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    SubjectRe: [PATCH] dmaengine: at_hdmac: add device tree probe
    On Fri, Aug 05, 2011 at 01:58:40PM +0100, Nicolas Ferre wrote:
    > Add device tree probe support for atmel at_hdmac DMA driver.
    > Bindings are added to specify the number of channels that the implementation of
    > the controller actually has. They also allow to tell if the peripherals/DMA
    > transfer is supported by the IP.
    >
    > Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
    > ---
    > .../devicetree/bindings/dma/atmel-hdmac.txt | 23 +++++++++
    > drivers/dma/at_hdmac.c | 51 ++++++++++++++++----
    > 2 files changed, 65 insertions(+), 9 deletions(-)
    > create mode 100644 Documentation/devicetree/bindings/dma/atmel-hdmac.txt
    >
    > diff --git a/Documentation/devicetree/bindings/dma/atmel-hdmac.txt b/Documentation/devicetree/bindings/dma/atmel-hdmac.txt
    > new file mode 100644
    > index 0000000..0e48553
    > --- /dev/null
    > +++ b/Documentation/devicetree/bindings/dma/atmel-hdmac.txt
    > @@ -0,0 +1,23 @@
    > +* Atmel Direct Memory Access Controller
    > +
    > +Required properties:
    > +- compatible: Should be "atmel,<chip>-hdmac"
    > +- reg: Should contain DMA registers location and length
    > +- interrupts: Should contain DMA interrupt
    > +- atmel,hdmac-nr-channels: Should contain number of channels
    > + available in the controller
    > +
    > +Optional properties:
    > +- atmel,hdmac-cap-memcpy: Chip can do memory to memory transfers
    > +- atmel,hdmac-cap-slave: Chip can do peripherals/memory transfers

    Heh, ignore my comments on the other patch about missing documentation
    for the dma engine. :-)

    Otherwise the patch looks pretty good. I suspect there is a thing or
    two that won't compile correctly when !CONFIG_OF, but I haven't
    checked closely. Just make sure !CONFIG_OF is tested. :-)

    g.


    > +
    > +Examples:
    > +
    > +dma@ffffec00 {
    > + compatible = "atmel,at91sam9g45-hdmac";
    > + reg = <0xffffec00 0x200>;
    > + interrupts = <21>;
    > + atmel,hdmac-nr-channels = <8>;
    > + atmel,hdmac-cap-memcpy;
    > + atmel,hdmac-cap-slave;
    > +};
    > diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c
    > index 8f1d2ee..4a0cefe 100644
    > --- a/drivers/dma/at_hdmac.c
    > +++ b/drivers/dma/at_hdmac.c
    > @@ -23,6 +23,8 @@
    > #include <linux/module.h>
    > #include <linux/platform_device.h>
    > #include <linux/slab.h>
    > +#include <linux/of.h>
    > +#include <linux/of_device.h>
    >
    > #include "at_hdmac_regs.h"
    >
    > @@ -1167,6 +1169,18 @@ static void atc_free_chan_resources(struct dma_chan *chan)
    >
    > /*-- Module Management -----------------------------------------------*/
    >
    > +#if defined(CONFIG_OF)
    > +static const struct of_device_id atmel_dma_dt_ids[] = {
    > + { .compatible = "atmel,at91sam9rl-hdmac" },
    > + { .compatible = "atmel,at91sam9g45-hdmac" },
    > + { /* sentinel */ }
    > +};
    > +
    > +MODULE_DEVICE_TABLE(of, atmel_dma_dt_ids);
    > +#else
    > +#define atmel_dma_dt_ids NULL
    > +#endif
    > +
    > /**
    > * at_dma_off - disable DMA controller
    > * @atdma: the Atmel HDAMC device
    > @@ -1185,17 +1199,36 @@ static void at_dma_off(struct at_dma *atdma)
    >
    > static int __init at_dma_probe(struct platform_device *pdev)
    > {
    > - struct at_dma_platform_data *pdata;
    > + const struct of_device_id *of_id =
    > + of_match_device(atmel_dma_dt_ids, &pdev->dev);
    > + struct device_node *np = pdev->dev.of_node;
    > + struct at_dma_platform_data *pdata = pdev->dev.platform_data;
    > struct resource *io;
    > struct at_dma *atdma;
    > size_t size;
    > int irq;
    > int err;
    > int i;
    > + u32 nr_channels;
    > + dma_cap_mask_t cap_mask = {};
    > +
    > + /* get DMA Controller parameters */
    > + if (of_id) {
    > + if (of_property_read_u32(np, "atmel,hdmac-nr-channels",
    > + &nr_channels))
    > + return -EINVAL;
    > + if (of_find_property(np, "atmel,hdmac-cap-memcpy", NULL))
    > + dma_cap_set(DMA_MEMCPY, cap_mask);
    > + if (of_find_property(np, "atmel,hdmac-cap-slave", NULL))
    > + dma_cap_set(DMA_SLAVE, cap_mask);
    > + } else if (pdata) {
    > + nr_channels = pdata->nr_channels;
    > + cap_mask = pdata->cap_mask;
    > + } else {
    > + return -EINVAL;
    > + }
    >
    > - /* get DMA Controller parameters from platform */
    > - pdata = pdev->dev.platform_data;
    > - if (!pdata || pdata->nr_channels > AT_DMA_MAX_NR_CHANNELS)
    > + if (!nr_channels || nr_channels > AT_DMA_MAX_NR_CHANNELS)
    > return -EINVAL;
    >
    > io = platform_get_resource(pdev, IORESOURCE_MEM, 0);
    > @@ -1207,14 +1240,13 @@ static int __init at_dma_probe(struct platform_device *pdev)
    > return irq;
    >
    > size = sizeof(struct at_dma);
    > - size += pdata->nr_channels * sizeof(struct at_dma_chan);
    > + size += nr_channels * sizeof(struct at_dma_chan);
    > atdma = kzalloc(size, GFP_KERNEL);
    > if (!atdma)
    > return -ENOMEM;
    >
    > - /* discover transaction capabilites from the platform data */
    > - atdma->dma_common.cap_mask = pdata->cap_mask;
    > - atdma->all_chan_mask = (1 << pdata->nr_channels) - 1;
    > + atdma->dma_common.cap_mask = cap_mask;
    > + atdma->all_chan_mask = (1 << nr_channels) - 1;
    >
    > size = io->end - io->start + 1;
    > if (!request_mem_region(io->start, size, pdev->dev.driver->name)) {
    > @@ -1260,7 +1292,7 @@ static int __init at_dma_probe(struct platform_device *pdev)
    >
    > /* initialize channels related values */
    > INIT_LIST_HEAD(&atdma->dma_common.channels);
    > - for (i = 0; i < pdata->nr_channels; i++, atdma->dma_common.chancnt++) {
    > + for (i = 0; i < nr_channels; i++, atdma->dma_common.chancnt++) {
    > struct at_dma_chan *atchan = &atdma->chan[i];
    >
    > atchan->chan_common.device = &atdma->dma_common;
    > @@ -1406,6 +1438,7 @@ static struct platform_driver at_dma_driver = {
    > .driver = {
    > .name = "at_hdmac",
    > .pm = &at_dma_dev_pm_ops,
    > + .of_match_table = atmel_dma_dt_ids,
    > },
    > };
    >
    > --
    > 1.7.4.1
    >
    >
    > _______________________________________________
    > linux-arm-kernel mailing list
    > linux-arm-kernel@lists.infradead.org
    > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel


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