openwrt/target/linux/brcm2708/patches-4.9/0019-dmaengine-bcm2835-Load-driver-early-and-support-lega.patch

From b4e0c1c3facd38ef5e615248c42dba90d2622257 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Noralf=20Tr=C3=B8nnes?= <noralf@tronnes.org>
Date: Sat, 3 Oct 2015 22:22:55 +0200
Subject: [PATCH] dmaengine: bcm2835: Load driver early and support legacy API
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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: Noralf Trønnes <noralf@tronnes.org>
---
 drivers/dma/Kconfig       |  2 +-
 drivers/dma/bcm2835-dma.c | 26 +++++++++++++++++++++++++-
 2 files changed, 26 insertions(+), 2 deletions(-)

--- a/drivers/dma/Kconfig
+++ b/drivers/dma/Kconfig
@@ -108,7 +108,7 @@ 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
 
--- a/drivers/dma/bcm2835-dma.c
+++ b/drivers/dma/bcm2835-dma.c
@@ -37,6 +37,7 @@
 #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>
@@ -48,6 +49,7 @@
 
 #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 {
 	struct dma_device ddev;
@@ -922,6 +924,9 @@ static int bcm2835_dma_probe(struct plat
 	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;
 
@@ -959,6 +964,9 @@ static int bcm2835_dma_probe(struct plat
 		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 */
@@ -1033,6 +1041,7 @@ static int bcm2835_dma_remove(struct pla
 {
 	struct bcm2835_dmadev *od = platform_get_drvdata(pdev);
 
+	bcm_dmaman_remove(pdev);
 	dma_async_device_unregister(&od->ddev);
 	bcm2835_dma_free(od);
 
@@ -1048,7 +1057,22 @@ static struct platform_driver bcm2835_dm
 	},
 };
 
-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");