drivers/usb/host/ehci-mem.c

Source file repositories/reference/linux-study-clean/drivers/usb/host/ehci-mem.c

File Facts

System
Linux kernel
Corpus path
drivers/usb/host/ehci-mem.c
Extension
.c
Size
5780 bytes
Lines
225
Domain
Driver Families
Bucket
drivers/usb
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0+
/*
 * Copyright (c) 2001 by David Brownell
 */

/* this file is part of ehci-hcd.c */

/*-------------------------------------------------------------------------*/

/*
 * There's basically three types of memory:
 *	- data used only by the HCD ... kmalloc is fine
 *	- async and periodic schedules, shared by HC and HCD ... these
 *	  need to use dma_pool or dma_alloc_coherent
 *	- driver buffers, read/written by HC ... single shot DMA mapped
 *
 * There's also "register" data (e.g. PCI or SOC), which is memory mapped.
 * No memory seen by this driver is pageable.
 */

/*-------------------------------------------------------------------------*/

/* Allocate the key transfer structures from the previously allocated pool */

static inline void ehci_qtd_init(struct ehci_hcd *ehci, struct ehci_qtd *qtd,
				  dma_addr_t dma)
{
	memset (qtd, 0, sizeof *qtd);
	qtd->qtd_dma = dma;
	qtd->hw_token = cpu_to_hc32(ehci, QTD_STS_HALT);
	qtd->hw_next = EHCI_LIST_END(ehci);
	qtd->hw_alt_next = EHCI_LIST_END(ehci);
	INIT_LIST_HEAD (&qtd->qtd_list);
}

static struct ehci_qtd *ehci_qtd_alloc (struct ehci_hcd *ehci, gfp_t flags)
{
	struct ehci_qtd		*qtd;
	dma_addr_t		dma;

	qtd = dma_pool_alloc (ehci->qtd_pool, flags, &dma);
	if (qtd != NULL) {
		ehci_qtd_init(ehci, qtd, dma);
	}
	return qtd;
}

static inline void ehci_qtd_free (struct ehci_hcd *ehci, struct ehci_qtd *qtd)
{
	dma_pool_free (ehci->qtd_pool, qtd, qtd->qtd_dma);
}


static void qh_destroy(struct ehci_hcd *ehci, struct ehci_qh *qh)
{
	/* clean qtds first, and know this is not linked */
	if (!list_empty (&qh->qtd_list) || qh->qh_next.ptr) {
		ehci_dbg (ehci, "unused qh not empty!\n");
		BUG ();
	}
	if (qh->dummy)
		ehci_qtd_free (ehci, qh->dummy);
	dma_pool_free(ehci->qh_pool, qh->hw, qh->qh_dma);
	kfree(qh);
}

static struct ehci_qh *ehci_qh_alloc (struct ehci_hcd *ehci, gfp_t flags)
{
	struct ehci_qh		*qh;
	dma_addr_t		dma;

	qh = kzalloc_obj(*qh, GFP_ATOMIC);
	if (!qh)
		goto done;
	qh->hw = (struct ehci_qh_hw *)
		dma_pool_zalloc(ehci->qh_pool, flags, &dma);
	if (!qh->hw)
		goto fail;
	qh->qh_dma = dma;
	// INIT_LIST_HEAD (&qh->qh_list);
	INIT_LIST_HEAD (&qh->qtd_list);
	INIT_LIST_HEAD(&qh->unlink_node);

	/* dummy td enables safe urb queuing */
	qh->dummy = ehci_qtd_alloc (ehci, flags);
	if (qh->dummy == NULL) {
		ehci_dbg (ehci, "no dummy td\n");
		goto fail1;
	}
done:

Annotation

Implementation Notes