PCI: mediatek: Add support for Airoha AN7583 SoC

Add support for the second PCIe Root Complex present on Airoha AN7583
SoC.

This is based on the Mediatek Gen1/2 PCIe driver and similar to Gen3
also require workaround for the reset signals.

Introduce a new quirk to skip having to reset signals and also introduce
some additional logic to configure the PBUS registers required for Airoha
SoC.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://patch.msgid.link/20251020111121.31779-6-ansuelsmth@gmail.com

Author: Ansuel

drivers/pci/controller/pcie-mediatek.c

@@ -147,11 +147,13 @@ struct mtk_pcie_port;
  * @MTK_PCIE_FIX_CLASS_ID: host's class ID needed to be fixed
  * @MTK_PCIE_FIX_DEVICE_ID: host's device ID needed to be fixed
  * @MTK_PCIE_NO_MSI: Bridge has no MSI support, and relies on an external block
+ * @MTK_PCIE_SKIP_RSTB: Skip calling RSTB bits on PCIe probe
  */
 enum mtk_pcie_quirks {
 	MTK_PCIE_FIX_CLASS_ID = BIT(0),
 	MTK_PCIE_FIX_DEVICE_ID = BIT(1),
 	MTK_PCIE_NO_MSI = BIT(2),
+	MTK_PCIE_SKIP_RSTB = BIT(3),
 };
 
 /**
@@ -687,23 +689,25 @@ static int mtk_pcie_startup_port_v2(struct mtk_pcie_port *port)
 		regmap_update_bits(pcie->cfg, PCIE_SYS_CFG_V2, val, val);
 	}
 
-	/* Assert all reset signals */
-	writel(0, port->base + PCIE_RST_CTRL);
+	if (!(soc->quirks & MTK_PCIE_SKIP_RSTB)) {
+		/* Assert all reset signals */
+		writel(0, port->base + PCIE_RST_CTRL);
 
-	/*
-	 * Enable PCIe link down reset, if link status changed from link up to
-	 * link down, this will reset MAC control registers and configuration
-	 * space.
-	 */
-	writel(PCIE_LINKDOWN_RST_EN, port->base + PCIE_RST_CTRL);
+		/*
+		 * Enable PCIe link down reset, if link status changed from
+		 * link up to link down, this will reset MAC control registers
+		 * and configuration space.
+		 */
+		writel(PCIE_LINKDOWN_RST_EN, port->base + PCIE_RST_CTRL);
 
-	msleep(PCIE_T_PVPERL_MS);
+		msleep(PCIE_T_PVPERL_MS);
 
-	/* De-assert PHY, PE, PIPE, MAC and configuration reset	*/
-	val = readl(port->base + PCIE_RST_CTRL);
-	val |= PCIE_PHY_RSTB | PCIE_PERSTB | PCIE_PIPE_SRSTB |
-	       PCIE_MAC_SRSTB | PCIE_CRSTB;
-	writel(val, port->base + PCIE_RST_CTRL);
+		/* De-assert PHY, PE, PIPE, MAC and configuration reset	*/
+		val = readl(port->base + PCIE_RST_CTRL);
+		val |= PCIE_PHY_RSTB | PCIE_PERSTB | PCIE_PIPE_SRSTB |
+		       PCIE_MAC_SRSTB | PCIE_CRSTB;
+		writel(val, port->base + PCIE_RST_CTRL);
+	}
 
 	/* Set up vendor ID and class code */
 	if (soc->quirks & MTK_PCIE_FIX_CLASS_ID) {
@@ -824,6 +828,41 @@ static int mtk_pcie_startup_port(struct mtk_pcie_port *port)
 	return 0;
 }
 
+static int mtk_pcie_startup_port_an7583(struct mtk_pcie_port *port)
+{
+	struct mtk_pcie *pcie = port->pcie;
+	struct device *dev = pcie->dev;
+	struct pci_host_bridge *host;
+	struct resource_entry *entry;
+	struct regmap *pbus_regmap;
+	resource_size_t addr;
+	u32 args[2], size;
+
+	/*
+	 * Configure PBus base address and base address mask to allow
+	 * the hw to detect if a given address is accessible on PCIe
+	 * controller.
+	 */
+	pbus_regmap = syscon_regmap_lookup_by_phandle_args(dev->of_node,
+							   "mediatek,pbus-csr",
+							   ARRAY_SIZE(args),
+							   args);
+	if (IS_ERR(pbus_regmap))
+		return PTR_ERR(pbus_regmap);
+
+	host = pci_host_bridge_from_priv(pcie);
+	entry = resource_list_first_type(&host->windows, IORESOURCE_MEM);
+	if (!entry)
+		return -ENODEV;
+
+	addr = entry->res->start - entry->offset;
+	regmap_write(pbus_regmap, args[0], lower_32_bits(addr));
+	size = lower_32_bits(resource_size(entry->res));
+	regmap_write(pbus_regmap, args[1], GENMASK(31, __fls(size)));
+
+	return mtk_pcie_startup_port_v2(port);
+}
+
 static void mtk_pcie_enable_port(struct mtk_pcie_port *port)
 {
 	struct mtk_pcie *pcie = port->pcie;
@@ -1208,6 +1247,13 @@ static const struct mtk_pcie_soc mtk_pcie_soc_mt7622 = {
 	.quirks = MTK_PCIE_FIX_CLASS_ID,
 };
 
+static const struct mtk_pcie_soc mtk_pcie_soc_an7583 = {
+	.ops = &mtk_pcie_ops_v2,
+	.startup = mtk_pcie_startup_port_an7583,
+	.setup_irq = mtk_pcie_setup_irq,
+	.quirks = MTK_PCIE_FIX_CLASS_ID | MTK_PCIE_SKIP_RSTB,
+};
+
 static const struct mtk_pcie_soc mtk_pcie_soc_mt7629 = {
 	.device_id = PCI_DEVICE_ID_MEDIATEK_7629,
 	.ops = &mtk_pcie_ops_v2,
@@ -1217,6 +1263,7 @@ static const struct mtk_pcie_soc mtk_pcie_soc_mt7629 = {
 };
 
 static const struct of_device_id mtk_pcie_ids[] = {
+	{ .compatible = "airoha,an7583-pcie", .data = &mtk_pcie_soc_an7583 },
 	{ .compatible = "mediatek,mt2701-pcie", .data = &mtk_pcie_soc_v1 },
 	{ .compatible = "mediatek,mt7623-pcie", .data = &mtk_pcie_soc_v1 },
 	{ .compatible = "mediatek,mt2712-pcie", .data = &mtk_pcie_soc_mt2712 },