[PATCH v6 2/8] pinctrl: imx27: imx27 pincontrol driver

[Markus Pargmann]

On Mon, Oct 28, 2013 at 06:17:41AM -0500, Kumar Gala wrote:
> 
> On Oct 28, 2013, at 4:00 AM, Markus Pargmann wrote:
> 
> > imx27 pincontrol driver using the imx1 core driver. The DT bindings are
> > similar to other imx pincontrol drivers.
> > 
> > Signed-off-by: Markus Pargmann <mpa at pengutronix.de>
> > Acked-by: Sascha Hauer <s.hauer at pengutronix.de>
> > Acked-by: Shawn Guo <shawn.guo at linaro.org>
> > ---
> > .../bindings/pinctrl/fsl,imx27-pinctrl.txt         |  89 ++++
> > drivers/pinctrl/Kconfig                            |   8 +
> > drivers/pinctrl/Makefile                           |   1 +
> > drivers/pinctrl/pinctrl-imx27.c                    | 477 +++++++++++++++++++++
> > 4 files changed, 575 insertions(+)
> > create mode 100644 Documentation/devicetree/bindings/pinctrl/fsl,imx27-pinctrl.txt
> > create mode 100644 drivers/pinctrl/pinctrl-imx27.c
> > 
> > diff --git a/Documentation/devicetree/bindings/pinctrl/fsl,imx27-pinctrl.txt b/Documentation/devicetree/bindings/pinctrl/fsl,imx27-pinctrl.txt
> > new file mode 100644
> > index 0000000..32c81c8
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/pinctrl/fsl,imx27-pinctrl.txt
> > @@ -0,0 +1,89 @@
> > +* Freescale IMX27 IOMUX Controller
> > +
> > +Required properties:
> > +- compatible: "fsl,imx27-iomuxc"
> > +
> > +The iomuxc driver node should define subnodes containing of pinctrl configuration subnodes.
> 
> Here would probably be a good point to reference "pinctrl/pinctrl-bindings.txt"

Okay.

> 
> > +
> > +Required properties for pin configuration node:
> > +- fsl,pins: three integers array, represents a group of pins mux and config
> > +  setting. The format is fsl,pins = <PIN MUX_ID CONFIG>.
> > +
> > +  PIN is an integer between 0 and 0xbf. imx27 has 6 ports with 32 configurable
> > +  configurable pins each. PIN is PORT * 32 + PORT_PIN, PORT_PIN is the pin
> > +  number on the specific port (between 0 and 31).
> 
> I might be coming late to this, so feel free to ignore if this has already been discussed.
> 
> Why not encode PORT in fsl,pins so it would be <PORT PORT_PIN MUX_ID CONFIG> ?

The port is still visible in the pin id as each port has 32 pins = 0x20.
So the ports start at 0x00, 0x20, 0x40, 0x60, 0x80 and 0xa0. So I am not
sure if it is necessary to seperate PORT and PORT_PIN, I personally
prefer only one PIN_ID field.

> 
> > +
> > +  MUX_ID is
> > +    function + (direction << 2) + (gpio_oconf << 4) + (gpio_iconfa << 8) + (gpio_iconfb << 10)
> > +
> > +    function:      0 - Primary function
> > +                   1 - Alternate function
> > +                   2 - GPIO
> > +      Registers GIUS (GPIO In Use) and GPR (General Purpose Register)
> > +
> > +    direction:     0 - Input
> > +                   1 - Output
> > +      Register DDIR
> > +
> > +    gpio_oconf:    0 - A_IN
> > +                   1 - B_IN
> > +                   2 - C_IN
> > +                   3 - Data Register
> 
> what does this mean?

These are additional output configurations for GPIO. 3 is normal GPIO,
0-2 are other pinfunctions that are mapped as output to this pin. It is
described in the i.MX27 reference manual in detail.

> 
> > +      Registers OCR1 and OCR2
> > +
> > +    gpio_iconfa/b: 0 - GPIO_IN
> > +                   1 - Interrupt Status Register
> > +                   2 - 0
> > +                   3 - 1
> 
> What does any of these option mean (especially 2 & 3)?

This is the input configuration for a pin in GPIO mode. 0 will connect
it to GPIO input of the pad, 1 to the interrupt status register, 2 and 3
to constant low or high.

> 
> > +      Registers ICONFA1, ICONFA2, ICONFB1 and ICONFB2
> > +
> > +
> 
> Someone should be able to reasonable read this and determine how to set MUX_ID w/o having to reference the HW manual.

I will add a little bit more documentation here. But in general the
corresponding reference manual chapters should be used to create a
correct MUX_ID. I don't think DT binding documentation is the right
place to describe the hardware.

> 
> > +  CONFIG can be 0 or 1, meaning Pullup disable/enable.
> 
> just for clarity do:
>     CONFIG: 0 - Pullup disabled
>             1 - Pullup enabled

Okay, will change.

Thanks,

Markus Pargmann

> 
> > +
> > +
> > +
> > +
> > +Example:
> > +
> > +iomuxc: iomuxc at 10015000 {
> > +	compatible = "fsl,imx27-iomuxc";
> > +	reg = <0x10015000 0x600>;
> > +
> > +	uart {
> > +		pinctrl_uart1: uart-1 {
> > +			fsl,pins = <
> > +				0x8c 0x004 0x0 /* UART1_TXD__UART1_TXD */
> > +				0x8d 0x000 0x0 /* UART1_RXD__UART1_RXD */
> > +				0x8e 0x004 0x0 /* UART1_CTS__UART1_CTS */
> > +				0x8f 0x000 0x0 /* UART1_RTS__UART1_RTS */
> > +			>;
> > +		};
> > +
> > +		...
> > +	};
> > +};
> > +
> > +
> > +For convenience there are macros defined in imx27-pinfunc.h which provide PIN
> > +and MUX_ID. They are structured as MX27_PAD_<Pad name>__<Signal name>. The names
> > +are defined in the i.MX27 reference manual.
> 
> 
> > +
> > +The above example using macros:
> > +
> > +iomuxc: iomuxc at 10015000 {
> > +	compatible = "fsl,imx27-iomuxc";
> > +	reg = <0x10015000 0x600>;
> > +
> > +	uart {
> > +		pinctrl_uart1: uart-1 {
> > +			fsl,pins = <
> > +				MX27_PAD_UART1_TXD__UART1_TXD 0x0
> > +				MX27_PAD_UART1_RXD__UART1_RXD 0x0
> > +				MX27_PAD_UART1_CTS__UART1_CTS 0x0
> > +				MX27_PAD_UART1_RTS__UART1_RTS 0x0
> > +			>;
> > +		};
> > +
> > +		...
> > +	};
> > +};
> 
> - k
> 
> -- 
> Employee of Qualcomm Innovation Center, Inc.
> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation
> 
> 

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