On Mon, May 2, 2022 at 7:59 PM Frank Li <Frank.Li@xxxxxxx> wrote:
>
> Some Endpoints controllers have DMA capabilities. This DMA controller has
> more efficiency then a general external DMA controller. And this DMA
> controller can bypass outbound memory address translation unit.
>
> The whole flow use standard DMA usage module
>
> 1. Using dma_request_channel() and filter function to find correct
> RX and TX Channel. if not exist, fallback to try allocate
> general DMA controller channel.
> 2. dmaengine_slave_config() config remote side physcial address.
> 3. using dmaengine_prep_slave_single() create transfer descriptor.
> 4. tx_submit();
> 5. dma_async_issue_pending();
>
> Signed-off-by: Frank Li <Frank.Li@xxxxxxx>
> Acked-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
Added kishon@xxxxxx
best regards
Frank Li
> ---
> Change from v9 to v10:
> - rewrite commit message
> Change from v4 to v9:
> - none
> Change from v3 to v4:
> - reverse Xmas tree order
> - local -> dma_local
> - change error message
> - IS_ERR -> IS_ERR_OR_NULL
> - check return value of dmaengine_slave_config()
> Change from v1 to v2:
> - none
>
> drivers/pci/endpoint/functions/pci-epf-test.c | 108 ++++++++++++++++--
> 1 file changed, 98 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c
> index 90d84d3bc868f..f26afd02f3a86 100644
> --- a/drivers/pci/endpoint/functions/pci-epf-test.c
> +++ b/drivers/pci/endpoint/functions/pci-epf-test.c
> @@ -52,9 +52,11 @@ struct pci_epf_test {
> enum pci_barno test_reg_bar;
> size_t msix_table_offset;
> struct delayed_work cmd_handler;
> - struct dma_chan *dma_chan;
> + struct dma_chan *dma_chan_tx;
> + struct dma_chan *dma_chan_rx;
> struct completion transfer_complete;
> bool dma_supported;
> + bool dma_private;
> const struct pci_epc_features *epc_features;
> };
>
> @@ -105,12 +107,15 @@ static void pci_epf_test_dma_callback(void *param)
> */
> static int pci_epf_test_data_transfer(struct pci_epf_test *epf_test,
> dma_addr_t dma_dst, dma_addr_t dma_src,
> - size_t len)
> + size_t len, dma_addr_t dma_remote,
> + enum dma_transfer_direction dir)
> {
> + struct dma_chan *chan = (dir == DMA_DEV_TO_MEM) ? epf_test->dma_chan_tx : epf_test->dma_chan_rx;
> + dma_addr_t dma_local = (dir == DMA_MEM_TO_DEV) ? dma_src : dma_dst;
> enum dma_ctrl_flags flags = DMA_CTRL_ACK | DMA_PREP_INTERRUPT;
> - struct dma_chan *chan = epf_test->dma_chan;
> struct pci_epf *epf = epf_test->epf;
> struct dma_async_tx_descriptor *tx;
> + struct dma_slave_config sconf = {};
> struct device *dev = &epf->dev;
> dma_cookie_t cookie;
> int ret;
> @@ -120,7 +125,22 @@ static int pci_epf_test_data_transfer(struct pci_epf_test *epf_test,
> return -EINVAL;
> }
>
> - tx = dmaengine_prep_dma_memcpy(chan, dma_dst, dma_src, len, flags);
> + if (epf_test->dma_private) {
> + sconf.direction = dir;
> + if (dir == DMA_MEM_TO_DEV)
> + sconf.dst_addr = dma_remote;
> + else
> + sconf.src_addr = dma_remote;
> +
> + if (dmaengine_slave_config(chan, &sconf)) {
> + dev_err(dev, "DMA slave config fail\n");
> + return -EIO;
> + }
> + tx = dmaengine_prep_slave_single(chan, dma_local, len, dir, flags);
> + } else {
> + tx = dmaengine_prep_dma_memcpy(chan, dma_dst, dma_src, len, flags);
> + }
> +
> if (!tx) {
> dev_err(dev, "Failed to prepare DMA memcpy\n");
> return -EIO;
> @@ -148,6 +168,23 @@ static int pci_epf_test_data_transfer(struct pci_epf_test *epf_test,
> return 0;
> }
>
> +struct epf_dma_filter {
> + struct device *dev;
> + u32 dma_mask;
> +};
> +
> +static bool epf_dma_filter_fn(struct dma_chan *chan, void *node)
> +{
> + struct epf_dma_filter *filter = node;
> + struct dma_slave_caps caps;
