PCI: dwc: Refactor dw_pcie_edma_find_chip() API

In order to add support for Hyper DMA (HDMA), refactor the existing
dw_pcie_edma_find_chip() API by moving the common code to separate
functions.

No functional change.
Suggested-by: Serge Semin <fancer.lancer@gmail.com>
Link: https://lore.kernel.org/linux-pci/20240318-dw-hdma-v5-1-f04c5cdde760@linaro.orgSigned-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Frank Li <frank.li@nxp.com>
Reviewed-by: Serge Semin <fancer.lancer@gmail.com>
Reviewed-by: Siddharth Vadapalli <s-vadapalli@ti.com>
Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>

drivers/pci/controller/dwc/pcie-designware.c

@@ -880,7 +880,17 @@ static struct dw_edma_plat_ops dw_pcie_edma_ops = {
 	.irq_vector = dw_pcie_edma_irq_vector,
 };
 
-static int dw_pcie_edma_find_chip(struct dw_pcie *pci)
+static void dw_pcie_edma_init_data(struct dw_pcie *pci)
+{
+	pci->edma.dev = pci->dev;
+
+	if (!pci->edma.ops)
+		pci->edma.ops = &dw_pcie_edma_ops;
+
+	pci->edma.flags |= DW_EDMA_CHIP_LOCAL;
+}
+
+static int dw_pcie_edma_find_mf(struct dw_pcie *pci)
 {
 	u32 val;
 
@@ -902,8 +912,6 @@ static int dw_pcie_edma_find_chip(struct dw_pcie *pci)
 
 	if (val == 0xFFFFFFFF && pci->edma.reg_base) {
 		pci->edma.mf = EDMA_MF_EDMA_UNROLL;
-
-		val = dw_pcie_readl_dma(pci, PCIE_DMA_CTRL);
 	} else if (val != 0xFFFFFFFF) {
 		pci->edma.mf = EDMA_MF_EDMA_LEGACY;
 
@@ -912,12 +920,14 @@ static int dw_pcie_edma_find_chip(struct dw_pcie *pci)
 		return -ENODEV;
 	}
 
-	pci->edma.dev = pci->dev;
+	return 0;
+}
 
-	if (!pci->edma.ops)
-		pci->edma.ops = &dw_pcie_edma_ops;
+static int dw_pcie_edma_find_channels(struct dw_pcie *pci)
+{
+	u32 val;
 
-	pci->edma.flags |= DW_EDMA_CHIP_LOCAL;
+	val = dw_pcie_readl_dma(pci, PCIE_DMA_CTRL);
 
 	pci->edma.ll_wr_cnt = FIELD_GET(PCIE_DMA_NUM_WR_CHAN, val);
 	pci->edma.ll_rd_cnt = FIELD_GET(PCIE_DMA_NUM_RD_CHAN, val);
@@ -930,6 +940,19 @@ static int dw_pcie_edma_find_chip(struct dw_pcie *pci)
 	return 0;
 }
 
+static int dw_pcie_edma_find_chip(struct dw_pcie *pci)
+{
+	int ret;
+
+	dw_pcie_edma_init_data(pci);
+
+	ret = dw_pcie_edma_find_mf(pci);
+	if (ret)
+		return ret;
+
+	return dw_pcie_edma_find_channels(pci);
+}
+
 static int dw_pcie_edma_irq_verify(struct dw_pcie *pci)
 {
 	struct platform_device *pdev = to_platform_device(pci->dev);