linux-kernel - Re: [PATCH v2 1/2] pinctrl: qcom: Add egpio feature support

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Date:   Fri, 29 Oct 2021 15:49:04 +0530
From:   Rajendra Nayak <rnayak@...eaurora.org>
To:     Stephen Boyd <swboyd@...omium.org>, agross@...nel.org,
        bjorn.andersson@...aro.org, linus.walleij@...aro.org
Cc:     linux-arm-msm@...r.kernel.org, linux-gpio@...r.kernel.org,
        linux-kernel@...r.kernel.org, psodagud@...eaurora.org,
        dianders@...omium.org
Subject: Re: [PATCH v2 1/2] pinctrl: qcom: Add egpio feature support



On 10/29/2021 12:24 PM, Stephen Boyd wrote:
> Quoting Rajendra Nayak (2021-10-26 05:07:35)
>> From: Prasad Sodagudi <psodagud@...eaurora.org>
>>
>> egpio is a scheme which allows special power Island Domain IOs
>> (LPASS,SSC) to be reused as regular chip GPIOs by muxing regular
>> TLMM functions with Island Domain functions.
>> With this scheme, an IO can be controlled both by the cpu running
>> linux and the Island processor. This provides great flexibility to
>> re-purpose the Island IOs for regular TLMM usecases.
>>
>> 2 new bits are added to ctl_reg, egpio_present is a read only bit
>> which shows if egpio feature is available or not on a given gpio.
>> egpio_enable is the read/write bit and only effective if egpio_present
>> is 1. Once its set, the Island IO is controlled from Chip TLMM.
>> egpio_enable when set to 0 means the GPIO is used as Island Domain IO.
>>
>> To support this we add a new function 'egpio' which can be used to
>> set the egpio_enable to 0, for any other TLMM controlled functions
>> we set the egpio_enable to 1.
>>
>> Signed-off-by: Prasad Sodagudi <psodagud@...eaurora.org>
>> Signed-off-by: Rajendra Nayak <rnayak@...eaurora.org>
>> ---
> 
> Does this supersede adding support for lpass pinctrl in this series[1]?

No, the driver in [1] actually manages the LPASS TLMM instance, while this patch
makes it possible for the 'same' pins to be managed by the SoC TLMM instance.
On sc7280 SoC for instance GPIO144-158 maps to LPI-GPIO-0-14, and GPIO159-174
maps to SSC-GPIO-0-15.

> [1] https://lore.kernel.org/r/1635342097-2726-1-git-send-email-srivasam@codeaurora.org
> 

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