Add 16550_WAIT_LCR to Kconfig. Tested OK

lupyuen2 · Aug 2, 2023 · 7ee02d6 · 7ee02d6
1 parent 2464d7a
commit 7ee02d6
Show file tree

Hide file tree

Showing 3 changed files with 18 additions and 7 deletions.
diff --git a/boards/risc-v/qemu-rv/rv-virt/configs/knsh64/defconfig b/boards/risc-v/qemu-rv/rv-virt/configs/knsh64/defconfig
@@ -15,6 +15,7 @@ CONFIG_16550_UART0_CLOCK=23040000
 CONFIG_16550_UART0_IRQ=57
 CONFIG_16550_UART0_SERIAL_CONSOLE=y
 CONFIG_16550_UART=y
+CONFIG_16550_WAIT_LCR=y
 CONFIG_ARCH="risc-v"
 CONFIG_ARCH_ADDRENV=y
 CONFIG_ARCH_BOARD="rv-virt"

diff --git a/drivers/serial/Kconfig-16550 b/drivers/serial/Kconfig-16550
@@ -519,4 +519,13 @@ config 16550_ADDRWIDTH
 		Default: 8
 		Note: 0 means auto detect address size (uintptr_t)
 
+config 16550_WAIT_LCR
+	bool "Wait for UART before setting LCR"
+	default n
+	---help---
+		Before setting the Line Control Register (LCR), wait until UART is
+		not busy.  This is required for Synopsys DesignWare 8250, which
+		will trigger spurious interrupts when setting the LCR without
+		waiting.  Default: n
+
 endif # 16550_UART
diff --git a/drivers/serial/uart_16550.c b/drivers/serial/uart_16550.c
@@ -630,8 +630,7 @@ static inline void u16550_serialout(FAR struct u16550_s *priv, int offset,
 #endif
 }
 
-#define CONFIG_16550_SERIAL_WAIT_LCR //// TODO: JH7110 must wait till UART is not busy before setting LCR
-#ifdef CONFIG_16550_SERIAL_WAIT_LCR
+#ifdef CONFIG_16550_WAIT_LCR
 /***************************************************************************
  * Name: u16550_wait
  *
@@ -666,7 +665,7 @@ static int u16550_wait(FAR struct u16550_s *priv)
   _err("UART timeout\n");
   return ERROR;
 }
-#endif /* CONFIG_16550_SERIAL_WAIT_LCR */
+#endif /* CONFIG_16550_WAIT_LCR */
 
 /****************************************************************************
  * Name: u16550_disableuartint
@@ -713,14 +712,14 @@ static inline void u16550_enablebreaks(FAR struct u16550_s *priv,
       lcr &= ~UART_LCR_BRK;
     }
 
-#ifdef CONFIG_16550_SERIAL_WAIT_LCR
+#ifdef CONFIG_16550_WAIT_LCR
   /* Wait till UART is not busy before setting LCR */
 
   if (u16550_wait(priv) < 0)
     {
       _err("UART wait failed\n");
     }
-#endif /* CONFIG_16550_SERIAL_WAIT_LCR */
+#endif /* CONFIG_16550_WAIT_LCR */
 
   u16550_serialout(priv, UART_LCR_OFFSET, lcr);
 }
@@ -816,15 +815,15 @@ static int u16550_setup(FAR struct uart_dev_s *dev)
       lcr |= (UART_LCR_PEN | UART_LCR_EPS);
     }
 
-#ifdef CONFIG_16550_SERIAL_WAIT_LCR
+#ifdef CONFIG_16550_WAIT_LCR
   /* Wait till UART is not busy before setting LCR */
 
   if (u16550_wait(priv) < 0)
     {
       _err("UART wait failed\n");
       return ERROR;
     }
-#endif /* CONFIG_16550_SERIAL_WAIT_LCR */
+#endif /* CONFIG_16550_WAIT_LCR */
 
   /* Enter DLAB=1 */
 
@@ -836,13 +835,15 @@ static int u16550_setup(FAR struct uart_dev_s *dev)
   u16550_serialout(priv, UART_DLM_OFFSET, div >> 8);
   u16550_serialout(priv, UART_DLL_OFFSET, div & 0xff);
 
+#ifdef CONFIG_16550_WAIT_LCR
   /* Wait till UART is not busy before setting LCR */
 
   if (u16550_wait(priv) < 0)
     {
       _err("UART wait failed\n");
       return ERROR;
     }
+#endif /* CONFIG_16550_WAIT_LCR */
 
   /* Clear DLAB */