Re: [PATCH v2 5/7] staging: board: Add support for devices with complex dependencies

[Geert Uytterhoeven <geert@linux-m68k.org>]

	Hi Ulf,

On Fri, 4 Sep 2015, Ulf Hansson wrote:
> On 3 September 2015 at 15:35, Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> > On Thu, Sep 3, 2015 at 2:53 PM, Ulf Hansson <ulf.hansson@linaro.org> wrote:
> >> On 17 June 2015 at 10:38, Geert Uytterhoeven <geert+renesas@glider.be> wrote:
> >>> Add support for easy registering of one ore more platform devices that
> >>> may:
> >>>   - need clocks that are described in DT,
> >>>   - be part of a PM Domain.
> >
> >>> diff --git a/drivers/staging/board/board.c b/drivers/staging/board/board.c
> >>> index 8712f566b31196e0..29d456e29f38feac 100644
> >>> --- a/drivers/staging/board/board.c
> >>> +++ b/drivers/staging/board/board.c
> >
> >>> +int __init board_staging_register_device(const struct board_staging_dev *dev)
> >>> +{
> >>> +       struct platform_device *pdev = dev->pdev;
> >>> +       unsigned int i;
> >>> +       int error;
> >>> +
> >>> +       pr_debug("Trying to register device %s\n", pdev->name);
> >>> +       if (board_staging_dt_node_available(pdev->resource,
> >>> +                                           pdev->num_resources)) {
> >>> +               pr_warn("Skipping %s, already in DT\n", pdev->name);
> >>> +               return -EEXIST;
> >>> +       }
> >>> +
> >>> +       board_staging_gic_fixup_resources(pdev->resource, pdev->num_resources);
> >>> +
> >>> +       for (i = 0; i < dev->nclocks; i++)
> >>> +               board_staging_register_clock(&dev->clocks[i]);
> >>> +
> >>> +       error = platform_device_register(pdev);
> >>> +       if (error) {
> >>> +               pr_err("Failed to register device %s (%d)\n", pdev->name,
> >>> +                      error);
> >>> +               return error;
> >>> +       }
> >>> +
> >>> +       if (dev->domain)
> >>> +               __pm_genpd_name_add_device(dev->domain, &pdev->dev, NULL);
> >>
> >> Urgh, this managed to slip through my filters.
> >>
> >> It seems like we almost managed to remove all users of the
> >> "..._name_add..." APIs for genpd. If hasn't been for $subject patch.
> >> :-)
> >>
> >> Now, I realize this is already too late here, but let's try to fix
> >> this before it turns into a bigger issue.
> >>
> >> Geert, do you think it's possible to convert into using the non-named
> >> bases APIs?
> >
> > That will be difficult. This code is meant to use drivers that are not yet
> > DT-aware on DT-based systems. Hence it uses platform devices with named PM
> > domains, while the PM domains are described in DT.
> > I don't think there's another way to look up a PM domain by name, is there?
> 
> As a matter of fact there are, especially for those genpds that has
> been created through DT as in this case. The API to use is
> of_genpd_get_from_provider() to find the struct generic_pm_domain.

Thanks!

> Yes, I do realize that you need to manage the parsing of the domain
> name to make sure it's the one you want, but I would rather keep that
> "hack" in this driver than in the generic API.

OK. It turned out not to be that complex, cfr. the patch below.
For now this supports PM domains with "#power-domain-cells = <0>" only,
but of course it can be extended if the need arises.

I've also tried:

    np = of_find_compatible_node(NULL, NULL, "renesas,sysc-rmobile");
    np = of_find_node_by_name(np, "a4lc");

(the second step is needed because of the domain hierarchy in DT), but that
would require adding the compatible string to struct board_staging_dev,
and doesn't work if you have multiple identical power providers.

I hope you like it?

>From 5fb11904845eb929a5b3382a9d5153c151cde1cf Mon Sep 17 00:00:00 2001
From: Geert Uytterhoeven <geert+renesas@glider.be>
Date: Fri, 4 Sep 2015 16:52:33 +0200
Subject: [PATCH/RFC] staging: board: Migrate away from
 __pm_genpd_name_add_device()

The named genpd APIs are deprecated. Hence convert the board staging
code from using genpd names to DT node paths.

For now this supports PM domains with "#power-domain-cells = <0>" only.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
 drivers/staging/board/armadillo800eva.c |  2 +-
 drivers/staging/board/board.c           | 36 ++++++++++++++++++++++++++++++++-
 2 files changed, 36 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/board/armadillo800eva.c b/drivers/staging/board/armadillo800eva.c
index 0165591a52443c46..912c96b0536def7c 100644
--- a/drivers/staging/board/armadillo800eva.c
+++ b/drivers/staging/board/armadillo800eva.c
@@ -91,7 +91,7 @@ static const struct board_staging_dev armadillo800eva_devices[] __initconst = {
 		.pdev		= &lcdc0_device,
 		.clocks		= lcdc0_clocks,
 		.nclocks	= ARRAY_SIZE(lcdc0_clocks),
-		.domain		= "a4lc",
+		.domain		= "/system-controller@e6180000/pm-domains/c5/a4lc@1"
 	},
 };
 
diff --git a/drivers/staging/board/board.c b/drivers/staging/board/board.c
index 29d456e29f38feac..3eb5eb8f069c236d 100644
--- a/drivers/staging/board/board.c
+++ b/drivers/staging/board/board.c
@@ -135,6 +135,40 @@ int __init board_staging_register_clock(const struct board_staging_clk *bsc)
 	return error;
 }
 
+#ifdef CONFIG_PM_GENERIC_DOMAINS_OF
+static int board_staging_add_dev_domain(struct platform_device *pdev,
+					const char *domain)
+{
+	struct of_phandle_args pd_args;
+	struct generic_pm_domain *pd;
+	struct device_node *np;
+
+	np = of_find_node_by_path(domain);
+	if (!np) {
+		pr_err("Cannot find domain node %s\n", domain);
+		return -ENOENT;
+	}
+
+	pd_args.np = np;
+	pd_args.args_count = 0;
+	pd = of_genpd_get_from_provider(&pd_args);
+	if (IS_ERR(pd)) {
+		pr_err("Cannot find genpd %s (%ld)\n", domain, PTR_ERR(pd));
+		return PTR_ERR(pd);
+
+	}
+	pr_debug("Found genpd %s for device %s\n", pd->name, pdev->name);
+
+	return pm_genpd_add_device(pd, &pdev->dev);
+}
+#else
+static inline int board_staging_add_dev_domain(struct platform_device *pdev,
+					       const char *domain)
+{
+	return 0;
+}
+#endif
+
 int __init board_staging_register_device(const struct board_staging_dev *dev)
 {
 	struct platform_device *pdev = dev->pdev;
@@ -161,7 +195,7 @@ int __init board_staging_register_device(const struct board_staging_dev *dev)
 	}
 
 	if (dev->domain)
-		__pm_genpd_name_add_device(dev->domain, &pdev->dev, NULL);
+		board_staging_add_dev_domain(pdev, dev->domain);
 
 	return error;
 }
-- 
1.9.1

Gr{oetje,eeting}s,

						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
							    -- Linus Torvalds