PCI: rcar: Add the initialization of PCIe link in resume_noirq()

Reestablish the PCIe link very early in the resume process in case it
went down to prevent PCI accesses from hanging the bus. Such accesses
can happen early in the PCI resume process, as early as the
SUSPEND_RESUME_NOIRQ step, thus the link must be reestablished in the
driver resume_noirq() callback.

Fixes: e015f88c ("PCI: rcar: Add support for R-Car H3 to pcie-rcar")
Signed-off-by: Kazufumi Ikeda <kaz-ikeda@xc.jp.nec.com>
Signed-off-by: Gaku Inami <gaku.inami.xw@bp.renesas.com>
Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
[lorenzo.pieralisi@arm.com: reformatted commit log]
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Cc: stable@vger.kernel.org
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Phil Edworthy <phil.edworthy@renesas.com>
Cc: Simon Horman <horms+renesas@verge.net.au>
Cc: Wolfram Sang <wsa@the-dreams.de>
Cc: linux-renesas-soc@vger.kernel.org

drivers/pci/controller/pcie-rcar.c

@@ -46,6 +46,7 @@
 
 /* Transfer control */
 #define PCIETCTLR		0x02000
+#define  DL_DOWN		BIT(3)
 #define  CFINIT			1
 #define PCIETSTR		0x02004
 #define  DATA_LINK_ACTIVE	1
@@ -94,6 +95,7 @@
 #define MACCTLR			0x011058
 #define  SPEED_CHANGE		BIT(24)
 #define  SCRAMBLE_DISABLE	BIT(27)
+#define PMSR			0x01105c
 #define MACS2R			0x011078
 #define MACCGSPSETR		0x011084
 #define  SPCNGRSN		BIT(31)
@@ -1130,6 +1132,7 @@ static int rcar_pcie_probe(struct platform_device *pdev)
 	pcie = pci_host_bridge_priv(bridge);
 
 	pcie->dev = dev;
+	platform_set_drvdata(pdev, pcie);
 
 	err = pci_parse_request_of_pci_ranges(dev, &pcie->resources, NULL);
 	if (err)
@@ -1221,10 +1224,28 @@ static int rcar_pcie_probe(struct platform_device *pdev)
 	return err;
 }
 
+static int rcar_pcie_resume_noirq(struct device *dev)
+{
+	struct rcar_pcie *pcie = dev_get_drvdata(dev);
+
+	if (rcar_pci_read_reg(pcie, PMSR) &&
+	    !(rcar_pci_read_reg(pcie, PCIETCTLR) & DL_DOWN))
+		return 0;
+
+	/* Re-establish the PCIe link */
+	rcar_pci_write_reg(pcie, CFINIT, PCIETCTLR);
+	return rcar_pcie_wait_for_dl(pcie);
+}
+
+static const struct dev_pm_ops rcar_pcie_pm_ops = {
+	.resume_noirq = rcar_pcie_resume_noirq,
+};
+
 static struct platform_driver rcar_pcie_driver = {
 	.driver = {
 		.name = "rcar-pcie",
 		.of_match_table = rcar_pcie_of_match,
+		.pm = &rcar_pcie_pm_ops,
 		.suppress_bind_attrs = true,
 	},
 	.probe = rcar_pcie_probe,