Re: [PATCH/RFC 3/6] DMA: shdma: add DT support

[Vinod Koul]

On Thu, Apr 11, 2013 at 12:19:46AM +0200, Guennadi Liakhovetski wrote:
> This patch adds Device Tree support to the shdma driver. No special DT
> properties are used, only standard DMA DT bindings are implemented. Since
> shdma controllers reside on SoCs, their configuration is SoC-specific and
> shall be passed to the driver from the SoC platform data, using the
> auxdata procedure.
> 
> Signed-off-by: Guennadi Liakhovetski <g.liakhovetski+renesas@xxxxxxxxx>
> ---
Need Arnd to review :)
> 
> Note concerning the filtering parameter. Without DT slave channels are 
> configured, based on a purely virtual slave ID, passed by DMA clients 
> to the shdma dmaengine driver. In the DT case we cannot use such 
> virtual IDs, we use a hardware MID/RID (DMA request ID) value. This is 
> confusing, ideally, all existing users should be converted to also use 
> MID/RID. This patch doesn't do that, it leaves existing users 
> unaffected and only uses MID/RID for DT.
> 
>  drivers/dma/sh/shdma-base.c |   51 +++++++++++++++++++++++++++++++++++++-----
>  drivers/dma/sh/shdma.c      |   44 ++++++++++++++++++++++++++++++++-----
>  include/linux/shdma-base.h  |    5 ++++
>  3 files changed, 88 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/dma/sh/shdma-base.c b/drivers/dma/sh/shdma-base.c
> index 4acb85a..4fd8293 100644
> --- a/drivers/dma/sh/shdma-base.c
> +++ b/drivers/dma/sh/shdma-base.c
> @@ -14,6 +14,8 @@
>   */
>  
>  #include <linux/delay.h>
> +#include <linux/of.h>
> +#include <linux/of_dma.h>
>  #include <linux/shdma-base.h>
>  #include <linux/dmaengine.h>
>  #include <linux/init.h>
> @@ -175,7 +177,18 @@ static int shdma_setup_slave(struct shdma_chan *schan, int slave_id)
>  {
>  	struct shdma_dev *sdev = to_shdma_dev(schan->dma_chan.device);
>  	const struct shdma_ops *ops = sdev->ops;
> -	int ret;
> +	int ret, match;
> +
> +	if (schan->dev->of_node) {
> +		match = schan->hw_req;
> +		ret = ops->set_slave(schan, match, true);
> +		if (ret < 0)
> +			return ret;
> +
> +		slave_id = schan->slave_id;
> +	} else {
> +		match = slave_id;
> +	}
>  
>  	if (slave_id < 0 || slave_id >= slave_num)
>  		return -EINVAL;
> @@ -183,7 +196,7 @@ static int shdma_setup_slave(struct shdma_chan *schan, int slave_id)
>  	if (test_and_set_bit(slave_id, shdma_slave_used))
>  		return -EBUSY;
>  
> -	ret = ops->set_slave(schan, slave_id, false);
> +	ret = ops->set_slave(schan, match, false);
>  	if (ret < 0) {
>  		clear_bit(slave_id, shdma_slave_used);
>  		return ret;
> @@ -206,23 +219,26 @@ static int shdma_setup_slave(struct shdma_chan *schan, int slave_id)
>   * services would have to provide their own filters, which first would check
>   * the device driver, similar to how other DMAC drivers, e.g., sa11x0-dma.c, do
>   * this, and only then, in case of a match, call this common filter.
> + * NOTE 2: This filter function is also used in the DT case by shdma_xlate().
> + * In that case the MID-RID value is used for slave channel filtering and is
> + * passed to this function in the "arg" parameter.
>   */
>  bool shdma_chan_filter(struct dma_chan *chan, void *arg)
>  {
>  	struct shdma_chan *schan = to_shdma_chan(chan);
>  	struct shdma_dev *sdev = to_shdma_dev(schan->dma_chan.device);
>  	const struct shdma_ops *ops = sdev->ops;
> -	int slave_id = (int)arg;
> +	int match = (int)arg;
>  	int ret;
>  
> -	if (slave_id < 0)
> +	if (match < 0)
>  		/* No slave requested - arbitrary channel */
>  		return true;
>  
> -	if (slave_id >= slave_num)
> +	if (!schan->dev->of_node && match >= slave_num)
>  		return false;
>  
> -	ret = ops->set_slave(schan, slave_id, true);
> +	ret = ops->set_slave(schan, match, true);
>  	if (ret < 0)
>  		return false;
>  
> @@ -867,6 +883,29 @@ void shdma_chan_remove(struct shdma_chan *schan)
>  }
>  EXPORT_SYMBOL(shdma_chan_remove);
>  
> +struct dma_chan *shdma_xlate(struct of_phandle_args *dma_spec,
> +				 struct of_dma *ofdma)
> +{
> +	struct shdma_dev *sdev = ofdma->of_dma_data;
> +	u32 id = dma_spec->args[0];
> +	dma_cap_mask_t mask;
> +	struct dma_chan *chan;
> +
> +	if (dma_spec->args_count != 1 || !sdev)
> +		return NULL;
> +
> +	dma_cap_zero(mask);
