linux-kernel - Re: [PATCH v3 14/18] firmware: qcom_scm: provide a read-modify-write function

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Date:   Thu, 18 May 2023 11:48:52 -0700
From:   Trilok Soni <quic_tsoni@...cinc.com>
To:     Mukesh Ojha <quic_mojha@...cinc.com>, <agross@...nel.org>,
        <andersson@...nel.org>, <konrad.dybcio@...aro.org>,
        <corbet@....net>, <keescook@...omium.org>, <tony.luck@...el.com>,
        <gpiccoli@...lia.com>, <catalin.marinas@....com>,
        <will@...nel.org>, <krzysztof.kozlowski+dt@...aro.org>,
        <robh+dt@...nel.org>, <linus.walleij@...aro.org>,
        <linux-gpio@...r.kernel.org>, <srinivas.kandagatla@...aro.org>
CC:     <linux-arm-msm@...r.kernel.org>,
        <linux-remoteproc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-hardening@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>, <linux-doc@...r.kernel.org>
Subject: Re: [PATCH v3 14/18] firmware: qcom_scm: provide a read-modify-write
 function

On 5/3/2023 10:02 AM, Mukesh Ojha 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_update_field() which masks
> out the bits and write the passed value to that
> bit-offset. Subsequent patch will use this function.
> 
> Suggested-by: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
> Signed-off-by: Mukesh Ojha <quic_mojha@...cinc.com>
> ---
>   drivers/firmware/qcom_scm.c            | 15 +++++++++++++++
>   include/linux/firmware/qcom/qcom_scm.h |  2 ++
>   2 files changed, 17 insertions(+)
> 
> diff --git a/drivers/firmware/qcom_scm.c b/drivers/firmware/qcom_scm.c
> index fde33acd..003cbcb 100644
> --- a/drivers/firmware/qcom_scm.c
> +++ b/drivers/firmware/qcom_scm.c
> @@ -407,6 +407,21 @@ int qcom_scm_set_remote_state(u32 state, u32 id)
>   }
>   EXPORT_SYMBOL(qcom_scm_set_remote_state);
>   
> +int qcom_scm_io_update_field(phys_addr_t addr, unsigned int mask, unsigned int val)
> +{
> +	unsigned int old, new;
> +	int ret;
> +
> +	ret = qcom_scm_io_readl(addr, &old);
> +	if (ret)
> +		return ret;
> +
> +	new = (old & ~mask) | val << (ffs(mask) - 1);
> +
> +	return qcom_scm_io_writel(addr, new);
> +}
> +EXPORT_SYMBOL(qcom_scm_io_update_field);

EXPORT_SYMBOL_GPL?

There are other symbols in this driver marked as EXPORT_SYMBOL only. Can 
you submit a separate patch to convert them into EXPORT_SYMBOL_GPL. OR I 
want to know why we are marking them without _GPL.

checkpatch should catch this as well? By default we should have all the 
new additions as EXPORT_SYMBOL_GPL and only few existing APIs w/ 
exceptions?

---Trilok Soni