From 2df159b5cfcea2fa4af6be6848c0e2ca0f917761 Mon Sep 17 00:00:00 2001
From: Vidya Sagar <vidyas@nvidia.com>
Date: Tue, 11 Sep 2018 14:53:34 +0530
Subject: PCI: tegra: add hot-plug/unplug support

Adds hot-plug/unplug APIs to support dynamic
creation and destruction of PCIe hierarchy of a
respective host controller

Bug 2312016
Bug 200427921

Change-Id: Id8ecef5ab6b2c55543a3c43de2561f47a80fe282
Signed-off-by: Vidya Sagar <vidyas@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1819382
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>
---
 drivers/pci/dwc/pcie-tegra.c | 89 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 89 insertions(+)

diff --git a/drivers/pci/dwc/pcie-tegra.c b/drivers/pci/dwc/pcie-tegra.c
index 90d9b7100..49b353171 100644
--- a/drivers/pci/dwc/pcie-tegra.c
+++ b/drivers/pci/dwc/pcie-tegra.c
@@ -566,6 +566,9 @@ static unsigned int pcie_gen_freq[] = {
 
 static void tegra_pcie_downstream_dev_to_D0(struct tegra_pcie_dw *pcie);
 static int tegra_pcie_dw_pme_turnoff(struct tegra_pcie_dw *pcie);
+static int tegra_pcie_dw_runtime_suspend(struct device *dev);
+static int tegra_pcie_dw_runtime_resume(struct device *dev);
+static int tegra_pcie_dw_link_up(struct dw_pcie *pci);
 
 static inline void dma_common_wr16(void __iomem *p, u32 val, u32 offset)
 {
@@ -1773,6 +1776,80 @@ static int verify_voltage_margin(struct seq_file *s, void *data)
 	return 0;
 }
 
+static int __attach_controller(struct tegra_pcie_dw *pcie)
+{
+	int ret;
+
+	if (!pcie->link_state && !pcie->power_down_en) {
+		ret = pm_runtime_put_sync(pcie->dev);
+		if (ret)
+			return ret;
+	}
+
+	ret = pm_runtime_get_sync(pcie->dev);
+	if (ret)
+		return ret;
+	pcie->link_state = tegra_pcie_dw_link_up(&pcie->pci);
+
+	return 0;
+}
+
+static int __detach_controller(struct tegra_pcie_dw *pcie)
+{
+	if (!pcie->link_state && pcie->power_down_en)
+		return 0;
+
+	return pm_runtime_put_sync(pcie->dev);
+}
+
+/* Enables root port controller and attempts PCIe link up with the device
+ * connected downstream. If link is up, registers host controller with
+ * PCIe sub-system.
+ * @cookie : opaque pointer returned by tegra_pcie_detach_controller() API
+ */
+int tegra_pcie_attach_controller(void *cookie)
+{
+	struct tegra_pcie_dw *pcie = (struct tegra_pcie_dw *)cookie;
+
+	return __attach_controller(pcie);
+}
+EXPORT_SYMBOL(tegra_pcie_attach_controller);
+
+/* Removes PCIe hierarchy of the respective host controller and brings PCIe
+ * link down in a safe way
+ * @pdev: pointer to end point's pci_dev structure
+ * returns a cookie which needs to be passed to
+ * tegra_pcie_attach_controller() API
+ */
+void *tegra_pcie_detach_controller(struct pci_dev *pdev)
+{
+	struct pcie_port *pp = pdev->sysdata;
+	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
+	struct tegra_pcie_dw *pcie = dw_pcie_to_tegra_pcie(pci);
+	int ret;
+
+	ret = __detach_controller(pcie);
+	if (ret)
+		return ERR_PTR(ret);
+
+	return (void *)pcie;
+}
+EXPORT_SYMBOL(tegra_pcie_detach_controller);
+
+static int hot_plug(struct seq_file *s, void *data)
+{
+	struct tegra_pcie_dw *pcie = (struct tegra_pcie_dw *)(s->private);
+
+	return __attach_controller(pcie);
+}
+
+static int hot_unplug(struct seq_file *s, void *data)
+{
+	struct tegra_pcie_dw *pcie = (struct tegra_pcie_dw *)(s->private);
+
+	return __detach_controller(pcie);
+}
+
 #define DEFINE_ENTRY(__name)	\
 static int __name ## _open(struct inode *inode, struct file *file)	\
 {									\
@@ -1798,6 +1875,8 @@ DEFINE_ENTRY(apply_sbr);
 DEFINE_ENTRY(aspm_state_cnt);
 DEFINE_ENTRY(verify_timing_margin);
 DEFINE_ENTRY(verify_voltage_margin);
+DEFINE_ENTRY(hot_plug);
+DEFINE_ENTRY(hot_unplug);
 
 #ifdef CONFIG_PCIE_TEGRA_DW_DMA_TEST
 static void init_dma_test_debugfs(struct tegra_pcie_dw *pcie)
@@ -1925,6 +2004,16 @@ static int init_debugfs(struct tegra_pcie_dw *pcie)
 	if (!d)
 		dev_err(pcie->dev, "debugfs for verify_voltage_margin failed\n");
 
+	d = debugfs_create_file("hot_plug", 0444, pcie->debugfs,
+				(void *)pcie, &hot_plug_fops);
+	if (!d)
+		dev_err(pcie->dev, "debugfs for hot_plug failed\n");
+
+	d = debugfs_create_file("hot_unplug", 0444, pcie->debugfs,
+				(void *)pcie, &hot_unplug_fops);
+	if (!d)
+		dev_err(pcie->dev, "debugfs for hot_unplug failed\n");
+
 	init_dma_test_debugfs(pcie);
 
 	return 0;
-- 
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