linux-kernel - Re: [PATCH v2 3/8] pinctrl: msm: Add ability for drivers to supply a reserved GPIO list

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Message-ID: <CAKv+Gu-1QhX-9aNhFJauc9NVe6ceQQueE8Kd14031XJ-2yaupA@mail.gmail.com>
Date:   Fri, 7 Jun 2019 13:10:04 +0200
From:   Ard Biesheuvel <ard.biesheuvel@...aro.org>
To:     Lee Jones <lee.jones@...aro.org>
Cc:     alokc@...eaurora.org, Andy Gross <andy.gross@...aro.org>,
        David Brown <david.brown@...aro.org>,
        wsa+renesas@...g-engineering.com,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Linus Walleij <linus.walleij@...aro.org>, balbi@...nel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        linux-usb <linux-usb@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        linux-i2c <linux-i2c@...r.kernel.org>,
        Jeffrey Hugo <jlhugo@...il.com>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v2 3/8] pinctrl: msm: Add ability for drivers to supply a
 reserved GPIO list

On Fri, 7 Jun 2019 at 10:29, Lee Jones <lee.jones@...aro.org> wrote:
>
> When booting MSM based platforms with Device Tree or some ACPI
> implementations, it is possible to provide a list of reserved pins
> via the 'gpio-reserved-ranges' and 'gpios' properties respectively.
> However some ACPI tables are not populated with this information,
> thus it has to come from a knowledgable device driver instead.
>
> Here we provide the MSM common driver with additional support to
> parse this informtion and correctly populate the widely used
> 'valid_mask'.
>
> Signed-off-by: Lee Jones <lee.jones@...aro.org>

I'm not sure if this is the correct approach. Presumably, on ACPI
systems, all the pinctl stuff is already set up by the firmware, and
so we shouldn't touch *any* pins unless they have been requested
explicitly. Is there any way we can support this in the current
framework?

> ---
>  drivers/pinctrl/qcom/pinctrl-msm.c | 18 ++++++++++++++++++
>  drivers/pinctrl/qcom/pinctrl-msm.h |  1 +
>  2 files changed, 19 insertions(+)
>
> diff --git a/drivers/pinctrl/qcom/pinctrl-msm.c b/drivers/pinctrl/qcom/pinctrl-msm.c
> index ee8119879c4c..3ac740b36508 100644
> --- a/drivers/pinctrl/qcom/pinctrl-msm.c
> +++ b/drivers/pinctrl/qcom/pinctrl-msm.c
> @@ -607,8 +607,23 @@ static int msm_gpio_init_valid_mask(struct gpio_chip *chip)
>         int ret;
>         unsigned int len, i;
>         unsigned int max_gpios = pctrl->soc->ngpios;
> +       const int *reserved = pctrl->soc->reserved_gpios;
>         u16 *tmp;
>
> +       /* Driver provided reserved list overrides DT and ACPI */
> +       if (reserved) {
> +               bitmap_fill(chip->valid_mask, max_gpios);
> +               for (i = 0; reserved[i] >= 0; i++) {
> +                       if (i >= max_gpios || reserved[i] >= max_gpios) {
> +                               dev_err(pctrl->dev, "invalid list of reserved GPIOs\n");
> +                               return -EINVAL;
> +                       }
> +                       clear_bit(reserved[i], chip->valid_mask);
> +               }
> +
> +               return 0;
> +       }
> +
>         /* The number of GPIOs in the ACPI tables */
>         len = ret = device_property_read_u16_array(pctrl->dev, "gpios", NULL,
>                                                    0);
> @@ -964,6 +979,9 @@ static void msm_gpio_irq_handler(struct irq_desc *desc)
>
>  static bool msm_gpio_needs_valid_mask(struct msm_pinctrl *pctrl)
>  {
> +       if (pctrl->soc->reserved_gpios)
> +               return true;
> +
>         return device_property_read_u16_array(pctrl->dev, "gpios", NULL, 0) > 0;
>  }
>
> diff --git a/drivers/pinctrl/qcom/pinctrl-msm.h b/drivers/pinctrl/qcom/pinctrl-msm.h
> index c12048e54a6f..23b93ae92269 100644
> --- a/drivers/pinctrl/qcom/pinctrl-msm.h
> +++ b/drivers/pinctrl/qcom/pinctrl-msm.h
> @@ -121,6 +121,7 @@ struct msm_pinctrl_soc_data {
>         bool pull_no_keeper;
>         const char *const *tiles;
>         unsigned int ntiles;
> +       const int *reserved_gpios;
>  };
>
>  extern const struct dev_pm_ops msm_pinctrl_dev_pm_ops;
> --
> 2.17.1
>
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

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