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Subject: Re: [PATCH] pinctrl: meson: fix G12A ao pull registers base address
To:     Jerome Brunet <jbrunet@baylibre.com>,
        Neil Armstrong <narmstrong@baylibre.com>,
        <linus.walleij@linaro.org>, <linux-gpio@vger.kernel.org>
CC:     <khilman@baylibre.com>, <carlo@caione.org>,
        <martin.blumenstingl@googlemail.com>, <robh@kernel.org>,
        <jianxin.pan@amlogic.com>, <linux-amlogic@lists.infradead.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>,
        Xingyu Chen <xingyu.chen@amlogic.com>
References: <20181203030533.10989-1-xingyu.chen@amlogic.com>
 <a240773f-7b05-d950-e5e9-23d7983c7f35@baylibre.com>
 <f2ceff1edcb2c103d0128a838ff630bb3c147bf5.camel@baylibre.com>
From:   Xingyu Chen <xingyu.chen@amlogic.com>
Message-ID: <e0fd351c-91ee-b662-80d6-ac4d2a8b6cb0@amlogic.com>
Date:   Tue, 4 Dec 2018 10:10:22 +0800
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On 2018/12/3 18:36, Jerome Brunet wrote:
> On Mon, 2018-12-03 at 11:27 +0100, Neil Armstrong wrote:
>> Hi Xingyu,
>>
>>
>> On 03/12/2018 04:05, Xingyu Chen wrote:
>>> Since Meson G12A SoC, Introduce new ao registers AO_RTI_PULL_UP_EN_REG
>>> and AO_GPIO_O.
>>>
>>> These bits of controlling output level are remapped to the new register
>>> AO_GPIO_O, and the AO_GPIO_O_EN_N support only controlling output enable.
>>>
>>> These bits of controlling pull enable are remapped to the new register
>>> AO_RTI_PULL_UP_EN_REG, and the AO_RTI_PULL_UP_REG support only controlling
>>> pull type(up/down).
>>>
>>> The new layout of ao gpio/pull registers is as follows:
>>> - AO_GPIO_O_EN_N        [offset: 0x9 << 2]
>>> - AO_GPIO_I             [offset: 0xa << 2]
>>> - AO_RTI_PULL_UP_REG    [offset: 0xb << 2]
>>> - AO_RTI_PULL_UP_EN_REG [offset: 0xc << 2]
>>> - AO_GPIO_O             [offset: 0xd << 2]
>>>
>>>  From above, we can see ao GPIO registers region has been separated by the
>>> ao pull registers. In order to ensure the continuity of the region on
>>> software, the ao GPIO and ao pull registers use the same base address, but
>>> can be identified by the offset.
>>>
>>> Fixes: 29ae0952e85f ("pinctrl: meson-g12a: add pinctrl driver support")
>>> Signed-off-by: Xingyu Chen <xingyu.chen@amlogic.com>
>>> Signed-off-by: Jianxin Pan <jianxin.pan@amlogic.com>
>>> ---
>>>   drivers/pinctrl/meson/pinctrl-meson.c | 22 ++++++++++++----------
>>>   1 file changed, 12 insertions(+), 10 deletions(-)
>>>
>>> diff --git a/drivers/pinctrl/meson/pinctrl-meson.c
>>> b/drivers/pinctrl/meson/pinctrl-meson.c
>>> index 53d449076dee..7ff40cd7a0cb 100644
>>> --- a/drivers/pinctrl/meson/pinctrl-meson.c
>>> +++ b/drivers/pinctrl/meson/pinctrl-meson.c
>>> @@ -31,6 +31,9 @@
>>>    * In some cases the register ranges for pull enable and pull
>>>    * direction are the same and thus there are only 3 register ranges.
>>>    *
>>> + * Since Meson G12A SoC, the ao register ranges for gpio, pull enable
>>> + * and pull direction are the same, so there are only 2 register ranges.
>>> + *
>>>    * For the pull and GPIO configuration every bank uses a contiguous
>>>    * set of bits in the register sets described above; the same register
>>>    * can be shared by more banks with different offsets.
>>> @@ -487,23 +490,22 @@ static int meson_pinctrl_parse_dt(struct
>>> meson_pinctrl *pc,
>>>   		return PTR_ERR(pc->reg_mux);
>>>   	}
>>>   
>>> -	pc->reg_pull = meson_map_resource(pc, gpio_np, "pull");
>>> -	if (IS_ERR(pc->reg_pull)) {
>>> -		dev_err(pc->dev, "pull registers not found\n");
>>> -		return PTR_ERR(pc->reg_pull);
>>> +	pc->reg_gpio = meson_map_resource(pc, gpio_np, "gpio");
>>> +	if (IS_ERR(pc->reg_gpio)) {
>>> +		dev_err(pc->dev, "gpio registers not found\n");
>>> +		return PTR_ERR(pc->reg_gpio);
>>>   	}
>>>   
>>> +	pc->reg_pull = meson_map_resource(pc, gpio_np, "pull");
>>> +	/* Use gpio region if pull one is not present */
>>> +	if (IS_ERR(pc->reg_pull))
>>> +		pc->reg_pull = pc->reg_gpio;
>>> +
>>>   	pc->reg_pullen = meson_map_resource(pc, gpio_np, "pull-enable");
>>>   	/* Use pull region if pull-enable one is not present */
>>>   	if (IS_ERR(pc->reg_pullen))
>>>   		pc->reg_pullen = pc->reg_pull;
>>>   
>>> -	pc->reg_gpio = meson_map_resource(pc, gpio_np, "gpio");
>>> -	if (IS_ERR(pc->reg_gpio)) {
>>> -		dev_err(pc->dev, "gpio registers not found\n");
>>> -		return PTR_ERR(pc->reg_gpio);
>>> -	}
>>> -
>>>   	return 0;
>>>   }
>>>   
>>>
>> Doesn't it need an update of the bindings ?
> 
> Going even further, shouldn't we stop trying make multiple regions out of
> this, and have just one ?
> 
> On all the Amlogic SoC we have seen so far, all the regions a very (VERY)
> close to each other. It seems very unlikely that there something unrelated to
> GPIO in between.
> 
> It looks like everything is mostly there in the driver to deal with offset, so
> change would be minimal.
> 
> Of course, for  DT stability we will need to carry the legacy, but for newer
> SoC, such as the g12, does it really makes sense to have multiple regions ?
> 
Hi, Jerome
the ee gpio, pull and pull-en register regions are discontinuous, some 
addresses are reserved between them and maybe used for other module. For 
example [G12A]:
range of gpio register address offset:    (0x010 << 2) - (0x022 << 2)
range of pull register address offset:    (0x03a << 2) - (0x03f << 2)
range of pull-en register address offset: (0x048 << 2) - (0x04d << 2)

keeping the multiple register regions seems to be more flexible and 
friendly for Meson Series SoCs at present.

>>
>> Neil
>>
> 
> 
> .
>