linux-kernel - Re: [PATCH v1 1/2] pinctrl: pinctrl-loongson2: add pinctrl driver support

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CACRpkdbBW1YNGfec2jEPsUGwqosc8TwwSP9ft+he5KWPf0otvw@mail.gmail.com>
Date:   Fri, 21 Oct 2022 11:45:49 +0200
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Yinbo Zhu <zhuyinbo@...ngson.cn>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        linux-gpio@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        zhanghongchen <zhanghongchen@...ngson.cn>
Subject: Re: [PATCH v1 1/2] pinctrl: pinctrl-loongson2: add pinctrl driver support

Hi Yinbo,

thanks for your patch!

On Fri, Oct 21, 2022 at 3:27 AM Yinbo Zhu <zhuyinbo@...ngson.cn> wrote:

> The loongson2 SoC has a few pins that can be used as GPIOs or take
> multiple other functions. Add a driver for the pinmuxing.
>
> There is currently no support for GPIO pin pull-up and pull-down.
>
> Signed-off-by: zhanghongchen <zhanghongchen@...ngson.cn>
> Signed-off-by: Yinbo Zhu <zhuyinbo@...ngson.cn>

(...)

> +static int loongson2_pmx_set_mux(struct pinctrl_dev *pcdev, unsigned int func_num,
> +                             unsigned int group_num)
> +{
> +       struct loongson2_pinctrl *pctrl = pinctrl_dev_get_drvdata(pcdev);
> +       unsigned long reg = (unsigned long)pctrl->reg_base +
> +                               loongson2_pmx_groups[group_num].reg;
> +       unsigned int mux_bit = loongson2_pmx_groups[group_num].bit;
> +       unsigned int val;
> +       unsigned long flags;
> +
> +       raw_spin_lock_irqsave(&pctrl->lock, flags);
> +       val = readl((void *)reg);
> +       if (func_num == 0)
> +               val &= ~(1<<mux_bit);
> +       else
> +               val |= (1<<mux_bit);
> +       writel(val, (void *)reg);
> +       raw_spin_unlock_irqrestore(&pctrl->lock, flags);

Can you explain in the commit message or with a comment in the code
why you have to use a raw spinlock for this?

We usually only use raw spinlocks for things like low level
interrupt handlers...

My guess is that you can replace this with an ordinary spinlock.

Yours,
Linus Walleij