Hello,
I've added statements to my device tree to enable gpio2 for input. To keep it simple, just gpio2_6:
gpio2_pins: pinmux-gpio2_pins {
pinctrl-single,pins = <
AM33XX_IOPAD(0x8a0, PIN_INPUT | MUX_MODE7) /* (R1) lcd_data0.gpio2[6] */
>;
};
&gpio2 {
status = "okay";
pinctrl-names = "default";
pinctrl-0 = <&gpio2_pins>;
};
With the addition of those two sections, I still can't access gpio2. When I try it crashes:
# devmem2 0x481AC134
/dev/mem opened.[ 1178.015843] Unhandled fault: external abort on non-linefetch (0x1018) at 0xb6f32134
[ 1178.024764] pgd = 08bbe99d
[ 1178.027486] [b6f32134] *pgd=99abe831, *pte=481ac303, *ppte=481aca33
Memory mapped at address 0xb6f32000.
Bus error (core dumped)
I've determined the problem is gpio2 isn't enabled. When I read CM_PER_GPIO2_CLKCTRL (using devmem2) it reports a value of 0x00030000 which means "Module is disabled and cannot be accessed". I can use devmem2 and write 2 to enable gpio2 and then I can read gpio2 but this should be able to be part of the device tree.
I've verified the statement "AM33XX_IOPAD(0x8a0, PIN_INPUT | MUX_MODE7)" is working, because I can change PIN_INPUT to PIN_INPUT_PULLUP or PIN_INPUT_PULLDOWN and I see the value of conf_lcd_data0 (0x44E108A0) change correctly from no pull up/down to pull up or pull down. (I've also used the "pinmux" program and verified the address 0x8a0 is correct according to the TRM)
I can read the gpio2 bits if I add these statements to the "gpio2" section:
BMODE00 {
gpio-hog;
input;
gpios = <6 GPIO_ACTIVE_LOW>;
Should that be needed? I've also tried "ti,gpio-always-on" and "ti,reset-on-init" but neither seem to make a difference. (
I'm probably missing something simple, but most of the web searches result in a TI web page stating the content is no longer available. (conf_lcd_data0 still reads as disabled)
Do you have any suggestions?
Thanks,
Scott
