[PATCH v2] PCI: imx6: Save and restore MSI control of RC in suspend and resume

[Richard Zhu]

The MSI Enable bit controls delivery of MSI interrupts from components
below the Root Port. This bit might lost during the suspend, should be
re-stored during resume.

Save the MSI control during suspend, and restore it in resume.

Signed-off-by: Richard Zhu <hongxing.zhu@xxxxxxx>
---
Changes v1-->v2:
New create one save/restore function, used save the setting in suspend and
restore the configuration in resume.
v1 https://patchwork.kernel.org/project/linux-pci/patch/1667289595-12440-1-git-send-email-hongxing.zhu@xxxxxxx/

---
 drivers/pci/controller/dwc/pci-imx6.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
index 1dde5c579edc..aa3096890c3b 100644
--- a/drivers/pci/controller/dwc/pci-imx6.c
+++ b/drivers/pci/controller/dwc/pci-imx6.c
@@ -76,6 +76,7 @@ struct imx6_pcie {
 	struct clk		*pcie;
 	struct clk		*pcie_aux;
 	struct regmap		*iomuxc_gpr;
+	u16			msi_ctrl;
 	u32			controller_id;
 	struct reset_control	*pciephy_reset;
 	struct reset_control	*apps_reset;
@@ -1042,6 +1043,26 @@ static void imx6_pcie_pm_turnoff(struct imx6_pcie *imx6_pcie)
 	usleep_range(1000, 10000);
 }
 
+static void imx6_pcie_msi_save_restore(struct imx6_pcie *imx6_pcie, bool save)
+{
+	u8 offset;
+	u16 val;
+	struct dw_pcie *pci = imx6_pcie->pci;
+
+	if (pci_msi_enabled()) {
+		offset = dw_pcie_find_capability(pci, PCI_CAP_ID_MSI);
+		if (save) {
+			val = dw_pcie_readw_dbi(pci, offset + PCI_MSI_FLAGS);
+			imx6_pcie->msi_ctrl = val;
+		} else {
+			dw_pcie_dbi_ro_wr_en(pci);
+			val = imx6_pcie->msi_ctrl;
+			dw_pcie_writew_dbi(pci, offset + PCI_MSI_FLAGS, val);
+			dw_pcie_dbi_ro_wr_dis(pci);
+		}
+	}
+}
+
 static int imx6_pcie_suspend_noirq(struct device *dev)
 {
 	struct imx6_pcie *imx6_pcie = dev_get_drvdata(dev);
@@ -1050,6 +1071,7 @@ static int imx6_pcie_suspend_noirq(struct device *dev)
 	if (!(imx6_pcie->drvdata->flags & IMX6_PCIE_FLAG_SUPPORTS_SUSPEND))
 		return 0;
 
+	imx6_pcie_msi_save_restore(imx6_pcie, true);
 	imx6_pcie_pm_turnoff(imx6_pcie);
 	imx6_pcie_stop_link(imx6_pcie->pci);
 	imx6_pcie_host_exit(pp);
@@ -1069,6 +1091,7 @@ static int imx6_pcie_resume_noirq(struct device *dev)
 	ret = imx6_pcie_host_init(pp);
 	if (ret)
 		return ret;
+	imx6_pcie_msi_save_restore(imx6_pcie, false);
 	dw_pcie_setup_rc(pp);
 
 	if (imx6_pcie->link_is_up)
-- 
2.25.1