b43: Add panic reason code that doesn't trigger restart

Add a firmware panic reason code that doesn't trigger a restart.
This is useful for firmware debugging and avoiding endless
restart loops. We can use FWPANIC_DIE to halt the firmware at a
well defined point.
Signed-off-by: Michael Buesch <mb@bu3sch.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/b43/b43.h

@@ -422,12 +422,21 @@ enum {
 					 B43_IRQ_RFKILL | \
 					 B43_IRQ_TX_OK)
 
+/* The firmware register to fetch the debug-IRQ reason from. */
+#define B43_DEBUGIRQ_REASON_REG		63
 /* Debug-IRQ reasons. */
 #define B43_DEBUGIRQ_PANIC		0	/* The firmware panic'ed */
 #define B43_DEBUGIRQ_DUMP_SHM		1	/* Dump shared SHM */
 #define B43_DEBUGIRQ_DUMP_REGS		2	/* Dump the microcode registers */
 #define B43_DEBUGIRQ_ACK		0xFFFF	/* The host writes that to ACK the IRQ */
 
+/* The firmware register to fetch the panic reason from. */
+#define B43_FWPANIC_REASON_REG		3
+/* Firmware panic reason codes */
+#define B43_FWPANIC_DIE			0 /* Firmware died. Don't auto-restart it. */
+#define B43_FWPANIC_RESTART		1 /* Firmware died. Schedule a controller reset. */
+
+
 /* Device specific rate values.
  * The actual values defined here are (rate_in_mbps * 2).
  * Some code depends on this. Don't change it. */

drivers/net/wireless/b43/main.c

@@ -1662,6 +1662,30 @@ static void b43_set_beacon_int(struct b43_wldev *dev, u16 beacon_int)
 	b43dbg(dev->wl, "Set beacon interval to %u\n", beacon_int);
 }
 
+static void b43_handle_firmware_panic(struct b43_wldev *dev)
+{
+	u16 reason;
+
+	/* Read the register that contains the reason code for the panic. */
+	reason = b43_shm_read16(dev, B43_SHM_SCRATCH, B43_FWPANIC_REASON_REG);
+	b43err(dev->wl, "Whoopsy, firmware panic! Reason: %u\n", reason);
+
+	switch (reason) {
+	default:
+		b43dbg(dev->wl, "The panic reason is unknown.\n");
+		/* fallthrough */
+	case B43_FWPANIC_DIE:
+		/* Do not restart the controller or firmware.
+		 * The device is nonfunctional from now on.
+		 * Restarting would result in this panic to trigger again,
+		 * so we avoid that recursion. */
+		break;
+	case B43_FWPANIC_RESTART:
+		b43_controller_restart(dev, "Microcode panic");
+		break;
+	}
+}
+
 static void handle_irq_ucode_debug(struct b43_wldev *dev)
 {
 	unsigned int i, cnt;
@@ -1672,15 +1696,12 @@ static void handle_irq_ucode_debug(struct b43_wldev *dev)
 	if (!dev->fw.opensource)
 		return;
 
-	/* Microcode register 63 contains the debug-IRQ reason. */
-	reason = b43_shm_read16(dev, B43_SHM_SCRATCH, 63);
+	/* Read the register that contains the reason code for this IRQ. */
+	reason = b43_shm_read16(dev, B43_SHM_SCRATCH, B43_DEBUGIRQ_REASON_REG);
+
 	switch (reason) {
 	case B43_DEBUGIRQ_PANIC:
-		/* The reason for the panic is in register 3. */
-		reason = b43_shm_read16(dev, B43_SHM_SCRATCH, 3);
-		b43err(dev->wl, "Whoopsy, the microcode panic'ed! Reason: %u\n",
-		       reason);
-		b43_controller_restart(dev, "Microcode panic");
+		b43_handle_firmware_panic(dev);
 		break;
 	case B43_DEBUGIRQ_DUMP_SHM:
 		if (!B43_DEBUG)
@@ -1721,7 +1742,9 @@ static void handle_irq_ucode_debug(struct b43_wldev *dev)
 		       reason);
 	}
 out:
-	b43_shm_write16(dev, B43_SHM_SCRATCH, 63, B43_DEBUGIRQ_ACK);
+	/* Acknowledge the debug-IRQ, so the firmware can continue. */
+	b43_shm_write16(dev, B43_SHM_SCRATCH,
+			B43_DEBUGIRQ_REASON_REG, B43_DEBUGIRQ_ACK);
 }
 
 /* Interrupt handler bottom-half */