fsldma: 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(). Instead, the DMA channels are manually probed,
similar to what fsl_elbc_nand.c does.

Cc: Scott Wood <[e-mail]>
Acked-by: Li Yang <[e-mail]>
Signed-off-by: Timur Tabi <[e-mail]>
Signed-off-by: Dan Williams <[e-mail]>

drivers/dma/Kconfig

···
 	  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 FSL_SOC
 	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 some 82xx and 83xx parts, and the
+	  Elo Plus is the DMA controller on 85xx and 86xx parts.
 
 config MV_XOR
 	bool "Marvell XOR engine support"

drivers/dma/fsldma.c

···
 					struct dma_client *client)
 {
 	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.
···
 	}
 	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 *
···
 	fsl_chan_ld_cleanup(fsl_chan);
 }
 
-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;
 	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;
 	}
 
 	/* 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;
···
 	 */
 	WARN_ON(fdev->feature != new_fsl_chan->feature);
 
-	new_fsl_chan->dev = &dev->dev;
+	new_fsl_chan->dev = &new_fsl_chan->common.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",
+		dev_err(fdev->dev, "There is no %d channel!\n",
 				new_fsl_chan->id);
 		err = -EINVAL;
 		goto err_no_chan;
···
 			&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;
 		}
 	}
 
-	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;
 
···
 	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);
+	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) {
···
 	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 "
···
 	}
 
 	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.  Instead, we 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;
···
 	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++)
+		if (fdev->chan[i])
+			fsl_dma_chan_remove(fdev->chan[i]);
+
+	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", },
···
 };
 
 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;
 }
 
-subsys_initcall(of_fsl_dma_chan_init);
+static void __exit of_fsl_dma_exit(void)
+{
+	of_unregister_platform_driver(&of_fsl_dma_driver);
+}
+
 subsys_initcall(of_fsl_dma_init);
+module_exit(of_fsl_dma_exit);
+
+MODULE_DESCRIPTION("Freescale Elo / Elo Plus DMA driver");
+MODULE_LICENSE("GPL");

drivers/dma/fsldma.h

···
 	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 */