linux-kernel - Re: [PATCH] gpio: gpio-dwapb: add optional reset

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Date:   Wed, 11 Oct 2017 12:47:25 -0500
From:   Alan Tull <atull@...nel.org>
To:     Hoan Tran <hotran@....com>,
        Linus Walleij <linus.walleij@...aro.org>
Cc:     Alan Tull <atull@...nel.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        "linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] gpio: gpio-dwapb: add optional reset

On Wed, Oct 11, 2017 at 11:34 AM, Alan Tull <atull@...nel.org> wrote:

Sorry, I forgot to specify PATCH v2 in the subject.

Alan

> Some platforms require reset to be released to allow register
> access.
>
> Signed-off-by: Alan Tull <atull@...nel.org>
> ---
> v2: Request shared controller
>     return all errors from reset controller request
>     drop conditions on asserting/deasserting reset
> ---
>  drivers/gpio/gpio-dwapb.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
>
> diff --git a/drivers/gpio/gpio-dwapb.c b/drivers/gpio/gpio-dwapb.c
> index f051c45..0df8cdf 100644
> --- a/drivers/gpio/gpio-dwapb.c
> +++ b/drivers/gpio/gpio-dwapb.c
> @@ -25,6 +25,7 @@
>  #include <linux/of_irq.h>
>  #include <linux/platform_device.h>
>  #include <linux/property.h>
> +#include <linux/reset.h>
>  #include <linux/spinlock.h>
>  #include <linux/platform_data/gpio-dwapb.h>
>  #include <linux/slab.h>
> @@ -97,6 +98,7 @@ struct dwapb_gpio {
>         unsigned int            nr_ports;
>         struct irq_domain       *domain;
>         unsigned int            flags;
> +       struct reset_control    *rst;
>  };
>
>  static inline u32 gpio_reg_v2_convert(unsigned int offset)
> @@ -608,6 +610,12 @@ static int dwapb_gpio_probe(struct platform_device *pdev)
>         gpio->dev = &pdev->dev;
>         gpio->nr_ports = pdata->nports;
>
> +       gpio->rst = devm_reset_control_get_optional_shared(dev, NULL);
> +       if (IS_ERR(gpio->rst))
> +               return PTR_ERR(gpio->rst);
> +
> +       reset_control_deassert(gpio->rst);
> +
>         gpio->ports = devm_kcalloc(&pdev->dev, gpio->nr_ports,
>                                    sizeof(*gpio->ports), GFP_KERNEL);
>         if (!gpio->ports)
> @@ -659,6 +667,7 @@ static int dwapb_gpio_remove(struct platform_device *pdev)
>
>         dwapb_gpio_unregister(gpio);
>         dwapb_irq_teardown(gpio);
> +       reset_control_assert(gpio->rst);
>
>         return 0;
>  }
> --
> 2.7.4
>