dmaengine: bcm2835: Load driver early and support legacy API

raspberrypi inclusion
category: feature
bugzilla: 50432

--------------------------------

Load driver early since at least bcm2708_fb doesn't support deferred
probing and even if it did, we don't want the video driver deferred.
Support the legacy DMA API which is needed by bcm2708_fb.
Don't mask out channel 2.
Signed-off-by: NNoralf Trønnes <noralf@tronnes.org>
Signed-off-by: NFang Yafen <yafen@iscas.ac.cn>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

drivers/dma/Kconfig

@@ -133,7 +133,7 @@ config COH901318
 
 config DMA_BCM2835
 	tristate "BCM2835 DMA engine support"
-	depends on ARCH_BCM2835
+	depends on ARCH_BCM2835 || ARCH_BCM2708 || ARCH_BCM2709
 	select DMA_ENGINE
 	select DMA_VIRTUAL_CHANNELS
 

drivers/dma/bcm2835-dma.c

@@ -25,6 +25,7 @@
 #include <linux/interrupt.h>
 #include <linux/list.h>
 #include <linux/module.h>
+#include <linux/platform_data/dma-bcm2708.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>
 #include <linux/io.h>
@@ -36,6 +37,7 @@
 
 #define BCM2835_DMA_MAX_DMA_CHAN_SUPPORTED 14
 #define BCM2835_DMA_CHAN_NAME_SIZE 8
+#define BCM2835_DMA_BULK_MASK  BIT(0)
 
 /**
  * struct bcm2835_dmadev - BCM2835 DMA controller
@@ -906,6 +908,9 @@ static int bcm2835_dma_probe(struct platform_device *pdev)
 	base = devm_ioremap_resource(&pdev->dev, res);
 	if (IS_ERR(base))
 		return PTR_ERR(base);
+	rc = bcm_dmaman_probe(pdev, base, BCM2835_DMA_BULK_MASK);
+	if (rc)
+		dev_err(&pdev->dev, "Failed to initialize the legacy API\n");
 
 	od->base = base;
 
@@ -951,6 +956,9 @@ static int bcm2835_dma_probe(struct platform_device *pdev)
 		goto err_no_dma;
 	}
 
+	/* Channel 0 is used by the legacy API */
+	chans_available &= ~BCM2835_DMA_BULK_MASK;
+
 	/* get irqs for each channel that we support */
 	for (i = 0; i <= BCM2835_DMA_MAX_DMA_CHAN_SUPPORTED; i++) {
 		/* skip masked out channels */
@@ -1025,6 +1033,7 @@ static int bcm2835_dma_remove(struct platform_device *pdev)
 {
 	struct bcm2835_dmadev *od = platform_get_drvdata(pdev);
 
+	bcm_dmaman_remove(pdev);
 	dma_async_device_unregister(&od->ddev);
 	bcm2835_dma_free(od);
 
@@ -1040,7 +1049,22 @@ static struct platform_driver bcm2835_dma_driver = {
 	},
 };
 
-module_platform_driver(bcm2835_dma_driver);
+static int bcm2835_dma_init(void)
+{
+	return platform_driver_register(&bcm2835_dma_driver);
+}
+
+static void bcm2835_dma_exit(void)
+{
+	platform_driver_unregister(&bcm2835_dma_driver);
+}
+
+/*
+ * Load after serial driver (arch_initcall) so we see the messages if it fails,
+ * but before drivers (module_init) that need a DMA channel.
+ */
+subsys_initcall(bcm2835_dma_init);
+module_exit(bcm2835_dma_exit);
 
 MODULE_ALIAS("platform:bcm2835-dma");
 MODULE_DESCRIPTION("BCM2835 DMA engine driver");