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gpio: toggle the RESET_N pin before booting the modem to ensure it is actually off

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This commit is contained in:
Aren Moynihan
2024-09-11 18:51:45 -04:00
parent 1acd15ca2f
commit 3c5d455f20
1 changed files with 30 additions and 2 deletions
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32
src/gpio.c
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@@ -74,11 +74,36 @@ int gpio_line_set_value(struct EG25Manager *manager, int line, enum gpiod_line_v
int gpio_sequence_poweron(struct EG25Manager *manager)
{
/*
* Force the modem to poweroff using the RESET_N pin before attempting to
* boot in case the it got into a bad state.
*
* If the modem was on, this will cause it to start booting, so press the
* power button while in reset to avoid a (probably only theoretical) race
* condition where it starts booting after reset, and then powers off from
* the power key.
*/
gpio_line_set_value(manager, GPIO_OUT_RESET, GPIOD_LINE_VALUE_ACTIVE);
gpio_line_set_value(manager, GPIO_OUT_PWRKEY, GPIOD_LINE_VALUE_ACTIVE);
/*
* The datasheet says to pull the pin low for between 150 and 460 ms. usleep
* should always sleep for at least the specified amount of time, so use
* 200ms because it's closer to the bottom of that range.
*/
usleep(200000);
gpio_line_set_value(manager, GPIO_OUT_RESET, GPIOD_LINE_VALUE_INACTIVE);
/*
* The modem has finished it's reset, now we wait to allow it a chance to
* react to the power key
*/
sleep(1);
gpio_line_set_value(manager, GPIO_OUT_PWRKEY, GPIOD_LINE_VALUE_INACTIVE);
g_message("Executed power-on/off sequence");
g_message("Executed power-on sequence");
return 0;
}
@@ -86,7 +111,10 @@ int gpio_sequence_poweron(struct EG25Manager *manager)
int gpio_sequence_shutdown(struct EG25Manager *manager)
{
gpio_line_set_value(manager, GPIO_OUT_DISABLE, GPIOD_LINE_VALUE_ACTIVE);
gpio_sequence_poweron(manager);
gpio_line_set_value(manager, GPIO_OUT_PWRKEY, GPIOD_LINE_VALUE_ACTIVE);
sleep(1);
gpio_line_set_value(manager, GPIO_OUT_PWRKEY, GPIOD_LINE_VALUE_INACTIVE);
g_message("Executed power-off sequence");