linux-kernel - [PATCH 1/8] dmaengine: stm32-dma: add suspend/resume power management support

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Date:   Wed, 29 Jan 2020 16:36:21 +0100
From:   Amelie Delaunay <amelie.delaunay@...com>
To:     Vinod Koul <vkoul@...nel.org>,
        Dan Williams <dan.j.williams@...el.com>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...com>
CC:     <dmaengine@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>,
        Amelie Delaunay <amelie.delaunay@...com>,
        Pierre-Yves MORDRET <pierre-yves.mordret@...com>
Subject: [PATCH 1/8] dmaengine: stm32-dma: add suspend/resume power management support

From: Pierre-Yves MORDRET <pierre-yves.mordret@...com>

Add suspend/resume power management relying on PM Runtime engine.

Signed-off-by: Pierre-Yves MORDRET <pierre-yves.mordret@...com>
Signed-off-by: Amelie Delaunay <amelie.delaunay@...com>
---
 drivers/dma/stm32-dma.c | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/drivers/dma/stm32-dma.c b/drivers/dma/stm32-dma.c
index 5989b0893521..136deabd1aa3 100644
--- a/drivers/dma/stm32-dma.c
+++ b/drivers/dma/stm32-dma.c
@@ -1427,7 +1427,39 @@ static int stm32_dma_runtime_resume(struct device *dev)
 }
 #endif
 
+#ifdef CONFIG_PM_SLEEP
+static int stm32_dma_suspend(struct device *dev)
+{
+	struct stm32_dma_device *dmadev = dev_get_drvdata(dev);
+	int id, ret, scr;
+
+	ret = pm_runtime_get_sync(dev);
+	if (ret < 0)
+		return ret;
+
+	for (id = 0; id < STM32_DMA_MAX_CHANNELS; id++) {
+		scr = stm32_dma_read(dmadev, STM32_DMA_SCR(id));
+		if (scr & STM32_DMA_SCR_EN) {
+			dev_warn(dev, "Suspend is prevented by Chan %i\n", id);
+			return -EBUSY;
+		}
+	}
+
+	pm_runtime_put_sync(dev);
+
+	pm_runtime_force_suspend(dev);
+
+	return 0;
+}
+
+static int stm32_dma_resume(struct device *dev)
+{
+	return pm_runtime_force_resume(dev);
+}
+#endif
+
 static const struct dev_pm_ops stm32_dma_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(stm32_dma_suspend, stm32_dma_resume)
 	SET_RUNTIME_PM_OPS(stm32_dma_runtime_suspend,
 			   stm32_dma_runtime_resume, NULL)
 };
-- 
2.17.1