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Date: Fri, 7 Jun 2013 22:57:41 +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 7 June 2013 19:32, Christian Ruppert <christian.ruppert@...lis.com> wrote:
> On Fri, Jun 07, 2013 at 08:00:57AM +0800, Haojian Zhuang wrote:
>> 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.
>
> In the above example, bits 0 and 1 of register 0x0 control pins 1
> through 4 and bit 0 of register 0x4 controls pins 5 through 8. The
> moment you write a new value in either of those registers, all four pins
> will change functionality simultaneously. There is no way to control the
> functionality of each pin individually.
>
Oh. So some bits in the same register control multiple pins.
Yeah, I also meet this in Hisilicon SoC. My solution is to only define the
pinmux register for one pin, and skip other pins.
1. You're using GPIOA0 & GPIOA1 in two different driver.
You only need to define GPIOA0 or GPIOA1 in one of driver. Don't define
them at the same time.
2. You're using GPIOA0 & GPIOA1 in the same driver.
You only need to define GPIOA0 or GPIOA1.
3. If you're using SPI or any other function, it's same as GPIO function.
4. There's no #4. Since you won't use GPIOA0 with SCL pin together.
Regards
Haojian
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