Message-Id: <1221837088-19539-1-git-send-email-timur@freescale.com>
Date:	Fri, 19 Sep 2008 10:11:28 -0500
From:	Timur Tabi <timur@...escale.com>
To:	leoli@...escale.com, zw@...kernel.org, linuxppc-dev@...abs.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] fsl-dma: allow Freescale Elo DMA driver to be compiled as a module

Modify the Freescale Elo / Elo Plus DMA driver so that it can be compiled as
a module.

The primary change is to stop treating the DMA controller as a bus, and the
DMA channels as devices on the bus.  This is because the Open Firmware (OF)
kernel code does not allow busses to be removed, so although we can call
of_platform_bus_probe() to probe the DMA channels, there is no
of_platform_bus_remove().  Therefore, the DMA channels must be manually probed.

Signed-off-by: Timur Tabi <timur@...escale.com>
---

(Reposting because I forgot to CC: the maintainers) 

This patch is for the 2.6.28 kernel.  This patch exposes a bug in the dmatest
module, so my other patch "dmatest: properly handle duplicate DMA channels"
should be applied if this patch is applied.

 drivers/dma/Kconfig  |   10 ++--
 drivers/dma/fsldma.c |  165 ++++++++++++++++++++++++++++++++++----------------
 drivers/dma/fsldma.h |    2 +
 3 files changed, 119 insertions(+), 58 deletions(-)

diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
index cd30390..9dfd502 100644
--- a/drivers/dma/Kconfig
+++ b/drivers/dma/Kconfig
@@ -48,13 +48,13 @@ config DW_DMAC
 	  can be integrated in chips such as the Atmel AT32ap7000.
 
 config FSL_DMA
-	bool "Freescale MPC85xx/MPC83xx DMA support"
-	depends on PPC
+	tristate "Freescale Elo and Elo Plus DMA support"
+	depends on PPC_83xx || PPC_85xx || PPC_86xx
 	select DMA_ENGINE
 	---help---
-	  Enable support for the Freescale DMA engine. Now, it support
-	  MPC8560/40, MPC8555, MPC8548 and MPC8641 processors.
-	  The MPC8349, MPC8360 is also supported.
+	  Enable support for the Freescale Elo and Elo Plus DMA controllers.
+	  The Elo is the DMA controller on 83xx parts, and the Elo Plus is
+	  the DMA controller on 85xx and 86xx parts.
 
 config MV_XOR
 	bool "Marvell XOR engine support"
diff --git a/drivers/dma/fsldma.c b/drivers/dma/fsldma.c
index c0059ca..327c485 100644
--- a/drivers/dma/fsldma.c
+++ b/drivers/dma/fsldma.c
@@ -372,6 +372,10 @@ static int fsl_dma_alloc_chan_resources(struct dma_chan *chan,
 	struct fsl_dma_chan *fsl_chan = to_fsl_chan(chan);
 	LIST_HEAD(tmp_list);
 
+	/* Has this channel already been allocated? */
+	if (fsl_chan->desc_pool)
+		return 1;
+
 	/* We need the descriptor to be aligned to 32bytes
 	 * for meeting FSL DMA specification requirement.
 	 */
@@ -381,7 +385,7 @@ static int fsl_dma_alloc_chan_resources(struct dma_chan *chan,
 	if (!fsl_chan->desc_pool) {
 		dev_err(fsl_chan->dev, "No memory for channel %d "
 			"descriptor dma pool.\n", fsl_chan->id);
-		return 0;
+		return -ENOMEM;
 	}
 
 	return 1;
@@ -410,6 +414,8 @@ static void fsl_dma_free_chan_resources(struct dma_chan *chan)
 	}
 	spin_unlock_irqrestore(&fsl_chan->desc_lock, flags);
 	dma_pool_destroy(fsl_chan->desc_pool);
+
+	fsl_chan->desc_pool = NULL;
 }
 
 static struct dma_async_tx_descriptor *
@@ -912,33 +918,37 @@ out:
 	return err;
 }
 
