linux-kernel - Re: [PATCH] Add default mux for pins that a free GPIO lines on the PocketBeagle

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Date:   Sat, 27 Jun 2020 16:09:27 +0200
From:   "H. Nikolaus Schaller" <hns@...delico.com>
To:     Drew Fustini <drew@...gleboard.org>
Cc:     Tony Lindgren <tony@...mide.com>, Rob Herring <robh+dt@...nel.org>,
        bcousson@...libre.com, linux-omap@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jason Kridner <jkridner@...gleboard.org>,
        Robert Nelson <robertcnelson@...il.com>,
        linux-gpio@...r.kernel.org
Subject: Re: [PATCH] Add default mux for pins that a free GPIO lines on the PocketBeagle


> Am 27.06.2020 um 15:55 schrieb Drew Fustini <drew@...gleboard.org>:
> 
> These pins on the PocketBeagle P1 and P2 headers are connected to AM3358
> balls with gpio lines, and these pins are not used for any other
> peripherals by default. These GPIO lines are unclaimed and could be used
> by userspace program through the gpiod ABI. However, no driver will have
> set mux mode for the pins.
> 
> This patch adds a "default" state in the am33xx_pinmux node and sets the
> pins to gpio output mux mode.

wouldn't it be more safe to set them to input mode?

BR,
Nikolaus Schaller

> 
> Signed-off-by: Drew Fustini <drew@...gleboard.org>
> ---
> arch/arm/boot/dts/am335x-pocketbeagle.dts | 98 +++++++++++++++++++++++
> 1 file changed, 98 insertions(+)
> 
> diff --git a/arch/arm/boot/dts/am335x-pocketbeagle.dts b/arch/arm/boot/dts/am335x-pocketbeagle.dts
> index f0b222201b86..900dc6558701 100644
> --- a/arch/arm/boot/dts/am335x-pocketbeagle.dts
> +++ b/arch/arm/boot/dts/am335x-pocketbeagle.dts
> @@ -60,6 +60,104 @@ vmmcsd_fixed: fixedregulator0 {
> };
> 
> &am33xx_pinmux {
> +
> +	pinctrl-names = "default";
> +	pinctrl-0 =   <	&P2_03_gpio &P1_34_gpio &P2_19_gpio &P2_24_gpio
> +			&P2_33_gpio &P2_22_gpio &P2_18_gpio &P2_10_gpio
> +			&P2_06_gpio &P2_04_gpio &P2_02_gpio &P2_08_gpio
> +			&P2_17_gpio >;
> +
> +	/* P2_03 (ZCZ ball T10) gpio0_23 0x824 */
> +	P2_03_gpio: pinmux_P2_03_gpio {
> +		pinctrl-single,pins = <
> +			AM33XX_PADCONF(AM335X_PIN_GPMC_AD9, PIN_OUTPUT, MUX_MODE7)
> +		>;
> +	};
> +
> +	/* P1_34 (ZCZ ball T11) gpio0_26 0x828 */
> +	P1_34_gpio: pinmux_P1_34_gpio {
> +		pinctrl-single,pins = <
> +			AM33XX_PADCONF(AM335X_PIN_GPMC_AD10, PIN_OUTPUT, MUX_MODE7)
> +		>;
> +	};
> +
> +		/* P2_19 (ZCZ ball U12) gpio0_27 0x82c */
> +	P2_19_gpio: pinmux_P2_19_gpio {
> +		pinctrl-single,pins = <
> +			AM33XX_PADCONF(AM335X_PIN_GPMC_AD11, PIN_OUTPUT, MUX_MODE7)
> +		>;
> +	};
> +
> +	/* P2_24 (ZCZ ball T12) gpio1_12 0x830 */
> +	P2_24_gpio: pinmux_P2_24_gpio {
> +		pinctrl-single,pins = <
> +			AM33XX_PADCONF(AM335X_PIN_GPMC_AD12, PIN_OUTPUT, MUX_MODE7)
> +		>;
> +	};
> +
> +	/* P2_33 (ZCZ ball R12) gpio1_13 0x834 */
> +	P2_33_gpio: pinmux_P2_33_gpio {
> +		pinctrl-single,pins = <
> +			AM33XX_PADCONF(AM335X_PIN_GPMC_AD13, PIN_OUTPUT, MUX_MODE7)
> +		>;
> +	};
> +
> +	/* P2_22 (ZCZ ball V13) gpio1_14 0x838 */
> +	P2_22_gpio: pinmux_P2_22_gpio {
> +		pinctrl-single,pins = <
> +			AM33XX_PADCONF(AM335X_PIN_GPMC_AD14, PIN_OUTPUT, MUX_MODE7)
> +		>;
> +	};
> +
> +	/* P2_18 (ZCZ ball U13) gpio1_15 0x83c */
> +	P2_18_gpio: pinmux_P2_18_gpio {
> +		pinctrl-single,pins = <
> +			AM33XX_PADCONF(AM335X_PIN_GPMC_AD15, PIN_OUTPUT, MUX_MODE7)
> +		>;
> +	};
> +
> +	/* P2_10 (ZCZ ball R14) gpio1_20 0x850 */
> +	P2_10_gpio: pinmux_P2_10_gpio {
> +		pinctrl-single,pins = <
> +			AM33XX_PADCONF(AM335X_PIN_GPMC_A4, PIN_OUTPUT, MUX_MODE7)
> +		>;
> +	};
> +
> +	/* P2_06 (ZCZ ball U16) gpio1_25 0x864 */
> +	P2_06_gpio: pinmux_P2_06_gpio {
> +		pinctrl-single,pins = <
> +			AM33XX_PADCONF(AM335X_PIN_GPMC_A9, PIN_OUTPUT, MUX_MODE7)
> +		>;
> +	};
> +
> +	/* P2_04 (ZCZ ball T16) gpio1_26 0x868 */
> +	P2_04_gpio: pinmux_P2_04_gpio {
> +		pinctrl-single,pins = <
> +			AM33XX_PADCONF(AM335X_PIN_GPMC_A10, PIN_OUTPUT, MUX_MODE7)
> +		>;
> +	};
> +
> +	/* P2_02 (ZCZ ball V17) gpio1_27 0x86c */
> +	P2_02_gpio: pinmux_P2_02_gpio {
> +		pinctrl-single,pins = <
> +			AM33XX_PADCONF(AM335X_PIN_GPMC_A11, PIN_OUTPUT, MUX_MODE7)
> +		>;
> +	};
> +
> +	/* P2_08 (ZCZ ball U18) gpio1_28 0x878 */
> +	P2_08_gpio: pinmux_P2_08_gpio {
> +		pinctrl-single,pins = <
> +			AM33XX_PADCONF(AM335X_PIN_GPMC_BEN1, PIN_OUTPUT, MUX_MODE7)
> +		>;
> +	};
> +
> +	/* P2_17 (ZCZ ball V12) gpio2_1 0x88c */
> +	P2_17_gpio: pinmux_P2_17_gpio {
> +		pinctrl-single,pins = <
> +			AM33XX_PADCONF(AM335X_PIN_GPMC_CLK, PIN_OUTPUT, MUX_MODE7)
> +		>;
> +	};
> +
> 	i2c2_pins: pinmux-i2c2-pins {
> 		pinctrl-single,pins = <
> 			AM33XX_PADCONF(AM335X_PIN_UART1_RTSN, PIN_INPUT_PULLUP, MUX_MODE3)	/* (D17) uart1_rtsn.I2C2_SCL */
> -- 
> 2.25.1
>