spi: cadence-quadspi: fix suspend-resume implementations

[ Upstream commit 2087e85 ]

The cadence QSPI driver misbehaves after performing a full system suspend
resume:
...
spi-nor spi0.0: resume() failed
...
This results in a flash connected via OSPI interface after system suspend-
resume to be unusable.
fix these suspend and resume functions.

Fixes: 1406234 ("mtd: spi-nor: Add driver for Cadence Quad SPI Flash Controller")
Signed-off-by: Dhruva Gole <d-gole@ti.com>
Link: https://lore.kernel.org/r/20230417091027.966146-3-d-gole@ti.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/spi/spi-cadence-quadspi.c

@@ -1806,17 +1806,30 @@ static int cqspi_remove(struct platform_device *pdev)
 static int cqspi_suspend(struct device *dev)
 {
 	struct cqspi_st *cqspi = dev_get_drvdata(dev);
+	struct spi_master *master = dev_get_drvdata(dev);
+	int ret;
 
+	ret = spi_master_suspend(master);
 	cqspi_controller_enable(cqspi, 0);
-	return 0;
+
+	clk_disable_unprepare(cqspi->clk);
+
+	return ret;
 }
 
 static int cqspi_resume(struct device *dev)
 {
 	struct cqspi_st *cqspi = dev_get_drvdata(dev);
+	struct spi_master *master = dev_get_drvdata(dev);
 
-	cqspi_controller_enable(cqspi, 1);
-	return 0;
+	clk_prepare_enable(cqspi->clk);
+	cqspi_wait_idle(cqspi);
+	cqspi_controller_init(cqspi);
+
+	cqspi->current_cs = -1;
+	cqspi->sclk = 0;
+
+	return spi_master_resume(master);
 }
 
 static const struct dev_pm_ops cqspi__dev_pm_ops = {