Re: [PATCH] soc: samsung: pm_domains: Convert to regular platform driver

[Saravana Kannan <saravanak@google.com>]

On Wed, Jan 13, 2021 at 3:03 AM Marek Szyprowski
<m.szyprowski@samsung.com> wrote:
>
> When Exynos power domain driver was introduced, the only way to ensure
> that power domains will be instantiated before the devices which belongs
> to them was to initialize them early enough, before the devices are
> instantiated in the system. This in turn required not to use any platform
> device infrastructure at all, as there have been no way to ensure proper
> probe order between devices.
>
> This has been finally changed and patch e590474768f1 ("driver core: Set
> fw_devlink=on by default") ensures that each device will be probbed only
> when its resource providers are ready. This allows to convert Exynos
> power domain driver to regular platform driver.
>
> This is also required by the mentioned commit to enable probing any
> device which belongs to the Exynos power domains, as otherwise the core
> won't notice that the power domains are in fact available.
>
> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
> ---
> Some more comments are in the following thread:
> https://lore.kernel.org/lkml/2556a69b-5da5-bf80-e051-df2d02fbc40f@samsung.com/
> ---
>  drivers/soc/samsung/pm_domains.c | 97 ++++++++++++++++----------------
>  1 file changed, 48 insertions(+), 49 deletions(-)
>
> diff --git a/drivers/soc/samsung/pm_domains.c b/drivers/soc/samsung/pm_domains.c
> index ab8582971bfc..5ec0c13f0aaf 100644
> --- a/drivers/soc/samsung/pm_domains.c
> +++ b/drivers/soc/samsung/pm_domains.c
> @@ -16,7 +16,7 @@
>  #include <linux/delay.h>
>  #include <linux/of_address.h>
>  #include <linux/of_platform.h>
> -#include <linux/sched.h>
> +#include <linux/pm_runtime.h>
>
>  struct exynos_pm_domain_config {
>         /* Value for LOCAL_PWR_CFG and STATUS fields for each domain */
> @@ -73,15 +73,15 @@ static int exynos_pd_power_off(struct generic_pm_domain *domain)
>         return exynos_pd_power(domain, false);
>  }
>
> -static const struct exynos_pm_domain_config exynos4210_cfg __initconst = {
> +static const struct exynos_pm_domain_config exynos4210_cfg = {
>         .local_pwr_cfg          = 0x7,
>  };
>
> -static const struct exynos_pm_domain_config exynos5433_cfg __initconst = {
> +static const struct exynos_pm_domain_config exynos5433_cfg = {
>         .local_pwr_cfg          = 0xf,
>  };
>
> -static const struct of_device_id exynos_pm_domain_of_match[] __initconst = {
> +static const struct of_device_id exynos_pm_domain_of_match[] = {
>         {
>                 .compatible = "samsung,exynos4210-pd",
>                 .data = &exynos4210_cfg,
> @@ -92,7 +92,7 @@ static const struct of_device_id exynos_pm_domain_of_match[] __initconst = {
>         { },
>  };
>
> -static __init const char *exynos_get_domain_name(struct device_node *node)
> +static const char *exynos_get_domain_name(struct device_node *node)
>  {
>         const char *name;
>
> @@ -101,60 +101,44 @@ static __init const char *exynos_get_domain_name(struct device_node *node)
>         return kstrdup_const(name, GFP_KERNEL);
>  }
>
> -static __init int exynos4_pm_init_power_domain(void)
> +static int exynos_pd_probe(struct platform_device *pdev)
>  {
> -       struct device_node *np;
> -       const struct of_device_id *match;
> -
> -       for_each_matching_node_and_match(np, exynos_pm_domain_of_match, &match) {
> -               const struct exynos_pm_domain_config *pm_domain_cfg;
> -               struct exynos_pm_domain *pd;
> -               int on;
> +       const struct exynos_pm_domain_config *pm_domain_cfg;
> +       struct device *dev = &pdev->dev;
> +       struct device_node *np = dev->of_node;
> +       struct of_phandle_args child, parent;
> +       struct exynos_pm_domain *pd;
> +       int on, ret;
>
> -               pm_domain_cfg = match->data;
