[PATCH v3 1/3] dmaengine: dw-edma-pcie: Discover endpoint DMA metadata

[Koichiro Den]

Teach dw-edma-pcie to discover a PCI endpoint DMA function from
BAR-resident metadata. The metadata supplies the DMA register window,
channel counts, descriptor windows, optional auxiliary windows, and
endpoint-local descriptor and auxiliary addresses. Accept DesignWare
eDMA unroll, HDMA compatible, and HDMA native linked-list layouts.

Endpoint-provided DMA channels use raw slave addresses because the host
programs transfers against endpoint physical addresses, not PCI BAR
addresses. The host-side dw-edma-pcie instance is remote-routed by
default, so delegated channels report completions through IMWr/MSI.

Endpoint DMA metadata currently has no static PCI ID. Let an explicit
driver_override bind use the generic endpoint DMA metadata parser, but
do not treat arbitrary dynamic IDs without driver data as endpoint DMA
devices.

The endpoint polls HOST_REQ at a low idle rate before programming DMA
window submaps and setting READY. Let the host wait for several endpoint
poll periods before treating the READY handshake as timed out.

Signed-off-by: Koichiro Den <den@xxxxxxxxxxxxx>
---
Changes in v3:
  - Select endpoint DMA match data before copying DMA data (Sashiko).
  - Require driver_override for the generic endpoint DMA fallback
    (Sashiko).
  - Accept HDMA native linked-list endpoint DMA metadata.

 drivers/dma/dw-edma/dw-edma-pcie.c | 380 ++++++++++++++++++++++++++++-
 1 file changed, 378 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/dw-edma/dw-edma-pcie.c b/drivers/dma/dw-edma/dw-edma-pcie.c
index 1e75fefae9b8..2a56ee19d4cb 100644
--- a/drivers/dma/dw-edma/dw-edma-pcie.c
+++ b/drivers/dma/dw-edma/dw-edma-pcie.c
@@ -11,9 +11,13 @@
 #include <linux/pci.h>
 #include <linux/device.h>
 #include <linux/dma/edma.h>
+#include <linux/iopoll.h>
 #include <linux/pci-epf.h>
 #include <linux/msi.h>
 #include <linux/bitfield.h>
+#include <linux/io.h>
+#include <linux/overflow.h>
+#include <linux/pci-ep-dma.h>
 #include <linux/sizes.h>
 
 #include "dw-edma-core.h"
@@ -45,6 +49,9 @@
 #define DW_PCIE_XILINX_MDB_DT_OFF_GAP		0x100000
 #define DW_PCIE_XILINX_MDB_DT_SIZE		0x800
 
+#define DW_PCIE_EP_DMA_READY_POLL_US		1000
+#define DW_PCIE_EP_DMA_READY_TIMEOUT_US		2000000
+
 #define DW_BLOCK(a, b, c) \
 	{ \
 		.bar = a, \
@@ -94,6 +101,12 @@ struct dw_edma_pcie_match_data {
 #define DW_EDMA_PCIE_F_DEVMEM_PHYS_OFF	BIT(0)
 #define DW_EDMA_PCIE_F_REG_OFFSET	BIT(1)
 
+struct dw_edma_pcie_ep_dma_view {
+	struct pci_dev *pdev;
+	void __iomem *base;
+	resource_size_t limit;
+};
+
 static const struct dw_edma_pcie_data snps_edda_data = {
 	/* eDMA registers location */
 	.rg.bar				= BAR_0,
@@ -158,6 +171,13 @@ static const struct dw_edma_pcie_data xilinx_cpm6_dma_data = {
 	.rd_ch_cnt			= 8,
 };
 
+static const struct dw_edma_pcie_data ep_dma_data = {
+	.mf				= EDMA_MF_EDMA_UNROLL,
+	.irqs				= EDMA_MAX_WR_CH + EDMA_MAX_RD_CH,
+	.wr_ch_cnt			= EDMA_MAX_WR_CH,
+	.rd_ch_cnt			= EDMA_MAX_RD_CH,
+};
+
 static void dw_edma_set_chan_region_offset(struct dw_edma_pcie_data *pdata,
 					   enum pci_barno bar, off_t start_off,
 					   off_t ll_off_gap, size_t ll_size,
@@ -227,6 +247,86 @@ static const struct dw_edma_plat_ops dw_edma_pcie_plat_ops = {
 	.pci_address = dw_edma_pcie_address,
 };
 
