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[dma] Modify DMA API to simplify calculation of medial addresses

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Redefine the value stored within a DMA mapping to be the offset
between physical addresses and DMA addresses within the mapped region.

Provide a dma() wrapper function to calculate the DMA address for any
pointer within a mapped region, thereby simplifying the use cases when
a device needs to be given addresses other than the region start
address.

On a platform using the "flat" DMA implementation the DMA offset for
any mapped region is always zero, with the result that dma_map() can
be optimised away completely and dma() reduces to a straightforward
call to virt_to_phys().

Signed-off-by: Michael Brown <mcb30@ipxe.org>
This commit is contained in:
Michael Brown
2020-11-25 15:52:00 +00:00
parent 24ef743778
commit cf12a41703
7 changed files with 100 additions and 58 deletions
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74
src/include/ipxe/dma.h
View File

@@ -30,8 +30,13 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
/** A DMA mapping */
struct dma_mapping {
/** Device-side address */
physaddr_t addr;
/** Address offset
*
* This is the value that must be added to a physical address
* within the mapping in order to produce the corresponding
* device-side DMA address.
*/
physaddr_t offset;
/** Platform mapping token */
void *token;
};
@@ -148,12 +153,10 @@ struct dma_operations {
* @ret rc Return status code
*/
static inline __always_inline int
DMAAPI_INLINE ( flat, dma_map ) ( struct dma_device *dma, physaddr_t addr,
DMAAPI_INLINE ( flat, dma_map ) ( struct dma_device *dma,
physaddr_t addr __unused,
size_t len __unused, int flags __unused,
struct dma_mapping *map ) {
/* Use physical address as device address */
map->addr = addr;
struct dma_mapping *map __unused ) {
/* Increment mapping count (for debugging) */
if ( DBG_LOG )
@@ -187,13 +190,13 @@ DMAAPI_INLINE ( flat, dma_unmap ) ( struct dma_device *dma,
* @ret addr Buffer address, or NULL on error
*/
static inline __always_inline void *
DMAAPI_INLINE ( flat, dma_alloc ) ( struct dma_device *dma, size_t len,
size_t align, struct dma_mapping *map ) {
DMAAPI_INLINE ( flat, dma_alloc ) ( struct dma_device *dma,
size_t len, size_t align,
struct dma_mapping *map __unused ) {
void *addr;
/* Allocate buffer */
addr = malloc_phys ( len, align );
map->addr = virt_to_phys ( addr );
/* Increment allocation count (for debugging) */
if ( DBG_LOG && addr )
@@ -236,6 +239,35 @@ DMAAPI_INLINE ( flat, dma_set_mask ) ( struct dma_device *dma __unused,
/* Nothing to do */
}
/**
* Get DMA address from physical address
*
* @v map DMA mapping
* @v addr Physical address within the mapped region
* @ret addr Device-side DMA address
*/
static inline __always_inline physaddr_t
DMAAPI_INLINE ( flat, dma_phys ) ( struct dma_mapping *map __unused,
physaddr_t addr ) {
/* Use physical address as device address */
return addr;
}
/**
* Get DMA address from physical address
*
* @v map DMA mapping
* @v addr Physical address within the mapped region
* @ret addr Device-side DMA address
*/
static inline __always_inline physaddr_t
DMAAPI_INLINE ( op, dma_phys ) ( struct dma_mapping *map, physaddr_t addr ) {
/* Adjust physical address using mapping offset */
return ( addr + map->offset );
}
/**
* Map buffer for DMA
*
@@ -288,6 +320,28 @@ void dma_free ( struct dma_device *dma, void *addr, size_t len,
*/
void dma_set_mask ( struct dma_device *dma, physaddr_t mask );
/**
* Get DMA address from physical address
*
* @v map DMA mapping
* @v addr Physical address within the mapped region
* @ret addr Device-side DMA address
*/
physaddr_t dma_phys ( struct dma_mapping *map, physaddr_t addr );
/**
* Get DMA address from virtual address
*
* @v map DMA mapping
* @v addr Virtual address within the mapped region
* @ret addr Device-side DMA address
*/
static inline __always_inline physaddr_t dma ( struct dma_mapping *map,
void *addr ) {
return dma_phys ( map, virt_to_phys ( addr ) );
}
/**
* Initialise DMA device
*