spi: cadence: Runtime pm adaptation

Currently the clocks are enabled at probe and disabled
at remove. This patch moves the clock enable to the
start of transaction and disables at the end.

Signed-off-by: Shubhrajyoti Datta <shubhraj@xilinx.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-cadence.c

@@ -19,6 +19,7 @@
 #include <linux/of_irq.h>
 #include <linux/of_address.h>
 #include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
 #include <linux/spi/spi.h>
 
 /* Name of this driver */
@@ -37,6 +38,7 @@
 #define CDNS_SPI_SICR	0x24 /* Slave Idle Count Register, RW */
 #define CDNS_SPI_THLD	0x28 /* Transmit FIFO Watermark Register,RW */
 
+#define SPI_AUTOSUSPEND_TIMEOUT		3000
 /*
  * SPI Configuration Register bit Masks
  *
@@ -509,6 +511,11 @@ static int cdns_spi_probe(struct platform_device *pdev)
 		goto clk_dis_apb;
 	}
 
+	pm_runtime_enable(&pdev->dev);
+	pm_runtime_use_autosuspend(&pdev->dev);
+	pm_runtime_set_autosuspend_delay(&pdev->dev, SPI_AUTOSUSPEND_TIMEOUT);
+	pm_runtime_set_active(&pdev->dev);
+
 	ret = of_property_read_u32(pdev->dev.of_node, "num-cs", &num_cs);
 	if (ret < 0)
 		master->num_chipselect = CDNS_SPI_DEFAULT_NUM_CS;
@@ -523,6 +530,9 @@ static int cdns_spi_probe(struct platform_device *pdev)
 	/* SPI controller initializations */
 	cdns_spi_init_hw(xspi);
 
+	pm_runtime_mark_last_busy(&pdev->dev);
+	pm_runtime_put_autosuspend(&pdev->dev);
+
 	irq = platform_get_irq(pdev, 0);
 	if (irq <= 0) {
 		ret = -ENXIO;
@@ -543,6 +553,7 @@ static int cdns_spi_probe(struct platform_device *pdev)
 	master->transfer_one = cdns_transfer_one;
 	master->unprepare_transfer_hardware = cdns_unprepare_transfer_hardware;
 	master->set_cs = cdns_spi_chipselect;
+	master->auto_runtime_pm = true;
 	master->mode_bits = SPI_CPOL | SPI_CPHA;
 
 	/* Set to default valid value */
@@ -560,6 +571,8 @@ static int cdns_spi_probe(struct platform_device *pdev)
 	return ret;
 
 clk_dis_all:
+	pm_runtime_set_suspended(&pdev->dev);
+	pm_runtime_disable(&pdev->dev);
 	clk_disable_unprepare(xspi->ref_clk);
 clk_dis_apb:
 	clk_disable_unprepare(xspi->pclk);
@@ -587,6 +600,8 @@ static int cdns_spi_remove(struct platform_device *pdev)
 
 	clk_disable_unprepare(xspi->ref_clk);
 	clk_disable_unprepare(xspi->pclk);
+	pm_runtime_set_suspended(&pdev->dev);
+	pm_runtime_disable(&pdev->dev);
 
 	spi_unregister_master(master);
 
@@ -649,8 +664,59 @@ static int __maybe_unused cdns_spi_resume(struct device *dev)
 	return 0;
 }
 
-static SIMPLE_DEV_PM_OPS(cdns_spi_dev_pm_ops, cdns_spi_suspend,
-			 cdns_spi_resume);
+/**
+ * cdns_spi_runtime_resume - Runtime resume method for the SPI driver
+ * @dev:	Address of the platform_device structure
+ *
+ * This function enables the clocks
+ *
+ * Return:	0 on success and error value on error
+ */
+static int cnds_runtime_resume(struct device *dev)
+{
+	struct spi_master *master = dev_get_drvdata(dev);
+	struct cdns_spi *xspi = spi_master_get_devdata(master);
+	int ret;
+
+	ret = clk_prepare_enable(xspi->pclk);
+	if (ret) {
+		dev_err(dev, "Cannot enable APB clock.\n");
+		return ret;
+	}
+
+	ret = clk_prepare_enable(xspi->ref_clk);
+	if (ret) {
+		dev_err(dev, "Cannot enable device clock.\n");
+		clk_disable(xspi->pclk);
+		return ret;
+	}
+	return 0;
+}
+
+/**
+ * cdns_spi_runtime_suspend - Runtime suspend method for the SPI driver
+ * @dev:	Address of the platform_device structure
+ *
+ * This function disables the clocks
+ *
+ * Return:	Always 0
+ */
+static int cnds_runtime_suspend(struct device *dev)
+{
+	struct spi_master *master = dev_get_drvdata(dev);
+	struct cdns_spi *xspi = spi_master_get_devdata(master);
+
+	clk_disable_unprepare(xspi->ref_clk);
+	clk_disable_unprepare(xspi->pclk);
+
+	return 0;
+}
+
+static const struct dev_pm_ops cdns_spi_dev_pm_ops = {
+	SET_RUNTIME_PM_OPS(cnds_runtime_suspend,
+			   cnds_runtime_resume, NULL)
+	SET_SYSTEM_SLEEP_PM_OPS(cdns_spi_suspend, cdns_spi_resume)
+};
 
 static const struct of_device_id cdns_spi_of_match[] = {
 	{ .compatible = "xlnx,zynq-spi-r1p6" },