-static int __devinit of_fsl_dma_chan_probe(struct of_device *dev,
-			const struct of_device_id *match)
+static int __devinit fsl_dma_chan_probe(struct fsl_dma_device *fdev,
+	struct device_node *node, u32 feature, const char *compatible)
 {
-	struct fsl_dma_device *fdev;
 	struct fsl_dma_chan *new_fsl_chan;
+	const u32 *iprop;
 	int err;
 
-	fdev = dev_get_drvdata(dev->dev.parent);
-	BUG_ON(!fdev);
-
 	/* alloc channel */
 	new_fsl_chan = kzalloc(sizeof(struct fsl_dma_chan), GFP_KERNEL);
 	if (!new_fsl_chan) {
-		dev_err(&dev->dev, "No free memory for allocating "
+		dev_err(fdev->dev, "No free memory for allocating "
 				"dma channels!\n");
 		return -ENOMEM;
 	}
 
+	new_fsl_chan->of_dev = of_platform_device_create(node, NULL, fdev->dev);
+	if (!new_fsl_chan->of_dev) {
+		dev_err(fdev->dev, "cannot create platform device\n");
+		err = -EINVAL;
+		goto err_no_dev;
+	}
+
 	/* get dma channel register base */
-	err = of_address_to_resource(dev->node, 0, &new_fsl_chan->reg);
+	err = of_address_to_resource(node, 0, &new_fsl_chan->reg);
 	if (err) {
-		dev_err(&dev->dev, "Can't get %s property 'reg'\n",
-				dev->node->full_name);
+		dev_err(fdev->dev, "Can't get %s property 'reg'\n",
+				node->full_name);
 		goto err_no_reg;
 	}
 
-	new_fsl_chan->feature = *(u32 *)match->data;
+	new_fsl_chan->feature = feature;
 
 	if (!fdev->feature)
 		fdev->feature = new_fsl_chan->feature;
@@ -948,17 +958,22 @@ static int __devinit of_fsl_dma_chan_probe(struct of_device *dev,
 	 */
 	WARN_ON(fdev->feature != new_fsl_chan->feature);
 
-	new_fsl_chan->dev = &dev->dev;
+	new_fsl_chan->dev = &new_fsl_chan->of_dev->dev;
 	new_fsl_chan->reg_base = ioremap(new_fsl_chan->reg.start,
 			new_fsl_chan->reg.end - new_fsl_chan->reg.start + 1);
 
-	new_fsl_chan->id = ((new_fsl_chan->reg.start - 0x100) & 0xfff) >> 7;
-	if (new_fsl_chan->id > FSL_DMA_MAX_CHANS_PER_DEVICE) {
-		dev_err(&dev->dev, "There is no %d channel!\n",
-				new_fsl_chan->id);
+	iprop = of_get_property(node, "cell-index", NULL);
+	if (!iprop) {
+		dev_err(fdev->dev, "missing cell-index property\n");
+		return -EINVAL;
+	}
+	if (*iprop >= FSL_DMA_MAX_CHANS_PER_DEVICE) {
+		dev_err(fdev->dev, "invalid cell-index value %u\n", *iprop);
 		err = -EINVAL;
 		goto err_no_chan;
 	}
+	new_fsl_chan->id = *iprop;
+
 	fdev->chan[new_fsl_chan->id] = new_fsl_chan;
 	tasklet_init(&new_fsl_chan->tasklet, dma_do_tasklet,
 			(unsigned long)new_fsl_chan);
@@ -988,14 +1003,14 @@ static int __devinit of_fsl_dma_chan_probe(struct of_device *dev,
 			&fdev->common.channels);
 	fdev->common.chancnt++;
 
-	new_fsl_chan->irq = irq_of_parse_and_map(dev->node, 0);
+	new_fsl_chan->irq = irq_of_parse_and_map(node, 0);
 	if (new_fsl_chan->irq != NO_IRQ) {
 		err = request_irq(new_fsl_chan->irq,
 					&fsl_dma_chan_do_interrupt, IRQF_SHARED,
 					"fsldma-channel", new_fsl_chan);
 		if (err) {
-			dev_err(&dev->dev, "DMA channel %s request_irq error "
-				"with return %d\n", dev->node->full_name, err);
+			dev_err(fdev->dev, "DMA channel %s request_irq error "
+				"with return %d\n", node->full_name, err);
 			goto err_no_irq;
 		}
 	}
@@ -1004,8 +1019,8 @@ static int __devinit of_fsl_dma_chan_probe(struct of_device *dev,
 	if (err)
 		goto err_self_test;
 
