linux/drivers/usb/core/buffer.c

// SPDX-License-Identifier: GPL-2.0
/*
 * DMA memory management for framework level HCD code (hc_driver)
 *
 * This implementation plugs in through generic "usb_bus" level methods,
 * and should work with all USB controllers, regardless of bus type.
 *
 * Released under the GPLv2 only.
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/device.h>
#include <linux/mm.h>
#include <linux/io.h>
#include <linux/dma-mapping.h>
#include <linux/dmapool.h>
#include <linux/genalloc.h>
#include <linux/usb.h>
#include <linux/usb/hcd.h>


/*
 * DMA-Coherent Buffers
 */

/* FIXME tune these based on pool statistics ... */
static size_t pool_max[HCD_BUFFER_POOLS] = …;

void __init usb_init_pool_max(void)
{ … }

/* SETUP primitives */

/**
 * hcd_buffer_create - initialize buffer pools
 * @hcd: the bus whose buffer pools are to be initialized
 *
 * Context: task context, might sleep
 *
 * Call this as part of initializing a host controller that uses the dma
 * memory allocators.  It initializes some pools of dma-coherent memory that
 * will be shared by all drivers using that controller.
 *
 * Call hcd_buffer_destroy() to clean up after using those pools.
 *
 * Return: 0 if successful. A negative errno value otherwise.
 */
int hcd_buffer_create(struct usb_hcd *hcd)
{ … }


/**
 * hcd_buffer_destroy - deallocate buffer pools
 * @hcd: the bus whose buffer pools are to be destroyed
 *
 * Context: task context, might sleep
 *
 * This frees the buffer pools created by hcd_buffer_create().
 */
void hcd_buffer_destroy(struct usb_hcd *hcd)
{ … }


/* sometimes alloc/free could use kmalloc with GFP_DMA, for
 * better sharing and to leverage mm/slab.c intelligence.
 */

void *hcd_buffer_alloc(
	struct usb_bus		*bus,
	size_t			size,
	gfp_t			mem_flags,
	dma_addr_t		*dma
)
{ … }

void hcd_buffer_free(
	struct usb_bus		*bus,
	size_t			size,
	void			*addr,
	dma_addr_t		dma
)
{ … }

void *hcd_buffer_alloc_pages(struct usb_hcd *hcd,
		size_t size, gfp_t mem_flags, dma_addr_t *dma)
{ … }

void hcd_buffer_free_pages(struct usb_hcd *hcd,
		size_t size, void *addr, dma_addr_t dma)
{ … }