+static const struct dw_edma_plat_ops dw_edma_pcie_raw_addr_plat_ops = {
+	.irq_vector = dw_edma_pcie_irq_vector,
+};
+
+static bool dw_edma_pcie_valid_bar(enum pci_barno bar)
+{
+	return bar >= BAR_0 && bar <= BAR_5;
+}
+
+static bool dw_edma_pcie_valid_bar_range(struct pci_dev *pdev,
+					 enum pci_barno bar, u64 off,
+					 size_t sz)
+{
+	resource_size_t bar_len;
+
+	if (!dw_edma_pcie_valid_bar(bar) || !sz)
+		return false;
+
+	bar_len = pci_resource_len(pdev, bar);
+
+	return off <= bar_len && sz <= bar_len - off;
+}
+
+static bool dw_edma_pcie_valid_block(struct pci_dev *pdev,
+				     const struct dw_edma_block *block)
+{
+	return dw_edma_pcie_valid_bar_range(pdev, block->bar, block->off,
+					    block->sz);
+}
+
+static bool dw_edma_pcie_ep_dma_bar_scannable(struct pci_dev *pdev,
+					      enum pci_barno bar)
+{
+	unsigned long flags = pci_resource_flags(pdev, bar);
+
+	if (!(flags & IORESOURCE_MEM))
+		return false;
+
+	if (flags & (IORESOURCE_UNSET | IORESOURCE_DISABLED))
+		return false;
+
+	return pci_resource_len(pdev, bar) >= PCI_EP_DMA_METADATA_HDR_LEN;
+}
+
+static u32 dw_edma_pcie_ep_dma_readl(struct dw_edma_pcie_ep_dma_view *view,
+				     u16 off)
+{
+	return readl(view->base + off);
+}
+
+static void dw_edma_pcie_ep_dma_writel(struct dw_edma_pcie_ep_dma_view *view,
+				       u16 off, u32 val)
+{
+	writel(val, view->base + off);
+}
+
+static u64 dw_edma_pcie_ep_dma_read64(struct dw_edma_pcie_ep_dma_view *view,
+				      u16 lo, u16 hi)
+{
+	u64 val;
+
+	val = dw_edma_pcie_ep_dma_readl(view, hi);
+
+	return (val << 32) | dw_edma_pcie_ep_dma_readl(view, lo);
+}
+
+static int dw_edma_pcie_ep_dma_read_off(struct dw_edma_pcie_ep_dma_view *view,
+					u16 lo, u16 hi, off_t *off)
+{
+	u64 val;
+
+	val = dw_edma_pcie_ep_dma_read64(view, lo, hi);
+	if (val > type_max(*off))
+		return -EINVAL;
+
+	*off = val;
+
+	return 0;
+}
+
 static void dw_edma_pcie_get_synopsys_dma_data(struct pci_dev *pdev,
 					       struct dw_edma_pcie_data *pdata)
 {
@@ -328,6 +428,265 @@ static void dw_edma_pcie_get_xilinx_dma_data(struct pci_dev *pdev,
 	pdata->devmem_phys_off = off;
 }
 