> +       pm_domain_cfg = of_device_get_match_data(dev);
> +       pd = devm_kzalloc(dev, sizeof(*pd), GFP_KERNEL);
> +       if (!pd)
> +               return -ENOMEM;
>
> -               pd = kzalloc(sizeof(*pd), GFP_KERNEL);
> -               if (!pd) {
> -                       of_node_put(np);
> -                       return -ENOMEM;
> -               }
> -               pd->pd.name = exynos_get_domain_name(np);
> -               if (!pd->pd.name) {
> -                       kfree(pd);
> -                       of_node_put(np);
> -                       return -ENOMEM;
> -               }
> +       pd->pd.name = exynos_get_domain_name(np);
> +       if (!pd->pd.name)
> +               return -ENOMEM;
>
> -               pd->base = of_iomap(np, 0);
> -               if (!pd->base) {
> -                       pr_warn("%s: failed to map memory\n", __func__);
> -                       kfree_const(pd->pd.name);
> -                       kfree(pd);
> -                       continue;
> -               }
> -
> -               pd->pd.power_off = exynos_pd_power_off;
> -               pd->pd.power_on = exynos_pd_power_on;
> -               pd->local_pwr_cfg = pm_domain_cfg->local_pwr_cfg;
> +       pd->base = of_iomap(np, 0);
> +       if (!pd->base) {
> +               kfree_const(pd->pd.name);
> +               return -ENODEV;
> +       }
>
> -               on = readl_relaxed(pd->base + 0x4) & pd->local_pwr_cfg;
> +       pd->pd.power_off = exynos_pd_power_off;
> +       pd->pd.power_on = exynos_pd_power_on;
> +       pd->local_pwr_cfg = pm_domain_cfg->local_pwr_cfg;
>
> -               pm_genpd_init(&pd->pd, NULL, !on);
> -               of_genpd_add_provider_simple(np, &pd->pd);
> -       }
> +       on = readl_relaxed(pd->base + 0x4) & pd->local_pwr_cfg;
>
> -       /* Assign the child power domains to their parents */
> -       for_each_matching_node(np, exynos_pm_domain_of_match) {
> -               struct of_phandle_args child, parent;
> +       pm_genpd_init(&pd->pd, NULL, !on);
> +       ret = of_genpd_add_provider_simple(np, &pd->pd);
>
> +       if (ret == 0 && of_parse_phandle_with_args(np, "power-domains",
> +                                     "#power-domain-cells", 0, &parent) == 0) {
>                 child.np = np;
>                 child.args_count = 0;
>
> -               if (of_parse_phandle_with_args(np, "power-domains",
> -                                              "#power-domain-cells", 0,
> -                                              &parent) != 0)
> -                       continue;
> -
>                 if (of_genpd_add_subdomain(&parent, &child))
>                         pr_warn("%pOF failed to add subdomain: %pOF\n",
>                                 parent.np, child.np);
> @@ -163,6 +147,21 @@ static __init int exynos4_pm_init_power_domain(void)
>                                 parent.np, child.np);
>         }
>
> -       return 0;
> +       pm_runtime_enable(dev);
> +       return ret;
> +}
> +
> +static struct platform_driver exynos_pd_driver = {
> +       .probe  = exynos_pd_probe,
> +       .driver = {
> +               .name           = "exynos-pd",
> +               .of_match_table = exynos_pm_domain_of_match,
> +               .suppress_bind_attrs = true,
> +       }
> +};
> +
> +static __init int exynos4_pm_init_power_domain(void)
> +{
> +       return platform_driver_register(&exynos_pd_driver);
>  }
>  core_initcall(exynos4_pm_init_power_domain);
> --
> 2.17.1
>

Skimmed through this patch and at a high level, it looks good for what
it's trying to do. Thanks for doing this!

Btw, I assume that this won't work with fw_devlink=off/permissive
(default since 5.10 or earlier)? My concern is that we might
temporarily set fw_devlink=permissive by default if the other
breakages aren't fixed in time for 5.12? How do you want to handle that?

-Saravana