Message-ID: <CAGb2v65G-8EECNjqnpKCxqAD5nATAb0S7AA_WMiGXYOR1avrvg@mail.gmail.com>
Date:   Wed, 13 Sep 2023 12:37:54 +0800
From:   Chen-Yu Tsai <wens@...nel.org>
To:     Linus Walleij <linus.walleij@...aro.org>
Cc:     Sascha Hauer <s.hauer@...gutronix.de>,
        Saravana Kannan <saravanak@...gle.com>,
        linux-rockchip@...ts.infradead.org,
        Heiko Stuebner <heiko@...ech.de>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, linux-gpio@...r.kernel.org,
        kernel@...gutronix.de,
        Quentin Schulz <quentin.schulz@...obroma-systems.com>,
        Michael Riesch <michael.riesch@...fvision.net>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>
Subject: Re: [PATCH 1/3] pinctrl: rockchip: add support for io-domain dependency

On Tue, Sep 12, 2023 at 4:07 PM Linus Walleij <linus.walleij@...aro.org> wrote:
>
> Top posting to bring Saravana Kannan into this discussion.
>
> This looks like a big hack to me, Saravana has been working
> tirelessly to make the device tree probe order "sort itself out"
> and I am pretty sure this issue needs to be fixed at the DT
> core level and not in a driver.

We could merge all the IO domain stuff into the pinctrl node/driver,
like is done for Allwinner? Maybe that would simplify things a bit?

IIRC on Allwinner SoCs the PMIC pins don't have a separate power rail,
or if they do they almost certainly use the default I/O rail that is
always on, and so we omit it to work around the dependency cycle.