+static int
+dw_edma_pcie_parse_ep_dma_ch_table(struct dw_edma_pcie_ep_dma_view *view,
+				   struct dw_edma_pcie_data *pdata,
+				   u16 table_off, u16 entry_size, u16 ch_cnt,
+				   bool write)
+{
+	struct dw_edma_block *desc_blocks = write ? pdata->ll_wr : pdata->ll_rd;
+	struct dw_edma_block *data_blocks = write ? pdata->dt_wr : pdata->dt_rd;
+	u32 ctrl;
+	u16 i;
+	int ret;
+
+	for (i = 0; i < ch_cnt; i++) {
+		struct dw_edma_block *desc_block = &desc_blocks[i];
+		struct dw_edma_block *data_block = &data_blocks[i];
+		u16 off = table_off + i * entry_size;
+		u16 field, lo, hi;
+
+		field = off + PCI_EP_DMA_METADATA_CH_CTRL;
+		ctrl = dw_edma_pcie_ep_dma_readl(view, field);
+		if (FIELD_GET(PCI_EP_DMA_METADATA_CH_CTRL_HW_CH, ctrl) != i)
+			return -EOPNOTSUPP;
+
+		desc_block->bar =
+			FIELD_GET(PCI_EP_DMA_METADATA_CH_CTRL_DESC_BAR, ctrl);
+		lo = off + PCI_EP_DMA_METADATA_CH_DESC_OFF_LO;
+		hi = off + PCI_EP_DMA_METADATA_CH_DESC_OFF_HI;
+		ret = dw_edma_pcie_ep_dma_read_off(view, lo, hi,
+						   &desc_block->off);
+		if (ret)
+			return ret;
+		field = off + PCI_EP_DMA_METADATA_CH_DESC_SIZE;
+		desc_block->sz = dw_edma_pcie_ep_dma_readl(view, field);
+		lo = off + PCI_EP_DMA_METADATA_CH_DESC_ADDR_LO;
+		hi = off + PCI_EP_DMA_METADATA_CH_DESC_ADDR_HI;
+		desc_block->paddr =
+			dw_edma_pcie_ep_dma_read64(view, lo, hi);
+		desc_block->paddr_valid = true;
+		if (!dw_edma_pcie_valid_block(view->pdev, desc_block))
+			return -EINVAL;
+
+		*data_block = (struct dw_edma_block) { .bar = NO_BAR };
+		if (!(ctrl & PCI_EP_DMA_METADATA_CH_CTRL_AUX_VALID))
+			continue;
+
+		data_block->bar =
+			FIELD_GET(PCI_EP_DMA_METADATA_CH_CTRL_AUX_BAR, ctrl);
+		lo = off + PCI_EP_DMA_METADATA_CH_AUX_OFF_LO;
+		hi = off + PCI_EP_DMA_METADATA_CH_AUX_OFF_HI;
+		ret = dw_edma_pcie_ep_dma_read_off(view, lo, hi,
+						   &data_block->off);
+		if (ret)
+			return ret;
+		field = off + PCI_EP_DMA_METADATA_CH_AUX_SIZE;
+		data_block->sz = dw_edma_pcie_ep_dma_readl(view, field);
+		lo = off + PCI_EP_DMA_METADATA_CH_AUX_ADDR_LO;
+		hi = off + PCI_EP_DMA_METADATA_CH_AUX_ADDR_HI;
+		data_block->paddr =
+			dw_edma_pcie_ep_dma_read64(view, lo, hi);
+		data_block->paddr_valid = true;
+		if (!dw_edma_pcie_valid_block(view->pdev, data_block))
+			return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int
+dw_edma_pcie_ep_dma_wait_ready(struct dw_edma_pcie_ep_dma_view *view)
+{
+	u32 val;
+
+	return read_poll_timeout(dw_edma_pcie_ep_dma_readl, val,
+				 val & PCI_EP_DMA_METADATA_CTRL_READY,
+				 DW_PCIE_EP_DMA_READY_POLL_US,
+				 DW_PCIE_EP_DMA_READY_TIMEOUT_US, false,
+				 view, PCI_EP_DMA_METADATA_CTRL);
+}
+
+static int
+dw_edma_pcie_validate_ep_dma_metadata(struct dw_edma_pcie_ep_dma_view *view,
+				      u32 *metadata_ctrl, u8 *reg_layout_data)
+{
+	size_t table_size, table_end;
+	enum pci_barno reg_bar;
+	u16 len, entry_size;
+	u16 wr_ch_cnt, rd_ch_cnt;
+	u8 layout, layout_data;
+	u32 val;
+
+	val = dw_edma_pcie_ep_dma_readl(view, 0);
+	if (val != PCI_EP_DMA_METADATA_MAGIC)
+		return -ENODEV;
+
+	val = dw_edma_pcie_ep_dma_readl(view, PCI_EP_DMA_METADATA_HDR);
+	if (FIELD_GET(PCI_EP_DMA_METADATA_HDR_REV, val) !=
+	    PCI_EP_DMA_METADATA_REV)
+		return -EINVAL;
+
+	len = FIELD_GET(PCI_EP_DMA_METADATA_HDR_LEN_FIELD, val);
+	if (len < PCI_EP_DMA_METADATA_HDR_LEN)
+		return -EINVAL;
+	if (len > view->limit)
+		return -EINVAL;
+
+	val = dw_edma_pcie_ep_dma_readl(view, PCI_EP_DMA_METADATA_REG_LAYOUT);
+	layout = FIELD_GET(PCI_EP_DMA_METADATA_REG_LAYOUT_ID, val);
+	if (layout != PCI_EP_DMA_METADATA_REG_LAYOUT_DW_EDMA)
+		return -EOPNOTSUPP;
+
+	layout_data = FIELD_GET(PCI_EP_DMA_METADATA_REG_LAYOUT_DATA, val);
+	if (layout_data == EDMA_MF_EDMA_LEGACY)
+		return -EOPNOTSUPP;
+	if (layout_data != EDMA_MF_EDMA_UNROLL &&
+	    layout_data != EDMA_MF_HDMA_COMPAT &&
+	    layout_data != EDMA_MF_HDMA_NATIVE)
+		return -EINVAL;
+
+	val = dw_edma_pcie_ep_dma_readl(view, PCI_EP_DMA_METADATA_CTRL);
+	reg_bar = FIELD_GET(PCI_EP_DMA_METADATA_CTRL_REG_BAR, val);
+	if (!dw_edma_pcie_valid_bar(reg_bar))
+		return -EINVAL;
+
+	wr_ch_cnt = FIELD_GET(PCI_EP_DMA_METADATA_CTRL_WR_CH_COUNT, val);
