GPIO expander access is not working in kernel

IoT Modules WP Series
1

Hi Jyijyi,

I am trying to access gpio expander max7321 in our custom board with WP7608. I can see a bug in Sierra wireless kernel code.
The gpio expander is listed as gpiochip812 successfully in /sys/class/gpio path. And i am trying to export that pin:
echo 812 > /sys/class/gpio/export

This command returns error. Because kernel allows to export only processor gpio pins. The function gpio_map_name_to_num in drivers/gpio/gpiolib-sysfs.c blocks gpios expander pins. The gpio_map_name_to_num() is Sierra Wireless code.

 Could you please help me to add gpio expander access from Linux user space?.

Thanks,
Raghavan.

Thanks,
Raghavan K.

2

You can see here on how to use gpio expander command

3

Hi Jyijyi,
What is the DTS file to change gpio expander details for WP7608?. How can I compile and include it yocto_wp76xx.4k.cwe?.
I have changed as following in kernel/arch/arm/boot/dts/qcom/swi-wp-mangoh-green.dtsi file. But gpioexp does not show new i2c address 0x69. It shows old i2c address from green board 0x3E, 0x3F and 0x70.

&soc {
sierra_gpio {
// IO expander 1
alias-ARDUINO_RESET_LEVEL = <300 0>;
alias-BATTCHRGR_PG_N = <301 0>;
alias-BATTGAUGE_GPIO = <302 0>;
alias-LED_ON = <303 0>;
alias-ATMEGA_RESET_GPIO = <304 0>;
alias-CONNECT_TO_AV_LED = <305 0>;
alias-PCM_ANALOG_SELECT = <306 0>;
alias-CONNECT_TO_AV = <307 0>;
};
};

&i2c_4 {
expander: max7321@69 {
#gpio-cells = <2>;
gpio-controller;
compatible = “maxim,max7321”;
reg = <0x69>;
max732x,gpio_base = <300>;
};
};

Thanks,
Raghavan.

4

No idea, but i guess you can use i2c tool in console to send command to the gpio expander