+#ifdef CONFIG_DEBUG_SERIAL
+uint16_t cached_lsr[256];
+uint16_t cached_rbr[256];
+size_t cache_count;
+
+/* The LSR is read-to-clear on some parts, so we have to make sure status
+ * bits aren't inadvertently lost when doing various tests.
+ */
+static uint16_t uart_lsr_save;
+static uint16_t uart_lsr_read(void)
+{
+ uint16_t lsr = *pUART_LSR;
+ uart_lsr_save |= (lsr & (OE|PE|FE|BI));
+ return lsr | uart_lsr_save;
+}
+/* Just do the clear for everyone since it can't hurt. */
+static void uart_lsr_clear(void)
+{
+ uart_lsr_save = 0;
+ *pUART_LSR |= -1;
+}
+#else
+static inline uint16_t uart_lsr_read(void) { return *pUART_LSR; }
+static inline void uart_lsr_clear(void) { *pUART_LSR = -1; }
+#endif
+