Re: [PATCH v5 16/27] iommu/mediatek: Add device link for smi-common and m4u

[Tomasz Figa <tfiga@chromium.org>]

On Wed, Dec 09, 2020 at 04:00:51PM +0800, Yong Wu wrote:
> In the lastest SoC, M4U has its special power domain. thus, If the engine
> begin to work, it should help enable the power for M4U firstly.
> Currently if the engine work, it always enable the power/clocks for
> smi-larbs/smi-common. This patch adds device_link for smi-common and M4U.
> then, if smi-common power is enabled, the M4U power also is powered on
> automatically.
> 
> Normally M4U connect with several smi-larbs and their smi-common always
> are the same, In this patch it get smi-common dev from the first smi-larb
> device(i==0), then add the device_link only while m4u has power-domain.
> 
> Signed-off-by: Yong Wu <yong.wu@mediatek.com>
> ---
>  drivers/iommu/mtk_iommu.c | 30 ++++++++++++++++++++++++++++--
>  drivers/iommu/mtk_iommu.h |  1 +
>  2 files changed, 29 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
> index 09c8c58feb78..5614015e5b96 100644
> --- a/drivers/iommu/mtk_iommu.c
> +++ b/drivers/iommu/mtk_iommu.c
> @@ -20,6 +20,7 @@
>  #include <linux/of_irq.h>
>  #include <linux/of_platform.h>
>  #include <linux/platform_device.h>
> +#include <linux/pm_runtime.h>
>  #include <linux/regmap.h>
>  #include <linux/slab.h>
>  #include <linux/spinlock.h>
> @@ -706,7 +707,7 @@ static int mtk_iommu_probe(struct platform_device *pdev)
>  		return larb_nr;
>  
>  	for (i = 0; i < larb_nr; i++) {
> -		struct device_node *larbnode;
> +		struct device_node *larbnode, *smicomm_node;
>  		struct platform_device *plarbdev;
>  		u32 id;
>  
> @@ -732,6 +733,26 @@ static int mtk_iommu_probe(struct platform_device *pdev)
>  
>  		component_match_add_release(dev, &match, release_of,
>  					    compare_of, larbnode);
> +		if (i != 0)
> +			continue;

How about using the last larb instead and moving the code below outside
of the loop?

> +		smicomm_node = of_parse_phandle(larbnode, "mediatek,smi", 0);
> +		if (!smicomm_node)
> +			return -EINVAL;
> +
> +		plarbdev = of_find_device_by_node(smicomm_node);
> +		of_node_put(smicomm_node);
> +		data->smicomm_dev = &plarbdev->dev;
> +	}
> +
> +	if (dev->pm_domain) {
> +		struct device_link *link;
> +
> +		link = device_link_add(data->smicomm_dev, dev,
> +				       DL_FLAG_STATELESS | DL_FLAG_PM_RUNTIME);
> +		if (!link) {
> +			dev_err(dev, "Unable link %s.\n", dev_name(data->smicomm_dev));
> +			return -EINVAL;
> +		}
>  	}
>  
>  	platform_set_drvdata(pdev, data);
> @@ -739,7 +760,7 @@ static int mtk_iommu_probe(struct platform_device *pdev)
>  	ret = iommu_device_sysfs_add(&data->iommu, dev, NULL,
>  				     "mtk-iommu.%pa", &ioaddr);
>  	if (ret)
> -		return ret;
> +		goto out_link_remove;
>  
>  	iommu_device_set_ops(&data->iommu, &mtk_iommu_ops);
>  	iommu_device_set_fwnode(&data->iommu, &pdev->dev.of_node->fwnode);
> @@ -763,6 +784,9 @@ static int mtk_iommu_probe(struct platform_device *pdev)
>  	iommu_device_unregister(&data->iommu);
>  out_sysfs_remove:
>  	iommu_device_sysfs_remove(&data->iommu);
> +out_link_remove:
> +	if (dev->pm_domain)
> +		device_link_remove(data->smicomm_dev, dev);
>  	return ret;
>  }
>  
> @@ -777,6 +801,8 @@ static int mtk_iommu_remove(struct platform_device *pdev)
>  		bus_set_iommu(&platform_bus_type, NULL);
>  
>  	clk_disable_unprepare(data->bclk);
> +	if (pdev->dev.pm_domain)
> +		device_link_remove(data->smicomm_dev, &pdev->dev);
>  	devm_free_irq(&pdev->dev, data->irq, data);
>  	component_master_del(&pdev->dev, &mtk_iommu_com_ops);
>  	return 0;
> diff --git a/drivers/iommu/mtk_iommu.h b/drivers/iommu/mtk_iommu.h
> index d0c93652bdbe..5e03a029c4dc 100644
> --- a/drivers/iommu/mtk_iommu.h
> +++ b/drivers/iommu/mtk_iommu.h
> @@ -68,6 +68,7 @@ struct mtk_iommu_data {
>  
>  	struct iommu_device		iommu;
>  	const struct mtk_iommu_plat_data *plat_data;
> +	struct device			*smicomm_dev;
>  
>  	struct dma_iommu_mapping	*mapping; /* For mtk_iommu_v1.c */
>  
> -- 
> 2.18.0
> 
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