On 07/31/2017 07:14 PM, Dan Williams wrote:
> On Mon, Jul 31, 2017 at 3:24 PM, Dave Jiang <dave.jiang@xxxxxxxxx> wrote:
>> Adding ioatdma support to copy from a physically contiguos buffer to a
>> provided scatterlist and vice versa. This is used to support
>> reading/writing persistent memory in the pmem driver.
>>
>> Signed-off-by: Dave Jiang <dave.jiang@xxxxxxxxx>
>> ---
>> drivers/dma/ioat/dma.h | 8 +++
>> drivers/dma/ioat/init.c | 3 +
>> drivers/dma/ioat/prep.c | 105 +++++++++++++++++++++++++++++++++++++++++++++
>> include/linux/dmaengine.h | 10 ++++
>> 4 files changed, 126 insertions(+)
>>
>> diff --git a/drivers/dma/ioat/dma.h b/drivers/dma/ioat/dma.h
>> index 56200ee..b9a8d82 100644
>> --- a/drivers/dma/ioat/dma.h
>> +++ b/drivers/dma/ioat/dma.h
>> @@ -370,6 +370,14 @@ struct dma_async_tx_descriptor *
>> ioat_dma_prep_memcpy_lock(struct dma_chan *c, dma_addr_t dma_dest,
>> dma_addr_t dma_src, size_t len, unsigned long flags);
>> struct dma_async_tx_descriptor *
>> +ioat_dma_prep_memcpy_to_sg_lock(struct dma_chan *c,
>> + struct scatterlist *dst_sg, unsigned int dst_nents,
>> + dma_addr_t src, unsigned long flags);
>> +struct dma_async_tx_descriptor *
>> +ioat_dma_prep_memcpy_from_sg_lock(struct dma_chan *c, dma_addr_t dst,
>> + struct scatterlist *dst_sg, unsigned int dst_nents,
>> + unsigned long flags);
>> +struct dma_async_tx_descriptor *
>> ioat_prep_interrupt_lock(struct dma_chan *c, unsigned long flags);
>> struct dma_async_tx_descriptor *
>> ioat_prep_xor(struct dma_chan *chan, dma_addr_t dest, dma_addr_t *src,
>> diff --git a/drivers/dma/ioat/init.c b/drivers/dma/ioat/init.c
>> index e437112..1e03f3e 100644
>> --- a/drivers/dma/ioat/init.c
>> +++ b/drivers/dma/ioat/init.c
>> @@ -1091,6 +1091,9 @@ static int ioat3_dma_probe(struct ioatdma_device *ioat_dma, int dca)
>>
>> dma = &ioat_dma->dma_dev;
>> dma->device_prep_dma_memcpy = ioat_dma_prep_memcpy_lock;
>> + dma->device_prep_dma_memcpy_to_sg = ioat_dma_prep_memcpy_to_sg_lock;
>> + dma->device_prep_dma_memcpy_from_sg =
>> + ioat_dma_prep_memcpy_from_sg_lock;
>> dma->device_issue_pending = ioat_issue_pending;
>> dma->device_alloc_chan_resources = ioat_alloc_chan_resources;
>> dma->device_free_chan_resources = ioat_free_chan_resources;
>> diff --git a/drivers/dma/ioat/prep.c b/drivers/dma/ioat/prep.c
>> index 243421a..49e220c 100644
>> --- a/drivers/dma/ioat/prep.c
>> +++ b/drivers/dma/ioat/prep.c
>> @@ -159,6 +159,111 @@ ioat_dma_prep_memcpy_lock(struct dma_chan *c, dma_addr_t dma_dest,
>> return &desc->txd;
>> }
>>
>> +struct dma_async_tx_descriptor *
>> +ioat_dma_prep_memcpy_to_sg_lock(struct dma_chan *c,
>> + struct scatterlist *dst_sg, unsigned int dst_nents,
>> + dma_addr_t dma_src, unsigned long flags)
>> +{
>> + struct ioatdma_chan *ioat_chan = to_ioat_chan(c);
>> + struct ioat_dma_descriptor *hw = NULL;
>> + struct ioat_ring_ent *desc = NULL;
>> + dma_addr_t src = dma_src;
>> + int num_descs, idx, i;
>> + struct scatterlist *s;
>> + size_t total_len = 0, len;
>> +
>> +
>> + if (test_bit(IOAT_CHAN_DOWN, &ioat_chan->state))
>> + return NULL;
>> +
>> + /*
>> + * The upper layer will garantee that each entry does not exceed
>> + * xfercap.
