MIPS: Loongson1B: Improve early printk

- Determine serial port for early printk according to kernel command line.
  - Move to 8250/16550 serial early printk driver.

Signed-off-by: Kelvin Cheung <keguang.zhang@gmail.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/8023/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

2 files changed, 14 insertions, 17 deletions

diff --git a/arch/mips/loongson1/Kconfig b/arch/mips/loongson1/Kconfig
index e23c25d09963..4ed9744fe051 100644
--- a/arch/mips/loongson1/Kconfig
+++ b/arch/mips/loongson1/Kconfig
@@ -16,6 +16,7 @@ config LOONGSON1_LS1B
         select SYS_SUPPORTS_HIGHMEM
         select SYS_SUPPORTS_MIPS16
         select SYS_HAS_EARLY_PRINTK
+        select USE_GENERIC_EARLY_PRINTK_8250
         select COMMON_CLK
 
 endchoice
diff --git a/arch/mips/loongson1/common/prom.c b/arch/mips/loongson1/common/prom.c
index 2a47af5a55c3..68600980ea49 100644
--- a/arch/mips/loongson1/common/prom.c
+++ b/arch/mips/loongson1/common/prom.c
@@ -27,7 +27,7 @@ char *prom_getenv(char *envname)
         i = strlen(envname);
 
         while (*env) {
-                if (strncmp(envname, *env, i) == 0 && *(*env+i) == '=')
+                if (strncmp(envname, *env, i) == 0 && *(*env + i) == '=')
                         return *env + i + 1;
                 env++;
         }
@@ -49,7 +49,7 @@ void __init prom_init_cmdline(void)
         for (i = 1; i < prom_argc; i++) {
                 strcpy(c, prom_argv[i]);
                 c += strlen(prom_argv[i]);
-                if (i < prom_argc-1)
+                if (i < prom_argc - 1)
                         *c++ = ' ';
         }
         *c = 0;
@@ -57,6 +57,7 @@ void __init prom_init_cmdline(void)
 
 void __init prom_init(void)
 {
+        void __iomem *uart_base;
         prom_argc = fw_arg0;
         prom_argv = (char **)fw_arg1;
         prom_envp = (char **)fw_arg2;
@@ -65,23 +66,18 @@ void __init prom_init(void)
 
         memsize = env_or_default("memsize", DEFAULT_MEMSIZE);
         highmemsize = env_or_default("highmemsize", 0x0);
-}
 
-void __init prom_free_prom_memory(void)
-{
+        if (strstr(arcs_cmdline, "console=ttyS3"))
+                uart_base = ioremap_nocache(LS1X_UART3_BASE, 0x0f);
+        else if (strstr(arcs_cmdline, "console=ttyS2"))
+                uart_base = ioremap_nocache(LS1X_UART2_BASE, 0x0f);
+        else if (strstr(arcs_cmdline, "console=ttyS1"))
+                uart_base = ioremap_nocache(LS1X_UART1_BASE, 0x0f);
+        else
+                uart_base = ioremap_nocache(LS1X_UART0_BASE, 0x0f);
+        setup_8250_early_printk_port((unsigned long)uart_base, 0, 0);
 }
 
-#define PORT(offset)    (u8 *)(KSEG1ADDR(LS1X_UART0_BASE + offset))
-
-void prom_putchar(char c)
+void __init prom_free_prom_memory(void)
 {
-        int timeout;
-
-        timeout = 1024;
-
-        while (((readb(PORT(UART_LSR)) & UART_LSR_THRE) == 0)
-                        && (timeout-- > 0))
-                ;
-
-        writeb(c, PORT(UART_TX));
 }