On 10/8/19 2:34 PM, Thomas Hellström (VMware) wrote:
Hi, Christoph,
Following our previous discussion I wonder if something along the
lines of the following could work / be acceptible
typedef unsigned long dma_pfn_t /* Opaque pfn type. Arch dependent.
This could if needed be a struct with a pointer and an offset */
/* Similar to vmf_insert_mixed() */
vm_fault_t dma_vmf_insert_mixed(struct device *dev,
struct vm_area_struct *vma,
unsigned long addr,
dma_pfn_t dpfn,
unsigned long attrs);
/* Similar to vmf_insert_pfn_pmd() */
vm_fault_t dma_vmf_insert_pfn_pmd(struct device *dev,
struct vm_area_struct *vma,
unsigned long addr,
dma_pfn_t dpfn,
unsigned long attrs);
/* Like vmap, but takes struct dma_pfns. */
extern void *dma_vmap(struct device *dev,
dma_pfn_t dpfns[],
unsigned int count, unsigned long flags,
unsigned long attrs);
/* Obtain struct dma_pfn pointers from a dma coherent allocation */
int dma_get_dpfns(struct device *dev, void *cpu_addr, dma_addr_t
dma_addr,
pgoff_t offset, pgoff_t num, dma_pfn_t dpfns[]);
I figure, for most if not all architectures we could use an ordinary
pfn as dma_pfn_t, but the dma layer would still have control over how
those pfns are obtained and how they are used in the kernel's mapping
APIs.
If so, I could start looking at this, time permitting, for the cases
where the pfn can be obtained from the kernel address or from
arch_dma_coherent_to_pfn(), and also the needed work to have a
tailored vmap_pfn().
Thanks,
/Thomas
Ping?
Thanks,
Thomas
