On Fri, Jan 16, 2026 at 07:02:33PM +0800, Randolph wrote:

From: Randolph Lin <randolph@andestech.com>

Add driver support for DesignWare based PCIe controller in Andes
QiLai SoC. The driver only supports the Root Complex mode.

Signed-off-by: Randolph Lin <randolph@andestech.com>

Just a couple of nits. Overall this driver LGTM!

Avoid mentioning IP revision here as this driver may evolve to support multiple
IP versions.

2026

+ */
+
+#include <linux/bitfield.h>
+#include <linux/bits.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/platform_device.h>
+#include <linux/types.h>
+
+#include "pcie-designware.h"
+
+#define PCIE_INTR_CONTROL1			0x15c
+#define PCIE_MSI_CTRL_INT_EN			BIT(28)
+
+#define PCIE_LOGIC_COHERENCY_CONTROL3		0x8e8
+
+/*
+ * Refer to Table A4-5 (Memory type encoding) in the
+ * AMBA AXI and ACE Protocol Specification.
+ *
+ * The selected value corresponds to the Memory type field:
+ * "Write-back, Read and Write-allocate".
+ *
+ * The last three rows in the table A4-5 in
+ * AMBA AXI and ACE Protocol Specification:
+ * ARCACHE        AWCACHE        Memory type
+ * ------------------------------------------------------------------
+ * 1111 (0111)    0111           Write-back Read-allocate
+ * 1011           1111 (1011)    Write-back Write-allocate
+ * 1111           1111           Write-back Read and Write-allocate (selected)
+ */
+#define IOCP_ARCACHE				0b1111
+#define IOCP_AWCACHE				0b1111
+
+#define PCIE_CFG_MSTR_ARCACHE_MODE		GENMASK(6, 3)
+#define PCIE_CFG_MSTR_AWCACHE_MODE		GENMASK(14, 11)
+#define PCIE_CFG_MSTR_ARCACHE_VALUE		GENMASK(22, 19)
+#define PCIE_CFG_MSTR_AWCACHE_VALUE		GENMASK(30, 27)
+
+#define PCIE_GEN_CONTROL2			0x54
+#define PCIE_CFG_LTSSM_EN			BIT(0)
+
+#define PCIE_REGS_PCIE_SII_PM_STATE		0xc0
+#define SMLH_LINK_UP				BIT(6)
+#define RDLH_LINK_UP				BIT(7)
+#define PCIE_REGS_PCIE_SII_LINK_UP		(SMLH_LINK_UP | RDLH_LINK_UP)
+
+struct qilai_pcie {
+	struct dw_pcie pci;
+	void __iomem *apb_base;
+};
+
+#define to_qilai_pcie(_pci) container_of(_pci, struct qilai_pcie, pci)
+
+static bool qilai_pcie_link_up(struct dw_pcie *pci)
+{
+	struct qilai_pcie *pcie = to_qilai_pcie(pci);
+	u32 val;
+
+	/* Read smlh & rdlh link up by checking debug port */

No need of this comment.

+	val = readl(pcie->apb_base + PCIE_REGS_PCIE_SII_PM_STATE);
+
+	return (val & PCIE_REGS_PCIE_SII_LINK_UP) == PCIE_REGS_PCIE_SII_LINK_UP;

Use FIELD_ macros throughout the driver.

+}
+
+static int qilai_pcie_start_link(struct dw_pcie *pci)
+{
+	struct qilai_pcie *pcie = to_qilai_pcie(pci);
+	u32 val;
+
+	val = readl(pcie->apb_base + PCIE_GEN_CONTROL2);
+	val |= PCIE_CFG_LTSSM_EN;
+	writel(val, pcie->apb_base + PCIE_GEN_CONTROL2);
+
+	return 0;
+}
+
+static const struct dw_pcie_ops qilai_pcie_ops = {
+	.link_up = qilai_pcie_link_up,
+	.start_link = qilai_pcie_start_link,
+};
+
+/*
+ * Set up the QiLai PCIe IOCP (IO Coherence Port) Read/Write Behaviors to the
+ * Write-Back, Read and Write Allocate mode.
+ *
+ * The IOCP HW target is SoC last-level cache (L2 Cache), which serves as the
+ * system cache. The IOCP HW helps maintain cache monitoring, ensuring that
+ * the device can snoop data from/to the cache.

