linux-kernel - [”PATCH” 2/5] PCI: armada8k: Add link-down handle

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Message-ID: <1618241456-27200-3-git-send-email-bpeled@marvell.com>
Date:   Mon, 12 Apr 2021 18:30:53 +0300
From:   <bpeled@...vell.com>
To:     <thomas.petazzoni@...tlin.com>, <lorenzo.pieralisi@....com>,
        <bhelgaas@...gle.com>
CC:     <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <devicetree@...r.kernel.org>, <linux-pci@...r.kernel.org>,
        <sebastian.hesselbarth@...il.com>, <gregory.clement@...tlin.com>,
        <andrew@...n.ch>, <robh+dt@...nel.org>, <mw@...ihalf.com>,
        <jaz@...ihalf.com>, <kostap@...vell.com>, <nadavh@...vell.com>,
        <stefanc@...vell.com>, <oferh@...vell.com>, <bpeled@...vell.com>
Subject: [”PATCH” 2/5] PCI: armada8k: Add link-down handle

From: Ben Peled <bpeled@...vell.com>

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: Ben Peled <bpeled@...vell.com>
---
 drivers/pci/controller/dwc/pcie-armada8k.c | 68 ++++++++++++++++++++
 1 file changed, 68 insertions(+)

diff --git a/drivers/pci/controller/dwc/pcie-armada8k.c b/drivers/pci/controller/dwc/pcie-armada8k.c
index b2278b1..4eb8607 100644
--- a/drivers/pci/controller/dwc/pcie-armada8k.c
+++ b/drivers/pci/controller/dwc/pcie-armada8k.c
@@ -22,6 +22,8 @@
 #include <linux/resource.h>
 #include <linux/of_pci.h>
 #include <linux/of_irq.h>
+#include <linux/mfd/syscon.h>
+#include <linux/regmap.h>
 
 #include "pcie-designware.h"
 
@@ -33,6 +35,9 @@ 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
@@ -73,6 +78,8 @@ 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)
@@ -224,6 +231,49 @@ static int armada8k_pcie_host_init(struct pcie_port *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 pcie_port *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 = armada8k_pcie_host_init(pp);
+	if (ret) {
+		dev_err(pcie->pci->dev, "failed to initialize host: %d\n", ret);
+		pci_unlock_rescan_remove();
+		pci_dev_put(root_port);
+		return;
+	}
+
+	bus = NULL;
+	while ((bus = pci_find_next_bus(bus)) != NULL)
+		pci_rescan_bus(bus);
+	pci_unlock_rescan_remove();
+	pci_dev_put(root_port);
+}
 
 static irqreturn_t armada8k_pcie_irq_handler(int irq, void *arg)
 {
@@ -262,6 +312,9 @@ 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__);
 	}
 
@@ -330,6 +383,8 @@ 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);
@@ -357,6 +412,19 @@ 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;
-- 
2.7.4