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risc-v: implement DBCN based debug console

Use the DBCN SBI extension to implement a debug console.
Make it the default for S-mode RISC-V.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>
Heinrich Schuchardt 9 月之前
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dfe0837494
共有 2 個文件被更改,包括 24 次插入1 次删除
  1. 4 1
      drivers/serial/Kconfig
  2. 20 0
      drivers/serial/serial_sbi.c

+ 4 - 1
drivers/serial/Kconfig

@@ -218,6 +218,7 @@ config DEBUG_UART
 choice
 	prompt "Select which UART will provide the debug UART"
 	depends on DEBUG_UART
+	default DEBUG_SBI_CONSOLE if RISCV_SMODE
 	default DEBUG_UART_NS16550
 
 config DEBUG_UART_ALTERA_JTAGUART
@@ -289,11 +290,13 @@ config DEBUG_EFI_CONSOLE
 
 config DEBUG_SBI_CONSOLE
 	bool "SBI"
-	depends on SBI_V01
+	depends on RISCV_SMODE
 	help
 	  Select this to enable a debug console which calls back to SBI to
 	  output to the console. This can be useful for early debugging of
 	  U-Boot when running on top of SBI (Supervisor Binary Interface).
+	  This implementation of the debug UART is not available while in
+	  M-mode (e.g. during SPL).
 
 config DEBUG_UART_S5P
 	bool "Samsung S5P"

+ 20 - 0
drivers/serial/serial_sbi.c

@@ -3,6 +3,8 @@
 #include <debug_uart.h>
 #include <asm/sbi.h>
 
+#ifdef CONFIG_SBI_V01
+
 static inline void _debug_uart_init(void)
 {
 }
@@ -13,4 +15,22 @@ static inline void _debug_uart_putc(int c)
 		sbi_console_putchar(c);
 }
 
+#else
+
+static int sbi_dbcn_available;
+
+static inline void _debug_uart_init(void)
+{
+	if (CONFIG_IS_ENABLED(RISCV_SMODE))
+		sbi_dbcn_available = sbi_probe_extension(SBI_EXT_DBCN);
+}
+
+static inline void _debug_uart_putc(int ch)
+{
+	if (CONFIG_IS_ENABLED(RISCV_SMODE) && sbi_dbcn_available)
+		sbi_dbcn_write_byte(ch);
+}
+
+#endif
+
 DEBUG_UART_FUNCS