[PATCH 1/2] dmaengine: qcom-bam-dma: Add pm_runtime support

[Pramod Gurav]

Adds pm_runtime support for BAM DMA so that clock
is enabled only when there is a transaction going on to help
save power.

Signed-off-by: Pramod Gurav <pramod.gurav@xxxxxxxxxx>
---
 drivers/dma/qcom/bam_dma.c | 88 +++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 87 insertions(+), 1 deletion(-)

diff --git a/drivers/dma/qcom/bam_dma.c b/drivers/dma/qcom/bam_dma.c
index 5b427c4..577f323 100644
--- a/drivers/dma/qcom/bam_dma.c
+++ b/drivers/dma/qcom/bam_dma.c
@@ -48,6 +48,7 @@
 #include <linux/of_dma.h>
 #include <linux/clk.h>
 #include <linux/dmaengine.h>
+#include <linux/pm_runtime.h>
 
 #include "../dmaengine.h"
 #include "../virt-dma.h"
@@ -58,6 +59,8 @@ struct bam_desc_hw {
 	u16 flags;
 };
 
+#define BAM_DMA_AUTOSUSPEND_DELAY 100
+
 #define DESC_FLAG_INT BIT(15)
 #define DESC_FLAG_EOT BIT(14)
 #define DESC_FLAG_EOB BIT(13)
@@ -535,6 +538,7 @@ static void bam_free_chan(struct dma_chan *chan)
 		return;
 	}
 
+	pm_runtime_get_sync(bdev->dev);
 	spin_lock_irqsave(&bchan->vc.lock, flags);
 	bam_reset_channel(bchan);
 	spin_unlock_irqrestore(&bchan->vc.lock, flags);
@@ -550,6 +554,8 @@ static void bam_free_chan(struct dma_chan *chan)
 
 	/* disable irq */
 	writel_relaxed(0, bam_addr(bdev, bchan->id, BAM_P_IRQ_EN));
+	pm_runtime_mark_last_busy(bdev->dev);
+	pm_runtime_put_autosuspend(bdev->dev);
 }
 
 /**
@@ -696,10 +702,13 @@ static int bam_pause(struct dma_chan *chan)
 	struct bam_device *bdev = bchan->bdev;
 	unsigned long flag;
 
+	pm_runtime_get_sync(bdev->dev);
 	spin_lock_irqsave(&bchan->vc.lock, flag);
 	writel_relaxed(1, bam_addr(bdev, bchan->id, BAM_P_HALT));
 	bchan->paused = 1;
 	spin_unlock_irqrestore(&bchan->vc.lock, flag);
+	pm_runtime_mark_last_busy(bdev->dev);
+	pm_runtime_put_autosuspend(bdev->dev);
 
 	return 0;
 }
@@ -715,10 +724,13 @@ static int bam_resume(struct dma_chan *chan)
 	struct bam_device *bdev = bchan->bdev;
 	unsigned long flag;
 
+	pm_runtime_get_sync(bdev->dev);
 	spin_lock_irqsave(&bchan->vc.lock, flag);
 	writel_relaxed(0, bam_addr(bdev, bchan->id, BAM_P_HALT));
 	bchan->paused = 0;
 	spin_unlock_irqrestore(&bchan->vc.lock, flag);
+	pm_runtime_mark_last_busy(bdev->dev);
+	pm_runtime_put_autosuspend(bdev->dev);
 
 	return 0;
 }
@@ -943,6 +955,7 @@ static void bam_start_dma(struct bam_chan *bchan)
 	wmb();
 	writel_relaxed(bchan->tail * sizeof(struct bam_desc_hw),
 			bam_addr(bdev, bchan->id, BAM_P_EVNT_REG));
+
 }
 
 /**
@@ -967,6 +980,9 @@ static void dma_tasklet(unsigned long data)
 			bam_start_dma(bchan);
 		spin_unlock_irqrestore(&bchan->vc.lock, flags);
 	}
+
+	pm_runtime_mark_last_busy(bdev->dev);
+	pm_runtime_put_autosuspend(bdev->dev);
 }
 