If the IP allows device to snoop data to/from the cache, the controller should
be marked as 'dma-coherent' in devicetree. And you need to add this property in
the binding too.

+ */
+static void qilai_pcie_iocp_cache_setup(struct dw_pcie_rp *pp)
+{
+	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
+	u32 val;
+
+	dw_pcie_dbi_ro_wr_en(pci);
+
+	dw_pcie_read(pci->dbi_base + PCIE_LOGIC_COHERENCY_CONTROL3,
+		     sizeof(val), &val);
+	FIELD_MODIFY(PCIE_CFG_MSTR_ARCACHE_MODE, &val, IOCP_ARCACHE);
+	FIELD_MODIFY(PCIE_CFG_MSTR_AWCACHE_MODE, &val, IOCP_AWCACHE);
+	FIELD_MODIFY(PCIE_CFG_MSTR_ARCACHE_VALUE, &val, IOCP_ARCACHE);
+	FIELD_MODIFY(PCIE_CFG_MSTR_AWCACHE_VALUE, &val, IOCP_AWCACHE);
+	dw_pcie_write(pci->dbi_base + PCIE_LOGIC_COHERENCY_CONTROL3,
+		      sizeof(val), val);
+
+	dw_pcie_dbi_ro_wr_dis(pci);
+}
+
+static void qilai_pcie_enable_msi(struct qilai_pcie *pcie)
+{
+	u32 val;
+
+	val = readl(pcie->apb_base + PCIE_INTR_CONTROL1);
+	val |= PCIE_MSI_CTRL_INT_EN;
+	writel(val, pcie->apb_base + PCIE_INTR_CONTROL1);
+}
+
+static int qilai_pcie_host_init(struct dw_pcie_rp *pp)
+{
+	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
+	struct qilai_pcie *pcie = to_qilai_pcie(pci);
+
+	qilai_pcie_enable_msi(pcie);
+
+	return 0;
+}
+
+static void qilai_pcie_host_post_init(struct dw_pcie_rp *pp)
+{
+	qilai_pcie_iocp_cache_setup(pp);
+}
+
+static const struct dw_pcie_host_ops qilai_pcie_host_ops = {
+	.init = qilai_pcie_host_init,
+	.post_init = qilai_pcie_host_post_init,
+};
+
+static int qilai_pcie_probe(struct platform_device *pdev)
+{
+	struct qilai_pcie *pcie;
+	struct dw_pcie *pci;
+	struct device *dev = &pdev->dev;
+	int ret;
+
+	pcie = devm_kzalloc(&pdev->dev, sizeof(*pcie), GFP_KERNEL);
+	if (!pcie)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, pcie);
+
+	pci = &pcie->pci;
+	pcie->pci.dev = dev;
+	pcie->pci.ops = &qilai_pcie_ops;
+	pcie->pci.pp.ops = &qilai_pcie_host_ops;
+	pci->use_parent_dt_ranges = true;
+
+	dw_pcie_cap_set(&pcie->pci, REQ_RES);
+
+	pcie->apb_base = devm_platform_ioremap_resource_byname(pdev, "apb");
+	if (IS_ERR(pcie->apb_base))
+		return PTR_ERR(pcie->apb_base);
+

Mark controller PM runtime status as enabled:

        pm_runtime_set_active(dev);
        pm_runtime_no_callbacks(dev);
        devm_pm_runtime_enable(dev);

+	ret = dw_pcie_host_init(&pcie->pci.pp);
+	if (ret) {
+		dev_err_probe(dev, ret, "Failed to initialize PCIe host\n");

return dev_err_probe()...

- Mani

-- 
மணிவண்ணன் சதாசிவம்