[PATCH v3 3/3] dmaengine: sf-pdma: Get number of channel by device tree

[Zong Li]

It currently assumes that there are always four channels, it would
cause the error if there is actually less than four channels. Change
that by getting number of channel from device tree.

For backwards-compatible, it uses the default value (i.e. 4) when there
is no 'dma-channels' information in dts.

Signed-off-by: Zong Li <zong.li at sifive.com>
---
 drivers/dma/sf-pdma/Makefile  |  2 ++
 drivers/dma/sf-pdma/sf-pdma.c | 20 +++++++++++++-------
 drivers/dma/sf-pdma/sf-pdma.h |  8 ++------
 3 files changed, 17 insertions(+), 13 deletions(-)

diff --git a/drivers/dma/sf-pdma/Makefile b/drivers/dma/sf-pdma/Makefile
index 764552ab8d0a..cf1daff7e445 100644
--- a/drivers/dma/sf-pdma/Makefile
+++ b/drivers/dma/sf-pdma/Makefile
@@ -1 +1,3 @@
 obj-$(CONFIG_SF_PDMA)   += sf-pdma.o
+
+CFLAGS_sf-pdma.o += -O0
diff --git a/drivers/dma/sf-pdma/sf-pdma.c b/drivers/dma/sf-pdma/sf-pdma.c
index f12606aeff87..1264add9897e 100644
--- a/drivers/dma/sf-pdma/sf-pdma.c
+++ b/drivers/dma/sf-pdma/sf-pdma.c
@@ -482,9 +482,7 @@ static void sf_pdma_setup_chans(struct sf_pdma *pdma)
 static int sf_pdma_probe(struct platform_device *pdev)
 {
 	struct sf_pdma *pdma;
-	struct sf_pdma_chan *chan;
 	struct resource *res;
-	int len, chans;
 	int ret;
 	const enum dma_slave_buswidth widths =
 		DMA_SLAVE_BUSWIDTH_1_BYTE | DMA_SLAVE_BUSWIDTH_2_BYTES |
@@ -492,13 +490,21 @@ static int sf_pdma_probe(struct platform_device *pdev)
 		DMA_SLAVE_BUSWIDTH_16_BYTES | DMA_SLAVE_BUSWIDTH_32_BYTES |
 		DMA_SLAVE_BUSWIDTH_64_BYTES;
 
-	chans = PDMA_NR_CH;
-	len = sizeof(*pdma) + sizeof(*chan) * chans;
-	pdma = devm_kzalloc(&pdev->dev, len, GFP_KERNEL);
+	pdma = devm_kzalloc(&pdev->dev, sizeof(*pdma), GFP_KERNEL);
 	if (!pdma)
 		return -ENOMEM;
 
-	pdma->n_chans = chans;
+	ret = of_property_read_u32(pdev->dev.of_node, "dma-channels",
+				   &pdma->n_chans);
+	if (ret) {
+		dev_notice(&pdev->dev, "set number of channels to default value: 4\n");
+		pdma->n_chans = PDMA_MAX_NR_CH;
+	}
+
+	if (pdma->n_chans > PDMA_MAX_NR_CH) {
+		dev_err(&pdev->dev, "the number of channels exceeds the maximum\n");
+		return -EINVAL;
+	}
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	pdma->membase = devm_ioremap_resource(&pdev->dev, res);
@@ -556,7 +562,7 @@ static int sf_pdma_remove(struct platform_device *pdev)
 	struct sf_pdma_chan *ch;
 	int i;
 
-	for (i = 0; i < PDMA_NR_CH; i++) {
+	for (i = 0; i < pdma->n_chans; i++) {
 		ch = &pdma->chans[i];
 
 		devm_free_irq(&pdev->dev, ch->txirq, ch);
diff --git a/drivers/dma/sf-pdma/sf-pdma.h b/drivers/dma/sf-pdma/sf-pdma.h
index 0c20167b097d..8127d792f639 100644
--- a/drivers/dma/sf-pdma/sf-pdma.h
+++ b/drivers/dma/sf-pdma/sf-pdma.h
@@ -22,11 +22,7 @@
 #include "../dmaengine.h"
 #include "../virt-dma.h"
 
-#define PDMA_NR_CH					4
-
-#if (PDMA_NR_CH != 4)
-#error "Please define PDMA_NR_CH to 4"
-#endif
+#define PDMA_MAX_NR_CH					4
 
 #define PDMA_BASE_ADDR					0x3000000
 #define PDMA_CHAN_OFFSET				0x1000
@@ -118,7 +114,7 @@ struct sf_pdma {
 	void __iomem            *membase;
 	void __iomem            *mappedbase;
 	u32			n_chans;
-	struct sf_pdma_chan	chans[PDMA_NR_CH];
+	struct sf_pdma_chan	chans[PDMA_MAX_NR_CH];
 };
 
 #endif /* _SF_PDMA_H */
-- 
2.31.1