nmasic: limit retries in wait_for_bootrom()

If no device is connected or init failed, wait_for_bootrom() will
be stuck in an infinite loop trying to get a result from nm_read_reg().

Place an upper limit on the number of retries so we can recover from
this instead of being stuck here.

Author: benpicco

src/driver/source/nmasic.c

@@ -404,6 +404,7 @@ sint8 chip_reset(void)
 sint8 wait_for_bootrom(uint8 arg)
 {
 	sint8 ret = M2M_SUCCESS;
+	uint16 retries = 1000;
 	uint32 reg = 0, cnt = 0;
 	uint32 u32GpReg1 = 0;
 	uint32 u32DriverVerInfo = M2M_MAKE_VERSION_INFO(M2M_RELEASE_VERSION_MAJOR_NO,\
@@ -413,13 +414,19 @@ sint8 wait_for_bootrom(uint8 arg)
 
 
 	reg = 0;
-	while(1) {
+	while(--retries) {
 		reg = nm_read_reg(0x1014);	/* wait for efuse loading done */
 		if (reg & 0x80000000) {
 			break;
 		}
 		nm_bsp_sleep(1); /* TODO: Why bus error if this delay is not here. */
 	}
+
+	/* communication with device failed */
+	if(retries == 0) {
+		return M2M_ERR_INIT;
+	}
+
 	reg = nm_read_reg(M2M_WAIT_FOR_HOST_REG);
 	reg &= 0x1;