>> + */
>> + num_descs = dst_nents;
>> +
>> + if (likely(num_descs) &&
>> + ioat_check_space_lock(ioat_chan, num_descs) == 0)
>> + idx = ioat_chan->head;
>> + else
>> + return NULL;
>> +
>> + for_each_sg(dst_sg, s, dst_nents, i) {
>> + desc = ioat_get_ring_ent(ioat_chan, idx + i);
>> + hw = desc->hw;
>> + len = sg_dma_len(s);
>> + hw->size = len;
>> + hw->ctl = 0;
>> + hw->src_addr = src;
>> + hw->dst_addr = sg_dma_address(s);
>> + src += len;
>> + total_len += len;
>> + dump_desc_dbg(ioat_chan, desc);
>> + }
>> +
>> + desc->txd.flags = flags;
>> + desc->len = total_len;
>> + hw->ctl_f.int_en = !!(flags & DMA_PREP_INTERRUPT);
>> + hw->ctl_f.fence = !!(flags & DMA_PREP_FENCE);
>> + hw->ctl_f.compl_write = 1;
>> + dump_desc_dbg(ioat_chan, desc);
>> + /* we leave the channel locked to ensure in order submission */
>> +
>> + return &desc->txd;
>> +}
>> +
>> +struct dma_async_tx_descriptor *
>> +ioat_dma_prep_memcpy_from_sg_lock(struct dma_chan *c, dma_addr_t dma_dst,
>> + struct scatterlist *src_sg, unsigned int src_nents,
>> + unsigned long flags)
>> +{
>> + struct ioatdma_chan *ioat_chan = to_ioat_chan(c);
>> + struct ioat_dma_descriptor *hw = NULL;
>> + struct ioat_ring_ent *desc = NULL;
>> + dma_addr_t dst = dma_dst;
>> + int num_descs, idx, i;
>> + struct scatterlist *s;
>> + size_t total_len = 0, len;
>> +
>> +
>> + if (test_bit(IOAT_CHAN_DOWN, &ioat_chan->state))
>> + return NULL;
>> +
>> + /*
>> + * The upper layer will garantee that each entry does not exceed
>> + * xfercap.
>> + */
>> + num_descs = src_nents;
>> +
>> + if (likely(num_descs) &&
>> + ioat_check_space_lock(ioat_chan, num_descs) == 0)
>> + idx = ioat_chan->head;
>> + else
>> + return NULL;
>> +
>> + for_each_sg(src_sg, s, src_nents, i) {
>> + desc = ioat_get_ring_ent(ioat_chan, idx + i);
>> + hw = desc->hw;
>> + len = sg_dma_len(s);
>> + hw->size = len;
>> + hw->ctl = 0;
>> + hw->src_addr = sg_dma_address(s);
>> + hw->dst_addr = dst;
>> + dst += len;
>> + total_len += len;
>> + dump_desc_dbg(ioat_chan, desc);
>> + }
>> +
>> + desc->txd.flags = flags;
>> + desc->len = total_len;
>> + hw->ctl_f.int_en = !!(flags & DMA_PREP_INTERRUPT);
>> + hw->ctl_f.fence = !!(flags & DMA_PREP_FENCE);
>> + hw->ctl_f.compl_write = 1;
>> + dump_desc_dbg(ioat_chan, desc);
>> + /* we leave the channel locked to ensure in order submission */
>> +
>> + return &desc->txd;
>> +}
>>
>> static struct dma_async_tx_descriptor *
>> __ioat_prep_xor_lock(struct dma_chan *c, enum sum_check_flags *result,
>> diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
>> index 5336808..6202e7c 100644
>> --- a/include/linux/dmaengine.h
>> +++ b/include/linux/dmaengine.h
>> @@ -694,6 +694,8 @@ struct dma_filter {
>> * @device_prep_dma_memset: prepares a memset operation
>> * @device_prep_dma_memset_sg: prepares a memset operation over a scatter list
>> * @device_prep_dma_interrupt: prepares an end of chain interrupt operation
>> + * @device_prep_dma_memcpy_to_sg: prepares memcpy from buffer to scatterlist
>> + * @device_prep_dma_memcpy_from_sg: prepares memcpy from scatterlist to buffer
>> * @device_prep_slave_sg: prepares a slave dma operation
>> * @device_prep_dma_cyclic: prepare a cyclic dma operation suitable for audio.
>> * The function takes a buffer of size buf_len. The callback function will
>> @@ -776,6 +778,14 @@ struct dma_device {
>> struct scatterlist *dst_sg, unsigned int dst_nents,
>> struct scatterlist *src_sg, unsigned int src_nents,
>> unsigned long flags);
>> + struct dma_async_tx_descriptor *(*device_prep_dma_memcpy_to_sg)(
>> + struct dma_chan *chan,
>> + struct scatterlist *dst_sg, unsigned int dst_nents,
>> + dma_addr_t src, unsigned long flags);
>> + struct dma_async_tx_descriptor *(*device_prep_dma_memcpy_from_sg)(
>> + struct dma_chan *chan, dma_addr_t dst,
>> + struct scatterlist *dst_sg, unsigned int dst_nents,
>> + unsigned long flags);
>>
>> struct dma_async_tx_descriptor *(*device_prep_slave_sg)(
>> struct dma_chan *chan, struct scatterlist *sgl,
>>
>
> Can we get away with just adding one new operation with a flag to
> indicate whether it is the 'to' or' 'from' sg case?
>
Yes I can try to make that happen.
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