PCI: brcmstb: Add suspend and resume pm_ops

Broadcom Set-top (BrcmSTB) boards typically support S2, S3, and S5 suspend
and resume.  Now the PCIe driver may do so as well.

Link: https://lore.kernel.org/r/20200911175232.19016-5-james.quinlan@broadcom.comSigned-off-by: Jim Quinlan <jquinlan@broadcom.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>

drivers/pci/controller/pcie-brcmstb.c

@@ -978,6 +978,47 @@ static void brcm_pcie_turn_off(struct brcm_pcie *pcie)
 	brcm_pcie_bridge_sw_init_set(pcie, 1);
 }
 
+static int brcm_pcie_suspend(struct device *dev)
+{
+	struct brcm_pcie *pcie = dev_get_drvdata(dev);
+
+	brcm_pcie_turn_off(pcie);
+	clk_disable_unprepare(pcie->clk);
+
+	return 0;
+}
+
+static int brcm_pcie_resume(struct device *dev)
+{
+	struct brcm_pcie *pcie = dev_get_drvdata(dev);
+	void __iomem *base;
+	u32 tmp;
+	int ret;
+
+	base = pcie->base;
+	clk_prepare_enable(pcie->clk);
+
+	/* Take bridge out of reset so we can access the SERDES reg */
+	brcm_pcie_bridge_sw_init_set(pcie, 0);
+
+	/* SERDES_IDDQ = 0 */
+	tmp = readl(base + PCIE_MISC_HARD_PCIE_HARD_DEBUG);
+	u32p_replace_bits(&tmp, 0, PCIE_MISC_HARD_PCIE_HARD_DEBUG_SERDES_IDDQ_MASK);
+	writel(tmp, base + PCIE_MISC_HARD_PCIE_HARD_DEBUG);
+
+	/* wait for serdes to be stable */
+	udelay(100);
+
+	ret = brcm_pcie_setup(pcie);
+	if (ret)
+		return ret;
+
+	if (pcie->msi)
+		brcm_msi_set_regs(pcie->msi);
+
+	return 0;
+}
+
 static void __brcm_pcie_remove(struct brcm_pcie *pcie)
 {
 	brcm_msi_remove(pcie);
@@ -1087,12 +1128,18 @@ static int brcm_pcie_probe(struct platform_device *pdev)
 
 MODULE_DEVICE_TABLE(of, brcm_pcie_match);
 
+static const struct dev_pm_ops brcm_pcie_pm_ops = {
+	.suspend = brcm_pcie_suspend,
+	.resume = brcm_pcie_resume,
+};
+
 static struct platform_driver brcm_pcie_driver = {
 	.probe = brcm_pcie_probe,
 	.remove = brcm_pcie_remove,
 	.driver = {
 		.name = "brcm-pcie",
 		.of_match_table = brcm_pcie_match,
+		.pm = &brcm_pcie_pm_ops,
 	},
 };
 module_platform_driver(brcm_pcie_driver);