spi: cadence-xspi: support suspend/resume

Add system wide suspend and resume support, the suspend hook
implementation is straightforward, just call spi_controller_suspend()
While the resume hook implementation is a bit complex, we need to redo
something which is done during probe, such as enable the interrupts,
setup clk and config the phy for mrvl hw overlay.

Signed-off-by: Jisheng Zhang <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Mark Brown <[e-mail]>

drivers/spi/spi-cadence-xspi.c

···
 
 struct cdns_xspi_dev {
 	struct platform_device *pdev;
+	struct spi_controller *host;
 	struct device *dev;
 
 	void __iomem *iobase;
···
 	}
 	host->bus_num = -1;
 
-	platform_set_drvdata(pdev, host);
+	platform_set_drvdata(pdev, cdns_xspi);
 
 	cdns_xspi->pdev = pdev;
+	cdns_xspi->host = host;
 	cdns_xspi->dev = &pdev->dev;
 	cdns_xspi->cur_cs = 0;
 
···
 	return 0;
 }
 
+static int cdns_xspi_suspend(struct device *dev)
+{
+	struct cdns_xspi_dev *cdns_xspi = dev_get_drvdata(dev);
+
+	return spi_controller_suspend(cdns_xspi->host);
+}
+
+static int cdns_xspi_resume(struct device *dev)
+{
+	struct cdns_xspi_dev *cdns_xspi = dev_get_drvdata(dev);
+
+	if (cdns_xspi->driver_data->mrvl_hw_overlay) {
+		cdns_mrvl_xspi_setup_clock(cdns_xspi, MRVL_DEFAULT_CLK);
+		cdns_xspi_configure_phy(cdns_xspi);
+	}
+
+	cdns_xspi->set_interrupts_handler(cdns_xspi, false);
+
+	return spi_controller_resume(cdns_xspi->host);
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(cdns_xspi_pm_ops,
+				cdns_xspi_suspend, cdns_xspi_resume);
+
 static const struct of_device_id cdns_xspi_of_match[] = {
 	{
 		.compatible = "cdns,xspi-nor",
···
 	.driver = {
 		.name = CDNS_XSPI_NAME,
 		.of_match_table = cdns_xspi_of_match,
+		.pm = pm_sleep_ptr(&cdns_xspi_pm_ops),
 	},
 };