peci: Add timeouts to infinitely blocking waits

Add timeouts to the legacy PECI implementation to prevent the EC locking
up when PECI stops working, such as during S0ix opportunistic suspend.

This is not the optimal solution, as PECI should not be available at all
to cause the lock up in the first place, but it at least prevents the
issue.

Signed-off-by: Tim Crawford <[email protected]>

src/board/system76/common/peci.c

@@ -33,6 +33,9 @@ int16_t peci_temp = 0;
 
 #define PECI_TEMP(X) ((int16_t)(X))
 
+// Maximum OOB channel response time in ms
+#define PECI_ESPI_TIMEOUT 10
+
 // clang-format off
 #define FAN_POINT(T, D) { .temp = PECI_TEMP(T), .duty = PWM_DUTY(D) }
 // clang-format on
@@ -90,9 +93,6 @@ bool peci_available(void) {
 
 #if CONFIG_PECI_OVER_ESPI
 
-// Maximum OOB channel response time in ms
-#define PECI_ESPI_TIMEOUT 10
-
 void peci_init(void) {}
 
 // Returns true on success, false on error
@@ -291,7 +291,14 @@ void peci_init(void) {
 // Returns true on success, false on error
 bool peci_get_temp(int16_t *data) {
     // Wait for any in-progress transaction to complete
-    while (HOSTAR & BIT(0)) {}
+    uint32_t start = time_get();
+    while (HOSTAR & BIT(0)) {
+        if ((time_get() - start) >= PECI_ESPI_TIMEOUT) {
+            DEBUG("%s: host timeout\n", __func__);
+            return false;
+        }
+    }
+
     // Clear status
     HOSTAR = HOSTAR;
 
@@ -309,7 +316,13 @@ bool peci_get_temp(int16_t *data) {
     HOCTLR |= 1;
 
     // Wait for command completion
-    while (!(HOSTAR & BIT(1))) {}
+    start = time_get();
+    while (!(HOSTAR & BIT(1))) {
+        if ((time_get() - start) >= PECI_ESPI_TIMEOUT) {
+            DEBUG("%s: command timeout\n", __func__);
+            return false;
+        }
+    }
 
     uint8_t status = HOSTAR;
     if (status & 0xEC) {
@@ -333,7 +346,14 @@ bool peci_get_temp(int16_t *data) {
 // negative (0x1000 | status register) on PECI hardware error
 int16_t peci_wr_pkg_config(uint8_t index, uint16_t param, uint32_t data) {
     // Wait for any in-progress transaction to complete
-    while (HOSTAR & BIT(0)) {}
+    uint32_t start = time_get();
+    while (HOSTAR & BIT(0)) {
+        if ((time_get() - start) >= PECI_ESPI_TIMEOUT) {
+            DEBUG("%s: host timeout\n", __func__);
+            return false;
+        }
+    }
+
     // Clear status
     HOSTAR = HOSTAR;
 
@@ -365,7 +385,13 @@ int16_t peci_wr_pkg_config(uint8_t index, uint16_t param, uint32_t data) {
     HOCTLR |= 1;
 
     // Wait for command completion
-    while (!(HOSTAR & BIT(1))) {}
+    start = time_get();
+    while (!(HOSTAR & BIT(1))) {
+        if ((time_get() - start) >= PECI_ESPI_TIMEOUT) {
+            DEBUG("%s: command timeout\n", __func__);
+            return false;
+        }
+    }
 
     uint8_t status = HOSTAR;
     if (status & 0xEC) {