linux-kernel - [PATCH 4/4] dmaengine: sh: rz-dmac: Add system sleep power management

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Message-ID: <20250905144427.1840684-5-tommaso.merciai.xr@bp.renesas.com>
Date: Fri,  5 Sep 2025 16:44:20 +0200
From: Tommaso Merciai <tommaso.merciai.xr@...renesas.com>
To: tomm.merciai@...il.com
Cc: linux-renesas-soc@...r.kernel.org,
	biju.das.jz@...renesas.com,
	Tommaso Merciai <tommaso.merciai.xr@...renesas.com>,
	Vinod Koul <vkoul@...nel.org>,
	Philipp Zabel <p.zabel@...gutronix.de>,
	Geert Uytterhoeven <geert+renesas@...der.be>,
	Wolfram Sang <wsa+renesas@...g-engineering.com>,
	Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>,
	Fabrizio Castro <fabrizio.castro.jz@...esas.com>,
	Uwe Kleine-König <u.kleine-koenig@...libre.com>,
	dmaengine@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 4/4] dmaengine: sh: rz-dmac: Add system sleep power management

Add runtime and system sleep power management operations to the RZ DMAC
driver. This enables proper handling of suspend and resume sequences,
including device reset and channel re-initialization, preparing the driver
for power state transitions.

Signed-off-by: Tommaso Merciai <tommaso.merciai.xr@...renesas.com>
---
 drivers/dma/sh/rz-dmac.c | 47 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)

diff --git a/drivers/dma/sh/rz-dmac.c b/drivers/dma/sh/rz-dmac.c
index 4ab6076f5499e..d849e313a7f79 100644
--- a/drivers/dma/sh/rz-dmac.c
+++ b/drivers/dma/sh/rz-dmac.c
@@ -437,6 +437,24 @@ static int rz_dmac_xfer_desc(struct rz_dmac_chan *chan)
  * DMA engine operations
  */
 
+static int rz_dmac_chan_init_all(struct rz_dmac *dmac)
+{
+	unsigned int i;
+	int ret;
+
+	ret = pm_runtime_resume_and_get(dmac->dev);
+	if (ret < 0)
+		return ret;
+
+	rz_dmac_writel(dmac, DCTRL_DEFAULT, CHANNEL_0_7_COMMON_BASE + DCTRL);
+	rz_dmac_writel(dmac, DCTRL_DEFAULT, CHANNEL_8_15_COMMON_BASE + DCTRL);
+
+	for (i = 0; i < dmac->n_channels; i++)
+		rz_dmac_ch_writel(&dmac->channels[i], CHCTRL_DEFAULT, CHCTRL, 1);
+
+	return pm_runtime_put_sync(dmac->dev);
+}
+
 static int rz_dmac_alloc_chan_resources(struct dma_chan *chan)
 {
 	struct rz_dmac_chan *channel = to_rz_dmac_chan(chan);
@@ -1070,6 +1088,34 @@ static void rz_dmac_remove(struct platform_device *pdev)
 	platform_device_put(dmac->icu.pdev);
 }
 
+static int rz_dmac_suspend(struct device *dev)
+{
+	struct rz_dmac *dmac = dev_get_drvdata(dev);
+
+	return reset_control_assert(dmac->rstc);
+}
+
+static int rz_dmac_resume(struct device *dev)
+{
+	struct rz_dmac *dmac = dev_get_drvdata(dev);
+	int ret;
+
+	ret = reset_control_deassert(dmac->rstc);
+	if (ret)
+		return ret;
+
+	return rz_dmac_chan_init_all(dmac);
+}
+
+static const struct dev_pm_ops rz_dmac_pm_ops = {
+	/*
+	 * TODO for system sleep/resume:
+	 *   - Wait for the current transfer to complete and stop the device,
+	 *   - Resume transfers, if any.
+	 */
+	SYSTEM_SLEEP_PM_OPS(rz_dmac_suspend, rz_dmac_resume)
+};
+
 static const struct of_device_id of_rz_dmac_match[] = {
 	{ .compatible = "renesas,r9a09g057-dmac", },
 	{ .compatible = "renesas,rz-dmac", },
@@ -1079,6 +1125,7 @@ MODULE_DEVICE_TABLE(of, of_rz_dmac_match);
 
 static struct platform_driver rz_dmac_driver = {
 	.driver		= {
+		.pm	= pm_sleep_ptr(&rz_dmac_pm_ops),
 		.name	= "rz-dmac",
 		.of_match_table = of_rz_dmac_match,
 	},
-- 
2.43.0