openpower/package/skiboot/skiboot-0004-Add-xscom_ok-and-lpc_ok-to-check-XSCOM-and-LPC-usability.patch

diff --git a/hw/bt.c b/hw/bt.c
index 7bf1b2f..8bb44cd 100644
--- a/hw/bt.c
+++ b/hw/bt.c
@@ -350,7 +350,8 @@  static void print_debug_queue_info(void) {}
 
 static void bt_send_and_unlock(void)
 {
-	if (bt.state == BT_STATE_IDLE && !list_empty(&bt.msgq))
+	if (lpc_ok() &&
+	    bt.state == BT_STATE_IDLE && !list_empty(&bt.msgq))
 		bt_send_msg();
 
 	unlock(&bt.lock);
@@ -361,6 +362,10 @@  static void bt_poll(struct timer *t __unused, void *data __unused)
 {
 	uint8_t bt_ctrl;
 
+	/* Don't do anything if the LPC bus is offline */
+	if (!lpc_ok())
+		return;
+
 	/* If we can't get the lock assume someone else will notice
 	 * the new message and process it. */
 	lock(&bt.lock);
@@ -440,7 +445,9 @@  static int bt_add_ipmi_msg(struct ipmi_msg *ipmi_msg)
 
 void bt_irq(void)
 {
-	uint8_t ireg = bt_inb(BT_INTMASK);
+	uint8_t ireg;
+
+	ireg = bt_inb(BT_INTMASK);
 
 	bt.irq_ok = true;
 	if (ireg & BT_INTMASK_B2H_IRQ) {
diff --git a/hw/lpc-uart.c b/hw/lpc-uart.c
index 2e6114a..7c3190e 100644
--- a/hw/lpc-uart.c
+++ b/hw/lpc-uart.c
@@ -135,6 +135,10 @@  static size_t uart_con_write(const char *buf, size_t len)
 {
 	size_t written = 0;
 
+	/* If LPC bus is bad, we just swallow data */
+	if (!lpc_ok())
+		return written;
+
 	lock(&uart_lock);
 	while(written < len) {
 		if (tx_room == 0) {
diff --git a/hw/lpc.c b/hw/lpc.c
index 0db674f..b287020 100644
--- a/hw/lpc.c
+++ b/hw/lpc.c
@@ -500,3 +500,15 @@  void lpc_used_by_console(void)
 		unlock(&chip->lpc_lock);
 	}
 }
+
+bool lpc_ok(void)
+{
+	struct proc_chip *chip;
+
+	if (lpc_default_chip_id < 0)
+		return false;
+	if (!xscom_ok())
+		return false;
+	chip = get_chip(lpc_default_chip_id);
+	return !lock_held_by_me(&chip->lpc_lock);
+}
diff --git a/hw/xscom.c b/hw/xscom.c
index a3533be..07b9b94 100644
--- a/hw/xscom.c
+++ b/hw/xscom.c
@@ -531,3 +531,8 @@  void xscom_used_by_console(void)
 	lock(&xscom_lock);
 	unlock(&xscom_lock);
 }
+
+bool xscom_ok(void)
+{
+	return !lock_held_by_me(&xscom_lock);
+}
diff --git a/include/lpc.h b/include/lpc.h
index 5611c54..a0990fd 100644
--- a/include/lpc.h
+++ b/include/lpc.h
@@ -27,6 +27,12 @@  extern void lpc_init(void);
 /* Check for a default bus */
 extern bool lpc_present(void);
 
+/* Return of LPC is currently usable. This can be false if the caller
+ * currently holds a lock that would make it unsafe, or the LPC bus
+ * is known to be in some error condition (TBI).
+ */
+extern bool lpc_ok(void);
+
 /* Handle the interrupt from LPC source */
 extern void __attrconst lpc_interrupt(uint32_t chip_id);
 
diff --git a/include/xscom.h b/include/xscom.h
index b1ecaf5..a841261 100644
--- a/include/xscom.h
+++ b/include/xscom.h
@@ -173,6 +173,11 @@  extern void xscom_init(void);
 /* Mark XSCOM lock as being in console path */
 extern void xscom_used_by_console(void);
 
+/* Returns true if XSCOM can be used. Typically this returns false if
+ * the current CPU holds the XSCOM lock (to avoid re-entrancy from error path).
+ */
+extern bool xscom_ok(void);
+
 extern int64_t xscom_read_cfam_chipid(uint32_t partid, uint32_t *chip_id);
 
 #endif /* __XSCOM_H */