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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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