From 0c4ad0f29e795d4dfccaa3b22d64f7c1d18fba4c Mon Sep 17 00:00:00 2001
From: Vivek Pernamitta <vpernami@codeaurora.org>
Date: Tue, 8 Dec 2020 23:53:25 +0530
Subject: [PATCH] msm: pcie : Notify client driver on reading FF's

Disable access to PCIE config space registers and notify client
driver to recover link on reading PCIE endpoint config registers
as FF's.

Change-Id: Iea6b25036bc6d967d6598d08348bb41fc18ef304
Signed-off-by: Vivek Pernamitta <vpernami@codeaurora.org>
---
 drivers/pci/controller/pci-msm.c | 41 ++++++++++++++++++++++++++++++--
 include/linux/msm_pcie.h         |  1 +
 2 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/controller/pci-msm.c b/drivers/pci/controller/pci-msm.c
index 6141ab607025..29744c7b377a 100644
--- a/drivers/pci/controller/pci-msm.c
+++ b/drivers/pci/controller/pci-msm.c
@@ -762,6 +762,8 @@ struct msm_pcie_dev_t {
 	struct pinctrl_state *pins_default;
 	struct pinctrl_state *pins_sleep;
 	struct msm_pcie_device_info pcidev_table[MAX_DEVICE_NUM];
+	bool config_recovery;
+	struct work_struct link_recover_wq;
 
 	struct msm_pcie_drv_info *drv_info;
 
@@ -2946,14 +2948,22 @@ static inline int msm_pcie_oper_conf(struct pci_bus *bus, u32 devfn, int oper,
 
 		if (dev->shadow_en) {
 			if (rd_val == PCIE_LINK_DOWN &&
-				(readl_relaxed(config_base) == PCIE_LINK_DOWN))
+			   (readl_relaxed(config_base) == PCIE_LINK_DOWN)) {
 				PCIE_ERR(dev,
 					"Read of RC%d %d:0x%02x + 0x%04x[%d] is all FFs\n",
 					rc_idx, bus->number, devfn,
 					where, size);
-			else
+				if (dev->config_recovery) {
+					PCIE_ERR(dev,
+						"RC%d link recovery schedule\n",
+						rc_idx);
+					dev->cfg_access = false;
+					schedule_work(&dev->link_recover_wq);
+				}
+			} else {
 				msm_pcie_save_shadow(dev, word_offset, wr_val,
 					bdf, rc);
+			}
 		}
 
 		PCIE_DBG3(dev,
@@ -4859,6 +4869,16 @@ static void handle_wake_func(struct work_struct *work)
 	mutex_unlock(&dev->recovery_lock);
 }
 
+static void handle_link_recover(struct work_struct *work)
+{
+	struct msm_pcie_dev_t *dev = container_of(work, struct msm_pcie_dev_t,
+					link_recover_wq);
+
+	PCIE_DBG(dev, "PCIe: link recover start for RC%d\n", dev->rc_idx);
+
+	msm_pcie_notify_client(dev, MSM_PCIE_EVENT_LINK_RECOVER);
+}
+
 static irqreturn_t handle_aer_irq(int irq, void *data)
 {
 	struct msm_pcie_dev_t *dev = data;
@@ -6000,6 +6020,14 @@ static int msm_pcie_probe(struct platform_device *pdev)
 		msm_pcie_gpio_deinit(pcie_dev);
 		goto decrease_rc_num;
 	}
+	pcie_dev->config_recovery = of_property_read_bool(of_node,
+					"qcom,config-recovery");
+	if (pcie_dev->config_recovery) {
+		PCIE_DUMP(pcie_dev,
+			"PCIe RC%d config space recovery enabled\n",
+			pcie_dev->rc_idx);
+		INIT_WORK(&pcie_dev->link_recover_wq, handle_link_recover);
+	}
 
 	drv_supported = of_property_read_bool(of_node, "qcom,drv-supported");
 	if (drv_supported) {
@@ -6755,6 +6783,15 @@ static int msm_pcie_pm_suspend(struct pci_dev *dev,
 	pcie_dev->suspending = true;
 	spin_unlock_irqrestore(&pcie_dev->irq_lock, irqsave_flags);
 
+	if (pcie_dev->config_recovery) {
+		if (work_pending(&pcie_dev->link_recover_wq)) {
+			PCIE_DBG(pcie_dev,
+				"RC%d: cancel link_recover_wq at pm suspend\n",
+				pcie_dev->rc_idx);
+			cancel_work_sync(&pcie_dev->link_recover_wq);
+		}
+	}
+
 	if (!pcie_dev->power_on) {
 		PCIE_DBG(pcie_dev,
 			"PCIe: power of RC%d has been turned off.\n",
diff --git a/include/linux/msm_pcie.h b/include/linux/msm_pcie.h
index 3a5fa760ee45..070bf38f2b52 100644
--- a/include/linux/msm_pcie.h
+++ b/include/linux/msm_pcie.h
@@ -32,6 +32,7 @@ enum msm_pcie_event {
 	MSM_PCIE_EVENT_L1SS_TIMEOUT = BIT(3),
 	MSM_PCIE_EVENT_DRV_CONNECT = BIT(4),
 	MSM_PCIE_EVENT_DRV_DISCONNECT = BIT(5),
+	MSM_PCIE_EVENT_LINK_RECOVER = BIT(6),
 };
 
 enum msm_pcie_trigger {