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[AVR] Fix problems with USB CDC auto-reset #6055

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[AVR] Fix problems with USB CDC auto-reset #6055

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01408e8
Fix save/restore of magic key location during reset
MLXXXp Mar 10, 2017
4c550ce
Save/restore the watchdog during USB auto-reset
MLXXXp Mar 10, 2017
be653de
Always read key to check for new LUFA bootloader
MLXXXp Mar 10, 2017
2ea6efd
Don't use line coding to trigger USB auto-reset
MLXXXp Mar 10, 2017
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28 changes: 18 additions & 10 deletions hardware/arduino/avr/cores/arduino/CDC.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -34,7 +34,7 @@ typedef struct
static volatile LineInfo _usbLineInfo = { 57600, 0x00, 0x00, 0x00, 0x00 };
static volatile int32_t breakValue = -1;

bool _updatedLUFAbootloader = false;
static u8 wdtcsr_save;

#define WEAK __attribute__ ((weak))

Expand All @@ -57,6 +57,11 @@ const CDCDescriptor _cdcInterface =
D_ENDPOINT(USB_ENDPOINT_IN (CDC_ENDPOINT_IN ),USB_ENDPOINT_TYPE_BULK,USB_EP_SIZE,0)
};

bool isLUFAbootloader()
{
return pgm_read_word(FLASHEND - 1) == NEW_LUFA_SIGNATURE;
}

int CDC_GetInterface(u8* interfaceNum)
{
interfaceNum[0] += 2; // uses 2
Expand Down Expand Up @@ -92,10 +97,7 @@ bool CDC_Setup(USBSetup& setup)
if (CDC_SET_CONTROL_LINE_STATE == r)
{
_usbLineInfo.lineState = setup.wValueL;
}

if (CDC_SET_LINE_CODING == r || CDC_SET_CONTROL_LINE_STATE == r)
{
// auto-reset into the bootloader is triggered when the port, already
// open at 1200 bps, is closed. this is the signal to start the watchdog
// with a relatively long period so it can finish housekeeping tasks
Expand All @@ -109,7 +111,7 @@ bool CDC_Setup(USBSetup& setup)
#if MAGIC_KEY_POS != (RAMEND-1)
// For future boards save the key in the inproblematic RAMEND
// Which is reserved for the main() return value (which will never return)
if (_updatedLUFAbootloader) {
if (isLUFAbootloader()) {
// horray, we got a new bootloader!
magic_key_pos = (RAMEND-1);
}
Expand All @@ -119,25 +121,31 @@ bool CDC_Setup(USBSetup& setup)
if (1200 == _usbLineInfo.dwDTERate && (_usbLineInfo.lineState & 0x01) == 0)
{
#if MAGIC_KEY_POS != (RAMEND-1)
// Backup ram value if its not a newer bootloader.
// Backup ram value if its not a newer bootloader and it hasn't already been saved.
// This should avoid memory corruption at least a bit, not fully
if (magic_key_pos != (RAMEND-1)) {
if (magic_key_pos != (RAMEND-1) && *(uint16_t *)magic_key_pos != MAGIC_KEY) {
*(uint16_t *)(RAMEND-1) = *(uint16_t *)magic_key_pos;
}
#endif
// Store boot key
*(uint16_t *)magic_key_pos = MAGIC_KEY;
// Save the watchdog state in case the reset is aborted.
wdtcsr_save = WDTCSR;
wdt_enable(WDTO_120MS);
}
else
else if (*(uint16_t *)magic_key_pos == MAGIC_KEY)
{
// Most OSs do some intermediate steps when configuring ports and DTR can
// twiggle more than once before stabilizing.
// To avoid spurious resets we set the watchdog to 250ms and eventually
// To avoid spurious resets we set the watchdog to 120ms and eventually
// cancel if DTR goes back high.
// Cancellation is only done if an auto-reset was started, which is
// indicated by the magic key having been set.

wdt_disable();
wdt_reset();
// Restore the watchdog state in case the sketch was using it.
WDTCSR |= (1<<WDCE) | (1<<WDE);
WDTCSR = wdtcsr_save;
#if MAGIC_KEY_POS != (RAMEND-1)
// Restore backed up (old bootloader) magic key data
if (magic_key_pos != (RAMEND-1)) {
Expand Down
7 changes: 0 additions & 7 deletions hardware/arduino/avr/cores/arduino/USBCore.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -36,7 +36,6 @@ extern const u8 STRING_PRODUCT[] PROGMEM;
extern const u8 STRING_MANUFACTURER[] PROGMEM;
extern const DeviceDescriptor USB_DeviceDescriptor PROGMEM;
extern const DeviceDescriptor USB_DeviceDescriptorB PROGMEM;
extern bool _updatedLUFAbootloader;

const u16 STRING_LANGUAGE[2] = {
(3<<8) | (2+2),
Expand Down Expand Up @@ -815,12 +814,6 @@ void USBDevice_::attach()
UDIEN = (1<<EORSTE) | (1<<SOFE) | (1<<SUSPE); // Enable interrupts for EOR (End of Reset), SOF (start of frame) and SUSPEND

TX_RX_LED_INIT;

#if MAGIC_KEY_POS != (RAMEND-1)
if (pgm_read_word(FLASHEND - 1) == NEW_LUFA_SIGNATURE) {
_updatedLUFAbootloader = true;
}
#endif
}

void USBDevice_::detach()
Expand Down
3 changes: 1 addition & 2 deletions hardware/arduino/avr/cores/arduino/USBCore.h
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Original file line number Diff line number Diff line change
Expand Up @@ -285,8 +285,7 @@ typedef struct
// Old Caterina bootloader places the MAGIC key into unsafe RAM locations (it can be rewritten
// by the running sketch before to actual reboot).
// Newer bootloaders, recognizable by the LUFA "signature" at the end of the flash, can handle both
// the usafe and the safe location. Check once (in USBCore.cpp) if the bootloader in new, then set the global
// _updatedLUFAbootloader variable to true/false and place the magic key consequently
// the unsafe and the safe location.
#ifndef MAGIC_KEY
#define MAGIC_KEY 0x7777
#endif
Expand Down