root/drivers/usb/core/buffer.c

DEFINITIONS

1. usb_init_pool_max
2. hcd_buffer_create
3. hcd_buffer_destroy
4. hcd_buffer_alloc
5. hcd_buffer_free

   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 ... */
  29 static size_t pool_max[HCD_BUFFER_POOLS] = {
  30         32, 128, 512, 2048,
  31 };
  32 
  33 void __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  * Context: !in_interrupt()
  55  *
  56  * Call this as part of initializing a host controller that uses the dma
  57  * memory allocators.  It initializes some pools of dma-coherent memory that
  58  * will be shared by all drivers using that controller.
  59  *
  60  * Call hcd_buffer_destroy() to clean up after using those pools.
  61  *
  62  * Return: 0 if successful. A negative errno value otherwise.
  63  */
  64 int hcd_buffer_create(struct usb_hcd *hcd)
  65 {
  66         char            name[16];
  67         int             i, size;
  68 
  69         if (hcd->localmem_pool || !hcd_uses_dma(hcd))
  70                 return 0;
  71 
  72         for (i = 0; i < HCD_BUFFER_POOLS; i++) {
  73                 size = pool_max[i];
  74                 if (!size)
  75                         continue;
  76                 snprintf(name, sizeof(name), "buffer-%d", size);
  77                 hcd->pool[i] = dma_pool_create(name, hcd->self.sysdev,
  78                                 size, size, 0);
  79                 if (!hcd->pool[i]) {
  80                         hcd_buffer_destroy(hcd);
  81                         return -ENOMEM;
  82                 }
  83         }
  84         return 0;
  85 }
  86 
  87 
  88 /**
  89  * hcd_buffer_destroy - deallocate buffer pools
  90  * @hcd: the bus whose buffer pools are to be destroyed
  91  * Context: !in_interrupt()
  92  *
  93  * This frees the buffer pools created by hcd_buffer_create().
  94  */
  95 void hcd_buffer_destroy(struct usb_hcd *hcd)
  96 {
  97         int i;
  98 
  99         if (!IS_ENABLED(CONFIG_HAS_DMA))
 100                 return;
 101 
 102         for (i = 0; i < HCD_BUFFER_POOLS; i++) {
 103                 dma_pool_destroy(hcd->pool[i]);
 104                 hcd->pool[i] = NULL;
 105         }
 106 }
 107 
 108 
 109 /* sometimes alloc/free could use kmalloc with GFP_DMA, for
 110  * better sharing and to leverage mm/slab.c intelligence.
 111  */
 112 
 113 void *hcd_buffer_alloc(
 114         struct usb_bus          *bus,
 115         size_t                  size,
 116         gfp_t                   mem_flags,
 117         dma_addr_t              *dma
 118 )
 119 {
 120         struct usb_hcd          *hcd = bus_to_hcd(bus);
 121         int                     i;
 122 
 123         if (size == 0)
 124                 return NULL;
 125 
 126         if (hcd->localmem_pool)
 127                 return gen_pool_dma_alloc(hcd->localmem_pool, size, dma);
 128 
 129         /* some USB hosts just use PIO */
 130         if (!hcd_uses_dma(hcd)) {
 131                 *dma = ~(dma_addr_t) 0;
 132                 return kmalloc(size, mem_flags);
 133         }
 134 
 135         for (i = 0; i < HCD_BUFFER_POOLS; i++) {
 136                 if (size <= pool_max[i])
 137                         return dma_pool_alloc(hcd->pool[i], mem_flags, dma);
 138         }
 139         return dma_alloc_coherent(hcd->self.sysdev, size, dma, mem_flags);
 140 }
 141 
 142 void hcd_buffer_free(
 143         struct usb_bus          *bus,
 144         size_t                  size,
 145         void                    *addr,
 146         dma_addr_t              dma
 147 )
 148 {
 149         struct usb_hcd          *hcd = bus_to_hcd(bus);
 150         int                     i;
 151 
 152         if (!addr)
 153                 return;
 154 
 155         if (hcd->localmem_pool) {
 156                 gen_pool_free(hcd->localmem_pool, (unsigned long)addr, size);
 157                 return;
 158         }
 159 
 160         if (!hcd_uses_dma(hcd)) {
 161                 kfree(addr);
 162                 return;
 163         }
 164 
 165         for (i = 0; i < HCD_BUFFER_POOLS; i++) {
 166                 if (size <= pool_max[i]) {
 167                         dma_pool_free(hcd->pool[i], addr, dma);
 168                         return;
 169                 }
 170         }
 171         dma_free_coherent(hcd->self.sysdev, size, addr, dma);
 172 }