1 // SPDX-License-Identifier: GPL-2.0
3 * DMA memory management for framework level HCD code (hc_driver)
5 * This implementation plugs in through generic "usb_bus" level methods,
6 * and should work with all USB controllers, regardless of bus type.
8 * Released under the GPLv2 only.
11 #include <linux/module.h>
12 #include <linux/kernel.h>
13 #include <linux/slab.h>
14 #include <linux/device.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>
25 * DMA-Coherent Buffers
28 /* FIXME tune these based on pool statistics ... */
29 static size_t pool_max[HCD_BUFFER_POOLS] = {
33 void __init usb_init_pool_max(void)
36 * The pool_max values must never be smaller than
37 * ARCH_KMALLOC_MINALIGN.
39 if (ARCH_KMALLOC_MINALIGN <= 32)
40 ; /* Original value is okay */
41 else if (ARCH_KMALLOC_MINALIGN <= 64)
43 else if (ARCH_KMALLOC_MINALIGN <= 128)
44 pool_max[0] = 0; /* Don't use this pool */
46 BUILD_BUG(); /* We don't allow this */
49 /* SETUP primitives */
52 * hcd_buffer_create - initialize buffer pools
53 * @hcd: the bus whose buffer pools are to be initialized
54 * Context: !in_interrupt()
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.
60 * Call hcd_buffer_destroy() to clean up after using those pools.
62 * Return: 0 if successful. A negative errno value otherwise.
64 int hcd_buffer_create(struct usb_hcd *hcd)
69 if (hcd->localmem_pool || !hcd_uses_dma(hcd))
72 for (i = 0; i < HCD_BUFFER_POOLS; i++) {
76 snprintf(name, sizeof(name), "buffer-%d", size);
77 hcd->pool[i] = dma_pool_create(name, hcd->self.sysdev,
80 hcd_buffer_destroy(hcd);
89 * hcd_buffer_destroy - deallocate buffer pools
90 * @hcd: the bus whose buffer pools are to be destroyed
91 * Context: !in_interrupt()
93 * This frees the buffer pools created by hcd_buffer_create().
95 void hcd_buffer_destroy(struct usb_hcd *hcd)
99 if (!IS_ENABLED(CONFIG_HAS_DMA))
102 for (i = 0; i < HCD_BUFFER_POOLS; i++) {
103 dma_pool_destroy(hcd->pool[i]);
109 /* sometimes alloc/free could use kmalloc with GFP_DMA, for
110 * better sharing and to leverage mm/slab.c intelligence.
113 void *hcd_buffer_alloc(
120 struct usb_hcd *hcd = bus_to_hcd(bus);
126 if (hcd->localmem_pool)
127 return gen_pool_dma_alloc(hcd->localmem_pool, size, dma);
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);
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);
139 return dma_alloc_coherent(hcd->self.sysdev, size, dma, mem_flags);
142 void hcd_buffer_free(
149 struct usb_hcd *hcd = bus_to_hcd(bus);
155 if (hcd->localmem_pool) {
156 gen_pool_free(hcd->localmem_pool, (unsigned long)addr, size);
160 if (!hcd_uses_dma(hcd)) {
165 for (i = 0; i < HCD_BUFFER_POOLS; i++) {
166 if (size <= pool_max[i]) {
167 dma_pool_free(hcd->pool[i], addr, dma);
171 dma_free_coherent(hcd->self.sysdev, size, addr, dma);