-	dev_info(&dev->dev, "#%d (%s), irq %d\n", new_fsl_chan->id,
-				match->compatible, new_fsl_chan->irq);
+	dev_info(fdev->dev, "#%d (%s), irq %d\n", new_fsl_chan->id,
+				compatible, new_fsl_chan->irq);
 
 	return 0;
 
@@ -1016,42 +1031,30 @@ err_no_irq:
 err_no_chan:
 	iounmap(new_fsl_chan->reg_base);
 err_no_reg:
+	of_device_unregister(new_fsl_chan->of_dev);
+err_no_dev:
 	kfree(new_fsl_chan);
 	return err;
 }
 
-const u32 mpc8540_dma_ip_feature = FSL_DMA_IP_85XX | FSL_DMA_BIG_ENDIAN;
-const u32 mpc8349_dma_ip_feature = FSL_DMA_IP_83XX | FSL_DMA_LITTLE_ENDIAN;
-
-static struct of_device_id of_fsl_dma_chan_ids[] = {
-	{
-		.compatible = "fsl,eloplus-dma-channel",
-		.data = (void *)&mpc8540_dma_ip_feature,
-	},
-	{
-		.compatible = "fsl,elo-dma-channel",
-		.data = (void *)&mpc8349_dma_ip_feature,
-	},
-	{}
-};
-
-static struct of_platform_driver of_fsl_dma_chan_driver = {
-	.name = "of-fsl-dma-channel",
-	.match_table = of_fsl_dma_chan_ids,
-	.probe = of_fsl_dma_chan_probe,
-};
-
-static __init int of_fsl_dma_chan_init(void)
+static void fsl_dma_chan_remove(struct fsl_dma_chan *fchan)
 {
-	return of_register_platform_driver(&of_fsl_dma_chan_driver);
+	if (fchan) {
+		of_device_unregister(fchan->of_dev);
+
+		free_irq(fchan->irq, fchan);
+		list_del(&fchan->common.device_node);
+		iounmap(fchan->reg_base);
+		kfree(fchan);
+	}
 }
 
 static int __devinit of_fsl_dma_probe(struct of_device *dev,
 			const struct of_device_id *match)
 {
 	int err;
-	unsigned int irq;
 	struct fsl_dma_device *fdev;
+	struct device_node *child;
 
 	fdev = kzalloc(sizeof(struct fsl_dma_device), GFP_KERNEL);
 	if (!fdev) {
@@ -1085,9 +1088,9 @@ static int __devinit of_fsl_dma_probe(struct of_device *dev,
 	fdev->common.device_issue_pending = fsl_dma_memcpy_issue_pending;
 	fdev->common.dev = &dev->dev;
 
-	irq = irq_of_parse_and_map(dev->node, 0);
-	if (irq != NO_IRQ) {
-		err = request_irq(irq, &fsl_dma_do_interrupt, IRQF_SHARED,
+	fdev->irq = irq_of_parse_and_map(dev->node, 0);
+	if (fdev->irq != NO_IRQ) {
+		err = request_irq(fdev->irq, &fsl_dma_do_interrupt, IRQF_SHARED,
 					"fsldma-device", fdev);
 		if (err) {
 			dev_err(&dev->dev, "DMA device request_irq error "
@@ -1097,7 +1100,21 @@ static int __devinit of_fsl_dma_probe(struct of_device *dev,
 	}
 
