Commit 0acedc124aca35f5cce9d4ee288dc372bf517e09
Committed by
Linus Torvalds
Linus Torvalds
1 parent
f41b177157
Exists in
master
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39 other branches
dma-mapping.h: add the dma_unmap state API
Adds the following macros: DECLARE_DMA_UNMAP_ADDR(ADDR_NAME) DECLARE_DMA_UNMAP_LEN(LEN_NAME) dma_unmap_addr(PTR, ADDR_NAME) dma_unmap_addr_set(PTR, ADDR_NAME, VAL) dma_unmap_len(PTR, LEN_NAME) dma_unmap_len_set(PTR, LEN_NAME, VAL) The API corresponds to the pci_unmap state API. We'll move to this new generic API from the PCI specific API in the long term. As include/asm-generic/pci-dma-compat.h does, the pci_unmap API simply calls the new generic API for some time. Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Cc: James Bottomley <James.Bottomley@suse.de> Cc: David S. Miller <davem@davemloft.net> Cc: Jesse Barnes <jbarnes@virtuousgeek.org> Cc: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Showing 3 changed files with 80 additions and 15 deletions Side-by-side Diff
Documentation/DMA-API.txt
| ... | ... | @@ -472,6 +472,64 @@ |
| 472 | 472 | .... |
| 473 | 473 | |
| 474 | 474 | |
| 475 | +Part Ie - Optimizing Unmap State Space Consumption | |
| 476 | +-------------------------------- | |
| 477 | + | |
| 478 | +On some platforms, dma_unmap_{single,page}() is simply a nop. | |
| 479 | +Therefore, keeping track of the mapping address and length is a waste | |
| 480 | +of space. Instead of filling your drivers up with ifdefs and the like | |
| 481 | +to "work around" this (which would defeat the whole purpose of a | |
| 482 | +portable API) the following facilities are provided. | |
| 483 | + | |
| 484 | +Actually, instead of describing the macros one by one, we'll | |
| 485 | +transform some example code. | |
| 486 | + | |
| 487 | +1) Use DEFINE_DMA_UNMAP_{ADDR,LEN} in state saving structures. | |
| 488 | + Example, before: | |
| 489 | + | |
| 490 | + struct ring_state { | |
| 491 | + struct sk_buff *skb; | |
| 492 | + dma_addr_t mapping; | |
| 493 | + __u32 len; | |
| 494 | + }; | |
| 495 | + | |
| 496 | + after: | |
| 497 | + | |
| 498 | + struct ring_state { | |
| 499 | + struct sk_buff *skb; | |
| 500 | + DEFINE_DMA_UNMAP_ADDR(mapping); | |
| 501 | + DEFINE_DMA_UNMAP_LEN(len); | |
| 502 | + }; | |
| 503 | + | |
| 504 | +2) Use dma_unmap_{addr,len}_set to set these values. | |
| 505 | + Example, before: | |
| 506 | + | |
| 507 | + ringp->mapping = FOO; | |
| 508 | + ringp->len = BAR; | |
| 509 | + | |
| 510 | + after: | |
| 511 | + | |
| 512 | + dma_unmap_addr_set(ringp, mapping, FOO); | |
| 513 | + dma_unmap_len_set(ringp, len, BAR); | |
| 514 | + | |
| 515 | +3) Use dma_unmap_{addr,len} to access these values. | |
| 516 | + Example, before: | |
| 517 | + | |
| 518 | + dma_unmap_single(dev, ringp->mapping, ringp->len, | |
| 519 | + DMA_FROM_DEVICE); | |
| 520 | + | |
| 521 | + after: | |
| 522 | + | |
| 523 | + dma_unmap_single(dev, | |
| 524 | + dma_unmap_addr(ringp, mapping), | |
