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MIPS: ralink: Add tty detection 

MT7688 has several uarts that can be used for console. There are several
boards in the wild, that use ttyS1 or ttyS2. This patch applies a simply
autodetection routine to figure out which ttyS the bootloader used as
console. The uarts come up in 6 bit mode by default. The bootloader will
have set 8 bit mode on the console. Find that 8bit tty and use it.

Signed-off-by: John Crispin <blogic@openwrt.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/11459/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
John Crispin 2015-11-05 03:59:58 +01:00 committed by Ralf Baechle
parent b361bd762e
commit 73afa6c420
1 changed files with 26 additions and 0 deletions
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26
arch/mips/ralink/early_printk.c
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@ -25,11 +25,13 @@
#define MT7628_CHIP_NAME1 0x20203832
#define UART_REG_TX 0x04
#define UART_REG_LCR 0x0c
#define UART_REG_LSR 0x14
#define UART_REG_LSR_RT2880 0x1c
static __iomem void *uart_membase = (__iomem void *) KSEG1ADDR(EARLY_UART_BASE);
static __iomem void *chipid_membase = (__iomem void *) KSEG1ADDR(CHIPID_BASE);
static int init_complete;
static inline void uart_w32(u32 val, unsigned reg)
{
@ -47,8 +49,32 @@ static inline int soc_is_mt7628(void)
(__raw_readl(chipid_membase) == MT7628_CHIP_NAME1);
}
static void find_uart_base(void)
{
int i;
if (!soc_is_mt7628())
return;
for (i = 0; i < 3; i++) {
u32 reg = uart_r32(UART_REG_LCR + (0x100 * i));
if (!reg)
continue;
uart_membase = (__iomem void *) KSEG1ADDR(EARLY_UART_BASE +
(0x100 * i));
break;
}
}
void prom_putchar(unsigned char ch)
{
if (!init_complete) {
find_uart_base();
init_complete = 1;
}
if (IS_ENABLED(CONFIG_SOC_MT7621) || soc_is_mt7628()) {
uart_w32(ch, UART_TX);
while ((uart_r32(UART_REG_LSR) & UART_LSR_THRE) == 0)