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Date: Sat, 20 Sep 2008 14:32:09 -0700
From: "Dan Williams" <dan.j.williams@...el.com>
To: "Timur Tabi" <timur@...escale.com>
Cc: linux-kernel@...r.kernel.org,
"Andrew Morton" <akpm@...ux-foundation.org>, leoli@...escale.com
Subject: Re: [PATCH] fsl-dma: allow Freescale Elo DMA driver to be compiled as a module
[ added Li Yang to the cc ]
On Thu, Sep 18, 2008 at 9:24 AM, Timur Tabi <timur@...escale.com> wrote:
> 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>
I am not familiar with the Open Firmware interface so I'll trust you
on that piece, but please see 2 comments below.
Thanks,
Dan
> ---
>
> 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;
> }
The last three hunks should be broken out into a separate 'fix' patch
with its own changelog.
>
> 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);
> + }
> }
removing a NULL fchan should be an error right? Perhaps move the
check up to of_fsl_dma_remove().
>
> 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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