ChenYu



> Saravana, can you advice how we should handle this properly?
>
> Yours,
> Linus Walleij
>
> On Mon, Sep 4, 2023 at 1:58 PM Sascha Hauer <s.hauer@...gutronix.de> wrote:
> >
> > On some Rockchip SoCs, some SoC pins are split in what are called IO
> > domains.
> >
> > An IO domain is supplied power externally, by regulators from a PMIC for
> > example. This external power supply is then used by the IO domain as
> > "supply" for the IO pins if they are outputs.
> >
> > Each IO domain can configure which voltage the IO pins will be operating
> > on (1.8V or 3.3V).
> >
> > There already exists an IO domain driver for Rockchip SoCs[1]. This
> > driver allows to explicit the relationship between the external power
> > supplies and IO domains[2]. This makes sure the regulators are enabled
> > by the Linux kernel so the IO domains are supplied with power and
> > correctly configured as per the supplied voltage.
> > This driver is a regulator consumer and does not offer any other
> > interface for device dependency.
> >
> > However, IO pins belonging to an IO domain need to have this IO domain
> > configured correctly before they are being used otherwise they do not
> > operate correctly.
> >
> > We currently do not have any knowledge about which pin is on which IO
> > domain, so we assume that all pins are on some IO domain and defer
> > probing of the pin consumers until the IO domain driver has been probed.
> > Some pins however are needed to access the regulators driving an IO
> > domain. Deferring probe for them as well would introduce a cyclic
> > dependency. To break out of this dependency a pin group can be supplied
> > a rockchip,io-domain-boot-on property. Probe won't be deferred for pin
> > groups with this property. rockchip,io-domain-boot-on should be added
> > to all pin groups needed to access the PMIC driving the IO domains.
> >
> > [1] drivers/soc/rockchip/io-domain.c
> > [2] Documentation/devicetree/bindings/power/rockchip-io-domain.yaml
> >
> > Signed-off-by: Sascha Hauer <s.hauer@...gutronix.de>
> > ---
> >  drivers/pinctrl/pinctrl-rockchip.c | 64 ++++++++++++++++++++++++++++++
> >  drivers/pinctrl/pinctrl-rockchip.h |  3 ++
> >  2 files changed, 67 insertions(+)
> >
> > diff --git a/drivers/pinctrl/pinctrl-rockchip.c b/drivers/pinctrl/pinctrl-rockchip.c
> > index 0276b52f37168..663bd9d6840a5 100644
> > --- a/drivers/pinctrl/pinctrl-rockchip.c
> > +++ b/drivers/pinctrl/pinctrl-rockchip.c
> > @@ -24,6 +24,8 @@
> >  #include <linux/of_address.h>
> >  #include <linux/of_device.h>
> >  #include <linux/of_irq.h>
> > +#include <linux/of_platform.h>
> > +#include <linux/platform_device.h>
> >  #include <linux/pinctrl/machine.h>
> >  #include <linux/pinctrl/pinconf.h>
> >  #include <linux/pinctrl/pinctrl.h>
> > @@ -2678,6 +2680,43 @@ static int rockchip_pmx_get_groups(struct pinctrl_dev *pctldev,
> >         return 0;
> >  }
> >
> > +static int rockchip_pmx_check_io_domain(struct rockchip_pinctrl *info, unsigned group)
> > +{
> > +       struct platform_device *pdev;
> > +       int i;
> > +
> > +       if (!info->io_domains)
> > +               return 0;
> > +
> > +       if (info->groups[group].io_domain_skip)
> > +               return 0;
> > +
> > +       for (i = 0; i < info->num_io_domains; i++) {
> > +               if (!info->io_domains[i])
> > +                       continue;
> > +
> > +               pdev = of_find_device_by_node(info->io_domains[i]);
> > +               if (!pdev) {
> > +                       dev_err(info->dev, "couldn't find IO domain device\n");
> > +                       return -ENODEV;
> > +               }
> > +
> > +               if (!platform_get_drvdata(pdev)) {
> > +                       dev_err(info->dev, "IO domain device is not probed yet, deferring...(%s)",
> > +                               info->groups[group].name);
> > +                       return -EPROBE_DEFER;
> > +               }
> > +
> > +               of_node_put(info->io_domains[i]);
> > +               info->io_domains[i] = NULL;
> > +       }
> > +
> > +       devm_kfree(info->dev, info->io_domains);
> > +       info->io_domains = NULL;
> > +
> > +       return 0;
> > +}
> > +
> >  static int rockchip_pmx_set(struct pinctrl_dev *pctldev, unsigned selector,
> >                             unsigned group)
> >  {
> > @@ -2691,6 +2730,10 @@ static int rockchip_pmx_set(struct pinctrl_dev *pctldev, unsigned selector,
> >         dev_dbg(dev, "enable function %s group %s\n",
> >                 info->functions[selector].name, info->groups[group].name);
> >
> > +       ret = rockchip_pmx_check_io_domain(info, group);
> > +       if (ret)
> > +               return ret;
> > +
> >         /*
> >          * for each pin in the pin group selected, program the corresponding
> >          * pin function number in the config register.
> > @@ -3019,6 +3062,8 @@ static int rockchip_pinctrl_parse_groups(struct device_node *np,
> >         if (!size || size % 4)
> >                 return dev_err_probe(dev, -EINVAL, "wrong pins number or pins and configs should be by 4\n");
> >
> > +       grp->io_domain_skip = of_property_read_bool(np, "rockchip,io-domain-boot-on");
> > +
> >         grp->npins = size / 4;
> >
> >         grp->pins = devm_kcalloc(dev, grp->npins, sizeof(*grp->pins), GFP_KERNEL);
> > @@ -3417,6 +3462,22 @@ static int rockchip_pinctrl_probe(struct platform_device *pdev)
> >                         return PTR_ERR(info->regmap_pmu);
> >         }
> >
> > +       info->num_io_domains = of_property_count_u32_elems(np, "rockchip,io-domains");
> > +       if (info->num_io_domains) {
> > +               int i;
> > +
> > +               info->io_domains = devm_kmalloc_array(dev, info->num_io_domains,
> > +                                                     sizeof(*info->io_domains), GFP_KERNEL);
> > +               if (!info->io_domains)
> > +                       return -ENOMEM;
> > +
> > +               for (i = 0; i < info->num_io_domains; i++) {
> > +                       info->io_domains[i] = of_parse_phandle(np, "rockchip,io-domains", 0);
> > +                       if (!info->io_domains[i])
> > +                               return -EINVAL;
> > +               }
> > +       }
> > +
> >         ret = rockchip_pinctrl_register(pdev, info);
> >         if (ret)
> >                 return ret;
> > @@ -3439,6 +3500,9 @@ static int rockchip_pinctrl_remove(struct platform_device *pdev)
> >
> >         of_platform_depopulate(&pdev->dev);
> >
> > +       for (i = 0; i < info->num_io_domains; i++)
> > +               of_node_put(info->io_domains[i]);
> > +
> >         for (i = 0; i < info->ctrl->nr_banks; i++) {
> >                 bank = &info->ctrl->pin_banks[i];
> >
> > diff --git a/drivers/pinctrl/pinctrl-rockchip.h b/drivers/pinctrl/pinctrl-rockchip.h
> > index 4759f336941ef..d2ac79b0a7bc4 100644
> > --- a/drivers/pinctrl/pinctrl-rockchip.h
> > +++ b/drivers/pinctrl/pinctrl-rockchip.h
> > @@ -435,6 +435,7 @@ struct rockchip_pin_group {
> >         unsigned int                    npins;
> >         unsigned int                    *pins;
> >         struct rockchip_pin_config      *data;
> > +       bool                            io_domain_skip;
> >  };
> >
> >  /**
> > @@ -462,6 +463,8 @@ struct rockchip_pinctrl {
> >         unsigned int                    ngroups;
> >         struct rockchip_pmx_func        *functions;
> >         unsigned int                    nfunctions;
> > +       struct device_node              **io_domains;
> > +       int                             num_io_domains;
> >  };
> >
> >  #endif
> > --
> > 2.39.2
> >
>
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