Implement device wipe using the hardware button on Green #3523
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sairon
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agners
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Aug 14, 2024
Port Stefan's patch from Linux patchset to U-Boot.
Unlike Yellow, Green doesn't have a way to easily wipe the device, e.g. if the user forgets the password - in that case the only option is to use a microSD card and reflash the system. Fortunately, Green has a hardware button wired to the PMIC chip which exposes the button state in one of the registers. Read this value in U-Boot and decide if cmdline flag for device wipe should be set - same as we do on Yellow. Also enable LED driver and command in U-Boot. In the current implementation, if the button is held for ~5 seconds when plugging in the device (this time includes DDR training, SPL, etc.), the yellow LED turns solid to indicate wipe is about the start. When the Linux kernel starts, the kernel LED driver takes over and starts blinking in heartbeat pattern. Because it takes a while to load the kernel, the LED stays solid for 2-3 seconds, which should be enough to recognize it was acknowledged.
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sairon
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With #3523 as inspiration, it might be useful to wait for buttons to be released, e.g. in case when they become stuck. Also indicate the button operation (wipe, boot files removal, UMS) has been handled by turning on the yellow LED.
sairon
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Aug 16, 2024
With #3523 as inspiration, it might be useful to wait for buttons to be released, e.g. in case when they become stuck. Also indicate the button operation (wipe, boot files removal, UMS) has been handled by turning on the yellow LED.
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Unlike Yellow, Green doesn't have a way to easily wipe the device, e.g. if the user forgets the password - in that case the only option is to use a microSD card and reflash the system. Fortunately, Green has a hardware button wired to the PMIC chip which exposes the button state in one of the registers. Read this value in U-Boot and decide if cmdline flag for device wipe should be set - same as we do on Yellow.
Also enable LED driver and command in U-Boot. In the current implementation, if the button is held for ~5 seconds when plugging in the device (this time includes DDR training, SPL, etc.), the yellow LED turns solid to indicate wipe is about the start. When the Linux kernel starts, the kernel LED driver takes over and starts blinking in heartbeat pattern. Because it takes a while to load the kernel, the LED stays solid for 2-3 seconds, which should be enough to recognize it was acknowledged.