[PATCH v12 5/6] dmaengine: pl330: Add PM sleep support

[Krzysztof Kozlowski]

Add system suspend/resume capabilities to the pl330 driver so the amba
bus clock could be also unprepared to conserve energy.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@xxxxxxxxxxx>
---
 drivers/dma/pl330.c | 41 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/drivers/dma/pl330.c b/drivers/dma/pl330.c
index c3bd3584f261..e499bb118f0a 100644
--- a/drivers/dma/pl330.c
+++ b/drivers/dma/pl330.c
@@ -2627,6 +2627,46 @@ static int pl330_dma_device_slave_caps(struct dma_chan *dchan,
 	return 0;
 }
 
+/*
+ * Runtime PM callbacks are provided by amba/bus.c driver.
+ *
+ * It is assumed here that IRQ safe runtime PM is chosen in probe and amba
+ * bus driver will only disable/enable the clock in runtime PM callbacks.
+ */
+static int __maybe_unused pl330_suspend(struct device *dev)
+{
+	struct amba_device *pcdev = to_amba_device(dev);
+
+	pm_runtime_disable(dev);
+
+	if (!pm_runtime_status_suspended(dev)) {
+		/* amba did not disable the clock */
+		amba_pclk_disable(pcdev);
+	}
+	amba_pclk_unprepare(pcdev);
+
+	return 0;
+}
+
+static int __maybe_unused pl330_resume(struct device *dev)
+{
+	struct amba_device *pcdev = to_amba_device(dev);
+	int ret;
+
+	ret = amba_pclk_prepare(pcdev);
+	if (ret)
+		return ret;
+
+	if (!pm_runtime_status_suspended(dev))
+		ret = amba_pclk_enable(pcdev);
+
+	pm_runtime_enable(dev);
+
+	return ret;
+}
+
+static SIMPLE_DEV_PM_OPS(pl330_pm, pl330_suspend, pl330_resume);
+
 static int
 pl330_probe(struct amba_device *adev, const struct amba_id *id)
 {
@@ -2853,6 +2893,7 @@ static struct amba_driver pl330_driver = {
 	.drv = {
 		.owner = THIS_MODULE,
 		.name = "dma-pl330",
+		.pm = &pl330_pm,
 	},
 	.id_table = pl330_ids,
 	.probe = pl330_probe,
-- 
1.9.1

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