+	rd_ch_cnt = FIELD_GET(PCI_EP_DMA_METADATA_CTRL_RD_CH_COUNT, val);
+	if (!wr_ch_cnt && !rd_ch_cnt)
+		return -EINVAL;
+	if (wr_ch_cnt > EDMA_MAX_WR_CH || rd_ch_cnt > EDMA_MAX_RD_CH)
+		return -EINVAL;
+
+	entry_size = FIELD_GET(PCI_EP_DMA_METADATA_CTRL_CH_ENTRY_SIZE, val);
+	if (entry_size < PCI_EP_DMA_METADATA_CH_ENTRY_SIZE ||
+	    entry_size % sizeof(u32))
+		return -EINVAL;
+
+	if (check_mul_overflow((size_t)(wr_ch_cnt + rd_ch_cnt),
+			       (size_t)entry_size, &table_size) ||
+	    check_add_overflow((size_t)PCI_EP_DMA_METADATA_HDR_LEN,
+			       table_size, &table_end) ||
+	    table_end > len)
+		return -EINVAL;
+
+	if (metadata_ctrl)
+		*metadata_ctrl = val;
+	if (reg_layout_data)
+		*reg_layout_data = layout_data;
+
+	return 0;
+}
+
+static int
+dw_edma_pcie_parse_ep_dma_data(struct dw_edma_pcie_ep_dma_view *view,
+			       struct dw_edma_pcie_data *pdata)
+{
+	u32 ctrl, reg_sz;
+	u8 reg_layout_data;
+	u64 reg_off;
+	u16 wr_table, rd_table, entry_size;
+	u16 wr_ch_cnt, rd_ch_cnt;
+	int ret;
+
+	ret = dw_edma_pcie_validate_ep_dma_metadata(view, &ctrl,
+						    &reg_layout_data);
+	if (ret)
+		return ret;
+
+	pci_dbg(view->pdev, "Detected PCI endpoint DMA BAR metadata\n");
+
+	pdata->mf = reg_layout_data;
+	pdata->rg.bar = FIELD_GET(PCI_EP_DMA_METADATA_CTRL_REG_BAR, ctrl);
+
+	wr_ch_cnt = FIELD_GET(PCI_EP_DMA_METADATA_CTRL_WR_CH_COUNT, ctrl);
+	rd_ch_cnt = FIELD_GET(PCI_EP_DMA_METADATA_CTRL_RD_CH_COUNT, ctrl);
+	pdata->wr_ch_cnt = min_t(u16, pdata->wr_ch_cnt, wr_ch_cnt);
+	pdata->rd_ch_cnt = min_t(u16, pdata->rd_ch_cnt, rd_ch_cnt);
+	pdata->irqs = pdata->wr_ch_cnt + pdata->rd_ch_cnt;
+	reg_off = dw_edma_pcie_ep_dma_read64(view,
+					     PCI_EP_DMA_METADATA_REG_OFF_LO,
+					     PCI_EP_DMA_METADATA_REG_OFF_HI);
+	reg_sz = dw_edma_pcie_ep_dma_readl(view, PCI_EP_DMA_METADATA_REG_SIZE);
+	if (reg_off > type_max(pdata->rg.off) ||
+	    !dw_edma_pcie_valid_bar_range(view->pdev, pdata->rg.bar,
+					  reg_off, reg_sz))
+		return -EINVAL;
+	pdata->rg.off = reg_off;
+	pdata->rg.sz = reg_sz;
+
+	entry_size = FIELD_GET(PCI_EP_DMA_METADATA_CTRL_CH_ENTRY_SIZE, ctrl);
+	wr_table = PCI_EP_DMA_METADATA_HDR_LEN;
+	rd_table = PCI_EP_DMA_METADATA_HDR_LEN + wr_ch_cnt * entry_size;
+
+	ret = dw_edma_pcie_parse_ep_dma_ch_table(view, pdata, wr_table,
+						 entry_size, pdata->wr_ch_cnt,
+						 true);
+	if (ret)
+		return ret;
+
+	return dw_edma_pcie_parse_ep_dma_ch_table(view, pdata, rd_table,
+						  entry_size,
+						  pdata->rd_ch_cnt, false);
+}
+
+static int
+dw_edma_pcie_parse_ep_dma_caps(struct pci_dev *pdev,
+			       struct dw_edma_pcie_data *pdata)
+{
+	struct dw_edma_pcie_ep_dma_view metadata_view;
+	void __iomem *base;
+	resource_size_t bar_len;
+	enum pci_barno bar;
+	u32 ctrl;
+	int ret;
+
+	for (bar = BAR_0; bar < PCI_STD_NUM_BARS; bar++) {
+		if (!dw_edma_pcie_ep_dma_bar_scannable(pdev, bar))
+			continue;
+
+		bar_len = pci_resource_len(pdev, bar);
+		base = pci_iomap_range(pdev, bar, 0, 0);
+		if (!base)
+			continue;
+
+		metadata_view = (struct dw_edma_pcie_ep_dma_view) {
+			.pdev = pdev,
+			.base = base,
+			.limit = bar_len,
+		};
+		ret = dw_edma_pcie_validate_ep_dma_metadata(&metadata_view,
+							    NULL, NULL);
+		if (ret == -ENODEV) {
+			pci_iounmap(metadata_view.pdev, base);
+			continue;
+		}
+		if (ret) {
+			pci_iounmap(metadata_view.pdev, base);
+			return ret;
+		}
+
+		ctrl = dw_edma_pcie_ep_dma_readl(&metadata_view,
+						 PCI_EP_DMA_METADATA_CTRL);
+		ctrl |= PCI_EP_DMA_METADATA_CTRL_HOST_REQ;
+		dw_edma_pcie_ep_dma_writel(&metadata_view,
+					   PCI_EP_DMA_METADATA_CTRL, ctrl);
+
+		ret = dw_edma_pcie_ep_dma_wait_ready(&metadata_view);
+		if (ret) {
+			pci_iounmap(metadata_view.pdev, base);
+			return ret;
+		}
+
+		ret = dw_edma_pcie_parse_ep_dma_data(&metadata_view, pdata);
+		pci_iounmap(metadata_view.pdev, base);
+
+		return ret;
+	}
+
+	return -ENODEV;
+}
+
 static int
 dw_edma_pcie_parse_synopsys_caps(struct pci_dev *pdev,
 				 struct dw_edma_pcie_data *pdata)
@@ -367,6 +726,14 @@ dw_edma_pcie_parse_xilinx_caps(struct pci_dev *pdev,
 	return 0;
 }
 
