Messages in this thread | | | From | "Adam J. Richter" <> | Date | Tue, 25 Jun 2002 14:27:18 -0700 | Subject | Re: RFC: turn scatterlist into a linked list, eliminate bio_vec |
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> I believe that my proposal would make it much easier for > reduce the dependency on struct pci_device, because it should > greatly reduce the amount of code that would have to be changed.
>Fine but do it when we have the abstration to actually >make it work, not before. [...]
How can I help? Who is working on this? Is this just an idea right now? Are there patches floating around?
If you want this to work through drivers/base, I could rename struct bus_type to struct device_type (it really quite misnamed), and create a new struct bus. Here is roughly what I have in mind. I am cc'ing linux-kenrel in case anyone else wants to point out problems or indicate that they are working on this.
struct bus_type { #ifdef CONFIG_DEVICEFS /* I really want to be able to config driverfs out */ const char *name; /* "pci", "isa", "sbus"... */ #endif (void *)(*alloc_consistent)(struct device *dev, size_t size, dma_addr_t *dma_addr); void (*free_conistent)(struct device *dev, size_t size, void *addr, dma_addr_t dma_handle); map_single... unmap_single... sync_single... };
struct device { ... struct bus_type *bus_type; struct device_type *dev_type; /* Formerly device.bus */ u64 dma_mask; /* less than device.parent.dma_mask Individual DMA channels on this device might have tighter masks than this, but will never have looser ones. */ }
static inline void* dma_alloc_consistent(struct device *dev, size_t size, dma_addr_t *dma_addr) { return (*dev->bus_type->alloc_consistent)(dev, size, dma_addr); }
static inline dma_addr_t dma_map_single(struct device *dev, void *vaddr, size_t size, int direction) { #ifdef NEED_SEPARATE_DMA_ADDR return (*dev->bus_type->map_single)(dev, vaddr, size, directio); #else return virt_to_bus(vaddr); #endif }
static inline void pci_unmap_single(struct device *dev, dma_addr_t dma_addr, size_t size, int direction) { if (direction == PCI_DMA_NONE) BUG(); #ifdef NEED_SEPARATE_DMA_ADDR (*dev->bus_type->unmap_single)(dev, dma_addr, size, direction); #endif }
...in include/pci.h:...
/* Implemented in each arch subdirectory */ static void *__pci_alloc_consistent(struct device *dev, size_t size, dma_addr_t *dma_addr);
/* Legacy interface */ static inline void *pci_alloc_consistent(struct device *pcidev, size_t size, dma_addr_t *dma_addr) { return __pci_alloc_consistent(&pcidev->dev, size, dma_addr); }
....Somewhere in drivers/pci:....
struct bus_type pci_bus_type = { .name = "pci", .alloc_consistent = __pci_alloc_consistent, ... };
...Somewhere in drivers/?....
/* ISA uses the PCI routines. */ struct bus_type isa_bus_type = { .name = "isa", .alloc_consistent = __pci_alloc_consistent, ... };
...Somewhere in drivers/sbus... */ struct bus_type isa_bus_type = { .name = "isa", .alloc_consistent = __sbus_alloc_consistent, ... };
...In each arch/xxxx/pci.c...
void *__pci_alloc_consistent(struct device *dev, size_t size, dma_addr_t *dma_addr) { struct pci_dev *pci_dev = list_entry(dev, struct pci_dev, dev); ...guts of existing pci_alloc_consistent implementation... }
Adam J. Richter __ ______________ 575 Oroville Road adam@yggdrasil.com \ / Milpitas, California 95035 +1 408 309-6081 | g g d r a s i l United States of America "Free Software For The Rest Of Us." - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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