Re: [PATCH v4 13/24] iommu/mediatek: Add device link for smi-common and m4u

[Nicolas Boichat <drinkcat@chromium.org>]

On Wed, Nov 11, 2020 at 8:40 PM Yong Wu <yong.wu@mediatek.com> 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 | 36 +++++++++++++++++++++++++++++++++---
>  drivers/iommu/mtk_iommu.h |  1 +
>  2 files changed, 34 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
> index cfdf5ce696fd..4ce7e0883e4d 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>
> @@ -705,7 +706,7 @@ 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;
>
> @@ -731,6 +732,26 @@ static int mtk_iommu_probe(struct platform_device *pdev)
>
>                 component_match_add_release(dev, &match, release_of,
>                                             compare_of, larbnode);
> +               if (!i) {

Maybe more of a style preference, but since you are actually comparing
an integer, I prefer seeing i == 0.

Also, might be nicer to do

if (i != 0)
   continue;

And de-indent the rest.

> +                       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);
> @@ -738,14 +759,14 @@ 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);
>
>         ret = iommu_device_register(&data->iommu);
>         if (ret)
> -               return ret;
> +               goto out_sysfs_remove;

Technically, this change is unrelated.

>
>         spin_lock_init(&data->tlb_lock);
>         list_add_tail(&data->list, &m4ulist);
> @@ -754,6 +775,13 @@ static int mtk_iommu_probe(struct platform_device *pdev)
>                 bus_set_iommu(&platform_bus_type, &mtk_iommu_ops);
>
>         return component_master_add_with_match(dev, &mtk_iommu_com_ops, match);
> +
> +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;
>  }
>
>  static int mtk_iommu_remove(struct platform_device *pdev)
> @@ -767,6 +795,8 @@ 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
>