+static const struct dw_edma_pcie_match_data ep_dma_match_data = {
+	.data = &ep_dma_data,
+	.plat_ops = &dw_edma_pcie_raw_addr_plat_ops,
+	.parse_caps = dw_edma_pcie_parse_ep_dma_caps,
+	.flags = DW_EDMA_PCIE_F_REG_OFFSET,
+	.chip_flags = DW_EDMA_CHIP_PARTIAL,
+};
+
 static u64 dw_edma_get_phys_addr(struct pci_dev *pdev,
 				 const struct dw_edma_pcie_match_data *match,
 				 struct dw_edma_pcie_data *pdata,
@@ -400,8 +767,17 @@ static int dw_edma_pcie_probe(struct pci_dev *pdev,
 	int err, nr_irqs;
 	int i, mask;
 
-	if (!match)
-		return -ENODEV;
+	if (!match) {
+		/*
+		 * The endpoint DMA metadata path has no static PCI ID yet.
+		 * Accept it only for an explicit driver_override bind, not for
+		 * arbitrary dynamic IDs without driver data.
+		 */
+		if (!device_has_driver_override(&pdev->dev))
+			return -ENODEV;
+
+		match = &ep_dma_match_data;
+	}
 	pdata = match->data;
 
 	if (!pdata)
-- 
2.51.0