How to configure the gpio of the feisikar imx6 Processor

In Linux or android systems, if we want to configure the gpio pin of the feisikar imx6 processor, for example, the gpio_19 pin, we should look like this:

#define  MX6Q_PAD_GPIO_19__GPIO_4_5\(_MX6Q_PAD_GPIO_19__GPIO_4_5 | MUX_PAD_CTRL(NO_PAD_CTRL))

_ Mx6q_pad_gpio_1920.gpio_4_5 is defined:

#define _MX6Q_PAD_GPIO_19__GPIO_4_5\IOMUX_PAD(0x0624, 0x0254, 5, 0x0000, 0, 0)

The iomux_pad macro is a key macro defining gpio. Its prototype is:

#define IOMUX_PAD(_pad_ctrl_ofs, _mux_ctrl_ofs, _mux_mode, _sel_input_ofs, _sel_input, _pad_ctrl)

The iomux_pad macro has six parameters, each of which means:

Parameters	Description
_ Pad_ctrl_ofs	Offset address of the control register (hexadecimal)
_ Mux_ctrl_ofs	The offset address of the MUX control register (in hexadecimal format) for Pin selection.
_ Mux_mode	MUX mode, bit0 ~ 3, ranging from 0 ~ 7
_ Select_input_ofs	Select_input register offset address (hexadecimal)
_ Select_input	Daisy Chain Mode, bit0 ~ 1, ranging from 0 ~ 3
_ Pad_ctrl	Bits to be set in register _ pad_ctrl_ofs for configuration Selection

The specific meaning should be combined with the imx6 Data Manual Chapter 36 imoux controller (iomuxc.

The following describes the configuration of the gpio_19 pin:

1. _ pad_ctrl_ofs

Find the data manual page 2433:

We can see from the following: _ pad_ctrl_ofs = 0x624

2. _ mux_ctrl_ofs and _ mux_mode

Find the content of data manual page 2055:

For example, the value of _ mux_ctrl_ofs is 0x254, and the range of _ mux_mode is 000 ~ 110

 

Only when _ mux_mode is set to 0, _ select_input_ofs and _ select_input are valid. In other cases, _ select_input_ofs and _ select_input are both 0.

3. _ select_input_of and _ select_input

When _ mux_mode = 0, for the value of _ select_input_ofs, see data manual page 2654:

In this case, _ select_input_ofs = 0x8e8, _ select_input = 0x1

4. _ pad_ctrl

_ Pad_ctrl is generally set to 0.

To sum up, the configuration macro of gpio_19 is defined as follows:

#define _MX6Q_PAD_GPIO_19__KPP_COL_5\IOMUX_PAD(0x0624, 0x0254, 0, 0x08E8, 1, 0)#define _MX6Q_PAD_GPIO_19__ENET_1588_EVENT0_OUT\IOMUX_PAD(0x0624, 0x0254, 1, 0x0000, 0, 0)#define _MX6Q_PAD_GPIO_19__SPDIF_OUT1\IOMUX_PAD(0x0624, 0x0254, 2, 0x0000, 0, 0)#define _MX6Q_PAD_GPIO_19__CCM_CLKO\IOMUX_PAD(0x0624, 0x0254, 3, 0x0000, 0, 0)#define _MX6Q_PAD_GPIO_19__ECSPI1_RDY\IOMUX_PAD(0x0624, 0x0254, 4, 0x0000, 0, 0)#define _MX6Q_PAD_GPIO_19__GPIO_4_5\IOMUX_PAD(0x0624, 0x0254, 5, 0x0000, 0, 0)#define _MX6Q_PAD_GPIO_19__ENET_TX_ER\IOMUX_PAD(0x0624, 0x0254, 6, 0x0000, 0, 0)#define _MX6Q_PAD_GPIO_19__SRC_INT_BOOT\IOMUX_PAD(0x0624, 0x0254, 7, 0x0000, 0, 0)

The macro above defines ARM/ARCH/palt-mxc/include/Mach/iomux-mx6q.h from imx6 Linux source code