nuumio: dts/pcie: add configurable delay before pcie bus scan

Default delay in dts is 1000ms. To change it in kernel cmdline use:

  pcie_rockchip_host.pcie_rk_bus_scan_delay=1000

Author: nuumio

arch/arm64/boot/dts/rockchip/rk3399-rockpro64.dtsi

@@ -532,6 +532,7 @@
 	pinctrl-0 = <&pcie_perst>;
 	vpcie12v-supply = <&vcc12v_dcin>;
 	vpcie3v3-supply = <&vcc3v3_pcie>;
+	bus-scan-delay-ms = <1000>;
 	status = "okay";
 };
 

drivers/pci/controller/pcie-rockchip-host.c

@@ -24,6 +24,7 @@
 #include <linux/kernel.h>
 #include <linux/mfd/syscon.h>
 #include <linux/module.h>
+#include <linux/moduleparam.h>
 #include <linux/of_address.h>
 #include <linux/of_device.h>
 #include <linux/of_pci.h>
@@ -39,6 +40,9 @@
 #include "../pci.h"
 #include "pcie-rockchip.h"
 
+static int bus_scan_delay = -1;
+module_param_named(pcie_rk_bus_scan_delay, bus_scan_delay, int, S_IRUGO);
+
 static void rockchip_pcie_enable_bw_int(struct rockchip_pcie *rockchip)
 {
 	u32 status;
@@ -953,6 +957,7 @@ static int rockchip_pcie_probe(struct platform_device *pdev)
 	struct pci_host_bridge *bridge;
 	struct resource *bus_res;
 	int err;
+	u32 delay = 0;
 
 	if (!dev->of_node)
 		return -ENODEV;
@@ -1015,6 +1020,18 @@ static int rockchip_pcie_probe(struct platform_device *pdev)
 	bridge->map_irq = of_irq_parse_and_map_pci;
 	bridge->swizzle_irq = pci_common_swizzle;
 
+	/* Prefer command-line param over device tree */
+	if (bus_scan_delay > 0) {
+		delay = bus_scan_delay;
+		dev_info(dev, "wait %u ms (from command-line) before bus scan\n", delay);
+	} else if (rockchip->bus_scan_delay > 0 && bus_scan_delay < 0) {
+		delay = rockchip->bus_scan_delay;
+		dev_info(dev, "wait %u ms (from device tree) before bus scan\n", delay);
+	}
+	if (delay > 0) {
+		msleep(delay);
+	}
+
 	err = pci_scan_root_bus_bridge(bridge);
 	if (err < 0)
 		goto err_remove_irq_domain;

drivers/pci/controller/pcie-rockchip.c

@@ -150,6 +150,14 @@ int rockchip_pcie_parse_dt(struct rockchip_pcie *rockchip)
 		return PTR_ERR(rockchip->clk_pcie_pm);
 	}
 
+	err = of_property_read_u32(node, "bus-scan-delay-ms", &rockchip->bus_scan_delay);
+	if (err) {
+		dev_info(dev, "no bus-scan-delay-ms in device tree, default 0 ms\n");
+		rockchip->bus_scan_delay = 0;
+	} else {
+		dev_info(dev, "bus-scan-delay-ms in device tree is %u ms\n", rockchip->bus_scan_delay);
+	}
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(rockchip_pcie_parse_dt);

drivers/pci/controller/pcie-rockchip.h

@@ -308,6 +308,7 @@ struct rockchip_pcie {
 	phys_addr_t msg_bus_addr;
 	bool is_rc;
 	struct resource *mem_res;
+	u32	bus_scan_delay;
 };
 
 static u32 rockchip_pcie_read(struct rockchip_pcie *rockchip, u32 reg)