| 525 | + dma_unmap_len(ringp, len), | |
| 526 | + DMA_FROM_DEVICE); | |
| 527 | + | |
| 528 | +It really should be self-explanatory. We treat the ADDR and LEN | |
| 529 | +separately, because it is possible for an implementation to only | |
| 530 | +need the address in order to perform the unmap operation. | |
| 531 | + | |
| 532 | + | |
| 475 | 533 | Part II - Advanced dma_ usage |
| 476 | 534 | ----------------------------- |
| 477 | 535 |
include/linux/dma-mapping.h
| ... | ... | @@ -232,5 +232,21 @@ |
| 232 | 232 | |
| 233 | 233 | #endif /* CONFIG_HAVE_DMA_ATTRS */ |
| 234 | 234 | |
| 235 | +#ifdef CONFIG_NEED_DMA_MAP_STATE | |
| 236 | +#define DEFINE_DMA_UNMAP_ADDR(ADDR_NAME) dma_addr_t ADDR_NAME | |
| 237 | +#define DEFINE_DMA_UNMAP_LEN(LEN_NAME) __u32 LEN_NAME | |
| 238 | +#define dma_unmap_addr(PTR, ADDR_NAME) ((PTR)->ADDR_NAME) | |
| 239 | +#define dma_unmap_addr_set(PTR, ADDR_NAME, VAL) (((PTR)->ADDR_NAME) = (VAL)) | |
| 240 | +#define dma_unmap_len(PTR, LEN_NAME) ((PTR)->LEN_NAME) | |
| 241 | +#define dma_unmap_len_set(PTR, LEN_NAME, VAL) (((PTR)->LEN_NAME) = (VAL)) | |
| 242 | +#else | |
| 243 | +#define DEFINE_DMA_UNMAP_ADDR(ADDR_NAME) | |
| 244 | +#define DEFINE_DMA_UNMAP_LEN(LEN_NAME) | |
| 245 | +#define dma_unmap_addr(PTR, ADDR_NAME) (0) | |
| 246 | +#define dma_unmap_addr_set(PTR, ADDR_NAME, VAL) do { } while (0) | |
| 247 | +#define dma_unmap_len(PTR, LEN_NAME) (0) | |
| 248 | +#define dma_unmap_len_set(PTR, LEN_NAME, VAL) do { } while (0) | |
| 249 | +#endif | |
| 250 | + | |
| 235 | 251 | #endif |
include/linux/pci-dma.h
| 1 | 1 | #ifndef _LINUX_PCI_DMA_H |
| 2 | 2 | #define _LINUX_PCI_DMA_H |
| 3 | 3 | |
| 4 | -#ifdef CONFIG_NEED_DMA_MAP_STATE | |
| 5 | -#define DECLARE_PCI_UNMAP_ADDR(ADDR_NAME) dma_addr_t ADDR_NAME; | |
| 6 | -#define DECLARE_PCI_UNMAP_LEN(LEN_NAME) __u32 LEN_NAME; | |
| 7 | -#define pci_unmap_addr(PTR, ADDR_NAME) ((PTR)->ADDR_NAME) | |
| 8 | -#define pci_unmap_addr_set(PTR, ADDR_NAME, VAL) (((PTR)->ADDR_NAME) = (VAL)) | |
| 9 | -#define pci_unmap_len(PTR, LEN_NAME) ((PTR)->LEN_NAME) | |
| 10 | -#define pci_unmap_len_set(PTR, LEN_NAME, VAL) (((PTR)->LEN_NAME) = (VAL)) | |
| 11 | -#else | |
| 12 | -#define DECLARE_PCI_UNMAP_ADDR(ADDR_NAME) | |
| 13 | -#define DECLARE_PCI_UNMAP_LEN(LEN_NAME) | |
| 14 | -#define pci_unmap_addr(PTR, ADDR_NAME) (0) | |
| 15 | -#define pci_unmap_addr_set(PTR, ADDR_NAME, VAL) do { } while (0) | |
| 16 | -#define pci_unmap_len(PTR, LEN_NAME) (0) | |
| 17 | -#define pci_unmap_len_set(PTR, LEN_NAME, VAL) do { } while (0) | |
| 18 | -#endif | |
| 4 | +#define DECLARE_PCI_UNMAP_ADDR(ADDR_NAME) DEFINE_DMA_UNMAP_ADDR(ADDR_NAME); | |
| 5 | +#define DECLARE_PCI_UNMAP_LEN(LEN_NAME) DEFINE_DMA_UNMAP_LEN(LEN_NAME); | |
| 6 | +#define pci_unmap_addr dma_unmap_addr | |
| 7 | +#define pci_unmap_addr_set dma_unmap_addr_set | |
| 8 | +#define pci_unmap_len dma_unmap_len | |
| 9 | +#define pci_unmap_len_set dma_unmap_len_set | |
| 19 | 10 | |
| 20 | 11 | #endif |