[PATCH v5 9/9] PCI: endpoint: functions/pci-epf-test: Support PCI controller DMA

Frank Li
2022-03-10T19:25:56Z

Designware provided eDMA support in controller. This enabled use
this eDMA controller to transfer data.

The whole flow align with standard DMA usage module

1. Using dma_request_channel() and filter function to find correct
RX and TX 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();

Tested at i.MX8DXL platform.

root@imx8qmmek:~# /usr/bin/pcitest -d -w
WRITE ( 102400 bytes): OKAY
root@imx8qmmek:~# /usr/bin/pcitest -d -r
READ ( 102400 bytes): OKAY

WRITE => Size: 102400 bytes DMA: YES Time: 0.000180145 seconds Rate: 555108 KB/s
READ => Size: 102400 bytes DMA: YES Time: 0.000194397 seconds Rate: 514411 KB/s

READ => Size: 102400 bytes DMA: NO Time: 0.013532597 seconds Rate: 7389 KB/s
WRITE => Size: 102400 bytes DMA: NO Time: 0.000857090 seconds Rate: 116673 KB/s

Signed-off-by: Frank Li <Frank.Li@nxp.com>
---
Change from v4 to v5:
- 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);
--
2.24.0.rc1