> +
> + memset(&caps, 0, sizeof(caps));
> + dma_get_slave_caps(chan, &caps);
> +
> + return chan->device->dev == filter->dev
> + && (filter->dma_mask & caps.directions);
> +}
> +
> /**
> * pci_epf_test_init_dma_chan() - Function to initialize EPF test DMA channel
> * @epf_test: the EPF test device that performs data transfer operation
> @@ -158,10 +195,44 @@ static int pci_epf_test_init_dma_chan(struct pci_epf_test *epf_test)
> {
> struct pci_epf *epf = epf_test->epf;
> struct device *dev = &epf->dev;
> + struct epf_dma_filter filter;
> struct dma_chan *dma_chan;
> dma_cap_mask_t mask;
> int ret;
>
> + filter.dev = epf->epc->dev.parent;
> + filter.dma_mask = BIT(DMA_DEV_TO_MEM);
> +
> + dma_cap_zero(mask);
> + dma_cap_set(DMA_SLAVE, mask);
> + dma_chan = dma_request_channel(mask, epf_dma_filter_fn, &filter);
> + if (IS_ERR_OR_NULL(dma_chan)) {
> + dev_info(dev, "Failed to get private DMA channel. Falling back to generic one\n");
> + goto fail_back_tx;
> + }
> +
> + epf_test->dma_chan_rx = dma_chan;
> +
> + filter.dma_mask = BIT(DMA_MEM_TO_DEV);
> + dma_chan = dma_request_channel(mask, epf_dma_filter_fn, &filter);
> +
> + if (IS_ERR(dma_chan)) {
> + dev_info(dev, "Failed to get private DMA channel. Falling back to generic one\n");
> + goto fail_back_rx;
> + }
> +
> + epf_test->dma_chan_tx = dma_chan;
> + epf_test->dma_private = true;
> +
> + init_completion(&epf_test->transfer_complete);
> +
> + return 0;
> +
> +fail_back_rx:
> + dma_release_channel(epf_test->dma_chan_rx);
> + epf_test->dma_chan_tx = NULL;
> +
> +fail_back_tx:
> dma_cap_zero(mask);
> dma_cap_set(DMA_MEMCPY, mask);
>
> @@ -174,7 +245,7 @@ static int pci_epf_test_init_dma_chan(struct pci_epf_test *epf_test)
> }
> init_completion(&epf_test->transfer_complete);
>
> - epf_test->dma_chan = dma_chan;
> + epf_test->dma_chan_tx = epf_test->dma_chan_rx = dma_chan;
>
> return 0;
> }
> @@ -190,8 +261,17 @@ static void pci_epf_test_clean_dma_chan(struct pci_epf_test *epf_test)
> if (!epf_test->dma_supported)
> return;
>
> - dma_release_channel(epf_test->dma_chan);
> - epf_test->dma_chan = NULL;
> + dma_release_channel(epf_test->dma_chan_tx);
> + if (epf_test->dma_chan_tx == epf_test->dma_chan_rx) {
> + epf_test->dma_chan_tx = NULL;
> + epf_test->dma_chan_rx = NULL;
> + return;
> + }
> +
> + dma_release_channel(epf_test->dma_chan_rx);
> + epf_test->dma_chan_rx = NULL;
> +
> + return;
> }
>
> static void pci_epf_test_print_rate(const char *ops, u64 size,
> @@ -280,8 +360,14 @@ static int pci_epf_test_copy(struct pci_epf_test *epf_test)
> goto err_map_addr;
> }
>
> + if (epf_test->dma_private) {
> + dev_err(dev, "Cannot transfer data using DMA\n");
> + ret = -EINVAL;
> + goto err_map_addr;
> + }
> +
> ret = pci_epf_test_data_transfer(epf_test, dst_phys_addr,
> - src_phys_addr, reg->size);
> + src_phys_addr, reg->size, 0, DMA_MEM_TO_MEM);
> if (ret)
> dev_err(dev, "Data transfer failed\n");
> } else {
> @@ -363,7 +449,8 @@ static int pci_epf_test_read(struct pci_epf_test *epf_test)
>
> ktime_get_ts64(&start);
> ret = pci_epf_test_data_transfer(epf_test, dst_phys_addr,
> - phys_addr, reg->size);
> + phys_addr, reg->size,
> + reg->src_addr, DMA_DEV_TO_MEM);
> if (ret)
> dev_err(dev, "Data transfer failed\n");
> ktime_get_ts64(&end);
> @@ -453,8 +540,9 @@ static int pci_epf_test_write(struct pci_epf_test *epf_test)
> }
>
> ktime_get_ts64(&start);
> +
> ret = pci_epf_test_data_transfer(epf_test, phys_addr,
> - src_phys_addr, reg->size);
> + src_phys_addr, reg->size, reg->dst_addr, DMA_MEM_TO_DEV);
> if (ret)
> dev_err(dev, "Data transfer failed\n");
> ktime_get_ts64(&end);
> --
> 2.35.1
>
