Re: [PATCH v3 2/4] dmaengine: at_hdmac: add device tree support

[Grant Likely <grant.likely@secretlab.ca>]

On Wed, Oct 12, 2011 at 06:57:12PM +0200, Nicolas Ferre wrote:
> Add device tree probe support for atmel at_hdmac DMA driver.
> Bindings are added to specify DMA controller configuration.
> 
> Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
> ---
>  .../devicetree/bindings/dma/atmel-dma.txt          |   14 +++++++++
>  drivers/dma/at_hdmac.c                             |   30 +++++++++++++++++++-
>  2 files changed, 43 insertions(+), 1 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/dma/atmel-dma.txt
> 
> diff --git a/Documentation/devicetree/bindings/dma/atmel-dma.txt b/Documentation/devicetree/bindings/dma/atmel-dma.txt
> new file mode 100644
> index 0000000..3c046ee
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/dma/atmel-dma.txt
> @@ -0,0 +1,14 @@
> +* Atmel Direct Memory Access Controller (DMA)
> +
> +Required properties:
> +- compatible: Should be "atmel,<chip>-dma"
> +- reg: Should contain DMA registers location and length
> +- interrupts: Should contain DMA interrupt
> +
> +Examples:
> +
> +dma@ffffec00 {
> +	compatible = "atmel,at91sam9g45-dma";
> +	reg = <0xffffec00 0x200>;
> +	interrupts = <21>;
> +};
> diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c
> index d1869c5..42bd64c 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"
>  
> @@ -1175,6 +1177,20 @@ 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-dma",
> +		.data = (void *)ATDMA_DEVTYPE_SAM9RL
> +	}, {
> +		.compatible = "atmel,at91sam9g45-dma",
> +		.data = (void *)ATDMA_DEVTYPE_SAM9G45
> +	}, { /* sentinel */ }
> +};
> +
> +MODULE_DEVICE_TABLE(of, atmel_dma_dt_ids);
> +#endif
> +
>  static struct platform_device_id atdma_devtypes[] = {
>  	{
>  		.name = "at91sam9rl_dma",
> @@ -1187,6 +1203,17 @@ static struct platform_device_id atdma_devtypes[] = {
>  	}
>  };
>  
> +static inline enum atdma_devtype __init at_dma_get_driver_data(
> +					struct platform_device *pdev)
> +{
> +	if (pdev->dev.of_node) {
> +		const struct of_device_id *match;
> +		match = of_match_node(atmel_dma_dt_ids, pdev->dev.of_node);

You'll need to check the return value.  It is possible (though
unlikely) to have a device with an of_node but still happens to get
bound via the platform_driver id_table.  In which case match would be
NULL here.

Otherwise, you can add my a-b after fixing that bug.

Acked-by: Grant Likely <grant.likely@secretlab.ca>

g.


> +		return (enum atdma_devtype)match->data;
> +	}
> +	return platform_get_device_id(pdev)->driver_data;
> +}
> +
>  /**
>   * at_dma_off - disable DMA controller
>   * @atdma: the Atmel HDAMC device
> @@ -1218,7 +1245,7 @@ static int __init at_dma_probe(struct platform_device *pdev)
>  	dma_cap_set(DMA_MEMCPY, cap_mask);
>  
>  	/* get DMA parameters from controller type */
> -	atdmatype = platform_get_device_id(pdev)->driver_data;
> +	atdmatype = at_dma_get_driver_data(pdev);
>  
>  	switch (atdmatype) {
>  	case ATDMA_DEVTYPE_SAM9RL:
> @@ -1526,6 +1553,7 @@ static struct platform_driver at_dma_driver = {
>  	.driver = {
>  		.name	= "at_hdmac",
>  		.pm	= &at_dma_dev_pm_ops,
> +		.of_match_table	= of_match_ptr(atmel_dma_dt_ids),
>  	},
>  };
>  
> -- 
> 1.7.5.4
>