dmaengine: sh: rz-dmac: Add device_{pause,resume}() callbacks

The RZ/G2L SCIFA driver uses dmaengine_prep_slave_sg() to enqueue DMA
transfers and implements a timeout mechanism on RX to handle cases where
a DMA transfer does not complete. The timeout is implemented using an
hrtimer.

In the hrtimer callback, dmaengine_tx_status() is called (along with
dmaengine_pause()) to retrieve the transfer residue and handle incomplete
DMA transfers.

Add support for device_{pause, resume}() callbacks.

Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Link: https://patch.msgid.link/20260316133252.240348-9-claudiu.beznea.uj@bp.renesas.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

1 files changed, 46 insertions, 3 deletions

diff --git a/drivers/dma/sh/rz-dmac.c b/drivers/dma/sh/rz-dmac.c
index 4f6f9f4bacca..625ff29024de 100644
--- a/drivers/dma/sh/rz-dmac.c
+++ b/drivers/dma/sh/rz-dmac.c
@@ -140,10 +140,12 @@ struct rz_dmac {
 #define CHANNEL_8_15_COMMON_BASE	0x0700
 
 #define CHSTAT_ER			BIT(4)
+#define CHSTAT_SUS			BIT(3)
 #define CHSTAT_EN			BIT(0)
 
 #define CHCTRL_CLRINTMSK		BIT(17)
 #define CHCTRL_CLRSUS			BIT(9)
+#define CHCTRL_SETSUS			BIT(8)
 #define CHCTRL_CLRTC			BIT(6)
 #define CHCTRL_CLREND			BIT(5)
 #define CHCTRL_CLRRQ			BIT(4)
@@ -805,11 +807,18 @@ static enum dma_status rz_dmac_tx_status(struct dma_chan *chan,
 	if (status == DMA_COMPLETE || !txstate)
 		return status;
 
-	scoped_guard(spinlock_irqsave, &channel->vc.lock)
+	scoped_guard(spinlock_irqsave, &channel->vc.lock) {
+		u32 val;
+
 		residue = rz_dmac_chan_get_residue(channel, cookie);
 
-	/* if there's no residue, the cookie is complete */
-	if (!residue)
+		val = rz_dmac_ch_readl(channel, CHSTAT, 1);
+		if (val & CHSTAT_SUS)
+			status = DMA_PAUSED;
+	}
+
+	/* if there's no residue and no paused, the cookie is complete */
+	if (!residue && status != DMA_PAUSED)
 		return DMA_COMPLETE;
 
 	dma_set_residue(txstate, residue);
@@ -817,6 +826,38 @@ static enum dma_status rz_dmac_tx_status(struct dma_chan *chan,
 	return status;
 }
 
+static int rz_dmac_device_pause(struct dma_chan *chan)
+{
+	struct rz_dmac_chan *channel = to_rz_dmac_chan(chan);
+	u32 val;
+
+	guard(spinlock_irqsave)(&channel->vc.lock);
+
+	val = rz_dmac_ch_readl(channel, CHSTAT, 1);
+	if (!(val & CHSTAT_EN))
+		return 0;
+
+	rz_dmac_ch_writel(channel, CHCTRL_SETSUS, CHCTRL, 1);
+	return read_poll_timeout_atomic(rz_dmac_ch_readl, val,
+					(val & CHSTAT_SUS), 1, 1024,
+					false, channel, CHSTAT, 1);
+}
+
+static int rz_dmac_device_resume(struct dma_chan *chan)
+{
+	struct rz_dmac_chan *channel = to_rz_dmac_chan(chan);
+	u32 val;
+
+	guard(spinlock_irqsave)(&channel->vc.lock);
+
+	/* Do not check CHSTAT_SUS but rely on HW capabilities. */
+
+	rz_dmac_ch_writel(channel, CHCTRL_CLRSUS, CHCTRL, 1);
+	return read_poll_timeout_atomic(rz_dmac_ch_readl, val,
+					!(val & CHSTAT_SUS), 1, 1024,
+					false, channel, CHSTAT, 1);
+}
+
 /*
  * -----------------------------------------------------------------------------
  * IRQ handling
@@ -1153,6 +1194,8 @@ static int rz_dmac_probe(struct platform_device *pdev)
 	engine->device_terminate_all = rz_dmac_terminate_all;
 	engine->device_issue_pending = rz_dmac_issue_pending;
 	engine->device_synchronize = rz_dmac_device_synchronize;
+	engine->device_pause = rz_dmac_device_pause;
+	engine->device_resume = rz_dmac_device_resume;
 
 	engine->copy_align = DMAENGINE_ALIGN_1_BYTE;
 	dma_set_max_seg_size(engine->dev, U32_MAX);