dmaengine: dma-jz4780: Avoid hardcoding number of channels

As part of the work to support various other Ingenic JZ47xx SoC versions,
which don't feature the same number of DMA channels per core, we now
deduce the number of DMA channels available from the devicetree
compatible string.
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Tested-by: Mathieu Malaterre <malat@debian.org>
Signed-off-by: Vinod Koul <vkoul@kernel.org>

drivers/dma/dma-jz4780.c

@@ -16,6 +16,7 @@
 #include <linux/interrupt.h>
 #include <linux/module.h>
 #include <linux/of.h>
+#include <linux/of_device.h>
 #include <linux/of_dma.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>
@@ -23,8 +24,6 @@
 #include "dmaengine.h"
 #include "virt-dma.h"
 
-#define JZ_DMA_NR_CHANNELS	32
-
 /* Global registers. */
 #define JZ_DMA_REG_DMAC		0x1000
 #define JZ_DMA_REG_DIRQP	0x1004
@@ -135,14 +134,19 @@ struct jz4780_dma_chan {
 	unsigned int curr_hwdesc;
 };
 
+struct jz4780_dma_soc_data {
+	unsigned int nb_channels;
+};
+
 struct jz4780_dma_dev {
 	struct dma_device dma_device;
 	void __iomem *base;
 	struct clk *clk;
 	unsigned int irq;
+	const struct jz4780_dma_soc_data *soc_data;
 
 	uint32_t chan_reserved;
-	struct jz4780_dma_chan chan[JZ_DMA_NR_CHANNELS];
+	struct jz4780_dma_chan chan[];
 };
 
 struct jz4780_dma_filter_data {
@@ -648,7 +652,7 @@ static irqreturn_t jz4780_dma_irq_handler(int irq, void *data)
 
 	pending = jz4780_dma_readl(jzdma, JZ_DMA_REG_DIRQP);
 
-	for (i = 0; i < JZ_DMA_NR_CHANNELS; i++) {
+	for (i = 0; i < jzdma->soc_data->nb_channels; i++) {
 		if (!(pending & (1<<i)))
 			continue;
 
@@ -728,7 +732,7 @@ static struct dma_chan *jz4780_of_dma_xlate(struct of_phandle_args *dma_spec,
 	data.channel = dma_spec->args[1];
 
 	if (data.channel > -1) {
-		if (data.channel >= JZ_DMA_NR_CHANNELS) {
+		if (data.channel >= jzdma->soc_data->nb_channels) {
 			dev_err(jzdma->dma_device.dev,
 				"device requested non-existent channel %u\n",
 				data.channel);
@@ -755,6 +759,7 @@ static struct dma_chan *jz4780_of_dma_xlate(struct of_phandle_args *dma_spec,
 static int jz4780_dma_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
+	const struct jz4780_dma_soc_data *soc_data;
 	struct jz4780_dma_dev *jzdma;
 	struct jz4780_dma_chan *jzchan;
 	struct dma_device *dd;
@@ -766,10 +771,17 @@ static int jz4780_dma_probe(struct platform_device *pdev)
 		return -EINVAL;
 	}
 
-	jzdma = devm_kzalloc(dev, sizeof(*jzdma), GFP_KERNEL);
+	soc_data = device_get_match_data(dev);
+	if (!soc_data)
+		return -EINVAL;
+
+	jzdma = devm_kzalloc(dev, sizeof(*jzdma)
+				+ sizeof(*jzdma->chan) * soc_data->nb_channels,
+				GFP_KERNEL);
 	if (!jzdma)
 		return -ENOMEM;
 
+	jzdma->soc_data = soc_data;
 	platform_set_drvdata(pdev, jzdma);
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
@@ -844,7 +856,7 @@ static int jz4780_dma_probe(struct platform_device *pdev)
 
 	INIT_LIST_HEAD(&dd->channels);
 
-	for (i = 0; i < JZ_DMA_NR_CHANNELS; i++) {
+	for (i = 0; i < soc_data->nb_channels; i++) {
 		jzchan = &jzdma->chan[i];
 		jzchan->id = i;
 
@@ -889,15 +901,19 @@ static int jz4780_dma_remove(struct platform_device *pdev)
 
 	free_irq(jzdma->irq, jzdma);
 
-	for (i = 0; i < JZ_DMA_NR_CHANNELS; i++)
+	for (i = 0; i < jzdma->soc_data->nb_channels; i++)
 		tasklet_kill(&jzdma->chan[i].vchan.task);
 
 	dma_async_device_unregister(&jzdma->dma_device);
 	return 0;
 }
 
+static const struct jz4780_dma_soc_data jz4780_dma_soc_data = {
+	.nb_channels = 32,
+};
+
 static const struct of_device_id jz4780_dma_dt_match[] = {
-	{ .compatible = "ingenic,jz4780-dma", .data = NULL },
+	{ .compatible = "ingenic,jz4780-dma", .data = &jz4780_dma_soc_data },
 	{},
 };
 MODULE_DEVICE_TABLE(of, jz4780_dma_dt_match);