x86: baytrail: Add option to disable the internal UART to setup_early_uart()

This patch adds a parameter to the function setup_early_uart() to either
enable or disable the internal BayTrail legacy UART. Since the name
setup_early_uart() does not match its functionality any more, lets
rename it to setup_internal_uart() as well in this patch.

Signed-off-by: Stefan Roese <sr@denx.de>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

arch/x86/cpu/baytrail/early_uart.c

@@ -59,11 +59,15 @@ static void x86_pci_write_config32(int dev, unsigned int where, u32 value)
 }
 
 /* This can be called after memory-mapped PCI is working */
-int setup_early_uart(void)
+int setup_internal_uart(int enable)
 {
-	/* Enable the legacy UART hardware. */
+	/* Enable or disable the legacy UART hardware */
 	x86_pci_write_config32(PCI_DEV_CONFIG(0, LPC_DEV, LPC_FUNC), UART_CONT,
-			       1);
+			       enable);
+
+	/* All done for the disable part, so just return */
+	if (!enable)
+		return 0;
 
 	/*
 	 * Set up the pads to the UART function. This allows the signals to

arch/x86/include/asm/u-boot-x86.h

@@ -45,7 +45,7 @@ void dram_init_banksize(void);
 int default_print_cpuinfo(void);
 
 /* Set up a UART which can be used with printch(), printhex8(), etc. */
-int setup_early_uart(void);
+int setup_internal_uart(int enable);
 
 void setup_pcat_compatibility(void);
 

arch/x86/lib/fsp/fsp_support.c

@@ -111,7 +111,7 @@ void fsp_init(u32 stack_top, u32 boot_mode, void *nvs_buf)
 #endif
 
 #ifdef CONFIG_DEBUG_UART
-	setup_early_uart();
+	setup_internal_uart(1);
 #endif
 
 	fsp_hdr = find_fsp_header();

doc/README.x86

@@ -706,7 +706,7 @@ the board, then you can use post_code() calls from C or assembler to monitor
 boot progress. This can be good for debugging.
 
 If not, you can try to get serial working as early as possible. The early
-debug serial port may be useful here. See setup_early_uart() for an example.
+debug serial port may be useful here. See setup_internal_uart() for an example.
 
 During the U-Boot porting, one of the important steps is to write correct PIRQ
 routing information in the board device tree. Without it, device drivers in the