 	dev_set_drvdata(&(dev->dev), fdev);
-	of_platform_bus_probe(dev->node, of_fsl_dma_chan_ids, &dev->dev);
+
+	/* We cannot use of_platform_bus_probe() because there is no
+	 * of_platform_bus_remove.  We have to manually instantiate every DMA
+	 * channel object.
+	 */
+	for_each_child_of_node(dev->node, child) {
+		if (of_device_is_compatible(child, "fsl,eloplus-dma-channel"))
+			fsl_dma_chan_probe(fdev, child,
+				FSL_DMA_IP_85XX | FSL_DMA_BIG_ENDIAN,
+				"fsl,eloplus-dma-channel");
+		if (of_device_is_compatible(child, "fsl,elo-dma-channel"))
+			fsl_dma_chan_probe(fdev, child,
+				FSL_DMA_IP_83XX | FSL_DMA_LITTLE_ENDIAN,
+				"fsl,elo-dma-channel");
+	}
 
 	dma_async_device_register(&fdev->common);
 	return 0;
@@ -1109,6 +1126,31 @@ err_no_reg:
 	return err;
 }
 
+static int of_fsl_dma_remove(struct of_device *of_dev)
+{
+	struct fsl_dma_device *fdev;
+	unsigned int i;
+
+	fdev = dev_get_drvdata(&of_dev->dev);
+
+	dma_async_device_unregister(&fdev->common);
+
+	for (i = 0; i < FSL_DMA_MAX_CHANS_PER_DEVICE; i++) {
+		fsl_dma_chan_remove(fdev->chan[i]);
+		fdev->chan[i] = NULL;
+	}
+
+	if (fdev->irq != NO_IRQ)
+		free_irq(fdev->irq, fdev);
+
+	iounmap(fdev->reg_base);
+
+	kfree(fdev);
+	dev_set_drvdata(&of_dev->dev, NULL);
+
+	return 0;
+}
+
 static struct of_device_id of_fsl_dma_ids[] = {
 	{ .compatible = "fsl,eloplus-dma", },
 	{ .compatible = "fsl,elo-dma", },
@@ -1116,15 +1158,32 @@ static struct of_device_id of_fsl_dma_ids[] = {
 };
 
 static struct of_platform_driver of_fsl_dma_driver = {
-	.name = "of-fsl-dma",
+	.name = "fsl-elo-dma",
 	.match_table = of_fsl_dma_ids,
 	.probe = of_fsl_dma_probe,
+	.remove = of_fsl_dma_remove,
 };
 
 static __init int of_fsl_dma_init(void)
 {
-	return of_register_platform_driver(&of_fsl_dma_driver);
+	int ret;
+
+	pr_info("Freescale Elo / Elo Plus DMA driver\n");
+
+	ret = of_register_platform_driver(&of_fsl_dma_driver);
+	if (ret)
+		pr_err("fsldma: failed to register platform driver\n");
+
+	return ret;
+}
+
+static void __exit of_fsl_dma_exit(void)
+{
+	of_unregister_platform_driver(&of_fsl_dma_driver);
 }
 
-subsys_initcall(of_fsl_dma_chan_init);
 subsys_initcall(of_fsl_dma_init);
+module_exit(of_fsl_dma_exit);
+
+MODULE_DESCRIPTION("Freescale Elo / Elo Plus DMA driver");
+MODULE_LICENSE("GPL");
diff --git a/drivers/dma/fsldma.h b/drivers/dma/fsldma.h
index 6faf07b..e0902dd 100644
--- a/drivers/dma/fsldma.h
+++ b/drivers/dma/fsldma.h
@@ -114,6 +114,7 @@ struct fsl_dma_device {
 	struct dma_device common;
 	struct fsl_dma_chan *chan[FSL_DMA_MAX_CHANS_PER_DEVICE];
 	u32 feature;		/* The same as DMA channels */
+	int irq;		/* Channel IRQ */
 };
 
 /* Define macros for fsl_dma_chan->feature property */
@@ -135,6 +136,7 @@ struct fsl_dma_chan {
 	struct dma_chan common;		/* DMA common channel */
 	struct dma_pool *desc_pool;	/* Descriptors pool */
 	struct device *dev;		/* Channel device */
+	struct of_device *of_dev;	/* OF device */
 	struct resource reg;		/* Resource for register */
 	int irq;			/* Channel IRQ */
 	int id;				/* Raw id of this channel */
-- 
1.5.5

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