/* SPDX-License-Identifier: GPL-2.0 */
#include <linux/prefetch.h>
/**
* iommu_fill_pdir - Insert coalesced scatter/gather chunks into the I/O Pdir.
* @ioc: The I/O Controller.
* @startsg: The scatter/gather list of coalesced chunks.
* @nents: The number of entries in the scatter/gather list.
* @hint: The DMA Hint.
*
* This function inserts the coalesced scatter/gather list chunks into the
* I/O Controller's I/O Pdir.
*/
static inline unsigned int
iommu_fill_pdir(struct ioc *ioc, struct scatterlist *startsg, int nents,
unsigned long hint,
void (*iommu_io_pdir_entry)(u64 *, space_t, unsigned long,
unsigned long))
{
struct scatterlist *dma_sg = startsg; /* pointer to current DMA */
unsigned int n_mappings = 0;
unsigned long dma_offset = 0, dma_len = 0;
u64 *pdirp = NULL;
/* Horrible hack. For efficiency's sake, dma_sg starts one
* entry below the true start (it is immediately incremented
* in the loop) */
dma_sg--;
while (nents-- > 0) {
unsigned long vaddr;
long size;
DBG_RUN_SG(" %d : %08lx/%05x %p/%05x\n", nents,
(unsigned long)sg_dma_address(startsg), cnt,
sg_virt(startsg), startsg->length
);
/*
** Look for the start of a new DMA stream
*/
if (sg_dma_address(startsg) & PIDE_FLAG) {
u32 pide = sg_dma_address(startsg) & ~PIDE_FLAG;
BUG_ON(pdirp && (dma_len != sg_dma_len(dma_sg)));
dma_sg++;
dma_len = sg_dma_len(startsg);
sg_dma_len(startsg) = 0;
dma_offset = (unsigned long) pide & ~IOVP_MASK;
n_mappings++;
#if defined(ZX1_SUPPORT)
/* Pluto IOMMU IO Virt Address is not zero based */
sg_dma_address(dma_sg) = pide | ioc->ibase;
#else
/* SBA, ccio, and dino are zero based.
* Trying to save a few CPU cycles for most users.
*/
sg_dma_address(dma_sg) = pide;
#endif
pdirp = &(ioc->pdir_base[pide >> IOVP_SHIFT]);
prefetchw(pdirp);
}
BUG_ON(pdirp == NULL);
vaddr = (unsigned long)sg_virt(startsg);
sg_dma_len(dma_sg) += startsg->length;
size = startsg->length + dma_offset;
dma_offset = 0;
#ifdef IOMMU_MAP_STATS
ioc->msg_pages += startsg->length >> IOVP_SHIFT;
#endif
do {
iommu_io_pdir_entry(pdirp, KERNEL_SPACE,
vaddr, hint);
vaddr += IOVP_SIZE;
size -= IOVP_SIZE;
pdirp++;
} while(unlikely(size > 0));
startsg++;
}
return(n_mappings);
}
/*
** First pass is to walk the SG list and determine where the breaks are
** in the DMA stream. Allocates PDIR entries but does not fill them.
** Returns the number of DMA chunks.
**
** Doing the fill separate from the coalescing/allocation keeps the
** code simpler. Future enhancement could make one pass through
** the sglist do both.
*/
static inline unsigned int
iommu_coalesce_chunks(struct ioc *ioc, struct device *dev,
struct scatterlist *startsg, int nents,
int (*iommu_alloc_range)(struct ioc *, struct device *, size_t))
{
struct scatterlist *contig_sg; /* contig chunk head */
unsigned long dma_offset, dma_len; /* start/len of DMA stream */
unsigned int n_mappings = 0;
unsigned int max_seg_size = min(dma_get_max_seg_size(dev),
(unsigned)DMA_CHUNK_SIZE);
unsigned int max_seg_boundary = dma_get_seg_boundary(dev) + 1;
if (max_seg_boundary) /* check if the addition above didn't overflow */
max_seg_size = min(max_seg_size, max_seg_boundary);
while (nents > 0) {
/*
** Prepare for first/next DMA stream
*/
contig_sg = startsg;
dma_len = startsg->length;
dma_offset = startsg->offset;
/* PARANOID: clear entries */
sg_dma_address(startsg) = 0;
sg_dma_len(startsg) = 0;
/*
** This loop terminates one iteration "early" since
** it's always looking one "ahead".
*/
while(--nents > 0) {
unsigned long prev_end, sg_start;
prev_end = (unsigned long)sg_virt(startsg) +
startsg->length;
startsg++;
sg_start = (unsigned long)sg_virt(startsg);
/* PARANOID: clear entries */
sg_dma_address(startsg) = 0;
sg_dma_len(startsg) = 0;
/*
** First make sure current dma stream won't
** exceed max_seg_size if we coalesce the
** next entry.
*/
if (unlikely(ALIGN(dma_len + dma_offset + startsg->length, IOVP_SIZE) >
max_seg_size))
break;
/*
* Next see if we can append the next chunk (i.e.
* it must end on one page and begin on another, or
* it must start on the same address as the previous
* entry ended.
*/
if (unlikely((prev_end != sg_start) ||
((prev_end | sg_start) & ~PAGE_MASK)))
break;
dma_len += startsg->length;
}
/*
** End of DMA Stream
** Terminate last VCONTIG block.
** Allocate space for DMA stream.
*/
sg_dma_len(contig_sg) = dma_len;
dma_len = ALIGN(dma_len + dma_offset, IOVP_SIZE);
sg_dma_address(contig_sg) =
PIDE_FLAG
| (iommu_alloc_range(ioc, dev, dma_len) << IOVP_SHIFT)
| dma_offset;
n_mappings++;
}
return n_mappings;
}
