[PATCH 1/1] PCI: armada8k: Add link-down handle

[Jenishkumar Maheshbhai Patel <jpatel2@xxxxxxxxxxx>]

In PCIE ISR routine caused by RST_LINK_DOWN
we schedule work to handle the link-down procedure.
Link-down procedure will:
1. Remove PCIe bus
2. Reset the MAC
3. Reconfigure link back up
4. Rescan PCIe bus

Signed-off-by: Jenishkumar Maheshbhai Patel <jpatel2@xxxxxxxxxxx>
---
 drivers/pci/controller/dwc/pcie-armada8k.c | 84 ++++++++++++++++++++++
 1 file changed, 84 insertions(+)

diff --git a/drivers/pci/controller/dwc/pcie-armada8k.c b/drivers/pci/controller/dwc/pcie-armada8k.c
index 07775539b321..b1b48c2016f7 100644
--- a/drivers/pci/controller/dwc/pcie-armada8k.c
+++ b/drivers/pci/controller/dwc/pcie-armada8k.c
@@ -21,6 +21,8 @@
 #include <linux/platform_device.h>
 #include <linux/resource.h>
 #include <linux/of_pci.h>
+#include <linux/mfd/syscon.h>
+#include <linux/regmap.h>
 
 #include "pcie-designware.h"
 
@@ -32,6 +34,9 @@ struct armada8k_pcie {
 	struct clk *clk_reg;
 	struct phy *phy[ARMADA8K_PCIE_MAX_LANES];
 	unsigned int phy_count;
+	struct regmap *sysctrl_base;
+	u32 mac_rest_bitmask;
+	struct work_struct recover_link_work;
 };
 
 #define PCIE_VENDOR_REGS_OFFSET		0x8000
@@ -72,6 +77,8 @@ struct armada8k_pcie {
 #define AX_USER_DOMAIN_MASK		0x3
 #define AX_USER_DOMAIN_SHIFT		4
 
+#define UNIT_SOFT_RESET_CONFIG_REG	0x268
+
 #define to_armada8k_pcie(x)	dev_get_drvdata((x)->dev)
 
 static void armada8k_pcie_disable_phys(struct armada8k_pcie *pcie)
@@ -216,6 +223,65 @@ static int armada8k_pcie_host_init(struct dw_pcie_rp *pp)
 	return 0;
 }
 
+static void armada8k_pcie_recover_link(struct work_struct *ws)
+{
+	struct armada8k_pcie *pcie = container_of(ws, struct armada8k_pcie, recover_link_work);
+	struct dw_pcie_rp *pp = &pcie->pci->pp;
+	struct pci_bus *bus = pp->bridge->bus;
+	struct pci_dev *root_port;
+	int ret;
+
+	root_port = pci_get_slot(bus, 0);
+	if (!root_port) {
+		dev_err(pcie->pci->dev, "failed to get root port\n");
+		return;
+	}
+	pci_lock_rescan_remove();
+	pci_stop_and_remove_bus_device(root_port);
+	/*
+	 * Sleep needed to make sure all pcie transactions and access
+	 * are flushed before resetting the mac
+	 */
+	msleep(100);
+
+	/* Reset mac */
+	regmap_update_bits_base(pcie->sysctrl_base, UNIT_SOFT_RESET_CONFIG_REG,
+				pcie->mac_rest_bitmask, 0, NULL, false, true);
+	udelay(1);
+	regmap_update_bits_base(pcie->sysctrl_base, UNIT_SOFT_RESET_CONFIG_REG,
+				pcie->mac_rest_bitmask, pcie->mac_rest_bitmask,
+				NULL, false, true);
+	udelay(1);
+
+	ret = dw_pcie_setup_rc(pp);
+	if (ret)
+		goto fail;
+
+	ret = armada8k_pcie_host_init(pp);
+	if (ret) {
+		dev_err(pcie->pci->dev, "failed to initialize host: %d\n", ret);
+		goto fail;
+	}
+
+	if (!dw_pcie_link_up(pcie->pci)) {
+		ret = dw_pcie_start_link(pcie->pci);
+		if (ret)
+			goto fail;
+	}
+
+	/* Wait until the link becomes active again */
+	if (dw_pcie_wait_for_link(pcie->pci))
+		dev_err(pcie->pci->dev, "Link not up after reconfiguration\n");
+
+	bus = NULL;
+	while ((bus = pci_find_next_bus(bus)) != NULL)
+		pci_rescan_bus(bus);
+
+fail:
+	pci_unlock_rescan_remove();
+	pci_dev_put(root_port);
+}
+
 static irqreturn_t armada8k_pcie_irq_handler(int irq, void *arg)
 {
 	struct armada8k_pcie *pcie = arg;
@@ -253,6 +319,9 @@ static irqreturn_t armada8k_pcie_irq_handler(int irq, void *arg)
 		 * initiate a link retrain. If link retrains were
 		 * possible, that is.
 		 */
+		if (pcie->sysctrl_base && pcie->mac_rest_bitmask)
+			schedule_work(&pcie->recover_link_work);
+
 		dev_dbg(pci->dev, "%s: link went down\n", __func__);
 	}
 
@@ -322,6 +391,8 @@ static int armada8k_pcie_probe(struct platform_device *pdev)
 
 	pcie->pci = pci;
 
+	INIT_WORK(&pcie->recover_link_work, armada8k_pcie_recover_link);
+
 	pcie->clk = devm_clk_get(dev, NULL);
 	if (IS_ERR(pcie->clk))
 		return PTR_ERR(pcie->clk);
@@ -349,6 +420,19 @@ static int armada8k_pcie_probe(struct platform_device *pdev)
 		goto fail_clkreg;
 	}
 
+	pcie->sysctrl_base = syscon_regmap_lookup_by_phandle(pdev->dev.of_node,
+						       "marvell,system-controller");
+	if (IS_ERR(pcie->sysctrl_base)) {
+		dev_warn(dev, "failed to find marvell,system-controller\n");
+		pcie->sysctrl_base = 0x0;
+	}
+
+	ret = of_property_read_u32(pdev->dev.of_node, "marvell,mac-reset-bit-mask",
+				   &pcie->mac_rest_bitmask);
+	if (ret < 0) {
+		dev_warn(dev, "couldn't find mac reset bit mask: %d\n", ret);
+		pcie->mac_rest_bitmask = 0x0;
+	}
 	ret = armada8k_pcie_setup_phys(pcie);
 	if (ret)
 		goto fail_clkreg;
-- 
2.25.1