linux-kernel - Re: [PATCH 1/2] pinmux: Add TB10x pinmux driver

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Message-ID: <CAD6h2NQRdgeBkMJkJWeDt-304KY7e6+qyKVE-h9MY6bRnMAPLA@mail.gmail.com>
Date:	Fri, 7 Jun 2013 08:00:57 +0800
From:	Haojian Zhuang <haojian.zhuang@...aro.org>
To:	Christian Ruppert <christian.ruppert@...lis.com>
Cc:	Linus Walleij <linus.walleij@...aro.org>,
	Stephen Warren <swarren@...dotorg.org>,
	Shiraz HASHIM <shiraz.hashim@...com>,
	Patrice CHOTARD <patrice.chotard@...com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Grant Likely <grant.likely@...retlab.ca>,
	Rob Herring <rob.herring@...xeda.com>,
	Rob Landley <rob@...dley.net>,
	Sascha Leuenberger <sascha.leuenberger@...lis.com>,
	Pierrick Hascoet <pierrick.hascoet@...lis.com>,
	"devicetree-discuss@...ts.ozlabs.org" 
	<devicetree-discuss@...ts.ozlabs.org>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>
Subject: Re: [PATCH 1/2] pinmux: Add TB10x pinmux driver

On 6 June 2013 23:30, Christian Ruppert <christian.ruppert@...lis.com> wrote:
> On Thu, Jun 06, 2013 at 10:32:21PM +0800, Haojian Zhuang wrote:
>> On 6 June 2013 22:11, Christian Ruppert <christian.ruppert@...lis.com> wrote:
>> > On Wed, Jun 05, 2013 at 09:44:27AM +0800, Haojian Zhuang wrote:
>> >> On 3 June 2013 20:30, Christian Ruppert <christian.ruppert@...lis.com> wrote:
>> >> > OK, here's a simplified example of what we would like to do (this seems
>> >> > pretty common so I suppose there is a way I haven't understood). Our
>> >> > situation is slightly more complex but for the purpose of discussion
>> >> > let's assume a chip with 8 pins which can be configured for the
>> >> > following functions:
>> >> >
>> >> > Pin   GPIO-A    I2C    SPI0     SPI1
>> >> > ------------------------------------
>> >> >  1    GPIOA0    SDA             MISO1
>> >> >  2    GPIOA1    SCL             MOSI1
>> >> >  3    GPIOA2                    SS1_B
>> >> >  4    GPIOA3                    SCLK1
>> >> >  5    GPIOA4           MISO0
>> >> >  6    GPIOA5           MOSI0
>> >> >  7    GPIOA6           SS0_B
>> >> >  8    GPIOA7           SCLK0
>> >> >
>> >> > We can now define the following pinctrl-single:
>> >> >
>> >> > pinmux: pinmux@...FEE0000 {
>> >> >         compatible = "pinctrl-single";
>> >> >         reg = <0xFFEE0000 0x8>;
>> >> >         #address-cells = <1>;
>> >> >         #size-cells = <0>;
>> >> >         #gpio-range-cells = <3>;
>> >> >         pinctrl-single,register-width = <32>;
>> >> >         pinctrl-single,function-mask = <0xffffffff>;
>> >> >         pinctrl-single,gpio-range = <&range 1 8 0>;
>> >> >         gpioa_pins: pinmux_gpioa_pins {
>> >> >                 pinctrl-single,pins = <0x0 0 0x4 0>
>> >> >         };
>> >> >         i2c_pins: pinmux_i2c_pins {
>> >> >                 pinctrl-single,pins = <0x0 1>
>> >> >         };
>> >> >         spi0_pins: pinmux_spi0_pins {
>> >> >                 pinctrl-single,pins = <0x1 1>
>> >> <0x1 1>?
>> >>
>> >> If each pinmux register is only for one pin in your SoC.
>> >> I think that your definitions are wrong above. We use
>> >> register offset as the first argument, not pin number.
>> >> And the second argument should be pin function number.
>> >
>> > In our case each pinmux register (bit field) actually controls an entire
>> > group of pins.
>> >
>> >> If multiple pins are sharing one register with different bits,
>> >> you need to enable "pinctrl-single,bit-per-mux".
>> >
>> > Multiple pins are sharing the same bits in the same register. Do you
>> > think this prevents us from using pinctrl-single?
>> >
>> Could you give me your register definition? Then I can understand you
>> better.
>
> In our example, the register map would look a bit like the following.
> Note that every register configures four pins at a time.
>
> Register 0x0:
>  Mode  GPIO-A    I2C    SPI1
>  Value 0x0       0x1    0x2
>  ---------------------------
>  Pin1  GPIOA0    SDA    MISO1
>  Pin2  GPIOA1    SCL    MOSI1
>  Pin3  GPIOA2           SS1_B
>  Pin4  GPIOA3           SCLK1
>
> Register 0x4:
>  Mode  GPIO-A    SPI0
>  Value 0x0       0x1
>  ---------------------
>  Pin5  GPIOA4    MISO0
>  Pin6  GPIOA5    MOSI0
>  Pin7  GPIOA6    SS0_B
>  Pin8  GPIOA7    SCLK0
>

You said "Multiple pins are sharing the same bits in the same register.".
I need to understand which bits you're talking about in your register.

Regards
Haojian
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