[PATCH V2] PCI: rcar: Add the initialization of PCIe link in resume_noirq

[marek.vasut@gmail.com]

From: Kazufumi Ikeda <kaz-ikeda@xc.jp.nec.com>

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, in the resume_noirq, thus
the link must be reestablished in the resume_noirq callback of the
driver.

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>
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
---
V2: - Use BIT() macro for (1 << n)
    - Since polling in rcar_pcie_wait_for_dl() uses udelay(), do not
      add extra changes to this function anymore
    - Make resume_noirq return early and clean up parenthesis therein
---
 drivers/pci/controller/pcie-rcar.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/drivers/pci/controller/pcie-rcar.c b/drivers/pci/controller/pcie-rcar.c
index c8febb009454..b8f8fb3bc640 100644
--- a/drivers/pci/controller/pcie-rcar.c
+++ b/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
@@ -1130,6 +1131,7 @@ 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 +1223,28 @@ 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,
-- 
2.19.2