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Message-ID: <3a17f36a-04bf-04f2-7a22-82b76977b325@quicinc.com>
Date: Tue, 9 Jan 2024 18:54:22 +0530
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Subject: Re: [PATCH v11 1/4] firmware: qcom: scm: provide a read-modify-write
 function
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To: Linus Walleij <linus.walleij@linaro.org>, Mark Brown <broonie@kernel.org>
CC: <andersson@kernel.org>, <konrad.dybcio@linaro.org>,
        <linux-arm-msm@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <linux-gpio@vger.kernel.org>
References: <1704727654-13999-1-git-send-email-quic_mojha@quicinc.com>
 <1704727654-13999-2-git-send-email-quic_mojha@quicinc.com>
 <CACRpkdY7fbFyNNd6GAikxC3+wk0ca8Yn_8__zkp+Q-deJeJ_LQ@mail.gmail.com>
From: Mukesh Ojha <quic_mojha@quicinc.com>
In-Reply-To: <CACRpkdY7fbFyNNd6GAikxC3+wk0ca8Yn_8__zkp+Q-deJeJ_LQ@mail.gmail.com>
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On 1/9/2024 6:44 PM, Linus Walleij wrote:
> On Mon, Jan 8, 2024 at 4:28 PM Mukesh Ojha <quic_mojha@quicinc.com> wrote:
> 
>> It was realized by Srinivas K. that there is a need of
>> read-modify-write scm exported function so that it can
>> be used by multiple clients.
>>
>> Let's introduce qcom_scm_io_rmw() which masks out the bits
>> and write the passed value to that bit-offset.
> (...)
>> +int qcom_scm_io_rmw(phys_addr_t addr, unsigned int mask, unsigned int val)
>> +{
>> +       unsigned int old, new;
>> +       int ret;
>> +
>> +       if (!__scm)
>> +               return -EINVAL;
>> +
>> +       spin_lock(&__scm->lock);
>> +       ret = qcom_scm_io_readl(addr, &old);
>> +       if (ret)
>> +               goto unlock;
>> +
>> +       new = (old & ~mask) | (val & mask);
>> +
>> +       ret = qcom_scm_io_writel(addr, new);
>> +unlock:
>> +       spin_unlock(&__scm->lock);
>> +       return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(qcom_scm_io_rmw);
> 
> This looks a lot like you are starting to re-invent regmaps
> regmap_update_bits().
> 
> If you are starting to realize you need more and more of
> regmap, why not use regmap and its functions?

I think, this discussion has happened already ..

https://lore.kernel.org/lkml/CACRpkdb95V5GC81w8fiuLfx_V1DtWYpO33FOfMnArpJeC9SDQA@mail.gmail.com/

-Mukesh

> 
> Yours,
> Linus Walleij