * @hcd: the bus whose buffer pools are to be initialized
  54 *
  55 * Context: task context, might sleep
  56 *
  57 * Call this as part of initializing a host controller that uses the dma
  58 * memory allocators.  It initializes some pools of dma-coherent memory that
  59 * will be shared by all drivers using that controller.
  60 *
  61 * Call hcd_buffer_destroy() to clean up after using those pools.
  62 *
  63 * Return: 0 if successful. A negative errno value otherwise.
  64 */
  65int hcd_buffer_create(struct usb_hcd *hcd)
  66{
  67        char            name[16];
  68        int             i, size;
  69
  70        if (hcd->localmem_pool || !hcd_uses_dma(hcd))
  71                return 0;
  72
  73        for (i = 0; i < HCD_BUFFER_POOLS; i++) {
  74                size = pool_max[i];
  75                if (!size)
  76                        continue;
  77                snprintf(name, sizeof(name), "buffer-%d", size);
  78                hcd->pool[i] = dma_pool_create(name, hcd->self.sysdev,
  79                                size, size, 0);
  80                if (!hcd->pool[i]) {
  81                        hcd_buffer_destroy(hcd);
  82                        return -ENOMEM;
  83                }
  84        }
  85        return 0;
  86}
  87
  88
  89/**
  90 * hcd_buffer_destroy - deallocate buffer pools
  91 * @hcd: the bus whose buffer pools are to be destroyed
  92 *
  93 * Context: task context, might sleep
  94 *
  95 * This frees the buffer pools created by hcd_buffer_create().
  96 */
  97void hcd_buffer_destroy(struct usb_hcd *hcd)
  98{
  99        int i;
 100
 101        if (!IS_ENABLED(CONFIG_HAS_DMA))
 102                return;
 103
 104        for (i = 0; i < HCD_BUFFER_POOLS; i++) {
 105                dma_pool_destroy(hcd->pool[i]);
 106                hcd->pool[i] = NULL;
 107        }
 108}
 109
 110
 111/* sometimes alloc/free could use kmalloc with GFP_DMA, for
 112 * better sharing and to leverage mm/slab.c intelligence.
 113 */
 114
 115void *hcd_buffer_alloc(
 116        struct usb_bus          *bus,
 117        size_t                  size,
 118        gfp_t                   mem_flags,
 119        dma_addr_t              *dma
 120)
 121{
 122        struct usb_hcd          *hcd = bus_to_hcd(bus);
 123        int                     i;
 124
 125        if (size == 0)
 126                return NULL;
 127
 128        if (hcd->localmem_pool)
 129                return gen_pool_dma_alloc(hcd->localmem_pool, size, dma);
 130
 131        /* some USB hosts just use PIO */
 132        if (!hcd_uses_dma(hcd)) {
 133                *dma = ~(dma_addr_t) 0;
 134                return kmalloc(size, mem_flags);
 135        }
 136
 137        for (i = 0; i < HCD_BUFFER_POOLS; i++) {
 138                if (size <= pool_max[i])
 139                        return dma_pool_alloc(hcd->pool[i], mem_flags, dma);
 140        }
 141        return dma_alloc_coherent(hcd->self.sysdev, size, dma, mem_flags);
 142}
 143
 144void hcd_buffer_free(
 145        struct usb_bus          *bus,
 146        size_t                  size,
 147        void                    *addr,
 148        dma_addr_t              dma
 149)
 150{
 151        struct usb_hcd          *hcd = bus_to_hcd(bus);
 152        int                     i;
 153
 154        if (!addr)
 155                return;
 156
 157        if (hcd->localmem_pool) {
 158                gen_pool_free(hcd->localmem_pool, (unsigned long)addr, size);
 159                return;
 160        }
 161
 162        if (!hcd_uses_dma(hcd)) {
 163                kfree(addr);
 164                return;
 165        }
 166
 167        for (i = 0; i < HCD_BUFFER_POOLS; i++) {
 168                if (size <= pool_max[i]) {
 169                        dma_pool_free(hcd->pool[i], addr, dma);
 170                        return;
 171                }
 172        }
 173        dma_free_coherent(hcd->self.sysdev, size, addr, dma);
 174}
 175