platform: OKMX6Q-S2

System: Linux

Core version: Linux-3.0.35

  I.MX6Q GPIO multiplexing modification method, the verification platform is the Forlinx embedded OKMX6Q-S2 development board, based on the ARM Corte-A9 architecture, i.MX6Q quad-core processor, and other platforms can be used as a reference. This modification releases part of the pins occupied by the original SD card function and reuses them as GPIO. For the specific GPIO number, please refer to Chapter 4 of the i.MX6 CPU manual (IMX6DQRM.pdf), Chapter 4 External Signals and Pin Multiplexing.

i.MX6 CPU manual path: Forlinx Embedded OKMX6Q-S2,OKMX6DL-S2 User Information (A)/Hardware/Datasheet/i.MX6/IMX6DQRM.pdf

 

1. Modification process

Modify the file arch/arm/mach-mx6/board-mx6q_sabresd.h and add the following definitions in it:

        /*GPIO*/

       MX6Q_PAD_SD3_CLK__GPIO_7_3,

       MX6Q_PAD_SD3_CMD__GPIO_7_2,

       MX6Q_PAD_SD3_DAT2__GPIO_7_6,

       MX6Q_PAD_SD3_DAT3__GPIO_7_7,

       MX6Q_PAD_SD3_DAT4__GPIO_7_1,

       MX6Q_PAD_SD3_DAT5__GPIO_7_0,

       MX6Q_PAD_SD3_DAT6__GPIO_6_18,

       MX6Q_PAD_SD3_DAT7__GPIO_6_17,

       MX6Q_PAD_NANDF_D1__GPIO_2_1,

       MX6Q_PAD_NANDF_D0__GPIO_2_0,

Comment out the original SD card function

/* USDHC3 */

/*      MX6Q_PAD_SD3_CLK__USDHC3_CLK_50MHZ,

        MX6Q_PAD_SD3_CMD__USDHC3_CMD_50MHZ,

        MX6Q_PAD_SD3_DAT0__USDHC3_DAT0_50MHZ,

        MX6Q_PAD_SD3_DAT1__USDHC3_DAT1_50MHZ,

        MX6Q_PAD_SD3_DAT2__USDHC3_DAT2_50MHZ,

        MX6Q_PAD_SD3_DAT3__USDHC3_DAT3_50MHZ,

        MX6Q_PAD_SD3_DAT4__USDHC3_DAT4_50MHZ,

        MX6Q_PAD_SD3_DAT5__USDHC3_DAT5_50MHZ,

        MX6Q_PAD_SD3_DAT6__USDHC3_DAT6_50MHZ,

        MX6Q_PAD_SD3_DAT7__USDHC3_DAT7_50MHZ,

        MX6Q_PAD_NANDF_D0__GPIO_2_0,         

        MX6Q_PAD_NANDF_D1__GPIO_2_1,            */

 

Note: The Linux-3.0.35version of the kernel defines the pin function in the arch/arm/plat-mxc/include/mach/iomux-mx6q.h file, which defines all the multiplexing functions of each pin, and you can take a look if you are interested.

2. Test

GPIO

Ball number                           definition                                                       GPIO

        89                      MX6Q_PAD_SD3_CLK__GPIO_7_3                       195

        91                      MX6Q_PAD_SD3_CMD__GPIO_7_2                      194

        94                      MX6Q_PAD_SD3_DAT2__GPIO_7_6                     198

        93                      MX6Q_PAD_SD3_DAT3__GPIO_7_7                     199

        92                      MX6Q_PAD_SD3_DAT4__GPIO_7_1                     193

        90                      MX6Q_PAD_SD3_DAT5__GPIO_7_0                     192

        88                      MX6Q_PAD_SD3_DAT6__GPIO_6_18                   178

        87                      MX6Q_PAD_SD3_DAT7__GPIO_6_17                   177

        83                      MX6Q_PAD_NANDF_D1__GPIO_2_1                    33

        84                      MX6Q_PAD_NANDF_D0__GPIO_2_0                    32

GPIO_M_N GPIOX，GPIOX=（M-1）*32+N，For  example GPIO_4_28=(4-1)*32+28=124

Test command

echo 33 > /sys/class/gpio/export

echo out > /sys/class/gpio/gpio33/direction

echo 1 > /sys/class/gpio/gpio33/value

cat /sys/class/gpio/gpio33/value