How do I configure pins in FreeRTOS, uboot and Linux for an i.MX?

[paul_quiring]

Hello Community,

I want to configure the Pad GPIO1_IO02 to use alternate mode 5. Furthermore, I don't want to use the default settings of the pad as shown in table "Table 4-1. Pin Assignments" of the document IMX6SXRM.pdf.

default settings
HYS - DISABLED
PUS -
PUS_100KOHM_PD
PUE - KEEP
PKE - ENABLED
ODE - DISABLED
SPEED - 100MHZ
DSE - 43_OHM
SRE - SLOV

settings I want to use

HYS - ENABLED
PUS - 47K Ohm Pull Up
PUS_100KOHM_PD
PUE - KEEP
PKE - ENABLED
ODE - DISABLED
SPEED - 150MHz @ 3.3V
DSE - 43_OHM
SRE - SLOV

• What would the patch for the Yoko build look like (uboot, Linux) in order to get the desired settings for the pad GPIO1_IO02?
• What must be changed in the case I2C2_BASE of the function "void configure_i2c_pins(I2C_Type* base)" in order to achive the settings I want to use. Below is the piece of code that needs to be changed. It belongs to the FreeRTOS BSP v1.0.1 for the ai development board (FreeRTOS_BSP_1.0.1_iMX6SX\examples\imx6sx_ai_m4\pin_mux.h).

case I2C2_BASE:

// I2C2 iomux configuration

IOMUXC_SW_MUX_CTL_PAD_GPIO1_IO02 = IOMUXC_SW_MUX_CTL_PAD_GPIO1_IO02_MUX_MODE(0) |

IOMUXC_SW_MUX_CTL_PAD_GPIO1_IO02_SION_MASK;

IOMUXC_I2C2_IPP_SCL_IN_SELECT_INPUT = IOMUXC_I2C2_IPP_SCL_IN_SELECT_INPUT_DAISY(1);

IOMUXC_SW_MUX_CTL_PAD_GPIO1_IO03 = IOMUXC_SW_MUX_CTL_PAD_GPIO1_IO03_MUX_MODE(0) |

IOMUXC_SW_MUX_CTL_PAD_GPIO1_IO03_SION_MASK;

IOMUXC_I2C2_IPP_SDA_IN_SELECT_INPUT = IOMUXC_I2C2_IPP_SDA_IN_SELECT_INPUT_DAISY(1);

IOMUXC_SW_PAD_CTL_PAD_GPIO1_IO02 = IOMUXC_SW_PAD_CTL_PAD_GPIO1_IO02_PKE_MASK |

IOMUXC_SW_PAD_CTL_PAD_GPIO1_IO02_PUE_MASK |

IOMUXC_SW_PAD_CTL_PAD_GPIO1_IO02_PUS(2) |

IOMUXC_SW_PAD_CTL_PAD_GPIO1_IO02_SPEED(2) |

IOMUXC_SW_PAD_CTL_PAD_GPIO1_IO02_DSE(6) |

IOMUXC_SW_PAD_CTL_PAD_GPIO1_IO02_ODE_SHIFT |

IOMUXC_SW_PAD_CTL_PAD_GPIO1_IO02_SRE_MASK |

IOMUXC_SW_PAD_CTL_PAD_GPIO1_IO02_HYS_MASK;

IOMUXC_SW_PAD_CTL_PAD_GPIO1_IO03 = IOMUXC_SW_PAD_CTL_PAD_GPIO1_IO03_PKE_MASK |

IOMUXC_SW_PAD_CTL_PAD_GPIO1_IO03_PUE_MASK |

IOMUXC_SW_PAD_CTL_PAD_GPIO1_IO03_PUS(2) |

IOMUXC_SW_PAD_CTL_PAD_GPIO1_IO03_SPEED(2) |

IOMUXC_SW_PAD_CTL_PAD_GPIO1_IO03_DSE(6) |

IOMUXC_SW_PAD_CTL_PAD_GPIO1_IO03_ODE_SHIFT |

IOMUXC_SW_PAD_CTL_PAD_GPIO1_IO03_SRE_MASK |

IOMUXC_SW_PAD_CTL_PAD_GPIO1_IO03_HYS_MASK;

break;

imx6sx‌

freertos‌

uboot

#yocto imx‌

[radhikasomaiya]

Hi Paul Quiring,

For FreeRTOS BSP v1.0.1:

You can use the predefined macros to change values of register IOMUXC_SW_PAD_CTL_PAD_GPIO1_IO02 according to your required settings.

eg. for PUS

      IOMUXC_SW_PAD_CTL_PAD_GPIO1_IO02_PUS(1)  (to set 47K Ohm Pull Up)

You can refer section 35.5.213 from IMX6SXRM.pdf to change values according to your requirement.

Regards,

Radhika Somaiya.

[jimmychan]

In Yocto BSP, the IOMUX setting is in the device tree file.

For example:

imx6sx-sdb.dtsi

pinctrl_hog: hoggrp {

                          fsl,pins = <

                                   MX6SX_PAD_SD1_DATA0__GPIO6_IO_2 0x17059

                                   MX6SX_PAD_SD1_DATA3__GPIO6_IO_5 0xb000

                                   MX6SX_PAD_CSI_DATA03__GPIO1_IO_17 0x17059

                          >;

                  };

e.g. MX6SX_PAD_SD1_DATA0__GPIO6_IO_2                0x17059

The MUX Mode setting of this is set the PAD "SD1_DATA0" as GPIO6_IO02. All the MUX mode are well defined in the imx6sx-pinfunc.h.

So, for your case, you can use "MX6SX_PAD_GPIO1_IO02__GPIO1_IO_2" in your device tree file.

In this example, the PAD control setting is 0x17059. For the meaning of this, please refer to the Pad Control Register in RM.