Enable system WDT with timeout of 8s

Enable WDT to ensure the system: - Does not hang processing any task, such as previous cases of PECI commands never completing. - Does not take longer than the timeout period to complete all outstanding tasks. A timeout of 8s is used to remain close to the existing use of the WDT in scratch ROM, which was set to 10s. Signed-off-by: Tim Crawford <[email protected]>
system76 · Jul 16, 2024 · f0791b7 · f0791b7
1 parent 7cb9731
commit f0791b7
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Showing 5 changed files with 49 additions and 17 deletions.
diff --git a/src/board/system76/common/include/board/smfi.h b/src/board/system76/common/include/board/smfi.h
@@ -6,7 +6,6 @@
 #include <stdint.h>
 
 void smfi_init(void);
-void smfi_watchdog(void);
 void smfi_event(void);
 void smfi_debug(uint8_t byte);
 

diff --git a/src/board/system76/common/main.c b/src/board/system76/common/main.c
@@ -30,6 +30,7 @@
 #include <common/macro.h>
 #include <common/version.h>
 #include <ec/ec.h>
+#include <ec/etwd.h>
 
 #ifdef PARALLEL_DEBUG
 #include <board/parallel.h>
@@ -96,6 +97,8 @@ void main(void) {
     gpio_debug();
 #endif
 
+    wdt_init();
+
     INFO("System76 EC board '%s', version '%s'\n", board(), version());
 
     uint32_t last_time_battery = 0;
@@ -155,6 +158,9 @@ void main(void) {
         pmc_event(&PMC_1);
         // AP/EC communication over SMFI
         smfi_event();
+
+        wdt_kick();
+
         // Idle until next timer interrupt
         //Disabled until interrupts used: PCON |= 1;
     }

diff --git a/src/board/system76/common/scratch.c b/src/board/system76/common/scratch.c
@@ -6,6 +6,7 @@
 #include <board/dgpu.h>
 #include <board/smfi.h>
 #include <common/macro.h>
+#include <ec/etwd.h>
 #include <ec/pwm.h>
 #include <ec/scratch.h>
 
@@ -27,8 +28,8 @@ void scratch_trampoline(void) {
 
     //TODO: Clear keyboard presses
 
-    // Start watchdog timer
-    smfi_watchdog();
+    // Restart WDT before entry to scratch ROM
+    wdt_kick();
 
     // Disable interrupts
     EA = 0;

diff --git a/src/board/system76/common/smfi.c b/src/board/system76/common/smfi.c
@@ -335,26 +335,17 @@ static enum Result cmd_reset(void) {
 
 #endif // !defined(__SCRATCH__)
 
-    // Attempt to trigger watchdog reset
-    ETWCFG |= BIT(5);
-    EWDKEYR = 0;
+    wdt_trigger();
 
     // Failed if it got this far
     return RES_ERR;
 }
 
-// Set a watchdog timer of 10 seconds
-void smfi_watchdog(void) {
-    ET1CNTLLR = 0xFF;
-    EWDCNTLLR = 0xFF;
-    EWDCNTLHR = 0x04;
-}
-
 void smfi_event(void) {
     if (smfi_cmd[SMFI_CMD_CMD]) {
 #if defined(__SCRATCH__)
         // If in scratch ROM, restart watchdog timer when command received
-        smfi_watchdog();
+        wdt_kick();
 #endif
 
         switch (smfi_cmd[SMFI_CMD_CMD]) {

diff --git a/src/ec/ite/include/ec/etwd.h b/src/ec/ite/include/ec/etwd.h
@@ -1,8 +1,11 @@
 // SPDX-License-Identifier: GPL-3.0-only
 
-#ifndef _EC_ECWD_H
-#define _EC_ECWD_H
+// External Timer and External Watchdog (ETWD)
 
+#ifndef _EC_ETWD_H
+#define _EC_ETWD_H
+
+#include <common/macro.h>
 #include <stdint.h>
 
 volatile uint8_t __xdata __at(0x1F01) ETWCFG;
@@ -27,4 +30,36 @@ volatile uint8_t __xdata __at(0x1F13) ET3CNTLH2R;
 volatile uint8_t __xdata __at(0x1F16) ET4CNTLLR;
 #endif
 
-#endif // _EC_ECWD_H
+enum EtwdPrescaler {
+    ETWD_PRESCALER_32768_HZ = 0,
+    ETWD_PRESCALER_1024_HZ = 1,
+    ETWD_PRESCALER_32_HZ = 2,
+    ETWD_PRESCALER_9200_KHZ = 3,    // NOTE: Not available for ET1PS
+};
+
+// When the key match function of EWD is enabled (EWTCFG[5]), writing this
+// value to EWDKEY will reset the WDT.
+#define WDT_KEY 0x5C
+
+static inline void wdt_init(void) {
+    ET1PSR = ETWD_PRESCALER_1024_HZ;
+
+    // Enable WDT key match, use ET1 prescaler for WDT clock
+    ETWCFG = BIT(5) | BIT(4);
+
+    // Start WDT with timeout of 8s
+    // TODO: Determine time based on system performance
+    EWDCNTLHR = 0x20;
+    EWDCNTLLR = 0;
+}
+
+static inline void wdt_kick(void) {
+    EWDKEYR = WDT_KEY;
+}
+
+static inline void wdt_trigger(void) {
+    // Trigger watchdog reset by key mismatch
+    EWDKEYR = 0;
+}
+
+#endif // _EC_ETWD_H