> +	/* Only slave DMA channels can be allocated via DT */
> +	dma_cap_set(DMA_SLAVE, mask);
> +
> +	chan = dma_request_channel(mask, shdma_chan_filter, (void *)id);
> +	if (chan)
> +		to_shdma_chan(chan)->hw_req = id;
> +
> +	return chan;
> +}
> +EXPORT_SYMBOL(shdma_xlate);
> +
>  int shdma_init(struct device *dev, struct shdma_dev *sdev,
>  		    int chan_num)
>  {
> diff --git a/drivers/dma/sh/shdma.c b/drivers/dma/sh/shdma.c
> index a5a1887..db497d6 100644
> --- a/drivers/dma/sh/shdma.c
> +++ b/drivers/dma/sh/shdma.c
> @@ -20,6 +20,8 @@
>  
>  #include <linux/init.h>
>  #include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_dma.h>
>  #include <linux/slab.h>
>  #include <linux/interrupt.h>
>  #include <linux/dmaengine.h>
> @@ -301,20 +303,32 @@ static void sh_dmae_setup_xfer(struct shdma_chan *schan,
>  	}
>  }
>  
> +/*
> + * Find a slave channel configuration from the contoller list by either a slave
> + * ID in the non-DT case, or by a MID/RID value in the DT case
> + */
>  static const struct sh_dmae_slave_config *dmae_find_slave(
> -	struct sh_dmae_chan *sh_chan, int slave_id)
> +	struct sh_dmae_chan *sh_chan, int match)
>  {
>  	struct sh_dmae_device *shdev = to_sh_dev(sh_chan);
>  	struct sh_dmae_pdata *pdata = shdev->pdata;
>  	const struct sh_dmae_slave_config *cfg;
>  	int i;
>  
> -	if (slave_id >= SH_DMA_SLAVE_NUMBER)
> -		return NULL;
> +	if (!sh_chan->shdma_chan.dev->of_node) {
> +		if (match >= SH_DMA_SLAVE_NUMBER)
> +			return NULL;
>  
> -	for (i = 0, cfg = pdata->slave; i < pdata->slave_num; i++, cfg++)
> -		if (cfg->slave_id == slave_id)
> -			return cfg;
> +		for (i = 0, cfg = pdata->slave; i < pdata->slave_num; i++, cfg++)
> +			if (cfg->slave_id == match)
> +				return cfg;
> +	} else {
> +		for (i = 0, cfg = pdata->slave; i < pdata->slave_num; i++, cfg++)
> +			if (cfg->mid_rid == match) {
> +				sh_chan->shdma_chan.slave_id = cfg->slave_id;
> +				return cfg;
> +			}
> +	}
>  
>  	return NULL;
>  }
> @@ -841,6 +855,14 @@ static int sh_dmae_probe(struct platform_device *pdev)
>  	if (err < 0)
>  		goto edmadevreg;
>  
> +	if (pdev->dev.of_node) {
> +		int of_err = of_dma_controller_register(pdev->dev.of_node,
> +							shdma_xlate, shdev);
> +		if (of_err < 0 && of_err != -ENODEV)
> +			dev_err(&pdev->dev,
> +				"could not register of_dma_controller\n");
> +	}
> +
>  	return err;
>  
>  edmadevreg:
> @@ -889,6 +911,9 @@ static int sh_dmae_remove(struct platform_device *pdev)
>  
>  	dma_async_device_unregister(dma_dev);
>  
> +	if (pdev->dev.of_node)
> +		of_dma_controller_free(pdev->dev.of_node);
> +
>  	if (errirq > 0)
>  		free_irq(errirq, shdev);
>  
> @@ -920,11 +945,18 @@ static int sh_dmae_remove(struct platform_device *pdev)
>  	return 0;
>  }
>  
> +static const struct of_device_id sh_dmae_of_match[] = {
> +	{ .compatible = "renesas,shdma", },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, sh_dmae_of_match);
> +
>  static struct platform_driver sh_dmae_driver = {
>  	.driver 	= {
>  		.owner	= THIS_MODULE,
>  		.pm	= &sh_dmae_pm,
>  		.name	= SH_DMAE_DRV_NAME,
> +		.of_match_table = sh_dmae_of_match,
>  	},
>  	.remove		= sh_dmae_remove,
>  	.shutdown	= sh_dmae_shutdown,
> diff --git a/include/linux/shdma-base.h b/include/linux/shdma-base.h
> index 9a93897..0815a0e 100644
> --- a/include/linux/shdma-base.h
> +++ b/include/linux/shdma-base.h
> @@ -19,6 +19,7 @@
>  #include <linux/dmaengine.h>
>  #include <linux/interrupt.h>
>  #include <linux/list.h>
> +#include <linux/of_dma.h>
>  #include <linux/types.h>
>  
>  /**
> @@ -68,6 +69,8 @@ struct shdma_chan {
>  	int id;				/* Raw id of this channel */
>  	int irq;			/* Channel IRQ */
>  	int slave_id;			/* Client ID for slave DMA */
> +	int hw_req;			/* DMA request line for slave DMA - same
> +					 * as MID/RID, used with DT */
>  	enum shdma_pm_state pm_state;
>  };
>  
> @@ -123,5 +126,7 @@ int shdma_init(struct device *dev, struct shdma_dev *sdev,
>  		    int chan_num);
>  void shdma_cleanup(struct shdma_dev *sdev);
>  bool shdma_chan_filter(struct dma_chan *chan, void *arg);
> +struct dma_chan *shdma_xlate(struct of_phandle_args *dma_spec,
> +			     struct of_dma *ofdma);
>  
>  #endif
> -- 
> 1.7.2.5
> 
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