[PATCH v4 3/5] dmaengine: sun6i-dma: Add num_channels_per_reg for flexible interrupt mapping

[Yuanshen Cao <alex.caoys@gmail.com>]

The `sun6i-dma` driver previously assumed a fixed number of channels
per interrupt register. For example, `sun6i_kill_tasklet` was hardcoded
to disable interrupts only for registers 0 and 1. `DMA_MAX_CHANNELS` was
also not in used previously, and the old SoCs never has more than 16
channels.

The A733 has a different interrupt structure where the number of
channels per register may differ. Add `num_channels_per_reg` to `struct
sun6i_dma_config` to make the interrupt handling logic handware-agnostic
Update `sun6i_dma_interrupt`, `sun6i_dma_start_desc`, and
`sun6i_kill_tasklet` to use this value.

Additionally, set `DMA_MAX_CHANNELS` to 16 to ensure loops over
interrupts are correctly bounded, aligning with the hardware
specifications.

Signed-off-by: Yuanshen Cao <alex.caoys@gmail.com>
---
 drivers/dma/sun6i-dma.c | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/drivers/dma/sun6i-dma.c b/drivers/dma/sun6i-dma.c
index 53c54161e32a..b96d7d90f6b5 100644
--- a/drivers/dma/sun6i-dma.c
+++ b/drivers/dma/sun6i-dma.c
@@ -35,14 +35,13 @@
 #define DMA_IRQ_PKG			BIT(1)
 #define DMA_IRQ_QUEUE			BIT(2)
 
-#define DMA_IRQ_CHAN_NR			8
 #define DMA_IRQ_CHAN_WIDTH		4
 
 
 #define DMA_STAT		0x30
 
 /* Offset between DMA_IRQ_EN and DMA_IRQ_STAT limits number of channels */
-#define DMA_MAX_CHANNELS	(DMA_IRQ_CHAN_NR * 0x10 / 4)
+#define DMA_MAX_CHANNELS	16
 
 /*
  * sun8i specific registers
@@ -61,6 +60,8 @@
 #define DMA_IRQ_EN_OFFSET_A31		0x00
 #define DMA_IRQ_STAT_OFFSET_A31		0x10
 
+#define DMA_IRQ_CHAN_NR_A31		8
+
 /*
  * Channels specific registers
  */
@@ -157,6 +158,7 @@ struct sun6i_dma_config {
 	u32 irq_stride;
 	u32 irq_en_offset;
 	u32 irq_stat_offset;
+	u32 num_channels_per_reg;
 };
 
 /*
@@ -271,7 +273,7 @@ static inline void sun6i_dma_dump_com_regs(struct sun6i_dma_dev *sdev)
 {
 	int i;
 
-	for (i = 0; i < 2; i++) {
+	for (i = 0; i < DIV_ROUND_UP(sdev->num_pchans, sdev->cfg->num_channels_per_reg); i++) {
 		dev_dbg(sdev->slave.dev, "Common register:\n"
 			"chan num %d\n"
 			"\tmask(%04x): 0x%08x\n"
@@ -492,8 +494,8 @@ static int sun6i_dma_start_desc(struct sun6i_vchan *vchan)
 
 	sun6i_dma_dump_lli(vchan, pchan->desc->v_lli, pchan->desc->p_lli);
 
-	irq_reg = pchan->idx / DMA_IRQ_CHAN_NR;
-	irq_offset = pchan->idx % DMA_IRQ_CHAN_NR;
+	irq_reg = pchan->idx / sdev->cfg->num_channels_per_reg;
+	irq_offset = pchan->idx % sdev->cfg->num_channels_per_reg;
 
 	vchan->irq_type = vchan->cyclic ? DMA_IRQ_PKG : DMA_IRQ_QUEUE;
 
@@ -585,7 +587,7 @@ static irqreturn_t sun6i_dma_interrupt(int irq, void *dev_id)
 	int i, j, ret = IRQ_NONE;
 	u32 status;
 
-	for (i = 0; i < sdev->num_pchans / DMA_IRQ_CHAN_NR; i++) {
+	for (i = 0; i < sdev->num_pchans / sdev->cfg->num_channels_per_reg; i++) {
 		status = sun6i_read_irq_stat(sdev, i);
 		if (!status)
 			continue;
@@ -595,7 +597,7 @@ static irqreturn_t sun6i_dma_interrupt(int irq, void *dev_id)
 
 		sun6i_write_irq_stat(sdev, i, status);
 
-		for (j = 0; (j < DMA_IRQ_CHAN_NR) && status; j++) {
+		for (j = 0; (j < sdev->cfg->num_channels_per_reg) && status; j++) {
 			pchan = sdev->pchans + j;
 			vchan = pchan->vchan;
 			if (vchan && (status & vchan->irq_type)) {
@@ -1113,7 +1115,7 @@ static inline void sun6i_kill_tasklet(struct sun6i_dma_dev *sdev)
 	int i;
 
 	/* Disable all interrupts from DMA */
-	for (i = 0; i < 2; i++)
+	for (i = 0; i < DMA_MAX_CHANNELS / sdev->cfg->num_channels_per_reg; i++)
 		sun6i_write_irq_en(sdev, i, 0);
 
 	/* Prevent spurious interrupts from scheduling the tasklet */
@@ -1141,7 +1143,8 @@ static inline void sun6i_dma_free(struct sun6i_dma_dev *sdev)
 #define SUN6I_DMA_IRQ_A31_COMMON_CFG	\
 	.irq_stride      = DMA_IRQ_STRIDE_A31,	\
 	.irq_en_offset   = DMA_IRQ_EN_OFFSET_A31,	\
-	.irq_stat_offset = DMA_IRQ_STAT_OFFSET_A31,
+	.irq_stat_offset = DMA_IRQ_STAT_OFFSET_A31,	\
+	.num_channels_per_reg = DMA_IRQ_CHAN_NR_A31,
 
 /*
  * For A31:

-- 
2.55.0