[PATCH v9 4/4] PCI: qcom: Implement shutdown() callback

[Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>]

From: Manivannan Sadhasivam <mani@kernel.org>

PCIe host controllers should bring the link down cleanly before system
shutdown/reboot proceeds to remove power/clocks from the controller.
Without this, the link may still be up and endpoints still have
transactions in flight when power/clocks are cut, which can trip SMMU
translation faults or NoC protocol errors.

Reuse dw_pcie_suspend_noirq() in the shutdown path to force the link
into L2, putting it into D3cold.

device_shutdown() runs with interrupts enabled, unlike suspend_noirq().
Mask the chained MSI IRQ(s) and the Global IRQ before tearing down the
link and clocks/PHY, since a late/spurious interrupt could otherwise
reach a handler that touches now-unclocked PARF/DBI registers. Use
dw_pcie_mask_msi() rather than dw_pcie_free_msi() so the MSI IRQ domain
and the MSI mappings held by downstream devices (which device_shutdown()
does not remove) are left intact.

Stash a struct qcom_pcie in the platform drvdata in both the normal and
the firmware-managed (ECAM) probe paths, so shutdown() has a single
path and recovers everything it needs (Global IRQ, config, dw_pcie)
uniformly via platform_get_drvdata().

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
---
 drivers/pci/controller/dwc/pcie-qcom.c | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index 532779295734..0f548c6ce6a8 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -2020,9 +2020,14 @@ static int qcom_pcie_ecam_host_init(struct pci_config_window *cfg)
 {
 	struct device *dev = cfg->parent;
 	struct dw_pcie_rp *pp;
+	struct qcom_pcie *pcie;
 	struct dw_pcie *pci;
 	int ret;
 
+	pcie = devm_kzalloc(dev, sizeof(*pcie), GFP_KERNEL);
+	if (!pcie)
+		return -ENOMEM;
+
 	pci = devm_kzalloc(dev, sizeof(*pci), GFP_KERNEL);
 	if (!pci)
 		return -ENOMEM;
@@ -2032,6 +2037,9 @@ static int qcom_pcie_ecam_host_init(struct pci_config_window *cfg)
 	pci->dbi_base = cfg->win;
 	pp->num_vectors = MSI_DEF_NUM_VECTORS;
 
+	pcie->pci = pci;
+	pcie->cfg = of_device_get_match_data(dev);
+
 	/*
 	 * dw_pcie_msi_host_init() is called directly here, bypassing
 	 * dw_pcie_host_init() where pp->lock is normally initialized.
@@ -2047,6 +2055,9 @@ static int qcom_pcie_ecam_host_init(struct pci_config_window *cfg)
 
 	dw_pcie_msi_init(pp);
 
+	/* Stash pcie so qcom_pcie_shutdown() can mask the MSI IRQ(s) later */
+	platform_set_drvdata(to_platform_device(dev), pcie);
+
 	return devm_add_action_or_reset(dev, qcom_pci_free_msi, pp);
 }
 
@@ -2467,6 +2478,24 @@ static int qcom_pcie_probe(struct platform_device *pdev)
 	return ret;
 }
 
+static void qcom_pcie_shutdown(struct platform_device *pdev)
+{
+	struct qcom_pcie *pcie = platform_get_drvdata(pdev);
+	struct dw_pcie *pci = pcie->pci;
+
+	if (pcie->global_irq)
+		disable_irq(pcie->global_irq);
+
+	if (pci->pp.use_imsi_rx)
+		dw_pcie_mask_msi(&pci->pp);
+
+	if (!pcie->cfg->firmware_managed && !pci->suspended)
+		dw_pcie_suspend_noirq(pci, true);
+
+	pm_runtime_put_sync(&pdev->dev);
+	pm_runtime_disable(&pdev->dev);
+}
+
 static int qcom_pcie_suspend_noirq(struct device *dev)
 {
 	struct qcom_pcie *pcie;
@@ -2658,5 +2687,6 @@ static struct platform_driver qcom_pcie_driver = {
 		.pm = &qcom_pcie_pm_ops,
 		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
 	},
+	.shutdown = qcom_pcie_shutdown,
 };
 builtin_platform_driver(qcom_pcie_driver);

-- 
2.34.1