 /**
@@ -978,8 +994,12 @@ static void dma_tasklet(unsigned long data)
 static void bam_issue_pending(struct dma_chan *chan)
 {
 	struct bam_chan *bchan = to_bam_chan(chan);
+	struct bam_device *bdev = bchan->bdev;
 	unsigned long flags;
 
+	if (pm_runtime_status_suspended(bdev->dev))
+		pm_runtime_get_sync(bdev->dev);
+
 	spin_lock_irqsave(&bchan->vc.lock, flags);
 
 	/* if work pending and idle, start a transaction */
@@ -1210,6 +1230,13 @@ static int bam_dma_probe(struct platform_device *pdev)
 	if (ret)
 		goto err_unregister_dma;
 
+	pm_runtime_irq_safe(&pdev->dev);
+	pm_runtime_set_autosuspend_delay(&pdev->dev, BAM_DMA_AUTOSUSPEND_DELAY);
+	pm_runtime_use_autosuspend(&pdev->dev);
+	pm_runtime_mark_last_busy(&pdev->dev);
+	pm_runtime_set_active(&pdev->dev);
+	pm_runtime_enable(&pdev->dev);
+
 	return 0;
 
 err_unregister_dma:
@@ -1221,7 +1248,6 @@ err_tasklet_kill:
 	tasklet_kill(&bdev->task);
 err_disable_clk:
 	clk_disable_unprepare(bdev->bamclk);
-
 	return ret;
 }
 
@@ -1252,16 +1278,76 @@ static int bam_dma_remove(struct platform_device *pdev)
 
 	tasklet_kill(&bdev->task);
 
+	pm_runtime_get_sync(&pdev->dev);
 	clk_disable_unprepare(bdev->bamclk);
+	pm_runtime_disable(&pdev->dev);
+	pm_runtime_put_noidle(&pdev->dev);
+	pm_runtime_set_suspended(&pdev->dev);
+
+	return 0;
+}
+
+static int bam_dma_runtime_suspend(struct device *dev)
+{
+	struct bam_device *bdev = dev_get_drvdata(dev);
+
+	clk_disable(bdev->bamclk);
+
+	return 0;
+}
+
+static int bam_dma_runtime_resume(struct device *dev)
+{
+	struct bam_device *bdev = dev_get_drvdata(dev);
+	int ret;
+
+	ret = clk_enable(bdev->bamclk);
+	if (ret < 0) {
+		dev_err(dev, "clk_enable failed: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+#ifdef CONFIG_PM_SLEEP
+static int bam_dma_suspend(struct device *dev)
+{
+	struct bam_device *bdev = dev_get_drvdata(dev);
+
+	pm_runtime_force_suspend(dev);
+
+	clk_unprepare(bdev->bamclk);
+
+	return 0;
+}
+
+static int bam_dma_resume(struct device *dev)
+{
+	struct bam_device *bdev = dev_get_drvdata(dev);
+	int ret;
+
+	ret = clk_prepare(bdev->bamclk);
+	if (ret)
+		return ret;
+
+	pm_runtime_force_resume(dev);
 
 	return 0;
 }
+#endif
+
+static const struct dev_pm_ops bam_dma_pm_ops = {
+	SET_LATE_SYSTEM_SLEEP_PM_OPS(bam_dma_suspend, bam_dma_resume)
+	SET_RUNTIME_PM_OPS(bam_dma_runtime_suspend, bam_dma_runtime_resume,
+				NULL)
+};
 
 static struct platform_driver bam_dma_driver = {
 	.probe = bam_dma_probe,
 	.remove = bam_dma_remove,
 	.driver = {
 		.name = "bam-dma-engine",
+		.pm = &bam_dma_pm_ops,
 		.of_match_table = bam_of_match,
 	},
 };
-- 
1.8.2.1